Beneficial use of Savannah River dredged material in brick making: explorative study, draft final report [June 2010]

School of Civil and Environmental Engineering
Structural Engineering, Mechanics and Materials Research Report No. 2010-3
Beneficial Use of Savannah River Dredged Material in Brick Making: Explorative Study
Final Report
Prepared for Office of Materials and Research Georgia Department of Transportation GDOT Research Project No. 08-02
Task Order No. 02-56
by A. Mezencevova, K.E. Kurtis, B. W. Riall,
S.E. Burns, L.F. Kahn
June 2010

Contract Research Task Order No.02-56 GDOT Research Project No.08-02
Beneficial Use of Savannah River Dredged Material in Brick Making: Explorative Study
Final Report
Submitted to Office of Materials and Research Georgia Department of Transportation
Prepared by Andrea Mezencevova, Kimberly E. Kurtis, B. William Riall,
Susan E. Burns, and Lawrence F. Kahn School of Civil & Environmental Engineering
Georgia Institute of Technology Atlanta, Georgia 30332-0355
June 2010
The contents of the report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Georgia Department of Transportation. This report does not constitute a standard, specification, or
regulation.
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TABLE OF CONTENTS

CHAPTER 1: INTRODUCTION

1

1.1 Background and Need for Research

1

1.2 Objectives and Tasks

2

1.3 Scope

3

1.4 Report Organization

3

CHAPTER 2: EXPERIMENTAL DETAILS

4

2.1 Sampling (Task 1)

4

2.2 Raw Material Characterization (Task 2)

5

2.2.1 Physical Analysis

5

2.2.2 Chemical Analysis

6

2.3 Laboratory Scale Brick Production (Task 3)

6

2.3.1. Mixing and Extruding

7

2.3.2 Drying Process

7

2.3.3 Firing Process

8

2.4 Brick Testing (Task 4)

9

CHAPTER 3: RESULTS AND DISCUSSION

12

3.1 Raw Material Characterization

12

3.1.1 Physical Analysis

12

3.1.2 Chemical Analysis

15

3.1.3 Contaminants

18

3.2 Laboratory Scale Brick Production

20

3.2.1. Bricks Made of 100% Clay/Silt Dredged Material

21

3.2.2 Bricks Made of 80% Clay/Silt and 20% Sand Dredged Material

23

3.2.3. Physical Appearance of Bricks

24

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3.3 Brick Testing

29

3.3.1 Physical and Technological Properties

29

3.3.1.1 Dimensional Changes

29

3.3.1.2 Water Absorption, Porosity, Bulk Density

33

3.3.1.3 Compressive Strength

36

3.3.2 Micro-Structural Analysis

39

CHAPTER 4: ECONOMIC ANALYSIS

41

4.1. Overview

41

4.2 The Material

42

4.3 Brick Manufacturing

44

4.3.1 Option 1: Transport to Existing Brick Maker

44

4.3.2 Option 2: Constructing and Operating On Site Brick Plant

47

4.4 Conclusions

52

CHAPTER 5: CONCLUSIONS AND RECOMENDATIONS

54

5.1 Conclusions

54

5.2 Recommendations for Further Research and Production

56

APPENDIX

59

REFERENCES

63

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EXECUTIVE SUMMARY
Dredged sediment is a particularly difficult challenge for disposal throughout the world. In Georgia, 6.3 million cubic yards of sediments, which are dredged annually from the Savannah Harbor (Savannah, GA, USA), are currently being stored within seven disposal sites adjacent to the harbor, confined by 42 miles of dikes. This accumulation rate necessitates periodic raising of the dikes, and the high cost of dike maintenance and disposal of these sediments is a primary driver for identifying productive reuse applications for this dredged material. Given the composition of the sediment, it has been investigated as a suitable component for the raw materials in brick manufacture.
The purpose of this research was to assess the viability of producing fired bricks from materials dredged from the Savannah River. The objectives of this project were to conduct the technical, economic, and environmental feasibility assessments of using the dredged material in manufacturing brick. The following project tasks were performed: a) the physical and chemical characterization of the dredged material was performed, b) suitable processing operations in bench-scale brick production, including mixing, deairing, extruding, drying, firing and cooling processes were developed, c) the physical, chemical and technological properties of the produced bricks were assessed, d) an economic assessment and evaluation of the critical economic factors in using dredged material a raw material for brick making was conducted, and e) the appropriateness of the materials and the feasibility of brick production based upon the research performed was assessed.
Physical and chemical characteristics of dredged sediments from the Savannah Harbor showed no anomalies that would necessarily preclude their beneficial reuse in fired brick. Development and processing of the materials, including extrusion and firing, have been performed in a controlled laboratory setting. Brick samples were prepared in bench-scale conditions from a raw mix consisted of 100% dredged material (80% clay/silt and 20% sand) blended with only a minimal amount of other additives, such as soybean oil to improve the mix lubricity, and BaCO3 to prevent scum formation. Extruded bricks were fired at different temperatures between 600 and 1100C. Physical and mechanical properties of the bricks were found to generally comply with ASTM C 62
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criteria for building brick. Water absorption was in compliance with the criteria for SW grade brick. Average compressive strength of bricks prepared from several various mixes and fired at different temperatures ranged from 1490 to 1700 psi, thus meeting requirements for the lowest grade (NW) building brick. Bulk densities ranged from 1.7 to 1.8 g/cm3 and were comparable with the bulk densities of regular clay brick. Results of this study demonstrate that production of fired bricks is a promising and achievable productive reuse alternative for Savannah Harbor dredged sediments.
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ACKNOWLEDGEMENTS The research presented in this report was sponsored by the Georgia Department
of Transportation under Georgia DOT Task Order No. 02-56, Research Project No. 08-02. During the course of this research project, the research team at Georgia Tech received valuable support and guidance from Georgia DOT professionals including John Phillips and David Griffin (Waterways Program Managers, Office of Intermodal Programs, GDOT). Their support and guidance are gratefully acknowledged. Important data and valuable guidance were also received from the Boral Brick Company. The opinions and conclusions expressed herein are those of the authors and do not represent the opinions, conclusions, policies, standards or specifications of the Georgia Department of Transportation or of the other sponsoring and cooperating organizations.
The following students helped in the experimental investigation: Nortey Yeboah, Alex Crotty and Odalys Sandra Reyes.
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LIST OF TABLES
Table 3-1 Particle size distribution, plasticity analysis and specific gravity of clay/silt material collected from 12B, 13A, and 13B, and used for making bricks. The data are compared with brick clay material from a brick manufacturing facility located in Smyrna, Georgia................................................................................................14 Table 3-2 Oxide analysis and loss of ignition (LOI) of the dredged material collected at CDF 12B..............................................................................................16 Table 3-3 Soluble cations and anions analysis of the dredged material collected at CDF 12B ...................................................................................................17 Table 3-4 Metal contents, pH and total organic carbon (Buxton et al, 2000) of Savannah dredged material used for brick production compared with the regulatory limits on heavy metals in sewage sludges applied to agricultural land (U.S. EPA, 2010)....................19 Table 3-5 Composition of the raw mixtures and firing conditions...........................20 Table 3-6 Linear drying shrinkage (LDS), linear firing shrinkage (LS) and loss on ignition (LOI) of the bricks........................................................................29 Table 3-7 Water absorption properties, porosity and density of fired bricks................34 Table 3-8 ASTM Specifications for brick water absorption properties......................35 Table 3-9 Compressive strength of Savannah Harbor bricks.................................37 Table 3-10 ASTM specifications for compressive strength of bricks........................37 Table 4-1 Areas potentially mined for brick-making material.................................42 Table 4-2 Timing and quantities (cubic yards) deposited by area............................43 Table 4-3 Approximate material available for brick-making (cubic yards).................44 Table 4-4 Hypothetical harvesting regime.......................................................45 Table 4-5 Potential use of dredged material in existing brick plants..........................47 Table 4-6 Harvesting operations assumptions...................................................48 Table 4-7 Harvesting scenario.....................................................................48 Table 4-8 Dredged material conversions.........................................................49 Table 4-9 Initial investment costs for hypothetical brick factory.............................50 Table 4-10 Average annual brick plant operations..............................................51
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LIST OF FIGURES
Figure 2-1 Savannah Harbor Federal Navigation Project upland confined disposal facilities (CDFs). Areas currently known as 12B and 13A (labeled with red dots) are scheduled to be recombined into 13A (inset) in 2010...........................................5
Figure 2-2 Typical temperature profile used for drying brick samples. Bricks were kept in closed plastic box up to ~45 C, in half open plastic box up to ~70 C and in open air up to 110 C...............................................................................................8
Figure 2-3 Temperature profile used for firing brick samples. The peak temperature varied from 600 to 1100 C for the Thermolyne furnace and from 900 to 1000 C for the Nabertherm furnace..................................................................................9
Figure 3-1 Moisture content profile at CDF 12A...............................................13
Figure 3-2 Particle size distribution curves of clay/silt dredged material collected at CDFs 12B, 13A and 13B and sand dredged material collected at CDF 12A compared with psd profile of brick clay obtained from a brick manufacturing facility located in Smyrna, Georgia................................................................................................15
Figure 3-3 XRD pattern of the dredged material................................................18
Figure 3-4 Extruding of a brick mix containing 100% clay/silt material and 48% water...................................................................................................21
Figure 3-5 Drying and firing shrinkage cracks observed in brick samples made out of 100% clay/silt material and A) 48% B) 45% water.............................................22
Figure 3-6 Bricks prepared from mix containing 80% clay/silt and 20% sand material, 0.1% soybean oil and 0.5% BaCO3 with different moisture contents (MC). A) dried at 110 C, B) fired at 950 C.........................................................................24
Figure 3-7 Effect of firing temperature on the color of brick. Mix composition: 80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil..............................................25
Figure 3-8 Effect of the firing rate on the formation of firing shrinkage cracks: A) faster firing rate (Thermolyne furnace), B) slower firing rate (Nabertherm furnace). Mix composition: 80% clay/, 20% sand, 0.1% soybean oil, 0.5% BaCO3, 32% water...................................................................................................26
Figure 3-9 Effect of the firing program on the formation of black core: A) faster heating rate, B) slower heating rate. Mix composition: 80% clay/silt, 20% sand, soybean oil, BaCO3 (brick (B) only). Firing temperature: 950 C............................................27
Figure 3-10 Effect of BaCO3 addition in the raw mix on scum formation. Mix composition: 80% clay/silt, 20% sand, soybean oil A) 0% BaCO3, B) 0.5% BaCO3................................................................................................28
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Figure 3-11 Linear drying shrinkage (LDS) of brick samples. According to (BIA, 2006), drying shrinkage for different clays usually falls within 2-4 %.........................................30 Figure 3-12 Linear firing (total) shrinkage of brick samples. According to (BIA, 2006), firing shrinkage of a good quality brick usually falls below 8 %......................................32 Figure 3-13 Loss on ignition (LOI) of fired brick samples. According to (AASHTO, 1982) LOI of a good quality brick is usually below 15 %.................................................33 Figure 3-14 24 h absorption in cold water and 5 h absorption in boiling water of fired brick samples........................................................................................35 Figure 3-15 Effect of mix composition and firing temperature on compressive strength of bricks..................................................................................................38 Figure 3-16 XRD patterns of the dredged material and fired bricks. Mix composition: 80%, 15% sand, 5% kaolin, 0.2% soybean oil, 33% water....................................40
APPENDIX A1 Grain size distribution and plasticity characteristics of dredged material from CDF 13A....................................................................................................58 A2 Grain size distribution and plasticity characteristics of dredged material from CDF 13B....................................................................................................59 A3 Grain size distribution and plasticity characteristics of dredged material from CDF 12B....................................................................................................60 A4 Summary of bulk chemistries of the dredged material collected at each CDF (Buxton et al, 2000)...........................................................................................61
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CHAPTER 1: INTRODUCTION
1.1 Background and Need for Research The Savannah Harbor, located on the South Atlantic U.S. coast, comprises the
lower 21.3 miles of the Savannah River and 11.4 miles of channel across the bar to the Atlantic Ocean. The Georgia Department of Transportation (GDOT) Waterways Program partners with the U.S. Army Corps of Engineers to maintain the navigability of the Savannah River by dredging the inner harbor and bar channel. Dredged materials are accumulated at a rate of approximately 8 million cubic yards of solids each year, with 6.3 million cubic yards of those materials placed in several upland disposal areas in Jasper County, South Carolina, managed by GDOT and the Corps (Phillips, 2008). The confined disposal facilities (CDFs) are located adjacent to the harbor on the South Carolina side of the Savannah River. Costs for the dredging operation are divided between the two agencies, with the Army Corps funding dredging operations at a rate of approximately $15 M/yr. and GDOT providing approximately $4.2 M/yr. to match other Corps funds to raise and manage the dikes where the sediment is placed and to pay property tax on the land. Such high maintenance costs, combined with proposed land use changes around and in Jasper County, stemming from South Carolina's interest in establishing a port in that region, have become the primary drivers for identifying productive reuse applications for the dredged sediments.
Beneficial uses of dredged material have been discussed in many forums, from aquatic, island, beach renourishment, wetland, and upland habitat to strip-mine reclamation and construction in industrial/commercial uses (Lee, 2000). Due to natural variations of dredged sediments in different locations across the globe, criteria for their beneficial use are generally implemented on a site specific basis (Olin-Estes and Palermo, 2001). Given the composition of the sediment and its continuous availability, it is likely that this material may be suitable as a major component for manufacturing of bricks. Using the dredged material for bricks will reduce the volume of sediments to be disposed of on land and, at the same time, conserve natural resources.
Although the lack of established contaminant level and testing requirements for productive reuse of dredged sediments may complicate their beneficial use for brick making, there are many examples of successful productive reuse of these sediments
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world-wide from which much can be learned. In recent decades brick making has been assessed using river and marine sediments (Casado-Martinez, 2006; Lafhaj et al, 2007; Romero et al, 2008; Hamer and Karius, 2002; Karpuzcu et al, 1996), sediments from dams (Huang et al., 2001) and sewages (Liew et al, 2004). The U.S. Army Corps of Engineers also recognized dredged material as a potential beneficial raw material in brick production (Winfield and Lee, 1999). Many studies show that river and marine sediments can be used as natural clay replacement in manufacturing of bricks that comply with construction standards and legislative environmental requirements (Hamer and Karius, 2002; Samara et al, 2009). In Germany, an industrial-scale experiment conducted to manufacture bricks with 50 % wt. of sediments dredged out of the harbor basin of Bremen showed a promising alternative within the concept of harbor sediment management. During the sintering process, organic matter present in dredged material is oxidized and most metal contaminants are converted to stable compounds immobilized in the brick matrix or volatilized (Karius and Hamer, 2001).
1.2 Objectives and Tasks The objective of this research was to assess the feasibility of the production of
brick from materials dredged from the Savannah River in laboratory conditions. In most of the previously reported studies, dredged material has been used in bricks as a partial replacement for clay and sand. In this study, a possibility of making bricks using Savannah Harbor dredged sediments as the primary material was investigated.
The tasks which comprised research included the following: 1. the sampling of materials, obtained from dredging the Savannah River, from various disposal areas constructed and maintained by the Georgia Department of Transportation and the U.S. Army Corps of Engineers, 2. the physical and chemical characterization of the dredged material, 3. the optimization of suitable processing operations in bench-scale brick production, including mixing, de-airing, extruding, drying, firing and cooling processes, 4. the testing and assessment of physical, chemical and technological properties of the bricks produced,
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5. an economic analysis of bricks produced in this manner, and 6. an assessment of the appropriateness of the materials and the feasibility of brick
production, based upon the research performed.
1.3 Scope This research included the fabrication of laboratory-size green bricks produced by a
bench-scale extrusion method. These bricks were produced with formulations containing clay/silt and sand dredged material obtained from Savannah Harbor disposal facilities and blended with a minimal amount of additional materials, such as soybean oil and barium carbonate. Firing was conducted in laboratory muffle furnaces using various heating programs. Technological and mechanical properties of the bricks were tested and their compliance with current standards was determined. An economic analysis was performed to assess the feasibility of producing bricks in this manner.
1.4 Report Organization This report is presented in five chapters, including an introduction (Chapter 1).
Chapter 1 provides background and need for research, and asserts the purpose and main objectives of the research. Chapter 2 summarizes experimental details for tasks 1-4, and Chapter 3 discusses the experiments and outcomes of these tasks. Economic analysis which was to provide a rough measure of the net costs of diverting a portion of the dredged material to brick-making is included in Chapter 4. Finally, Chapter 5 provides the conclusions and recommendations for further research and application of the materials dredged from Savannah Harbor in brick production.
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CHAPTER 2: EXPERIMENTAL DETAILS
This chapter provides details on the experimental components of Tasks 1 through 4, which include the sampling of materials, their physical and chemical characterization, bench-scale brick production, and the testing and assessment of physical, chemical and technological properties of the produced bricks.
2.1 Sampling (Task 1) Samples of the dredged material were collected from the Savannah Harbor
Federal Navigation Project upland confined disposal facilities (CDFs) located in Jasper County, South Carolina. The locations of the CDFs are shown on Fig. 2-1. For material characterization testing, grab samples of the sediment were obtained from each CDF which were divided into three sub areas. Five samples were collected from each sub area and combined to form one composite sample for each of the sub areas. Samples for laboratory characterization were obtained from CDFs 12B and 13A by the U.S. Army Corps of Engineers in November 2008. Clay/silt material used for bench scale production of bricks as well as for additional testing was collected in bucket-size samples from sites 12B (south side), 13A (north side) and 13B (east side) in March 2009. More clay/silt material for brick production was collected from CDF 12B in January 2010. Sand material was obtained from CDF 12A, directly in front of the dredge discharge head location in March 2009.
A sample of brick clay (unfired) was obtained from a storage silo at a brick manufacturing facility located in Smyrna, Georgia. This brick clay was used as a reference in physical characterization testing.
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Figure 2-1 Savannah Harbor Federal Navigation Project upland confined disposal facilities (CDFs). Areas currently known as 12B and 13A (labeled with red dots) are scheduled to be recombined into 13A (inset) in 2010.
2.2 Raw Material Characterization (Task 2) An issue critical in the productive reuse of dredged sediments is characterization
of the physical properties and chemical composition of the materials. First, a thorough review was made of historical characterization data currently existing in the files of the Georgia Department of Transportation and the US Army Corps of Engineers in order to avoid duplication of effort. These data were obtained from a sediment assessment report prepared by General Engineering Laboratories, Inc. for the Savannah Harbor Federal Navigation Project Upland Disposal Facilities (Buxton et al, 2000). Gaps in data and knowledge were identified and additional sampling and characterization was performed to supplement the existing data.
2.2.1 Physical Analysis The physical analyses of the raw material included determination of water
content, particle size characterization, plasticity and specific gravity evaluation. Water content was determined by drying of the samples in an oven at 110 C to a constant mass in accordance with ASTM D 2216-05. Grain size distribution testing was
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conducted by dry sieving and hydrometer analysis in accordance with ASTM D 422. Plasticity analysis was performed using the British Standard BS 337 for the liquid limit (LL) and ASTM D 4318 for the plastic limit (PL). It should be noted that for LL and PL results the samples were not sieved over a #40 mesh prior to testing, as recommended by the respective standards. Thus the LL and PL results represent the bulk sample. Specific gravity tests were conducted in agreement with ASTM D 854. The dredged material was dried at 110 C prior to the analysis.
2.2.2 Chemical Analysis Chemical analysis was performed to measure major, minor, and trace elements,
total organic carbon (TOC), pH, as well as identification of major crystalline phases in the samples obtained.
Oxide analysis of the dredged material was determined by X-ray fluorescence method. Crystalline minerals present in the dredged material were identified by X-ray diffraction analysis. The concentration of total organic carbon was determined using USEPA Method 9060. These analyses were done on the as received material.
Metal content was determined using inductively coupled plasma (ICP) spectroscopy (USEPA Method 6010A/3050); mercury was analyzed by cold vapor atomic absorption spectrometry (USEPA Method 7471). The soil samples were digested as prescribed in the methods and their filtrates were used for analysis. The pH was measured on dredge-water slurries using electrode analysis in accordance with USEPA Method 9045C.
2.3 Laboratory Scale Brick Production (Task 3) The goal of this task was to identify appropriate materials, mix proportions, and
processing methods for laboratory production of brick using Savannah River dredged material as the primary constituent. Based upon the results of the material characterization performed, the need for pre-treatment of the dredged materials was evaluated. To gain insight into the brick-making process, the team members visited a regional brick plant (Boral Brick, Smyrna GA).
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2.3.1. Mixing and Extruding The raw mix consisted of the clay/silt material and sand dredged material sampled
from the Savannah Harbor disposal facilities, and water. A first attempt to mix and extrude bricks from the dredged material was made using only the clay/silt material. Upon the results obtained from this extrusion, sand material obtained from the site was used in later extrusions to reduce water demand in the mix and achieve better compaction; reduced water was expected to minimize cracking during drying.
The dredged materials were blended with only a minimal amount of other additives. For example, soybean oil was to improve the lubricity of the mix, and barium carbonate (BaCO3) to prevent scum formation. Also, a small amount of kaolin obtained from the Sandersville, Georgia kaolin district was used in one raw mix as a partial replacement for the clay/silt material.
Before mixing, the dredged material was dried at ~100 C, crushed and ground, and passed through a 10 mesh (2mm) sieve. The pre-treated material was mixed with water and other additives and processed in a pug mill (Peter Pugger VPM-30) to produce a homogeneous mix. The mix was then de-aired using a vacuum of 28-29 in. (710-740 mm) Hg and extruded. Extruded wet brick columns were cut into smaller brick blocks (5.45.4 cm in cross section) or cylinders (7.5 cm in diameter) and submitted to drying and firing.
2.3.2 Drying Process To avoid or minimize formation of drying shrinkage cracks, extruded bricks were
slowly dried for several days after extrusion. The drying process started with slow heating to encourage diffusion of moisture toward the surface combined with high humidity (bricks were kept in a closed plastic box) to suppress evaporation of moisture from the surface. As drying progressed, the temperature was gradually raised and the humidity gradually lowered with the final stage of drying done at low humidity and at about 110 C until the constant weight (Figure 2-2) was achieved.
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120

until

constatnt

100

weight

Temperature (oC)

80

60

40

20

0

0

2

4

6

8

10

Time (days)

Figure 2-2 Typical temperature profile used for drying brick samples. Bricks were kept in closed plastic box up to ~45 C, in half open plastic box up to ~70 C and in open air up to 110 C

2.3.3 Firing Process Firing of dried brick samples was conducted in two laboratory muffle furnaces
(Thermolyne FA1740-1 and Nabertherm N17 HR) with variations in heating rate, peak firing temperature and hold duration at the peak temperature to determine an optimal firing method. Figure 2-3 shows the heating profiles used for firing bricks. The heating rate of the Thermolyne furnace was faster; it was the inherent heating rate of the furnace and could not be modified. The Nabertherm furnace was programmable, allowing for better control of the heating rate during the firing process; bricks were fired more slowly in this furnace. Brick samples were fired to different temperatures ranging from 600 C to 1100 C. Cooling was slow and occurred by natural convection inside the furnaces after they were turned off.

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Figure 2-3 Temperature profile used for firing brick samples. The peak temperature varied from 600 to 1100 C for the Thermolyne furnace and from 900 to 1000 C for the Nabertherm furnace
2.4 Brick Testing (Task 4) The bench-scale bricks were analyzed for their color, physical appearance, and
the engineering properties (including water absorption and compressive strength). Bricks were sampled and tested in accordance with ASTM C67 and ASTM C 373, and compliance of their engineering properties with ASTM C62, C216 or C652 was determined.
Linear drying shrinkage on the dry basis (LDSd) and linear firing shrinkage (LFS) (incorporating both drying and firing shrinkage) were calculated as:
LDSd = (Lf Ld)/Ld 100 (%) LFS = (Lf LF)/LF 100 (%), where Lf is the dimension of the formed specimen, Ld is the same dimension of the dried specimen and LF is the same dimension of the fired specimen. Weight loss on ignition (LOI) was calculated by: LOI = (md mf)/md 100 (%), where md is the oven dry weight and mf is the weight of the fired specimen.
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For the water absorption test, the dry specimens were submerged in clean water at room temperature for 24 hours. After the prescribed time the saturated specimens were weighed in water and in air. The same specimens were then boiled in water for 5 hours, cooled and weighed again. Water absorption (A) was calculated by:
A = (m md)/md 100 (%) ,where m is saturated weight in air and md is the oven dry weight.
The saturation coefficient (SC), which is the ratio of 24-hour cold-water absorption to the five-hour boiling absorption was also determined:
SC = (mc md)/(mb md) where mc is saturated weight after 24-h submersion in cold water, and mb is saturated weight after 5-h submersion in boiling water.
Initial rate of water absorption (i.e. suction) is a measure of how quickly the brick will take in water from mortar spread on it. Suction was determined in accordance with ASTM C 67. Measured was the increase in the mass of a specimen resulting from absorption of water as a function of time when only one surface of the specimen was exposed to water. The exposed brick surface was immersed in water (1 to 3 mm deep) for 1 minute and then weighed. Suction (X) was determined as the gain in weight corrected to basis of 30 in2 (194 cm2) according the following equation:
X = 193.55 (m md) / a (g/min.30 in2) where a is exposed area of the specimen in cm2.
Bulk density (B) and apparent porosity (Pap) were determined from the weight measurements obtained during the water absorption test and calculated as follows:
B = md /(mb m*) (g/cm3) Pap = (mb - md)/(mb m*)100 (%) where m* is suspended mass (mass in water) of saturated brick Compressive strength was measured on laboratory bricks of approximately (554-6) cm nominal size. The brick samples were dried in an oven and capped with gypsum to assure reasonably parallel and smooth opposite bearing surfaces, as prescribed in ASTM C 67. Any depressions or larger cracks on the bearing surfaces were filled with a mortar composed of one part by weight of quick-hardening cement and two parts by weight of sand prior to capping. The bricks were then submitted to compressive strength testing using a hydraulic testing machine (SATEC, Instron). The load was applied
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uniformly with a speed of 2000 lb/min through two planar hardened steel platens. The compressive strength (C) was calculated by:
C= W/A where W is maximum load (lb) and A is average of the gross areas of the upper and lower bearing surfaces of the specimen (in.2 ).
In addition to the engineering properties, the composition of the brick specimens fired under varying conditions was evaluated by X-ray powder diffraction (XRD) using an X-ray diffractometer (Phillips PW 3050, CuK radiaton, 45 kV and 40 mA). Fine powders of brick samples were obtained from crushed brick pieces after the strength test, which were ground using mortar and pestle.
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CHAPTER 3: RESULTS AND DISCUSSION
This chapter summarizes and discusses the experiments and outcomes of Tasks 1 through 4, which included the physical and chemical characterization of the materials dredged from the Savannah Harbor, bench-scale production of bricks, and the testing and assessment of physical, chemical and technological properties of the bricks produced from the dredged sediments.
3.1 Raw Material Characterization 3.1.1 Physical Analysis
The moisture content of the dredged materials is highly variable and varies as a function of depth of burial and age of the sediments. Current Corps disposal methods for the sediments provide for drainage at the base of the sediment profile and at the surface of the ponds, creating a doubly drained interface which will yield the largest pore water pressures (lowest percent consolidation) in the center of the sediment deposits. As time progresses, the consolidation process will also progress, yielding a decrease in the water content and an increase in the solids content. Assuming that the bottom drains are functioning properly, it is anticipated that the highest water content samples will be encountered in the center of the sediment deposits.
A profile of soil moisture content is shown in Figure 3-1 which is a 3D contour map based on the results of soil tests on dredged sediment samples collected at disposal facility 12A by the Army Corps of Engineers (Buxton et al, 2000). The plot is an interpolation (Kriging) of data from 53 samples obtained at 15 boring locations around the perimeter of CDF-12A. Also, the 3D representation of CDF-12A is not to scale. The Z axis ranges from 0 to 20 ft below ground surface (bgs), which is the depth of the deepest sample. The X axis range is from 0 ft to 1,580 ft, and the Y axis range is from 0 ft to 1,250 ft. The figure shows that the water content generally increases with depth, reaching maximum water content approximately 20 ft below ground surface.
The natural water content of the sediments is of a concern in brick manufacturing, because energy consumption in the production process will be directly proportional to it.
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Figure 3-1 Moisture content profile at CDF 12A
Results of the grain size analyses of dredged sediment samples obtained from CDF 12B (south side), 13A (north side) and 13B (east side), and sand material collected at the entrance area of 12A are summarized in Table 3-1. The results provide a representative distribution of the likely grain size, plasticity, and specific gravity of the dredged sediment. These data are compared with physical characteristics of clay material for brick production obtained from a storage silo at a brick manufacturing facility located in Smyrna, Georgia. Combined particle size distribution (PSD) plot for clay/silt materials and for the sand material are presented in Figure 3-2. Individual data sets for each of the samples are also presented in an appendix at the end of this document.
Table 3-1 shows variability in clay, silt and sand composition within the samples of dredged material collected from the three disposal sites. The silt content in the dredged material ranges from 29 to 43% with the average value of 38% which is a little higher than the silt content in the brick soil (34%). Silt is considered a problematic material in brick production. The ratio of silt fraction to clay fraction within the sediment influences the quality of the final product with higher silt/clay ratios resulting in weak and porous brick. On the other hand the average clay content in the dredged material (47%) is higher
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than that in the brick soil (40%). Higher content of clay particles creates higher surface area which requires higher amount of water for the material to be plastic. The silt/clay ratios in the CDFs and brick soil material are approximately equal; the value is about 0.8 for both materials.
The average sand content in the clay/silt dredged material was 15%, which was much lower compared to the sand content in the brick making clay (26%). This is important to note, as in brick making, the coarse fraction in the clay mix is important for reducing shrinkage during firing. It is thus likely that additional sand may have to be added in the clay/silt to achieve a particle size distribution similar to that of the Smyrna, GA brick making clay. Specific gravity of the oven dried clay/silt dredged material was about 2.6 g.cm-3.
Raw materials for brick production must possess some specific properties and characteristics, e.g. plasticity that permits them to be shaped or molded. As seen in Table 3-1, Atterberg limits showed that the clay/silt sediments do in fact have some plasticity, with average plastic limit (PL) and liquid limit (LL) values of 49% and 99% respectively. These plasticity indices values are comparable with that of the brick clay sample.

Table 3-1 Particle size distribution, plasticity analysis and specific gravity of clay/silt material collected from 12B, 13A, and 13B, and used for making bricks. The data are compared with brick clay material from a brick manufacturing facility located in Smyrna, Georgia.

sand (%) silt (%) clay (%) liquid limit plastic limit plasticity index specific gravity (g.cm-3)

12B, 13A, 13B

Range

Average

8 26

15

29 43

38

32 63

47

82.6 116.3

99.2

48.1 52.1

49.5

34.5 64.2

49.7

2.55 2.66

2.61

Brick clay sample 26 34 40 98.7 51.2 47.4 -

14

Figure 3-2 Particle size distribution curves of clay/silt dredged material collected at CDFs 12B, 13A and 13B and sand collected at CDF 12A compared with psd profile of brick clay obtained from a brick manufacturing facility located in Smyrna, Georgia.
3.1.2 Chemical Analysis Chemical composition data of the Savannah Harbor clay/silt sediment expressed
as percentage of major oxides is shown in Table 3-2. Tests were performed at the National Brick Research Center (Anderson, SC). For reference, the data for dredged material from the Bremen Harbor in Germany, as well for a local clay used for brick production also in Germany (Hamer and Karius, 2002) are compared.
The data indicate that the main components in the Savannah dredged material were SiO2, Al2O3, Fe2O3, CaO, MgO and K2O. The SiO2 content is mainly associated with quartz particles, as well as Si and Al oxides can be associated with kaolinite structure present in the material. Iron oxide, Fe2O3, is the main colorant in clays and is responsible or the reddish color after firing. The dredged material also contains constituents that may act as fluxes and promote fusion of the particles at lower temperatures during the firing process, such as potassium, sodium and calcium oxides. TiO2 is also present; this constituent can be found in most clays and shales at the
15

concentration of about 1%; at this level of concentration it has little effect on products formed from them. Oxide analysis results showed no anomalies in the chemical composition of the Savannah dredged material from CDF-12B. Major constituents were comparable between all the sets of data shown.

Table 3-2 Oxide analysis and loss on ignition (LOI) of the dredged material collected at

CDF 12B

Major Constituents (%)

CDF 12B Bremen Samplea German Claya

Al2O3 SiO2 Fe2O3 CaO

17.16

11

22

52.17

63

67

8.41

8.3

6.1

1.76

1.8

0.19

MgO

1.56

0.9

0.4

K2O Na2O TiO2 MnO

1.34

1.6

2.5

0.50

1.9

0.2

0.89

nr

1.3

0.23

nr

0.01

P2O5 LOI (%)

0.24

nr

nr

15.06

10

6.3

a reported in (Hamer and Karius, 2002); "nr" = value not reported.

The amounts of soluble cations and anions are also presented in Table 3-3. Water soluble salts, mostly sulfates of calcium, magnesium, sodium and potassium, present in the dredged material are expected to be associated with the formation of a whitish scum during drying of bricks; such scum becomes permanently fixed during burning and negatively affects the aesthetical appearance of the bricks. CaSO4 is the most troublesome as it can persist through the firing operation. The other salts mentioned above melt, decompose or react with silicates during firing. However, when gaseous SO3 adsorbs on the internal silicate surfaces due to exposure to sulfurous gases during firing and cooling, sulfuric acid can be formed which will dissolve Mg, Na and K from various crystalline and glassy phases. These solutions can then migrate to the brick surface and salt deposition occurs (Brownell, 1976). In addition, soluble salts such as chlorides and sulfates present in the raw dredged material can become a source of gaseous pollutants, such as oxides of sulfur (SO2, SO3) and hydrogen chloride (HCl) (U.S. EPA, 1995).
The value of loss on ignition (LOI) is related to the dehydroxylation of the clay minerals, oxidation of the organic matter, decomposition of carbonates, sulfides,

16

hydroxides, etc. A certain amount of organic matter is desirable since it can contribute to a greater plasticity, however extensive total organic carbon content may render dredged material useless for brickmaking.

Table 3-3 Soluble cation and anion analysis of the dredged material collected at CDF 12B Cations (ppm)

Sodium

750

Potassium

240

Magnesium

220

Calcium

934

Anions (ppm)

Fluoride Chloride Bromide Nitrate Sulfate

61.2 190 4.3 44.3 2880

Mineralogical properties of the dredged material used for brick production were evaluated by XRD analysis. Figure 3-3 shows the X-ray diffraction pattern of the clay/silt material. In general, the phase composition of the dredged material is complex. The major phases found in the material included quartz and clay minerals (kaolinite, illite) that maintain the shape of the brick body during firing, and also some minerals that melt and lower temperatures such as feldspars (anorthite, albite).

17

Figure 3-3 XRD pattern of the dredged material
Productive reuse of dredged sediments can be problematic as these materials typically contain both organic and inorganic contaminants from agricultural, industrial and municipal activities (Bortone et al, 2007; Lafhaj et al, 2008; Ndiba et al, 2008; Zoubeir et al, 2007).
3.1.3 Contaminants The primary pollutants of concern in the sediments include heavy metals. The
most common problem causing cationic metals (metallic elements whose forms in soil are positively charged cations e.g., Pb2+) are mercury, cadmium, lead, nickel, copper, zinc, chromium, and manganese. The most common anionic compounds (elements whose forms in soil are combined with oxygen and are negatively charged e.g., MoO42-) are arsenic, molybdenum, selenium, and boron (USDA NRCS, 2000). The total metal concentrations and total organic carbon in the dredged material, as well as its pH values were obtained from historical data in the GDOT files (Buxton et al, 2000) and are summarized in Table 3-4 for the dredged material used for making bricks (disposal sites 12B, 13A,B). Summary of bulk chemistries of the dredged material collected at each
18

CDF is included in Appendix. In the U.S., testing criteria and acceptable contaminant levels for dredged sediments being considered for productive reuse have not been established. For reference, the regulatory limits on potentially toxic metals in sewage sludges (biosolids) applied to agricultural land set by the U.S. Environmental Protection Agency (EPA) are presented (U.S. EPA, 2010).

Table 3-4 Metal contents, pH and total organic carbon (Buxton et al, 2000) of Savannah dredged material used for brick production compared with the regulatory limits on heavy metals in sewage sludges applied to agricultural land (U.S. EPA, 2010).

CDF 12B

CDF 13A

range

AVE range

AVE

CDF 13B

range

AVE

U.S.EPA

1

2

pH

7.3-7.4

7.4 7.2-7.3

7.3

6.8-7.4

7.1

-

-

Hg

0.10-0.14

0.12 0.14-0.33

0.31

0.08-0.10

0.09

-

-

Sb

(0.20-0.21)

(0.21) (0.69-0.95)

(0.81) (0.40-0.59)

(0.47)

-

-

As

15.8-17.6

16.83 21.8-23.2

22.67 15.9-19.3

17.3

75 41

Be

1.56-1.68

1.63 1.90-2.14

2.00

1.24-1.80

1.54

-

-

Cd

(0.09-0.10)

(0.10) (0.32-0.44)

(0.38) (0.19-0.32)

(0.26)

85 39

Cr

56.7-61.0

59.4 67.6-77.2

71.33 46.1-63.7

55.5

-

-

Cu

14.7-15.1

15.2 15.9-19.1

17.30 10.9-16.3

13.97 4300 1500

Pb

21.3-22.4

21.8 24.2-28.4

25.70 15.0-22.5

19.13

840 300

Mn

1050-1150

1107 1070-1360

1187 713-1100

916

-

-

Mo

0.50-0.80

0.66 0.82-0.82

0.82

0.97-1.14

1.07

75

-

Ni

15.1-16.8

16.1 17.8-20.9

18.87 12.2-16.9

14.73

420 420

Se

1.64-2.10

1.89 1.69-2.20

1.97

1.19-1.83

1.51

100 100

Ag

(0.26-0.32)

(0.29) (0.85-1.17)

(0.99) (0.49-0.73)

(0.58)

-

-

Zn

93.7-103.0

98.2 97.2-112.0

104.1 66.8-89.4

79.3

7500 2800

Tl

(2.52-2.70)

(2.63) (8.73-11.90) (10.17) (5.06-7.43)

(5.90)

-

-

Al

23800-24600 24133 20000-31300 24800 18500-25600 22200

-

-

Fe

34800-36200 35667 25700-40000 32167 27300-34200 31267

-

-

TOC 21200-31200 24933 24100-33300 27167 20400-23500 22333

-

-

Concentrations are reported in ppm (mg/kg) on a dry weight basis
Values in parenthesis ( ) are mean detection limit values. It indicates that the component was analyzed but
not detected above the detection limit. 1 maximum concentration 2 monthly average concentrations

As Table 3-4 shows, no hazardous concentrations of heavy metals were detected in the dredged material. Moreover, an advantage for selecting fired bricks as a potential

19

productive reuse option of the dredged material is that most metal contaminants are converted to stable compounds within the brick matrix or volatilized during the firing process. Successful contaminant immobilization in fired bricks has been demonstrated for dredged sediments from Bremen, Germany (Hamer and Karius, 2002; Karius and Hamer, 2001).
Organic contaminants commonly found in dredged sediments typically include polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides, and nutrients. Although organic pollutants are volatized during the firing process, they could necessitate scrubbing of brick kiln emissions. Even so, emissions controls would already be in place at brick plants as mandated by the Clean Air Act (U.S. EPA, 1993). Thus, any necessary adjustments to emissions controls resulting from the introduction of dredged sediments into the brick making process may not be excessively taxing.

3.2 Laboratory Scale Brick Production Laboratory-size bricks were prepared from 100% dredged materials using
variations in raw mix composition and firing rates. Compositions and firing conditions of all raw mixes are summarized in Table 3-5. The clay/silt material used for the mixes 1 through 5 was obtained from CDFs 12B, 13A and 13B in March 2009, and the material for the mixes 6 through 8 was collected at from CDF 12B in January 2010. Sand was obtained from CDF 12A in March 2009.

Table 3-5 Composition of the raw mixtures and firing conditions

Clay/silt

1

100

2

80

3

80

4

80

5

80

6

80

7

80

Mix composition (% by mass)

Sand

Soybean oil1 BaCO3

-

-

-

20

-

-

15

0.2

-

20

0.4

-

20

0.1

0.5

20

0.1

0.5

20

0.1

0.5

Kaolin 5 -

Moisture 45, 48 27 33 32 32 36 46

Firing T (C)
11002 11002 600-11002 9502,3 950, 10003 950, 10003 900, 9503

8

80

20

0.1

0.5

-

38

-

1regular soybean oil in mixes 3 and 4, epoxy-soybean oil in mixes 5 through 8

2faster heating rate (Thermolyne furnace), 3slower heating rate (Nabertherm furnace) (see Fig. 2-2)

20

3.2.1. Bricks Made of 100% Clay/Silt Dredged Material Preliminary extrusions were performed using raw mixes that consisted entirely of
the clay/silt dredged material and water; no sand material or other additives were incorporated in the mixes. The extrusions run without failures and the 100% clay/silt raw mix was found to be extrudable (Fig. 3-4). However, a much higher amount of water (45 - 48%), compared to the ~19% moisture content that is normally used in extrusion processes in brick plants, was required to achieve good mixing and maintain an adequate plasticity. Attempts to lower the water content resulted in producing of a stiff mix that the laboratory extruder was not capable to extrude. However, mixing and extruding stiffer mixes may not be a problem for more powerful and more efficient large-scale extruders.
Figure 3-4 Extruding of a brick mix containing 100% clay/silt material and 48% water.
21

The presence of organic residues in the dredged material could have also contributed to the higher water demand. The organic substances in soil have a high absorptive capacity for water that is associated with their high specific surface. With a higher amount of water the brick mix expanded more, which resulted in a greater shrinkage when the water was forced out during the drying process. Cracks developed during drying caused a failure of the brick body in the firing process (Figure 3-5)
Figure 3-5 Drying and firing shrinkage cracks observed in brick samples made out of 100% clay/silt material and A) 48% B) 45% water.
22

3.2.2 Bricks Made of 80% Clay/Silt and 20% Sand Dredged Material In an effort to reduce water demand and achieve better compaction of the mix
sand was blended with the clay/silt material. This was expected to prevent cracking. Also, only a minimal amount of other additives were used in some mixes, such as soybean oil that was to improve the lubricity of the mix, and barium carbonate to prevent scum formation. A small amount of kaolin was added into one mix.
As Table 3-5 shows, incorporating sand in the raw mix resulted in reducing of the water content that was required to achieve good plasticity and workability of the mix. The minimal water content that we were able to achieve was 27%. This water content was still higher than the ~19% moisture content that is normally used in the extrusion process in brick plants. As predicted, reduced water content and better compaction of the raw mix due to sand addition along with the careful drying process resulted in minimizing the formation of drying shrinkage cracks. Depending on the moisture content brick samples showed no cracks or only minor cracks after the drying step, which later resulted in more successful firing. Unlike the bricks that consisted of 100% clay/silt, the bricks with sand material additions did not break apart during firing, and they maintained their shape (Figure 3-6).
23

Figure 3-6 Bricks prepared from mix containing 80% clay/silt and 20% sand material, 0.1% soybean oil and 0.5% BaCO3 with different moisture contents (MC). A) dried at 110 C, B) fired at 950 C
3.2.3. Physical Appearance of Bricks Aesthetically, with a relatively uniform red color, the bricks produced from the
dredged material were attractive. The tone changed and became darker with rising firing temperature (Figure 3-7). Bricks fired at low temperature (600 C) were light orange with a gray tint probably due to some unburnt organic matter. Also, the bricks produced a high-pitched clinking sound when struck together. The group had a chance to show some dredged bricks to members of ASTM committee C15 during an ASTM meeting in Atlanta in December 2009. They stated that the clinking sound was a good sign.
24

Figure 3-7 Effect of firing temperature on the color of brick. Mix composition: 80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil
Apart from the mix composition, the physical appearance of the bricks depended mostly on the moisture content of the raw mix and firing conditions. The effect of moisture content on formation of shrinkage cracks is shown in Figure 3-6 (Section 3.2.1). The figure compares bricks prepared from raw mixes of the same composition differing only in their moisture content. Bricks with higher water content were found to be more susceptible to cracking during firing. Shrinkage cracks started forming in the bricks with higher MC despite the very careful drying process; no drying shrinkage cracks were observed in samples with lower MC.
The development of cracks could also be controlled by modification of the firing profile. As shown on Figure 3-8, lowering the firing rate and keeping brick samples at the peak temperature for a longer period resulted in fewer cracks.
25

Figure 3-8 Effect of the firing rate on the formation of firing shrinkage cracks: A) faster firing rate (Thermolyne furnace), B) slower firing rate (Nabertherm furnace). Mix composition: 80% clay, 20% sand, 0.1% soybean oil, 0.5% BaCO3, 32% water.
The slower firing rate also prevented the formation of a black core. Figure 3-9 compares brick samples prepared from batches of similar composition and fired at 950 C using different heating programs. As Fig. 3-9A shows, a dark area of a steely appearance, sharply delineated from surrounding normal red color (ferric oxide) of the brick, was observed only in the brick that was fired more quickly and held at the peak temperature for a shorter time. This area, known as black heart or black core, is the result of incomplete oxidation of carbonaceous matter in the raw materials, and is caused by iron being held in the reduced (ferrous) state (Brownell, 1976;Sheppard, 1986). This reduced
26

state is caused by carbon impregnating the microstructure as carbon monoxide (CO). When the carbonaceous matter begins to oxidize, the change begins from the surface and works towards the center of the brick. Due to the shrinkage of the clay the body may become too dense to allow oxygen to enter, and there consequently remains a black or bluish clack core of ferrous iron, probably in the form of magnetite Fe3O4 (black iron oxide), wustite FeO or a complex ferrous silicate.
Figure 3-9 Effect of the firing program on the formation of black core: A) faster heating rate, B) slower heating rate. Mix composition: 80% clay/silt, 20% sand, soybean oil, BaCO3 (brick (B) only). Firing temperature: 950 C.
The observed black core probably results from fast firing in the temperature range of 400 - 850 C, in which the organic matter decomposes, and/or from insufficient oxygen inside the furnace forming a reducing atmosphere. The carbonaceous impurity has not been burnt before vitrification begun, and was retained by the vitreous outer skin.
Debate has existed in the past as to the effect of black coring on physical properties. ASTM C 1176 includes a statement in its test description mentioning that black coring shall not be cause for rejection of a clay product if it meets the physical criteria of the specification.
Scum formation. An insoluble white stain was found on the surfaces of some fired bricks. Water soluble salts (mostly calcium and magnesium sulfates) that are present in
27

the dredged material can be deposited on the surface of the brick during drying in the form of a whitish scum, and such scum becomes permanently fixed during burning (Brownell, 1976). When the salts are present in small amounts, the scumming can be controlled by adding barium carbonate BaCO3 into the raw mix. BaCO3 immobilizes the water soluble sulfates by converting them into insoluble carbonates that remain distributed throughout the mass of the brick instead of being deposited on the surface. Bricks prepared from mixes with and without BaCO3 and fired at 950 C are presented in Figure 3-10. A slight white scum was observed on both dried and fired bricks made out of the mix without BaCO3, while the surface of the bricks containing BaCO3 did not show any presence of such scum.
Figure 3-10 Effect of BaCO3 addition in the raw mix on scum formation. Mix composition: 80% clay/silt, 20% sand, soybean oil A) 0% BaCO3, B) 0.5% BaCO3
28

3.3 Brick Testing The bench-scale bricks were sampled and tested in accordance with ASTM C67
and ASTM C 373, and compliance of their engineering properties with ASTM C62, C216 or C652 was determined.

3.3.1 Physical and Technological Properties 3.3.1.1 Dimensional Changes
Dimensional changes of the bricks are summarized in Table 3-6 and Figures 3-11 and 3-12. W, H and L in the table and figures denote width, heights and length of the bricks respectively. As the table and figures show, the magnitude of shrinkage of the brick samples was affected by the moisture content (MC) of the raw mix.

Table 3-6 Linear drying shrinkage (LDS), linear firing shrinkage (LS) and loss on ignition (LOI) of the bricks.

Mix

100% clay/ silt

100% clay/silt,
20% sand

80% clay/silt, 15%
sand, 5% kaolin, 0.2% SO1

80%
clay/silt,
20% sand, 0.4% SO1

80% clay/silt, 20% sand, 0.1% ESO2, 0.5% BaCO3

MC (%)

45

27

33

32

32

36

38

47

LDSW,H (%) 10.2

5.9

8.0

LSDL (%)

7.7

3.2

5.6

8.0

8.0

5.9

5.2

10.2

10.2

12.5

8.1

7.5

9.0

T (C)

1100 1100 600 950 1100

950

950 1000 950 1000 950 900 950

LSW,H (%) LSL (%) LOI (%)

-

8.0 10.2 14.9 14.9

14.9

13.7 13.7 13.7 13.7 14.9 17.4 17.4

-

5.0

6.5 8.7 9.8

10.3

9.1 8.9 11.6 12.4 12.8 14.6 15.6

-

7.8

5.9 11.7 12.3

10.6

10.9 11.0 10.0 10.1 10.8 11.4 11.6

1soybean oil, 2epoxy soybean oil W, H, L denote width, height and length respectively

29

% linear drying shrinkage

14
12 MC=45%
10
8

MC=47% MC=36% MC=38% MC=33% MC=32% MC=32%

MC=27% 6

4 BIA
2

0

1

2

3

4

5

6

1 100% clay/silt 2 80% clay/silt, 20% sand 3 80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil 4 80% clay/silt, 20% sand, 0.4% soybean oil
5-8 80% clay/silt, 20% sand, 0.1% epoxy soybean oil, 0.5% BaCO3

7

8 Mix

W/H L

Figure 3-11 Linear drying shrinkage (LDS) of brick samples. According to (BIA, 2006), drying shrinkage for different clays usually falls within 2-4 %.

The linear drying shrinkage increased with increasing moisture content in the raw mix. Since the individual particles that made up the wet bricks contain thin layers of water, the removal of this water causes these high surface-area particles to contract together, resulting in an overall decrease in the dimensions of the bricks. According to the Brick Industry Association (BIA, 2006), drying shrinkage varies for different clays, usually falling within the range of 2-4 %. Linear drying shrinkage of these brick samples was above this range and varied from 3 to 12%.
With higher moisture content of the wet brick, there is a risk of crack formation during the drying process, especially when the rate of water evaporation is too high. During drying, water removal takes place only on the surface by evaporation; the interior water travels to the surface by seeping through interconnected pores. If the rate of evaporation of water from the surface is greater than the rate of water diffusion from the interior toward the surface, the air/water interface will move inward and the surface of the brick will dry faster than the interior. This causes the surface layers to shrink while
30

the interior layers remain less affected, and a network of tension cracks can develop in a brick when the intrinsic tensile capacity is exceeded (Jones and Berard, 1993). The prevention of formation of drying shrinkage cracks included combination of gentle heating to encourage diffusion toward the surface and high humidity to suppress evaporation, so that bricks dry uniformly. As drying progressed, the temperature was gradually raised and the humidity gradually lowered so that evaporation and seepage rates remained reasonably high. Despite the very careful drying process, small cracks developed in brick samples prepared from the mix containing 46% water (Fig.3.6B, Section 3.2.2). No drying shrinkage cracks were observed in samples with MC below 40%.
Linear firing shrinkage increased with increasing MC in the raw mix and with increasing firing temperature (Fig. 3-13). Depending on the MC and firing temperature firing shrinkages ranged from 5 to 17%. As expected, the lowest firing shrinkage was observed in bricks made out of the mix with lowest moisture content (80% clay/silt, 20% sand, 27% water, 1100 C), which was in accordance with BIA requirements for good quality brick (BIA, 2006). Normally a good quality brick exhibits shrinkage below 8%. Despite the higher firing shrinkage, the fired bricks showed no cracking or minor cracks. Exceptions were samples prepared from the mix with the highest water content. These bricks contained cracks that had started to form during the drying process.
31

Figure 3-12 Linear firing (total) shrinkage of brick samples. According to (BIA, 2006), firing shrinkage of a good quality brick usually falls below 8 %.
Figure 3-13 shows the weight loss on ignition (LOI) of the fired bricks. The brick LOI is a weigh loss that is not only attributed to the organic matter content in the dredged material, but it also depends on the inorganic substances in the material being burnt off during the firing process. The LOI criterion for a normal clay brick is 15% (AASHTO, 1982). As can be seen in Figure 3-13, all the bricks made for this study meet the weight loss criteria.
32

Figure 3-13 Loss on ignition (LOI) of fired brick samples. According to (AASHTO, 1982) LOI of a good quality brick is usually below 15 %.
3.3.1.2 Water Absorption, Porosity, Bulk Density Water absorption is one of the key factors affecting the durability of brick, and it
is based on the amount of open or surface-accessible porosity in fired specimen. The water absorption (along with the apparent porosity and bulk density) was determined by using the procedures described in ASTM C 67. Table 3-7 and Figure 3-14 summarize results of these characteristics for three brick mixes fired at different temperatures. The results are compared with the ASTM specifications for absorption limits of selected brick grades (Table 3-8). The results indicate that water absorption values of the evaluated bricks fired at temperatures from 600 C to 1100 C are in compliance with the ASTM criteria for building brick. 5-h absorption in boiling water of the bricks fired at 600 C was below the maximum absorption value of 22% required for building brick exposed to moderate weathering (MW), while absorption of the bricks fired at 950 and 1100 C was
33

below 17%, thus complying with the absorption requirements for building brick exposed to severe weathering (SW). The absorption coefficient values lie within the prescribed limits for bricks fired at temperatures 950 C and above. Influence of the firing temperature on brick water absorption can be observed on the bricks prepared from the Mix 3 (80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil). As Figure 3-14 and Table 3-7 show, with increasing sintering temperature water absorption decreases due to a decrease in the porosity (Pap).
Initial rate of water absorption (suction) is a measure of how quickly the brick will remove water from mortar spread on it. This value is not a qualifying property or condition of brick in the ASTM specifications, and may be of interest when selecting mortar and in use of the brick on the jobsite. High-suction brick absorbs excessive water from mortar, which weakens bond and retards cement hydration resulting in waterpermeable joints. Optimum bond is produced with units having suction between 5 and 25 g/min.30 in2 at the time they are laid. The ASTM specifications recommend that the limit on suction be 30 g/min. 30 in2. Due to the presence of surface cracks, sorptivity of some of the bricks (see Table 3-7) was above the recommended value. Bricks with field sorptivity above 30 g/min.30 in2 should have their initial rate of absorption reduced below this value prior to lying by thorough wetting to allow moisture to become distributed throughout the unit.

Table 3-7 Water absorption properties, porosity and density of fired bricks

Mix

100% clay/silt, 20% sand

80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil

80% clay/silt, 20% sand, 0.4%
soybean oil

MC (%)

26.9

32.9

31.6

T (C)

1100

600

950

1100

950

A24, cold (%)

14.4

19.7

14.9

14.9

14.9

A5,boil (%)

18.7

21.3

8.7

9.8

10.3

SC

0.77

0.92

0.79

0.58

0.75

X (g/min1. 30 in2)

214.8

14.9

70.3

22.0

-

Pap (%) B (g/cm3)

-

36.1

31.4

24.9

27.7

-

1.7

1.8

1.8

1.8

MC-moisture content, T-firing temperature, A24,cold-24h absorption in cold water, A5,boil-5h absorption in boiling water, SC-saturation coefficient, X- suction, Pap-apparent porosity, B-bulk density

34

Table 3-8 ASTM Specifications for brick water absorption properties

ASTM Grade Brick

Max. A24,cold (%) Max. A5,boil (%)

Max. SC

SW

-

17.0

0.78

C 62 Building Brick

MW

-

22.0

0.88

NW

-

No limit

No limit

C 216 Facing Brick

SW MW

-

17.0

0.78

22.0

0.88

C 652 Hollow Brick

SW MW

-

17.0

0.78

22.0

0.88

C 1088 Thin Veneer Brick

Ext. Int.

-

17.0

0.78

22.0

0.88

C 902 Pedestrian and Light Traffic Paving Brick

SX MX NX

8.0 14.0 No limit

-

0.78

-

No limit

-

No limit

- SW, MW, NW indicate severe, moderate and negligible weathering, respectively

- A24,cold-24h absorption in cold water, A5,boil-5h absorption in boiling water, SC-saturation coefficient,

Water Absorption (%)

24

ASTM limits for 4h absorption in boiling water:

22 MW brick
20

18

16

SW brick

14

12

10

8

6

24h cold water

4

5h boiling water

2

0 2
1100 oC

3 600 oC

3 950 oC

3 1100 oC

4

Mix

950 oC Temperature

2 80% clay/silt, 20% sand, 27% water 3 80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil, 33% water 4 80% clay/silt, 20% sand, 0.4% soybean oil, 32% water

Figure 3-14 24 h absorption in cold water and 5 h absorption in boiling water of fired brick samples.

35

The bulk density was determined on some bricks and ranged from 1.7-1.8 g/cm3 (Table 3-7). Bricks made with clay normally have a bulk density of 1.8 to 2.0 g/cm3. The bulk density was slightly affected by firing temperature with an increase in the temperature resulting in an increase in bulk density. The slightly lower density values of the brick may have resulted from differences in the raw material composition. The dredged material probably contained a higher amount of organic residues than regular brick making clay, which after the combustion during the firing process resulted in an increase in the apparent porosity and a reduction in the bulk density of the bricks. Demir (2008) observed that with increasing amounts of organic residues mixed with raw brick clay the bulk density of the produced fired bricks decreased.
3.3.1.3 Compressive Strength Compressive strength is one of the key properties of a brick. There is a close link
between brick density, porosity and strength, with bricks of a higher porosity being generally weaker than dense bricks with a low porosity. Water absorption is a useful indicator of brick strength, durability and structural integrity. Lower percentages of water absorption are associated with higher strength.
The compressive strength test was performed on fired bricks prepared from the raw mixes 2-5 (as denoted in Table 3-5, Chap. 3.2). The results of the compressive strength testing are summarized in Table 3-9 and Figure 3-15. For comparison, the ASTM specifications for minimum compressive strength of selected brick grades are shown in Table 3-10.
36

Table 3-9 Compressive strength of Savannah Harbor bricks

Mix composition

T (C)

Compressive Strength (psi)

average

individual

100% clay/silt, 20% sand, 27% water 80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil, 33% water
80% clay/silt, 20% sand, 0.4% soybean oil, 32% water 80% clay/silt, 20% sand, 0.1% epoxy-soybean oil, 0.5% BaCO3, 32% water

1100 600 950 1100
950
950 1000

570 1490 1530 1490
1615
1592 1703

440-690 1340-1820 1370-1800 1350-1610
1564-1729
1515-1663 1612-1825

Table 3-10 ASTM Specifications for compressive strength of bricks

Minimum compressive strength

ASTM Grade Brick

(psi)

Average of 5 bricks

Individual

SW

3000

2500

C 62 Building Brick

MW

2500

2200

NW

1500

1250

C 216 Facing Brick

SW

3000

MW

2500

2500 2200

C 652 Hollow Brick

SW

3000

MW

2500

2500 2200

C 1088 Thin Veneer Brick

Ext. Int.

-

-

C 902 Pedestrian and Light Traffic Paving Brick

SX MX NX

8000 3000 3000

7000 2500 2500

SW, MW, NW indicate severe, moderate and negligible weathering, respectively

37

2500

ASTM limts for building brick:

MW grade

Compressive strength (psi)

2000 1500

NW grade

1000

500

0 2
1100 oC

3 600 oC

3 950 oC

3 1100 oC

4 950 oC

5 950 oC

5

Mix

1000 oC Temperature

2 80% clay/silt, 20% sand, 27% water 3 80% clay/silt, 15% sand, 5% kaolin, 0.2% soybean oil, 33% water 4 80% clay/silt, 20% sand, 0.4% soybean oil, 32% water 5 80% clay/silt, 20% sand, 0.1% epoxy soybean oil, 0.5% BaCO3, 32% water

Figure 3-15 Effect of mix composition and firing temperature on compressive strength of bricks

The results indicate that except for the mix 2 (80% clay/silt, 20% sand, 27% water) the values of compressive strength of the studied bricks were in compliance with ASTM brick criteria for the lowest grade (NW) building brick. The highest compressive strength (1700 psi in average) was achieved in bricks prepared from mix 5 and fired at 1000 C. Bricks prepared from mix 2 and fired at 1100 C showed very low compressive strength and did not meet the ASTM requirements. The bricks were weak and brittle. The reason of this low strength may be insufficient mixing of the stiff raw mix which produced an inhomogeneous mix resulting in forming a weak and porous body during firing. Other reason may be failure in the thermal stage of the brick production. As Figure 3-14 shows, these weak bricks have higher water absorption than stronger bricks prepared from a different mix but fired at the same temperature.
As the results show, the compressive strength was mainly affected by the firing temperature, with higher compressive strength values being associated with higher firing temperatures. However, bricks from mix 3 fired at 1100 C showed slightly lower

38

strength than the bricks from the same mix fired at 950 C. This may be due to the fact that the bricks fired at 1100 C were uneven and bulged, and capping them prior to the strength measurement did not likely assure reasonably parallel and smooth opposite surfaces. This may have increased the likelihood of uneven bearing and stress concentrations which resulted in premature failure of the specimen. The bulging and cracking of the bricks fired at 1100 C could be a result of inversions of the forms of quartz that are associated with linear expansions of the material.
3.3.2 Micro-Structural Analysis Phase composition of the dredged material and fired bricks was evaluated by
XRD analysis. Figure 3-16 shows the X-ray diffraction patterns of bricks prepared from mix 2 and fired at different temperatures, and compared with the pattern of the raw material. In general, the phase composition of the raw material and fired bricks are complex. However the major phases found in the dredged material included quartz, clay minerals (kaolinite, illite) and feldspars (anorthite, albite). The results indicate that the major mineral phases found in the fired bricks were quartz, feldspars, hematite and traces of mullite. Since additional sand was added to the raw mix, the peaks of quartz (which usually is less abundant in fired bricks) in the XRD profile of the fired specimens have higher intensities than that in the pattern of the dredged material. Hematite, also called red iron oxide, is present in bricks fired at 950 C and above. Mullite, detected in bricks fired at 1100 C, is a product of decomposition of kaolinite and contributes to the compressive strength of bricks.
In the XRD pattern of the brick fired at 1100 C a peak around 21 2-theta, most probably representing high temperature polymorphs of quartz, tridymite and cristobalite, can be observed next to the peak of quartz. Tridymite is stable between 870 and 1470 C, and cristobalite is stable between 1470 and 1710 C. The changes from one to another form are very slow, and forming tridymite may not take place at all without the presence of some impurity. In practice, cristobalite must be formed first by heating quartz to about 1470 C, and then cool down to form tridymite. The addition of small amounts of impurity materials (mineralizers) can speed up the formation of these polymorphs of quartz. The presence of lime can catalyze the conversion of quartz to cristobalite, while iron compounds favor the formation of tridymite.
39

The three major forms of quartz can undergo minor structural changes (inversions) during cooling, which are associated with linear expansions. Cristobalite change causes the highest expansion (about 1%) among the three forms of quartz; the inversion of quartz and tridymite involves about 0.45% and 0.1 % linear expansion, respectively.
Figure 3-16 XRD patterns of the dredged material and fired bricks. Mix composition: 80%, 15% sand, 5% kaolin, 0.2% soybean oil, 33% water.
40

CHAPTER 4: ECONOMIC ANALYSIS
An economic evaluation was conducted as a preliminary examination of the major cost factors involved in producing bricks from dredged material. The analysis included the compilation of initial equipment costs and operating costs using the projected available dredged material (currently estimated to exceed six million cubic yards per year) as the base measurement for equipment sizing and production rates. Several operating scenarios were developed after (a) the physical characteristics of the material were determined, (b) the quantities of additional materials required (e.g., sand, additives) were found, and (c) the need for additional processes, such as dewatering, were identified.
The analysis included estimates of all major operating cost items (raw material harvesting, labor, fuel), equipment maintenance and replacement costs, and initial investment costs that would enable an estimate of total costs per brick under each of the operating scenarios. These were preliminary estimates based on available information at the time of the analysis.
4.1 Overview Currently, the Corps of Engineers (COE) planning documents for dredging in the
Savannah Harbor calls for the removal of 6.225 million cubic yards (1.68 million T) of material each year. It is a considerable mass that must find a home somewhere other than the bottom of the Savannah River.
Most of this material is deposited on a three-year cycle onto one of several Dredged Material Containment Areas (DMCAs) purchased by GDOT for this purpose. A given DMCA will accumulate dredged material annually for three years and then will "rest" for three years while deposits are made onto a paired DMCA. The three-year rest allows the material to dry somewhat (and thereby reduce its volume) prior to the next three-year deposition schedule. About every 6 years the dikes enclosing the dredged material must be raised, typically about six feet. Because the dry dredged material is used in the dike construction, not all of it would be available for brick-making.
Because of logistical concerns, the three areas most likely to be useable as a source of brick-making material are 12A, 13A, and 13B. Areas 12A and 13A are paired, i.e., they are of approximately the same size and when one is receiving material the other
41

is resting. It is during the second year of the resting phase that material is available to be retrieved for bricks.
The rationale for retrieving relatively dry dredged material and making bricks is that storing this material is becoming increasingly problematic as greater and alternative demands are being made on the adjacent properties, which reduces future options and increases the cost of those remaining. Dike construction is also expensive (although Georgia currently pays only 35% of these costs) and reducing the rate of accumulation of stored material will ameliorate both concerns.
The objective of this economic analysis was to provide a rough measure of the net costs of diverting a portion of the dredged material to brick-making. The material can take one of two paths; 1) it can be transported to an existing brick manufacturer for their use, or 2) it can be used to make bricks near the DMCAs. Because of irreducible uncertainties at this point, several scenarios were analyzed for each path.

4.2 The Material The three areas most likely to be the source of brick-making material are 12A,
13A, and 13B, with 13A actually referring to the scheduled (2010) recombination of areas currently known as 12B and 13A. As such, the approximate areas of these three DMCAs are shown in Table 4-1. Also shown in Table 4-1 are the approximate lineal feet of dike enclosing the area from which dike-raising costs are derived.

Table 4-1 Areas potentially mined for brick-making material

Area Size (acres) Lineal Feet of Dike

Material for Dikes (yd3)

12A

1,040

29,000

725,000

13A

1,347

29,950

748,750

13B

525

19,182

479,550

Source: John Phillips, GDOT (personal communications) and calculations by Georgia Tech

The deposition schedule determines the quantities and timing of material availability for brick-making, as displayed in Table 4-2. If it is assumed that one year is sufficient to dry and to leach chlorides to a level acceptable for the bricks, then harvesting of the material in 12A and 13B can occur in 2012 and 2013.

42

A factor to consider when estimating the quantity of dredged material available for harvest is that some material will be needed to construct the new dikes when the existing dikes are no longer adequate. From an example provided by GDOT, 22.6 cubic yards of material is needed per lineal foot of dike. Using a slightly more conservative 25 cubic yards of material per lineal foot, the estimates of dike material required for each of the areas is provided in Table 4-1. Because these areas share dikes, the dikes separating areas are included only once, i.e., area 12A is a complete perimeter, area 13A does not include the border with 12A, and 13B does not include its border with 13A.
The quantities deposited are not the same as the quantities available for harvest because volume decreases as time passes. The rule-of-thumb used to estimate the available volume is 70% of the deposited amount. The actual levels vary according to how much rainfall is seen, the existence and effectiveness of under-drains, and variations in the characteristics of the material itself. Table 4-2 provides the deposition schedules for each of the areas feasibly harvested.

Table 4-2 Timing and quantities (cubic yards) deposited by area

Year

Area

2010

2011

2012

2013

2014

2015

2016

12A 4,660,000 drying

drying

dike bldg 4,660,000 4,660,000 4,660,000

13A dike bldg 4,660,000 4,660,000 4,660,000 drying

drying

dike bldg

13B 782,500 drying

drying

dike bldg 782,500 782,500 782,500

Source: John Phillips, GDOT (personal communications) and calculations by Georgia Tech

2017 drying 4,660,000 drying

Material availability could be looked at two ways. First would be the total material (currently stored plus annual accumulations) and the second is the sustainable annual yield. Both perspectives are potentially useful, but it is more likely that brickmaking would only be able to absorb a portion of the annual accumulation. Table 4-3 provides a summary of the annual estimated availability of material and a rough estimate of the inventory of stored material. It is assumed that equal amounts are harvested in the second and third year of the drying cycle. Because the two-year harvesting cycle has three years of deposition available, even after the volumes are reduced to 70% of that

43

deposited (due to drying) and the estimated material needed for dikes is subtracted, the volumes available are similar to quantities deposited as shown in Table 4-2. Table 4-3 Approximate material available for brick-making (cubic yards)

Area Stored

2012

2013 2014 2015

2016

12A 50,336,000 4,450,350 4,450,350

13A 69,541,120

4,701,268 4,701,268

13B 11,011,000

1,353,995

Total 130,888,120 4,450,350 4,450,350

4,701,268 6,055,262

Source: John Phillips, GDOT (personal communications) and calculations by Georgia Tech

2017
1,353,995 1,353,995

4.3 Brick Manufacturing There are nine distinct stages in manufacturing a brick beginning with mining (or
in this case, harvesting) the raw materials and ending with the storage and shipping of the final product. The simplest, cheapest, and easiest alternative would be to transport this material to an existing brick-maker for their use, so it will be the first alternative investigated. The second option would be to construct a brick manufacturing plant adjacent to the areas from which material is harvested, which will be considered subsequently.

4.3.1 Option 1: Transport to Existing Brick-Maker A brick-maker in Augusta (Boral Bricks) has provided information that enables a
calculation of the amount of material that might be useful to a typical brick-maker. Modern brick factories are scaled to produce 80-120 million bricks per year depending on the type of brick and the operating regime used. A general rule of thumb for ordinary clay bricks is 120 million bricks per year and with a brick weighing about 4 lbs, then about 480 million lbs (240,000 tons) of raw material is needed. Preliminary tests indicate that the dredged material content of these bricks might be between 30-50%, which yields an estimate of annual tonnage of dredged material that can be taken by a typical brick plant of between 72,000-120,000 tons of material at about 18% moisture content. With an estimated density of 2.60 tons per cubic yard for the dredged material at an average of

44

40% moisture content, this translates into about 35-54 thousand cubic yards of material annually.
Another issue to be considered is the cost of transporting the material to the brick maker. Using Augusta as an example (about 140 miles from Savannah), the cost of one dump-truck load (15 cubic yards) is estimated to be about $375. This yields an annual cost of $.8 to $1.4 million per year to transport the dredged material to the brick maker. There are also additional costs associated with collecting these materials after they have had at least one year to dry. Using the equipment that is currently being used to build new dikes (a pan attached to a tractor), the annual cost estimated to harvest the material to be sent to the brick plant varies between areas because of the different one-way distance required to travel, i.e., 12,000 feet for areas 12A and 13A, and 8,000 feet for area 13B. How much is harvested from 13B and how much from the other areas is a function of the timing of material deposition. A hypothetical harvesting regime based on the scheduled depositions for these areas is provided in Table 4-4. The amounts differ from the annual demand because there are years when none of the three areas are "ripe" for harvest and this deficit must be made up in other years.

Table 4-4 Hypothetical harvesting regime

Year

Area

Amount Harvested (yd3)

30%

50%

2012

13B

2013

13B

48,917 48,917

81,528 81,528

2014

2015

13A

48,917

81,528

2016

13A

2017

2018

13B

48,917 48,917

81,528 81,528

2019

13B

48,917

81,528

2020

-

-

2021

13A

48,917

81,528

The 30% and 50% refer to the amount of dredged material used in the bricks at the existing plant.

The harvesting and transportation cost estimates, and some of the assumptions underlying them, are included in Table 4-5. Also included in Table 4-5 are the estimates of the benefits that would accrue from this harvesting. The benefits of removing this
45

material are two-fold. First, by slowing the accumulation of material, it reduces the need to build new dikes. Secondly, it delays (or, possibly, avoids) the necessity of adding booster pumps in the dredging operation which would essentially double dredging costs. These avoided costs are estimated on the basis of per cubic yard of material and assumes, for example, that if a dike will need to be raised by a smaller amount because of the reduced rate of net material accumulation, that these costs would be reduced proportionally, i.e., the cost functions are smooth. In practice, it would be more complicated and some of the cost functions may have some lumps in them. There is also the complication of having dikes separating areas needing to be raised to a height appropriate to the area with the highest level of anticipated accumulation. On top of all of this are the fluctuations in the time path of harvesting which would make an average annual figure differ slightly when discounting to present value. However, in the current economic climate any discount rates that would be applied would be so close to zero it makes present value issues largely moot.
As is seen in Table 4-5, the harvesting and transportation costs exceed the estimated costs avoided by a considerable amount. Because these costs are linear, it would be expected that including more brick plants would, if the distance is comparable, increase costs and avoided costs similarly. It should also be noted that brick plants are currently running considerably under capacity because of the real estate market decline, and it would be doubtful if any brick plant would be able to take significant quantities at the present time, i.e., this analysis presumes a return to reasonable levels of residential and commercial construction by 2012.
46

Table 4-5 Potential use of dredged material in existing brick plants

Assumptions

Brick Plant Annual Production Average Dump Truck Capacity

120 million bricks 15 yd3

One-way Distance to Brick Plant

140 mi

Average Cost to Transport Material to

$375 per load

Plant

Average Annual Amounts

Harvesting Costs Incurred

30% Mixture

Estimated Annual Demand for Material Dredged Material Demand

72,000 ton at 18% MC 32,611 yd3 at 40% MC

Dredged Material Transportation Cost

$815,278

Cost to Harvest

$73,124

Total Costs

$888,401

Avoided Costs

Dike Raising

$348,156

50% Mixture 120,000 ton at 18% MC 54,352 yd3 at 40% MC $1,358,796 $114,704
$1,473,499
$580,259

Booster Pump Costs Total Costs Avoided
Net Costs

$82,510 $430,666
$457,735

$137,517 $717,776
$755,723

4.3.2 Option 2: Constructing and Operating On-Site Brick Plant The first issue to be addressed must be the scale of operation that makes sense
from a material availability perspective. The quantity of material accumulating every year is clearly too much for subsequent harvesting and brick-making. A reasonable scenario is to examine the implications of assembling a crew and equipment roughly equal to that currently employed in dike-raising and estimating how much material they would provide to a brick-making plant.

47

The basic equipment for harvesting would be a tractor with a pan attached with a

capacity of about 14 cubic yards. Other basic operating assumptions, such as distances

traveled during harvesting, are provided in Table 4-6.

Table 4-6 Harvesting operations assumptions

15

Number of Tractor/pan Units

8

Average tractor speed (mph)

4.55 Average haul distance: Areas 12A and 13A (miles)

3.03 Average Haul distance: Areas 13B (miles)

65

Cost per hour of operation per piece of equipment

8

Hours per day operation

250

Days per year operation

These assumptions provide estimates of the quantity of material that can be harvested from a given area in a year. Because the areas rotate on a six year cycle where deposition years alternate with drying years, the harvesting operation may not always have an area where the previously deposited material has had at least one year to dry, such as 2014. There are also variations in the quantity that is harvested depending on the size of the area, with more material available when the smaller 13B is harvested. These estimates assume that this volume is harvested evenly throughout the area. A ten-year harvesting scenario based on the planned COE deposition/drying cycles is provided in Table 4-7. It is assumed that an area will be available to accumulate sufficient inventory to enable a stable annual supply of material (665,280 cubic yards) to be used as a basis for sizing the brick-making machinery.

Table 4-7 Harvesting scenario

Year 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Total Over 10 Years

Area 13B 13B
13A 13A
13B 13B
13A

yd3 1,108,800 1,108,800
739,200 739,200
1,108,800 1,108,800
739,200 6,652,800

48

One of the brick formulations that seem feasible is 80% clay/silt material and 20% sand material, with small quantities of soybean oil and barium carbonate added. The moisture content of the clay/silt and sandy materials is highly variable and is a significant determinant of the tonnage of material that would be available for brickmaking, and, therefore, the size of the brick-making plant. The density of the clay/silt material at 40% moisture content is estimated to be about 2.60 tons/yd3. The moisture content of the clay/sand mixture prior to drying/firing is assumed to be 40%. These assumptions and their implications for the raw materials are provided in Table 4-8.

Table 4-8 Dredged material conversions.
Clay/Silt Material Average Moisture Content of Harvested Material Average Density of Harvested Material Annual Tonnage of Material Available Annual Volume of Material Available Sandy Material Average Moisture Content of Harvested Material Average Density of Harvested Material Annual Tonnage of Material Available Annual Volume of Material Available Annual Tonnage of Brick Making Material Available Annual Number of Bricks

40% 2.60 g/cm3 1,726,681 T 665,280 yd3
40% 1.89 g/cm3 313,982 T 166,320 yd3 2,040,664 735,052,906

Brick plants in the U.S. are typically scaled to produce about 120 million bricks per year. The brick plant that would use the harvested material would therefore be over six times that size, although there are some elements of the hypothetical brick plant that would benefit from economies of scale, such as the kiln. The basic components of the factory and their estimated costs are provided in Table 4-9. Because these costs are based on scaling-up a typical U.S. brick-making plant they should be considered only as preliminary estimates.

49

Table 4-9 Initial investment costs for hypothetical brick factory

Brick Plant

Material Receiving and Processing Equipment

$55,128,968

Manufacturing Equipment

$24,501,764

Kilns & Dryers

$53,864,540

Packaging Equipment

$24,501,764

Buildings

$15,389,869

Utilities & Electrical Distribution

$24,501,764

Construction

$106,564,527

Total

$304,453,194

Harvesting Equipment

$3,000,000

Total Initial Investment

$307,453,194

The operating regime for a typical U.S. brick plant is to run the kilns 24/7 and run the other equipment on a single shift. The costs listed in Table 4-9 are based on this type of operating schedule. Another option more common in the European Union is to run the entire factory 24/7 with much of the components automated so that the labor required goes from about 75 persons (for a 120 million brick per year plant) to 2-6 for a smaller plant that also has a smaller initial investment. Attempts to obtain cost and operational information on this alternative have been unsuccessful to date, but this may offer an opportunity to develop a pilot plant at significantly lower initial capital costs.
The estimates for the operation of the plant depicted in Table 4-9 are presented in Table 4-10. These were derived from industry sources with updated natural gas prices and scaled up to the level of production implied from the quantity of harvested materials. Generally, the components scale linearly, but the kiln and construction components were assumed to have modest economies of scale.
The material harvesting costs are based on average hourly historical costs of operating the tractor/pan combinations and a cost estimate of $10 per cubic yard of dredged sand barged to the plant site from Jones Island. The total quantity of sand available on the island is about one million cubic yards and the deposition rate is about 200,000 yd3 per year, which is slightly less than the projected need for sand (about 166,000 yd3 per year) in the scenario presented here.
50

The costs avoided by diverting material to bricks arise from two sources. The first is a reduction in the dike raising necessary and the second is the avoidance of having to use booster pumps in the dredging operation currently expected to be incurred in about 2050. There were no corrections for the time value of money in this analysis because current discount rates are so close to zero that present values and nominal values would be almost the same.

Table 4-10 Average annual brick plant operations

Material Harvesting Labor Fuel Electrical Maintenance, Supplies, Misc Annual Depreciation
Total

Low $3,613,200 $15,436,111 $5,955,879 $5,145,370 $7,718,056 $7,611,330 $45,479,946

High $3,974,520 $19,846,428 $8,726,056 $6,615,476 $9,923,214 $7,611,330 $56,697,024

Avoided Costs Dike Raising Booster Pump Costs
Total Avoided Cost

$845,538 $1,603,084 $2,448,622

$930,092 $1,763,393 $2,693,484

Net Cost

$43,031,324 $54,003,540

Annual Brick Production Cost per brick

735,052,906 735,052,906

$0.059

$0.073

As Table 4-10 demonstrates, it would be expected that producing bricks from available materials, while reducing dike-raising costs and avoiding booster pump costs, the enterprise would cost between $43 and $54 million per year, assuming there are no revenues from the sale of bricks. It should also be noted that the annual brick production in the U.S. (under normal economic conditions) is about 9 billion bricks; this plant would add almost 10% to annual brick production. The cost per brick in the industry is generally between $.07 and $.09; the estimated average cost per brick for this facility is slightly lower, at $.059 to $.073 per brick.

51

4.4 Conclusions The economic analysis should be considered a preliminary analysis but two issues
are immediately clear. First, the core issue of reducing accumulations of dredged material by making it available to existing brick-making firms is transportation cost. It may be that this material would have a value to some brick makers who would therefore be willing to pay at least a part of the transportation cost of getting this material to their plant. Initial indications are that this material would be suitable for use in existing brickmaking operations, but that currently the demand for bricks (which are used primarily in residential construction) is so low that it is unlikely any brick-makers are looking for new sources of raw materials. This could change, however, as residential construction recovers. There is also the possibility that EPA could promulgate regulations that put ash (mostly from coal-fueled power plants) in the "hazardous material" category. If this should happen, any current brick-maker that uses either bottom or fly ash in their formulations will probably be looking for a new source of raw materials that could potentially be satisfied by dredged materials.
Another issue relating to the costs of transporting material to an existing brickmaker is the mode of transport. This analysis assumes the only mode available is trucking, but rail and/or barge transport may offer a cheaper alternative to some brickmakers, but use of either rail or barge transport may require additional capital expenditures for sidings or ports.
Second, the core issue relating to the use of dredged materials for on-site brick making is the tremendous volume of material that is available. In a typical year, about 9 billion bricks are manufactured in the U.S in about 160 plants, according to the Brick Industry of America. The volume of material that is harvested in the scenario used in this analysis would generate about 8% of that volume and this harvests about 10% of the total annual average deposition. In other words, if all of the material currently dredged were turned into bricks, it would satisfy about 80% of the national demand for bricks. It would be extremely difficult to find good homes for so many bricks, especially in current conditions.
One of the issues that could change this would be restrictions on the land available for depositing dredged materials. The current disposal sites are located in South Carolina, which includes the site of the new proposed Jasper Terminal. This terminal is
52

currently being studied by a cooperative joint project office consisting of representatives from Georgia and South Carolina. Defining alternative disposal sites is clearly beyond the scope of this analysis, but on-site brick making, (either by a private-sector firm given the appropriate licenses and incentives or by GDOT, or by a partnership with the COE), could then become one viable option for disposal of some of the dredged materials.
Another (perhaps more fanciful) option follows from the large number of ships delivering goods through the Port of Savannah (from China, for example), that leave empty. Bricks make wonderful ballast and offer the advantage of being a readily usable building material at their destination without significantly increasing transportation costs.
53

CHAPTER 5: CONCLUSIONS AND RECOMENDATIONS
In this research, the possibility of the production of brick from materials dredged from the Savannah River in laboratory conditions was studied. The physical and chemical characterization of the dredged materials were performed, appropriate materials and mix proportions were identified, and suitable processing operations in bench-scale brick production were optimized. Brick produced from the dredged materials were subjected to physical, chemical and technological assessment. Also, an economic evaluation was conducted to examine the major cost factors involved in producing bricks from dredged material. Key outcomes of the research and evaluation are summarized below, and directions for future research are identified.
5.1 Conclusions The following conclusions can be reached based upon the experimental, analytical
and numerical studies described in this report: 1. Physical and chemical characteristics of dredged sediments from the Savannah
Harbor showed no anomalies that would necessarily preclude their beneficial reuse in production of fired brick. Bricks with 100% dredged sediments (80% clay/silt material and 20% sand material) blended with minimal amounts of additives such as soybean oil and barium carbonate were successfully produced in laboratory-scale production test runs. 2. Moisture content (MC), as measured on extruded bricks, varied from 27 to 48% and was higher as compared to the ~19% moisture content that is normally used in extrusion processes in brick plants. This high demand of water was most probably due to higher organic residues content in the dredged material, as well as the lower capability of the laboratory extruder to process stiffer blends containing less than 27% water. With higher MC in the mix higher shrinkage of the brick bodies occurred after thermal treatment. Linear drying shrinkage of brick samples varied from 3 to 12% and for most of the bricks it was above the range of 2-4%, which is typical for drying shrinkage of regular bricks. Depending on the MC and firing temperature firing shrinkages ranged from 5 to 17%, which was again above the 8% limit for firing shrinkage of a good quality brick. The weight loss on ignition (LOI) of the bricks was
54

below 15%, thus meeting the AASHTO (1982) criterion for LOI of a normal clay brick. 3. Fired bricks appeared in red color, with the tone becoming darker with increasing firing temperature up to 1100 C. The physical appearance of bricks depended mainly on the mix composition, water content and drying and firing conditions. Bricks prepared from a mix consisting only of the clay/silt material failed to maintain their shape during the firing process. The addition of sand at a rate of ~20% by mass to the raw mix improved compaction of the mix and reduced water demand; this resulted in more successful firing. With increasing moisture content the bricks became more susceptible to cracking during the drying and firing process. Also, bricks fired at temperatures above 1000 C showed some bulging most probably resulting from structural changes of quartz occurring during heating and cooling. 4. The presence of soluble salts in the dredged material was found to cause an undesirable scumming of slightly yellow color on the surface of fired bricks. Bricks containing small amount of barium carbonate did not show any presence of such scumming. 5. Physical and mechanical properties of the bricks were found to generally comply with ASTM C 62 criteria for building brick. The 5-h absorption in boiling water of the bricks fired at 950 and 1100 C was below the maximum absorption value of 17% required for building brick exposed to severe weathering (MW). Bulk densities of studied bricks ranged from 1.7 to 1.8 g/cm3 and were slightly lower than the bulk densities of regular clay brick (1.9 2.0 g/cm3). 6. The average compressive strength of bricks prepared from several various mixes and fired at different temperatures ranged from 1490 to 1700 psi; these values were in compliance with ASTM brick criteria for the lowest grade (NW) building brick. The compressive strength was mainly affected by the firing temperature, with higher compressive strength values being associated with higher firing temperatures. 7. The economic analysis provided a preliminary measure of the net costs of using a portion of the dredged material in brick-making, and addressed two paths for use: 1) transporting the dredged material to an existing brick manufacturer and 2) constructing and operating an on-site brick plant. The core issue of making the dredged material available to existing brick-making firms is transportation cost,
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which is about 91% of the total costs associated with this option. The analysis estimates that the annual transportation costs of the dredged material by trucking to a brick maker located within 120 miles from the site would be approximately $815,000 ($1,350,000) for 30% (50%) additions in the raw brick mix. More economical transport alternatives, such as rail and/or barge transport, may require additional capital expenditures for sidings or ports. Even though the dredged material would be suitable for brick making, current market demand for bricks is low. Growth in the construction industry and/or increasing market demand for "green" building materials could spur interest in the scenarios examined, which given the current economic situation were deemed infeasible. 8. Economic analysis estimates that initial investment costs for hypothetical brick factory running 24 hours/day and 7days/week may be approximately $300 million. Annual operation of such enterprise while reducing dike-raising costs and avoiding booster pump costs would cost between $43 and $54 million, assuming there are no revenues from the sale of bricks. The core issue relating to the use of dredged materials for on-site brick making is the tremendous volume of material that is available. With an assumption that a stable annual supply of the clay/silt material is about 665,000 cubic yards and supply of sand material is about 166,000 cubic yards, annual production would be approximately 735 millions bricks, which is about 10% of annual brick production in the U.S.
5.2 Recommendations for Further Research and Production This study has answered a very important question asked by many for a long time.
It is now proven that the dredged material can be used to make bricks. However, at this time, it is not economically feasible to pursue this. The initial $300 million cost plus an annual cost of $50 million to remove only 10% of the dredged material is not attractive.
The next question to be answered is when, if ever, will it become feasible to manufacture bricks from this dredged material. It is recommended that the feasibility of the manufacture of bricks be reassessed if significant changes occur in regional transportation, federal regulation of materials and growth or changes in the construction sector, as considered below.
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Transportation: Because of the cost of transporting dredged material is a significant economic impediment to brick manufacture, development which could potentially decrease those costs should spur a re-examination of the feasibility of brick manufacture from the dredged material. Some examples which could significantly decrease materials transportation costs include rail construction linking Savannah and Augusta or increased navigability of the Savannah River allowing barge transport of materials.
Materials: Currently, nonhazardous industrial waste products, including fly ash, are sometimes used in brick manufacture. Changes in federal regulation of waste materials used in brick manufacture, such as the current proposal to regulate management of coal combustion products, could increase the value of alternative by-product materials such as the dredged material for brick manufacture. Further, new regulations or incentives related to recycled content in construction materials could also increase the material's value and promote its use in brick manufacture. Finally, any significant increases in the cost for acquiring virgin materials for brick manufacture could also improve the economics associated with the use of dredged material in bricks.
Construction: Given the potential volume of bricks which could be manufactured, it is improbable that utilization could keep pace with capacity even with an economic recovery in the construction sector. However, changes in building codes particularly those associate with energy efficiency could increase the rate of brick use. Thus, as the construction sector recovers and as building codes increase adoption of sustainability provisions, the feasibility of the use of dredged material in brick should be reassessed.
Finally, some scenarios for manufacture of brick and other products from the dredged material should be considered which were not examined in this research.
This research examined two options for brick manufacture transportation of material to off-site facility and construction of a facility near the harbor. However, manufacture could occur on an off-shore structure or could be done on a barge. With a barge, manufacturing using the dredged material obtained from the Savannah River could be located as needed to coincide with demand. An off-
57

shore structure could make use of the dredged material directly, potentially avoiding storage in dikes. This research examined the manufacture of fired bricks. Further research should examine other options for the productive reuse of the dredged material. The manufacture of other higher-value, clay-based products should be considered, including the production of "A-jacks" used for erosion control. In addition, research should examine its use in other types of applications, such as a feedstock for cement manufacture.
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APPENDIX A1 Grain size distribution and plasticity characteristics of dredged material from CDF 13A

CDF 13A (North Side) Rzero Rmen Rtemp (21.5 deg) K (from table) Mass of soil Hydroscopic Water Content Mass of solids
Time (min)
0.50 1.00 1.50 2.00 2.50 5.52 16.48 239.74 1009.40 2432.90

MH 4.5 1.5 5.5 0.01332 50.12 65.13 30.35

LL

116.3

PL

52.1

PI

64.2

% Sand 8 % Silt 29 % Clay 63

Actual Reading Corrected Reading

20.50 20.00 19.50 19.00 18.50 17.50 17.00 16.50 16.00 15.00

23.00 22.50 22.00 21.50 21.00 20.00 19.50 19.00 18.50 17.50

L (cm)
11.50 11.90 12.10 12.30 12.40 12.60 12.80 13.20 13.30 13.70

D (mm)
4.750 2.000 0.425 0.177 0.149 0.105 0.074 0.06 0.05 0.04 0.03 0.03 0.02 0.01 0.00 0.00 0.00

Percent Finer
100.00 100.00 99.65 98.96 97.24 95.46 91.56 75.78 74.13 72.48 70.84 69.19 65.89 64.25 62.60 60.95 57.66

Percent Finer

10.0000 100
90 80 70 60 50 40 30 20 10
0

1.0000

Grain Size Distribution Savannah Harbor Dredged Sediment
Particle Size (mm)

0.1000

0.0100

0.0010

0.0001

59

A2 Grain size distribution and plasticity characteristics of dredged material from CDF 13B

CDF 13B (East Side) Rzero Rmen Rtemp (21.5 deg) K (from table) Mass of soil Hydroscopic Water Content Mass of solids
Time (min)
0.50 1.00 1.50 2.00 2.50 6.26 13.90 188.56 1005.69 1988.65

MH 4.5 1.5 5.5 0.01332 50.91 35.65 37.53

LL

98.7

PL

48.2

PI

50.4

% Sand 11 % Silt 43 % Clay 46

Actual Reading Corrected Reading

19.50 18.50 18.00 17.00 16.50 15.50 15.00 14.50 14.00 14.00

22.00 21.00 20.50 19.50 19.00 18.00 17.50 17.00 16.50 16.50

L (cm)
11.50 11.90 12.10 12.30 12.40 12.60 12.80 13.20 13.30 13.70

D (mm)
4.750 2.000 0.425 0.177 0.149 0.105 0.074 0.06 0.05 0.04 0.03 0.03 0.02 0.01 0.00 0.00 0.00

Percent Finer
100.00 100.00 100.00 100.00 100.00 95.63 88.54 58.62 55.95 54.62 51.96 50.63 47.96 46.63 45.30 43.96 43.96

Percent Finer

10.0000 100
90 80 70 60 50 40 30 20 10
0

Grain Size Distribution Savannah Harbor Dredged Sediment

Particle Size (mm)

1.0000

0.1000

0.0100

0.0010

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A3 Grain size distribution and plasticity characteristics of dredged material from CDF 12B

CDF 12B (South Side) Rzero Rmen Rtemp (21.5 deg) K (from table) Mass of soil Hydroscopic Water Content Mass of solids
Time (min)
0.50 1.00 1.50 2.00 2.50 7.68 15.70 265.89 1005.98 2268.63

MH 4.5 1.5 5.5 0.01332 51.26 72.3 29.75

LL

82.6

PL

48.1

PI

34.5

% Sand 26 % Silt 42 % Clay 32

Actual Reading Corrected Reading

15.50 15.00 14.50 14.00 13.00 11.50 9.00 6.00 5.50 5.50

18.00 17.50 17.00 16.50 15.50 14.00 11.50 8.50 8.00 8.00

L (cm)
11.50 11.90 12.10 12.30 12.40 12.60 12.80 13.20 13.30 13.70

D (mm)
4.750 2.000 0.425 0.177 0.149 0.105 0.074 0.06 0.05 0.04 0.03 0.03 0.02 0.01 0.00 0.00 0.00

Percent Finer
100.00 100.00 96.00 92.00 88.62 82.16 73.65 60.50 58.82 57.14 55.46 52.10 47.06 38.65 28.57 26.89 26.89

Percent Finer

10.0000 100
90 80 70 60 50 40 30 20 10
0

Grain Size Distribution Savannah Harbor Dredged Sediment

Particle Size (mm)

1.0000

0.1000

0.0100

0.0010

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A4 Summary of bulk chemistries of the dredged material collected at each CDF (Buxton et al, 2000).

pH Hg (ppm) Sb (ppm) As (ppm) Be (ppm) Cd (ppm) Cr (ppm) Cu (ppm) Pb (ppm) Mn (ppm) Mo (ppm) Ni (ppm) Se (ppm) Ag (ppm) Zn (ppm) Tl (ppm) Al (ppm) Fe (ppm) TOC (ppm)

12A

range

AVE

7.4-7.6 0.071-0.274 (0.624-0.714) 18.4-20.1 1.70-1.83 (0.292-0.334) 57.9-62.7 17.2-21.3 20.4-24.3 1430-2630 0.89-1.55 16.2-17.5 1.39-2.72 (0.770-0.881) 87.8-104.0 (7.85-8.98) 19700-28000 26000-36500 19800-26600

7.5 0.168 (0.670) 19.23 1.75 (0.314) 60.3 19.6 22.4 2157 1.22 16.7 2.07 (0.827) 97.6 (8.43) 24100 31867 24067

Confined Disposal Facility (CDF)

12B

13A

13B

range

AVE

range

AVE

range

AVE

7.3-7.4 0.101-0.143 (0.200-0.214) 15.8-17.6 1.56-1.68 (0.094-0.100) 56.7-61.0 14.7-15.1 21.3-22.4 1050-1150 0.50-0.80 15.1-16.8 1.64-2.10 (0.261-0.324) 93.7-103.0 (2.52-2.70) 23800-24600 34800-36200 21200-31200

7.4 0.123 (0.213) 16.83 1.63 (0.098) 59.4 15.2 21.8 1107 0.66 16.1 1.89 (0.293) 98.2 (2.63) 24133 35667 24933

7.22-7.32 0.141-0.330 (0.694-0.948) 21.8-23.2 1.90-2.14 (0.325-0.444) 67.6-77.2 15.9-19.1 24.2-28.4 1070-1360 0.815-0.815* 17.8-20.9 1.69-2.20 (0.856-1.170) 97.2-112.0 (8.73-11.90) 20000-31300 25700-40000 24100-33300

7.26 0.309 (0.809) 22.67 2.00 (0.385) 71.33 17.30 25.70 1187 0.815* 18.87 1.97 (0.998) 104.1 (10.17) 24800 32167 27167

6.78-7.36 0.081-0.099 (0.403-0.590) 15.9-19.3 1.24-1.80 (0.194-0.319) 46.1-63.7 10.9-16.3 15.0-22.5 713-1100 0.97-1.14 12.2-16.9 1.19-1.83 (0.496-0.728)
66.8-89.4 (5.06-7.43) 18500-25600 27300-34200 20400-23500

7.11 0.089 (0.469) 17.3 1.54 (0.263) 55.5 13.97 19.13 916 1.07 14.73 1.51 (0.578) 79.3 (5.90) 22200 31267 22333

14A

14B

range

AVE

range

AVE

6.64-7.23 0.094-0.209 (0.387-2.170) 10.7-62.8 1.04-5.47 (0.181-1.010) 51.6-233.0 13.4-58.4 15.0-68.0 743-7730
1.05-4.6 16.8-45.3 1.16-4.79 (0.478-2.670) 64.7-239.0 (4.87-27.30) 16600-74800 35900-157000 25900-39600

6.87 0.157 (1.392) 30.7 2.65 (0.650) 117.1 28.47 34.93 3241 2.45 28.47 3.29 (1.716) 126.9 (17.52) 40200 81133 32967

7.39-7.72 0.281-0.513 (0.903-1.190) 18.5-19.1 1.61-1.88 (0.423-0.557) 61.1-79.2 13.0-15.2 15.8-20.5 755-2410 1.38-5.23 18.3-19.8 2.00-2.00* (1.110-1.470)
85.9-91.6 (11.40-15.00) 21000-48200 26300-65200 12000-40200

7.54 0.397 (1.016) 19.27 1.78 (0.476) 72.1 14.2 19.03 1356 2.79 19.17 2.00* (1.253) 89.7 (12.80) 32033 41233 23067

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REFERENCES
AASHTO. (1982). " AASHTO T-99 standard test methods for moisture density relations of soils and soil aggregate mixtures using 5.5 lb rammer and 12 in. drop." Standard specifications for highway materials and methods of sampling and testing, Part II, Washington.
(BIA) The Brick Industry Association, "Manufacturing of Brick". Technical Notes on Brick Construction (December 2006). Also available at http://www.gobrick.com/html/frmset_thnt.htm
Bortone, G., Palumbo, L., and SedNet (Organization). (2007). Sustainable management of sediment resources. Volume 2, Sediment and dredged material treatment, Elsevier, Amsterdam ; Boston.
Brownell, W.E. Structural clay products. Wien; New York: Springer-Verlag, 1976.
Buxton, J. E., Walker, J. T., and Carney, S. D. (2000). "Savannah Harbor Disposal Area Sediment Assessment Report." General Engineering Laboratories, Inc., Charleston, SC.
Casado-Martnez, M.C., Buceta, J.L., Belzunce, M.J., and DelValls, T.A. "Using sediment quality guidelines for dredged material management in commercial ports from Spain", Environment International 32 (2006) 388 396.
Demir, I. Effect of Organic Residues Addition on technological Properties of Clay Bricks. Waste Management, 28 (2008) 622-627
Hamer, K. and Karius, V. "Brick Production with Dredged Harbour Sediments. An Industrial-Scale Experiment", Waste Management, 22 (2002) 521530.
Huang, C., Pan, J.R., Sun, K.-D., Liaw, C.-T. "Reuse of Water Treatment Plant Sludge and Dam Sediment in Brick-Making", Water Science and Technology, Vol. 44 No. 10 (2001) pp 273277.
Jones JT, Berard, MF. Ceramics. Industrial Processing and Testing. 2nd Ed. Iowa State University Press, Ames, Iowa. 1993. 304p.
Karius, V. and Hamer, K. pH and grain-size variation in leaching tests with bricks made of harbour sediments compared to commercial bricks. The Science of the Total Environment, 278 (2001) 73-85
Karpuzcu, M., Buktel, D., Aydin, Z.S. "The Dewaterability, Heavy Metal Release and Reuse Characteristics of Golden Horn Surface Sediment". Water Science and Technology 34(7-8), 365-374 (1996)
63

Lafhaj, Z., Saliceto, A., Cohen, S.L., Coudray, Y., Huynh, T.T., Le Guen, B., and Anguoni, F., The use of the Novosol process for the treatment of polluted marine sediment, Journal of Hazardous Materials, 148 (2007) 606-612.
Lafhaj, Z., Samara, M., Agostini, F., Boucard, L., Skoczylas, F., and Depelsenaire, G., Polluted river sediments from the North region of France: Treatment with Novosol process and valorization in clay bricks, Construction and Building Materials, 22 (2008) 755-762.
Lee, C.R., Reclamation and beneficial use of contaminated dredged material: Implementation guidance for select options, DOER (The Dredging Operations and Environmental Research) Technical Notes Collection (TN DOER C-12), U.S. Army Engineer Research and Development Center, Vicksburg, MS, 2000. Also available at http://el.erdc.usace.army.mil/elpubs/pdf/doerc12.pdf
Liew, A.G., Idris, A., Samad, A.A., Wong, C.H.K., Jaafar, M.S., and Baki, A.M., Reusability of sewage sludge in clay bricks, Journal of Material Cycles and Waste Management, 6 (2004) 41-47.
Ndiba, P., Axe, L., and Boonfueng, T., Heavy metal immobilization through phosphate and thermal treatment of dredged sediments, Environmental Science and Technology, 42 (2008) 920-926.
Olin-Estes, T. J. and Palermo, M. R., Recovery of dredged material for beneficial use: The future role of physical separation processes, Journal of Hazardous Materials, 85 (2001) 39-51.
Phillips, J., Savannah Harbor presentation for general information, GaDOT Office of Intermodal Programs, January 2008
Romero, M., Andrs, A., Alonso, R., Viguri, J., and Ma. Rincn, J., Sintering behaviour of ceramic bodies from contaminated marine sediments, Ceramics International, 34 (2008) 1917-1924
Samara, M., Lafhaj, Y., and Chapiseau, C., Valorization of stabilized river sediments in fired clay bricks: Factory scale experiment, Journal of Hazardous Materials, 163 (2009) 701-710
Sheppard, W. L., Jr., Corrosion and chemical resistant masonry materials handbook, William Andrew Publishing/Noyes, 1986
US Department of Agriculture, Natural Resources Conservation Service (USDA NRCS), Heavy metal soil contamination. Soil quality Urban technical note No. 3., September 2000. ftp://ftp-fc.sc.egov.usda.gov/IL/urbanmnl/appendix/u03.pdf
U.S. EPA, Clean water act, sec. 503, vol. 58, no. 32., 1993 (U.S. Environmental
64

Protection Agency Washington, D.C.). U.S.EPA. AP 42 Compilation of air pollutant emission factors, 5th Edition, Vol. 1, January 1995 U.S. EPA. 40 CFR Section 503. Standards for the use or disposal of sewage sludge. Subpart 2: Land Application. Washington DC, 2010 http://ecfr.gpoaccess.gov/cgi/t/text/textidx?sid=2e066b696ec055d1d003a9b4cfc01ebc&c=ecfr&tpl=/ecfrbrowse/Title40/40cfrv2 9_02.tpl Winfield, L.E. and Lee, C.R., Dredged material characterization tests for beneficial use suitability, Technical note DOER-C2, May 1999 Zoubeir, L., Adeline, S., Laurent, C. S., Yoann, C., Truc, H. T., Benoit, L. G., and Federico, A. , The use of the Novosol process for the treatment of polluted marine sediment, Journal of Hazardous Materials, 148 (2007) 606-612.
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