at SciVerse ScienceDirect

Journal of Environmental Management 113 (2012) 128e136

Contents lists available

Journal of Environmental Management

journal homepage: www.elsevier .com/locate/ jenvman

Utilization of Savannah Harbor river sediment as the primary raw material inproduction of fired brick

Andrea Mezencevova*, Nortey N. Yeboah, Susan E. Burns, Lawrence F. Kahn, Kimberly E. KurtisGeorgia Institute of Technology, School of Civil and Environmental Engineering, 790 Atlantic Dr. NW, Atlanta, GA 30332-0355, USA

a r t i c l e i n f o

Article history:Received 23 September 2011Received in revised form2 July 2012Accepted 14 August 2012Available online 24 September 2012

Keywords:River sedimentRecyclingBuilding brickCompressive strengthWater absorption

* Corresponding author. Tel.: þ1 404 385 0064.E-mail addresses: andrea.mezen@gatech.edu (A

gatech.edu (N.N. Yeboah), susan.burns@ce.gatechce.gatech.edu (L.F. Kahn), kkurtis@ce.gatech.edu (K.E.

0301-4797/$ e see front matter � 2012 Elsevier Ltd.http://dx.doi.org/10.1016/j.jenvman.2012.08.030

a b s t r a c t

A laboratory-scale study was conducted to assess the feasibility of the production of fired bricks fromsediments dredged from the Savannah Harbor (Savannah, GA, USA). The dredged sediment was used asthe sole raw material, or as a 50% replacement for natural brick-making clay. Sediment bricks wereprepared using the stiff mud extrusion process from raw mixes consisted of 100% dredged sediment, or50% dredged sediment and 50% brick clay. The bricks were fired at temperatures between 900 and1000 �C. Physical and mechanical properties of the dredged sediment brick were found to generallycomply with ASTM criteria for building brick. Water absorption of the dredged sediment bricks was incompliance with the criteria for brick graded for severe (SW) or moderate (MW) weathering.Compressive strength of 100% dredged sediment bricks ranged from 8.3 to 11.7 MPa; the bricks sinteredat 1000 �C met the requirements for negligible weathering (NW) building brick. Mixing the dredgedsediment with natural clay resulted in an increase of the compressive strength. The compressive strengthof the sediment-clay bricks fired at 1000 �C was 29.4 MPa, thus meeting the ASTM requirements for theSW grade building brick. Results of this study demonstrate that production of fired bricks is a promisingand achievable productive reuse alternative for Savannah Harbor dredged sediments.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

The Savannah Harbor, located on the South Atlantic U.S. coast,comprises the lower 34.3 km of the Savannah River and 18.4 km ofchannel across the bar to the Atlantic Ocean. The Georgia Depart-ment of Transportation (GDOT) and the U.S. Army Corps of Engi-neers are responsible for maintaining the navigability of theSavannah River by dredging the inner harbor and bar channel.Annually, 5.9 million cubic meters of dredged sediments is exca-vated and placed in several disposal areas in Jasper County, SouthCarolina (USACE, 2007). Increasing dike elevations eventuallyrequiring dredge booster pumps, and proposed changes in land usearound and in Jasper County, stemming from South Carolina’sinterest in establishing a port in that region, have spurred renewedinterest in identifying options for productive reuse of the dredgedmaterial. Beneficial uses of dredgedmaterial have been discussed inmany forums, from aquatic, island, beach renourishment, wetland,and upland habitat to strip-mine reclamation and construction inindustrial/commercial uses (Lee, 2000).

. Mezencevova), nyeboah3@.edu (S.E. Burns), lkahn@Kurtis).

All rights reserved.

Given the composition of the sediment and its continuousavailability, it is likely that this material may be suitable as a majorcomponent for manufacturing of bricks. Although the lack ofestablished contaminant level and testing requirements forproductive reuse of dredged sediments may complicate theirbeneficial use for brick making, there are many examples ofsuccessful productive reuse of these sediments world-wide fromwhich much can be learned. In recent decades brick making hasbeen assessed using river and marine sediments (Casado-Martínezet al., 2006; Collins, 1980; Hamer and Karius, 2002; Karpuzcu et al.,1996; Lafhaj et al., 2008; Romero et al., 2008; Samara et al., 2009;Torres et al., 2009), sediments from lakes and dams (Chiang et al.,2008; Huang et al., 2001; Wu et al., 2012), and sewages (Cusidóand Cremades, 2012; Liew et al., 2004). The U.S. Army Corps ofEngineers also recognized dredge material as a potential beneficialraw material in brick production (Winfield and Lee, 1999).

Many studies show that river andmarine sediments can be usedas natural clay replacement in producing of bricks that comply withconstruction standards and legislative environmental requirements(Hamer and Karius, 2002; Samara et al., 2009). In Germany, brickswith 50 wt.% of sediments dredged out of the Bremen harbor weremanufactured in an industrial-scale experiment. Tests performedon the bricks did not show leaching of heavy metals to such extentthat would have hazardous impact on the environment (soil,

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136 129

groundwater) and would restrict the application of the dredgedbricks. During the sintering process, most metal contaminantswerefixed in new minerals and immobilized within the brick matrix(Karius and Hamer, 2001). Organic materials volatized during firingcould necessitate scrubbing of brick kiln emissions. Even so,emissions controls would already be in place at brick plants asmandated by the Clean Air Act (US EPA, 2003). Thus, any necessaryadjustments to emissions controls resulting from the introductionof dredge sediments into the brick making process may not beexcessively taxing.

Most of the studies found in the literature have reported theutilization of dredged material as a minor (Karpuzcu et al., 1996;Samara et al., 2009; Torres et al., 2009) or amajor component (Chianget al., 2008) of the brick-making mix. Preliminary bench scaleexperiments on dredged sediments from a basin in Elba Island inSavannah Harbor (Brosnan, 2008) did not find this material to besuitable for the use as the sole raw material in fired ceramic. Theobjective of this researchwas to identifyappropriatemixproportionsand processingmethodology for laboratory production of fired brickusing Savannah River dredged sediments as the primary constituentof the brick-making mix, and to demonstrate the possibility of theuse of such materials in manufacturing of good quality brick.

2. Materials and methods

2.1. Materials

Sediment dredged from the Savannah Harbor is placed inupland confined disposal facilities (CDFs) adjacent to the harbor.The dredged material is a mixture of sands and fines (clays andsilts). Sand is the predominant material in the lower and upperreaches of the harbor, while clay/silt material is removed from themiddle harbor and sediment basin. As dredged sediments arepumped into the upland disposal facilities, a natural particle sizeseparation occurs within each facility. Fine silts and clays arecarried into the deeper portions of the pond, and more bulky,coarse grained materials are retained near the inlet. Representativesamples of clay/silt and sand dredged material to be used for brickproduction were collected from several CDFs. For material charac-terization testing, five grab samples of the sediment were obtainedfrom three sub areas of each CDF. The grab samples were combinedto form one composite sample for each of the sub areas.

In addition, a sample of natural clay soil obtained from a localbrick manufacturing facility in Georgia was used as a reference toaid in the assessment of the suitability of the dredge for brickmaking. This natural clay was also used for bench scale productionof bricks.

2.2. Material characterization

Physical characterization of the dredged sediment includedparticle size characterization, and plasticity and specific gravityevaluation. The tests were performed using existing standards forsoil testing. Particle size analysis was conducted by dry sieving andhydrometer testing in accordance with ASTM D 422. Plasticityanalysis was performed using the British Standard BS 1377 for theliquid limit (LL) and ASTM D 4318 for the plastic limit (PL). Thematerial was dried in a laboratory oven at 105 � 5 �C for 24 h priorto the analysis. For the LL and PL measurements the samples werenot sieved over a #40mesh prior to testing, as recommended by therespective standards. Thus the LL and PL results represent the bulksample. Specific gravity tests were conducted in agreement withASTM D 854.

Oxide analysis of the materials was determined by x-ray fluo-rescence (XRF) method, and crystalline minerals present in the

material were identified by x-ray diffraction (XRD) analysis underCu-Ka radiation. These analyses were done on the dried material.Metal content was determined using inductively coupled plasma(ICP) spectroscopy. The samples were acid digested and theirfiltrates were used for analysis. The pH was measured on waterslurries using electrode analysis.

2.3. Laboratory scale brick production

Brick samples were formed using the stiff mud extrusionprocess (Fig. 1). Table 1 summarizes the compositions of raw mixesused for this laboratory scale brick production. Mixes 1e6 consistedof 100 wt. % dredged sediment (80% clay/silt sediment and 20%sand sediment); mix 7 contained 50% dredged sediment and 50%natural clay soil currently used in the brick production at a localmanufacturing facility. Reference bricks containing 100% clay soil(mix 8) were also prepared in this experiment. Only a minimalamount of other additives, such as soybean oil to improve the mixlubricity, and BaCO3 to prevent scum formation were added to therawmixtures. Thematerials were dried at 105� 5 �C, so an accurateamount of water could subsequently be added to the mixes. Thenthey were crushed and passed through a 2 mm sieve, blended withwater and other additives, and processed in a laboratory-scale pugmill (Peter Pugger VPM-30) to produce a homogeneous mix.Moisture content of the dredged sediment bricks, as measured onextruded bricks, varied from 30 to 47% by weight. Moisture contentof the reference clay bricks was 25%.

Extruded wet brick columns were cut into smaller brick blocksof 5.4 cm � 5.4 cm � (5e10) cm and thermally processed. Bricksamples were dried in an oven at temperature gradually increasingfrom 25 �C to 110 �C until no change in mass was observed. Driedspecimens were then fired at different temperatures from 900 �C to1000 �C in an electric laboratory furnace with variations in heatingrate and hold duration at the maximum temperature (Table 1).Cooling occurred by natural convection inside the furnace after itwas turned off.

2.4. Characterization of fired bricks

Fired brick samples were sampled and tested in accordancewithASTM C 67 and ASTM C 373. Physical and engineering properties ofbricks were compared with the ASTM C 62 criteria for buildingbrick.

Linear drying shrinkage on the dry basis (LDSd), linear firingshrinkage (LFS) incorporating both drying and firing shrinkage, andweight loss on ignition (LOI) were calculated according to thefollowing equations:

LDSd ¼�Lf � Ld

�.Ld � 100ð%Þ (1)

LFS ¼�Lf � LF

�.LF � 100ð%Þ (2)

LOI ¼�md �mf

�.md � 100ð%Þ; (3)

where Lf, Ld and LF is the length of the formed, dried and firedspecimen, respectively; md is the oven dry weight and mf is theweight of the fired specimen.

For the water absorption test, dry brick specimens weresubmerged in water at room temperature for 24 h, and weighed.The same specimens were then boiled in water for 5 h, cooled andweighed again. Water absorption after 24-h submersion in coldwater (A24c) and after 5-h submersion in boiling water (A5b), as wellas the saturation coefficient (SC), which is the ratio of 24-h cold-

Fig. 1. Laboratory scale brick production: (a) raw material mixing, (b) extrusion of a brick column, (c) dried brick, (d) fired bricks.

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136130

water absorption to the 5-h boiling absorption, were calculated asfollows:

A24c ¼ ðmc �mdÞ=md � 100ð%Þ (4)

A5b ¼ ðmb �mdÞ=md � 100ð%Þ (5)

SC ¼ ðmc �mdÞ=ðmb �mdÞ; (6)

where m is saturated weight in air, md is oven dry weight, mc issaturated weight after 24-h submersion in cold water, and mb issaturated weight after 5-h submersion in boiling water.

Table 1Raw mix compositions and the firing conditions used for laboratory brickproduction.

Mix Mix composition (% wt) FiringT (�C)

Dredged material Naturalclay soil

Soybeanoil

BaCO3 Water

Clay/silt Sand

1 80 20 e 0.1 0.5 32 950a

2 80 20 e 0.1 0.5 36 950, 1000a

3 80 20 e 0.1 e 37 950, 1000a

4 80 20 e 0.1 0.5 38 950a

5 80 20 e 0.1 e 40 900, 950,1000a

6 80 20 e 0.1 0.5 47 950a

7 40 10 50 0.1 e 30 950, 1000a

8 e e 100 e e 25 1000b

a Heating rate: 4.6 �C/min from 25 �C to 300 �C, 1.7 �C/min from 300 �C tomaximum T, 5 h hold at the max T.

b Heating rate: 1.7 �C/min from 25 �C to maximum T, 5 h hold at the max T.

Compressive strength was measured using a hydraulic testingmachine in accordance with ASTM C 67. Resistance of the bricks todamage by freezing when wet was evaluated by the freeze-thawtest prescribed in ASTM C 67. In addition to the engineering prop-erties, mineralogical composition of bricks was evaluated by XRDanalysis.

3. Results and discussion

3.1. Properties of dredged sediment

Physical properties of the clay/silt dredged sediment, includingparticle size distribution, plasticity and specific gravity, aresummarized in Table 2 and compared with physical characteristicsof natural clay soil currently used for brick production at a local

Table 2Particle size distribution, plasticity analysis and specific gravity of dredged clay/siltsediment. The data are compared with natural clay soil from a local brickmanufacturing facility.

Clay/silt dredged sediment Naturalclay

Range Average

Sand (%) 8e26 15 26Silt (%) 29e43 38 34Clay (%) 32e63 47 40Liquid limit 82.6e116.3 99.2 98.7Plastic limit 48.1e52.1 49.5 51.2Plasticity index 34.5e64.2 49.7 47.4Specific gravity (g cm�3) 2.55e2.66 2.61 e

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136 131

brick plant. The table shows variability in clay, silt and sandcompositionwithin the samples of dredgedmaterial collected fromthree confined disposal sites (CDFs) along with the average valuesamong the samples. The silt content in the dredged material rangesfrom 29 to 43% by weight with the average value of 38%, which isa little higher than the silt content in the natural clay (34%). Silt isconsidered a problematic material in brick production because it isnonplastic or very slightly plastic, and exhibits little or no strengthwhen air dry (Head, 1980). On the other hand, the average clayparticle content in the dredged material was 47%, which is higherthan that in the natural clay soil (40%). Higher fractions of clayresult in higher surface area which requires higher amount ofwater for the material to be plastic. The ratio of silt fraction to clayfraction within the raw material influences the quality of the finalproduct with higher silt/clay ratios resulting in weak and porousbrick. The silt/clay ratios in the dredged sediment and clay soilwere approximately equal; the value was about 0.8 for bothmaterials.

The average sand content in the clay/silt dredged material was15%, which was much lower than the sand content in the naturalclay (26%). This is important to note, as in brick making, the coarsefraction in the raw mix is significant for reducing shrinkage duringfiring. The low content of sand particles suggested that additionalsand would likely need to be added into the clay/silt dredgedmaterial to achieve a particle size distribution similar to that of thenatural clay. The specific gravity of the oven dried clay/silt dredgedmaterial was about 2.6 g cm�3.

Raw materials for brick production must possess some specificproperties and characteristics, e.g. plasticity that allows them to bemolded or shaped and to hold their shape during drying and firing.Inadequate plasticity can result in extrusion failure and develop-ment of heterogeneities in the brick body that can result in weakmechanical properties. As seen in Table 2, plasticity characteristicsof the clay/silt sediment were comparable with that of the naturalclay sample.

Chemical composition data of the clay/silt dredged sedimentexpressed as percentage of major oxides are shown in Table 3 andare compared with chemical composition of the natural clay soil.The data indicate that the main components in the dredgedmaterial were SiO2, Al2O3, Fe2O3, CaO, MgO and K2O. The SiO2content is mainly associated with quartz particles, as well as Si andAl oxides can be associated with kaolinite structure present in thematerial. Iron oxide, Fe2O3, is the main colorant in clays and isresponsible for the reddish color after firing. The dredged materialalso contained constituents that may act as fluxes and promotefusion of the particles at lower temperatures during the firingprocess, such as potassium, sodium and calcium oxides. Incomparison with the composition of the natural clay chemicalanalysis of the dredged sediment showed no anomalies.

Table 3Oxide analysis and loss on ignition (LOI) of the clay/silt dredged sediment comparedwith natural clay soil from a local brick manufacturing facility.

Composition (wt.%) Dredged sediment Natural clay

SiO2 54.79 60.45Al2O3 17.23 20.06Fe2O3 7.40 8.13CaO 2.03 0.07MgO 1.62 0.98K2O 1.36 2.63Na2O 0.61 0.35TiO2 0.87 0.98MnO 0.19 0.09P2O5 0.32 0.09LOI 12.81 6.06

Table 3 shows that loss on ignition (LOI) of the clay/silt dredgedsediment was 12.8%, which was about twice as high as LOI of thenatural clay soil. The LOI value is related to the dehydroxylation ofthe clayminerals, oxidation of the organic matter, decomposition ofcarbonates, sulfides, hydroxides, etc. A certain amount of organicmatter is desirable since it can contribute to a greater plasticity(Kirchhof, 2006); however extensive total organic carbon contentmay render dredged material useless for brickmaking.

An x-ray diffraction analysis was performed to identify thecrystalline phases of the clay/silt dredged sediment. In general, thephase composition of the sediment is complex and is similar to thephase composition of natural clay soil. The major phases found inthe dredged material included quartz and clay minerals of thekaolin group minerals, such as kaolinite, dickite, nacrite thatmaintain the shape of the brick body during firing. Also traces offeldspars that act as fluxes and promote fusion of the particles atlower temperatures during the firing process were detected(Worrall, 1986).

Soluble cations and anions identified in the clay/silt dredgedsediment are presented in Table 4. Water soluble salts, mostlysulfates of calcium, magnesium, sodium and potassium, present inthe dredged material are expected to be associated with theformation of a whitish scum during drying of bricks; such scum canbecome permanently fixed during burning and can negativelyaffect the aesthetical appearance of bricks. Calcium sulfate, CaSO4,is the most troublesome as it can persist through the firingoperation. The other salts mentioned above melt, decompose orreact with silicates during firing. However, when gaseous SO3adsorbs on the internal silicate surfaces due to exposure tosulfurous gases during firing and cooling, sulfuric acid can beformed which will dissolve Mg, Na and K from various crystallineand glassy phases (Brownell, 1976). These solutions can thenmigrate to the brick surface and salt deposition occurs. In addi-tion, soluble salts such as chlorides and sulfates present in theraw dredged material can become a source of gaseous pollutants,such as oxides of sulfur (SO2, SO3) and hydrogen chloride, HCl(U.S.EPA, 1995).

Productive reuse of dredged sediments can be problematic dueto elevated levels of both organic and inorganic contaminants fromagricultural, industrial and municipal activities (Bortone et al.,2007; Lafhaj et al., 2008; Ndiba et al., 2008). The primary pollut-ants of concern in river and marine sediments include heavymetals. The most common problem causing cationic metals(metallic elements whose forms in soil are positively chargedcations e.g., Pb2þ) are mercury, cadmium, lead, nickel, copper, zinc,chromium, and manganese (USDA NRCS, 2000). The most commonanionic compounds (elements whose forms in soil are combinedwith oxygen and are negatively charged e.g., MoO4

2�) are arsenic,molybdenum, selenium, and boron. Total metal concentrations andtotal organic carbon in the clay/silt dredged material, as well as itspH values were obtained from historical data in the GDOT files(Buxton et al., 2000) and are summarized in Table 5. In the U.S.,testing criteria and acceptable contaminant levels for dredgedsediments that could be considered for productive reuse have notbeen established. For reference, the regulatory limits on potentially

Table 4Soluble cation and anion analysis of the clay/silt dredged sediment.

Cations (ppm) Anions (ppm)

Sodium 750 Fluoride 61.2Potassium 240 Chloride 190Magnesium 220 Bromide 4.3Calcium 934 Nitrate 44.3

Sulfate 2880

Table 5pH and metal contents (ppm) of clay/silt dredged sediment compared with theregulatory limits on heavy metals in sewage sludge applied to agricultural land (U.S.EPA, 2010).

Dredged sediment U.S.EPA

Range AVE a b

pH 6.78e7.43 7.2 e e

Metal content (ppm)As 15.80e23.20 18.93 75 41Cd (0.094e0.444) (0.249) 85 39Cr 46.10e77.20 62.07 e e

Cu 10.90e19.10 15.49 4300 1500Pb 15.00e28.40 22.20 840 300Mo 0.498e1.140 0.858 75 e

Ni 12.20e20.90 16.58 420 420Se 1.19e2.20 1.77 100 100Zn 66.80e112.00 93.87 7500 2800

Values in parenthesis ( ) are mean detection limit values. It indicates that thecomponent was analyzed but not detected above the detection limit.

a Maximum concentration.b Monthly average concentrations.

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136132

toxic metals in sewage sludges (biosolids) applied to agriculturalland set by the U.S. Environmental Protection Agency are presented(U.S.EPA, 2010).

As Table 5 shows, no hazardous concentrations of heavy metalswere detected in the dredged material. Moreover, an advantagefor selecting fired bricks as a potential productive reuse option ofthe dredged material is that most metal contaminants are con-verted to stable compounds within the brick matrix or volatilizedduring the firing process. Successful contaminant immobilizationin fired bricks has been demonstrated for dredged sediments(Bernstein et al., 2002; Hamer and Karius, 2002; Karius andHamer, 2001).

3.2. Properties of bricks

3.2.1. Physical appearanceLaboratory-size clay bricks were prepared from raw mixes

containing 100% (mixes 1e6), 50% (mix 7), and 0% (mix 8) of thedredged sediment, as seen in Table 1. All the mixes, including the100% dredged sediment mixtures were found to be extrudable(Fig. 1b). However, a relatively high water content (ratio of the massof water to the mass of the dried rawmaterial) ranging from 32% to47% was required in the 100% dredged sediment mixes to achievegood mixing and to maintain an adequate plasticity. For compar-ison, the water content of a raw mix in extrusion processes in brickplants is normally about 19%. The higher water demand wasprobably a result of higher organic matter content in the dredgedmaterial which may impart a higher absorption capacity. Also, thelaboratory pug mill was not as efficient as commercial scaleextruders and was not able to process stiff mixes with lower watercontents. Based on the high water content of fresh bricks, a risk offormation of cracks during the drying process was expected. It isknown that during drying water evaporates from the surface whilethe interior water diffuses to the surface through interconnectedpores. If the rate of water evaporation from the surface is greaterthan the rate of water migration from the interior toward thesurface, the air/water interface will move inward and the surface ofthe brick will dry faster than the interior. This causes the surfacelayers to shrinkwhile the interior layers remain less affected, whichcreates a network of tension cracks in a brick (Jones and Berard,1993). Reducing the dredged sediment content in a mix resultedin a lower water demand. The moisture content of fresh bricksprepared from mix 7 that contained 50% dredged sediment was

30%, and the moisture content of bricks prepared from mix 8 with0% dredged sediment was 25%.

To prevent or minimize the formation of drying shrinkagecracks, a gentle heating to encourage water migration toward thesurface was combined with high humidity to suppress evaporation,so that bricks would dry uniformly. As drying progressed, thetemperature was gradually raised and the humidity graduallylowered so that evaporation and seepage rates would remainreasonably high. Despite the very careful drying process, shrinkagecracks were formed in bricks prepared from mixes with higherwater content. The effect of the moisture content of the rawmix onformation of drying and firing shrinkage cracks is shown on Fig. 2.The figure compares 100% dredged sediment bricks made of mix 6containing 47% water (Fig. 2a and b) and mix 2 containing 36%water (Fig. 2c and d). Bricks with the higher water content weremore susceptible to cracking; no drying shrinkage cracks wereobserved in brick specimens with the lower water content (Fig. 2c),which later resulted in more successful firing (Fig. 2d). Aestheti-cally, with a relatively uniform red color, bricks produced from thedredged material were attractive. The hue changed and becamedarker with rising firing temperature.

The addition of barium carbonate BaCO3 in the rawmix was alsoshown to affect the physical appearance of brick by controlling thedeposition of a white scum on the brick surface as a result of thepresence of water soluble salts. White staining was observed onbricks prepared from the mixes that did not contain BaCO3, whilethe surface of the bricks containing BaCO3 did not show any pres-ence of such scum. Barium carbonate immobilized water solublesalts present in the dredged sediment by converting them intoinsoluble carbonates that remain distributed throughout the massof the brick instead of being deposited on the surface.

3.2.2. Microstructural analysisXRD analysis of the fired bricks indicated that the major mineral

phases present were quartz SiO2 and hematite Fe2O3. Traces ofanorthite CaAl2Si2O8 were present in the dredged sediment brick.Mullite, a very stable crystalline product of thermal decompositionof aluminosilicates that contributes to the compressive strength ofbricks, was not observed. This phase usually forms above 1000 �C(Grimshaw, 1971).

3.2.3. Dimensional changesThe length changes of selected dried and fired brick specimens

are summarized in Table 6 and Fig. 3. The results show that themagnitude of shrinkage of the brick samples was affected by themoisture content of the raw mix. Since the individual particles thatmade up the wet bricks contain thin layers of water, the removal ofthis water causes these high surface-area particles to contracttogether, resulting in an overall decrease in the dimensions of thebricks. Fig. 3a shows the effect of the moisture content of the rawmix on the linear drying shrinkage of the 100% dredged sedimentbricks (mixes 1e6). The drying shrinkage increased with increasingmoisture content. According to the Brick Industry Association (BIA,2006), drying shrinkage varies for different clays, usually fallingwithin the range of 2e4%. Linear drying shrinkage of 100% dredgedsediment brick samples was above this range and varied from 5.9to 9%.

Linear firing (total) shrinkage increased with increasing mois-ture content in the raw mix and with increasing firing temperature(Table 6, Fig. 3b). For the 100% dredged sediment bricks the totalshrinkage ranged from 10.3 to 15.7%. As expected, the lowest firingshrinkage among these bricks was observed in bricks preparedfrom the batchwith the lowest moisture content, i.e. 32%. Normally,a good quality brick exhibits total shrinkage below 8% (BIA, 2006).As Table 6 shows, the firing shrinkage of only 100% natural clay

Table 6Linear drying shrinkage (LDS), linear firing (total) shrinkage (LFS) and weight loss onignition (LOI) of 100% dredged sediment bricks (mixes 1e6), 50% dredged sediment/50% natural clay bricks (mix 7), and 100% natural clay bricks (mix 8).

Mix no MC (%) LDS (%) T (�C) LFS (%) LOI (%)

100% dredged sediment bricks1 32 5.9 950 10.3 10.62 36 7.7 950 11.6 10.0

1000 12.4 10.1

3 37 8.0 950 12.6 11.01000 13.4 11.2

4 38 8.1 950 12.8 10.85 40 8.8 900 13.2 10.8

950 13.5 11.01000 13.7 11.1

6 47 9.0 950 15.7 11.5

50% dredged sediment e 50% natural clay bricks7 30 6.4 950 10.1 8.8

1000 11.4 9.0

100% natural clay bricks8 25 nd 1000 4.7 2.9

MCemoisture content of the rawmix, Te firing temperature, nde not determined.

Fig. 2. Effect of the water content on formation of cracks in 100% dredged sediment bricks dried at 110 �C (a, c) and fired at 950 �C (b, d).

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136 133

bricks was below this limit. The higher linear shrinkage of thedredged sediment bricks was a result of relatively high moisturecontent in the raw mixes. Moisture content, as measured onextruded bricks, varied from 32 to 47%, was higher as compared tothe w19% moisture content that is normally used in extrusionprocesses in brick plants. As previously stated, this high demand ofwater was most probably due to a higher content of organic resi-dues in the dredged material as well as the lower capability of thelaboratory extruder to process stiffer blends. The organicsubstances in soil have a high absorptive capacity for water that isassociated with their high specific surface. With a higher amount ofwater the brick mix expanded more, which resulted in a greatershrinkage when the water was forced out during the dryingprocess.

Table 6 also shows the weight loss on ignition (LOI) of the firedbricks. The brick LOI is a weight loss that is not only attributed tothe organic matter content in the dredged material, but it alsodepends on the inorganic substances in thematerial being burnt offduring the firing process. The LOI criterion for a normal clay brick is15% (AASHTO, 1982). As can be seen in Table 6, all the bricks madefor this study meet the weight loss criteria.

3.2.4. Water absorptionWater absorption is based on the amount of open or surface-

accessible pores in a fired specimen and is one of the key

Table 724 h absorption in cold water (A24c), 5 h absorption in boiling water (A5b) andsaturation coefficient (SC) of selected fired bricks compared with the ASTM C 62criteria for building brick.

Mix no MC (%) Firing T (�C) A24c A5b SC ASTMgrade

100% dredged sediment bricks1 32 950 11.4 15.3 0.75 SW5 40 900 15.0 18.8 0.80 MW

950 14.1 17.8 0.79 MW1000 11.8 15.8 0.74 SW

50% dredged sedimente50% natural clay bricks7 30 950 10.5 13.8 0.77 SW

1000 7.9 10.7 0.74 SW

100% natural clay bricks8 25 1000 11.0 11.3 0.98 SW

ASTM C 62 specifications for building brick

Grade Max A24, cold Max A5, boil Max SCSW e 17.0 0.78MW e 22.0 0.88NW e No limit No limit

MCemoisture content of the rawmix, SW, MW, NW indicate severe, moderate andnegligible weathering, respectively.

Fig. 3. Effect of the water content of the raw mix in 100% dredged sediment bricks(mixes 1e6) on (a) linear drying shrinkage and (b) linear firing shrinkage. Bricks werefired at 950 �C. Error bars represent the standard deviations. According to BIA (2006),drying shrinkage of regular clay bricks is 2e4%, and firing shrinkage usually fallsbelow 8%.

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136134

factors affecting the durability of brick. The higher amount ofwater that infiltrates the brick, the more susceptible is thismaterial to damage by freezing. The 24 h absorption in cold waterand 5 h absorption in boiling water were determined on selectedbricks using the procedures described in ASTM C 67. The resultsof the test are summarized in Table 7, and are compared withthe ASTM C 62 specifications for water absorption properties ofbuilding brick.

The results indicate that water absorption values of the dredgedbricks increased with increasing moisture content of the raw mix,and decreased with increasing temperature of firing. The waterabsorption of the tested bricks was in compliance with the criteriafor ASTM C62 building brick. Five-hour absorption in boiling waterof almost all tested bricks was below the maximum absorptionvalue of 17% required for building brick exposed to severe weath-ering (SW). Only bricks prepared from themix 5 that contained 40%water and fired at 900 �C and 950 �C had the boiling waterabsorption above 17%. However, this absorption value was below22%, thus complying with the absorption requirements for buildingbrick exposed to moderate weathering (MW).

3.2.5. Compressive strengthThe compressive strengths of 100% dredged sediment bricks

(mixes 1, 3 and 5) and 50% dredged sediment-50% natural claybricks (mix 7) are shown in Fig. 4. As the results show, thecompressive strength was affected by the mix composition andfiring temperature, with higher compressive strength valuesbeing associated with higher firing temperature. The data indicatethat the average values of compressive strength of the 100%dredged sediment bricks fired at different temperatures between

900 and 1000 �C ranged from 8.3 to 11.7 MPa. The compressivestrengths of 100% dredged sediment bricks fired at 1000 �C wereabove 10.3 MPa, which is the minimum ASTM C62 limit for thelowest grade (NW) building brick. Also bricks made from mix 1and fired at 950 �C met the criteria for grade NW brick. Thecompressive strengths of bricks prepared from mixes 2 and 3 andfired below 1000 �C did not comply with the ASTM requirements.Mixing the dredged sediment with natural clay (mix 7) resulted ina substantial increase in the compressive strength of bricks firedat 1000 �C. The average compressive strength of these bricks was29.4 MPa, thus meeting the ASTM requirements for the highest(SW) grade building brick. The results show that the optimalfiring temperature for maximum compressive strength was1000 �C.

3.2.6. Freeze- thaw resistanceBased on the compressive strength results, the freeze-thaw

resistance test was undertaken on 50% dredged sediment-50%natural clay bricks (mix 7) fired at 1000 �C. The strength of thesebricks met the ASTM C 62 requirements for the severe weathering(SW) grade bricks. Grade SW bricks are intended for usewhere highand uniform resistance to damage caused by cycling freezing isdesired. For comparison, 100% dredged sediment bricks made frommix 3 and fired at 950 �C were subjected to this test, although theydid not pass the ASTM limit for the minimum strength. Testedbricks were subjected to 50 cycles of freezing and thawing, asprescribed in ASTM C 67. After the completion of the test, brickswere first dried in open air at room temperature and then in anoven at 105 �C. Their weight loss was calculated as a percentage ofthe weight of the dried specimen measured before the freeze-thawtest.

The weight loss of the 50% dredged sediment-50% natural claybricks ranged from 0.16 to 0.25%, with an average value of 0.20%.According ASTM C 62, theweight loss of individual building brick ofgrade SW shall not be greater than 0.5%. The tested dredgedsediment-natural clay bricks complied with this requirement. Inaddition, no breakage and cracking due to repeated freezing andthawing occurred on the tested bricks. The weight loss of the 100%dredged sediment bricks ranged from 0.33 to 0.45%. These valueswere higher in comparison with the weight loss of the dredged

Fig. 4. Compressive strength of 100% dredged sediment bricks (mixes 1, 3, 5) and 50% dredged sediment-50% natural clay bricks (Mix 7) compared with ASTM C62 requirements forbuilding brick. Error bars represent the standard deviations.

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136 135

sediment-natural clay bricks, but they still were below the 0.5%limit. Also, the 100% sediment bricks did not show any signs ofcracking after the completion of the freeze-thaw test.

4. Conclusions

The possibility of making bricks using Savannah Harbor dredgedsediments as the primary material was investigated in this study.From the experimental investigation reported in this paper, thefollowing conclusions are derived:

� Physical and chemical characteristics of sediments dredgedfrom the Savannah Harbor showed no anomalies that wouldnecessarily preclude their beneficial reuse in production offired brick. Bricks prepared from 100% dredged sedimentmixtures and 50% dredged sediment-50% natural claymixtures, blended with minimal amounts of additives such assoybean oil and barium carbonate, were successfully producedin laboratory-scale production test runs. Due to a relativelyhigh water content in the raw mixes (30e47%) linear dryingand firing shrinkages of dredged sediment brick samplesexceeded the BIA shrinkage limits for good quality brick.Despite the higher firing shrinkage, the fired bricks, except forthe mix with the highest moisture content of 47%, showed nocracking or exhibited only minor cracks.

� Physical and mechanical properties of the bricks were found togenerally comply with ASTM C 62 criteria for building brick.The water absorption values of the dredged bricks increasedwith increasing moisture content of the raw mix, anddecreased with increasing temperature of firing. The waterabsorption of the bricks was in compliance with the ASTM C62criteria for building brick exposed to severe weathering (gradeSW) or moderate weathering (MW).

� Compressive strength test showed that the most favorablefiring temperature for maximum compressive strength was1000 �C. The average compressive strengths of 100% dredgedsediment bricks fired at 1000 �C were in compliance withASTM brick criteria for the lowest grade (NW) building brick.When natural clay was mixed with the dredged sediment, theaverage strength of bricks fired at 1000 �C was 29.4 MPa, wellabove 20.7 MPa, which is the minimum limit for the severeweathering (SW) building brick. These bricks also passed thefreezing and thawing test. Among the bricks fired at temper-atures below 1000 �C, only the 50% dredged sediment-50%

natural clay bricks and the 100% dredged sediment bricksfrom the mix containing the lowest moisture content, bothfired at 950 �C, had compressive strengths that complied withthe requirements for ASTM C 62 grade NW brick (10.3 MPaaverage). Additional testing needs to be done to prove that thisdredged sediment is suitable for the production of brick.

� The results demonstrate that production of fired bricks isa promising and achievable productive reuse for SavannahHarbor dredged sediments, and that this waste material couldbe a valuable resource of the rawmaterials in brick production.Even if the dredged sediment was used as the primary (100%)raw material, it could be turned into a relatively good qualitybrick. When the dredged sediment was used as a partialreplacement (50%) for natural clay, the quality of fired bricksubstantially improved. Beneficial use of the dredged sedimentwould slow its accumulation on land, thus reducing the costassociated with maintenance of the dikes and of building newdikes. Reuse of the sediments would improve sustainabilityand would have a positive impact on the environment bypreventing depletion of natural clay resources.

� The existing results found in the literature have not demon-strated success in the use of such silty materials in brickmanufacture. This research shows a pathway to overcomea significant challenge by using materials which are notconsidered appropriate for brickmaking based upon conven-tional practice.

Acknowledgement

The research presented in this paper was sponsored by theGeorgia Department of Transportation (GDOT). The authors wouldlike to thank GDOT professionals John Phillips and David Griffin(Waterways Program Managers, Office of Intermodal Programs,GDOT) for their valuable support and guidance.

References

AASHTO T-99, 1982. Standard Test Methods for Moisture Density Relations of Soilsand Soil Aggregate Mixtures Using 5.5 lb rammer and 12 in. drop. StandardSpecifications for Highway Materials and Methods of Sampling and Testing,Part II, Washington.

ASTM C 62, 2005. Standard Specification for Building Brick (Solid Masonry UnitsMade from Clay or Shale).

ASTM C 67, 2009. Standard Test Methods for Sampling and Testing Brick andStructural Clay Tile.

A. Mezencevova et al. / Journal of Environmental Management 113 (2012) 128e136136

ASTM C 373, 1988. (R 2006). Standard Test Method for Water Absorption, BulkDensity, Apparent Porosity, and Apparent Specific Gravity of Fired WhitewareProducts.

ASTM D 422, 1963. (R 2007). Standard Test Method for Particle-size Analysis ofSoils.

ASTM D 854, 2006. Standard Test Methods for Specific Gravity of Soil Solids byWater Pycnometer.

ASTM D 4318, 2005. Standard Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of Soils.

Bernstein, A.G., Bonsembiante, E., Brusatin, G., Calzolari, G., Colombo, P.,Dall’Igna, R., Hreglich, S., Scarinci, G., 2002. Inertization of hazardous dredgingspoils. Waste Manag. 22, 865e869.

BIA, The Brick Industry Association, 2006. Technical Notes on Brick Construction 9-Manufacturing of Brick. Reston, VA.

Bortone, G., Palumbo, L., SedNet (Organization), 2007. Sustainable management ofsediment resources. In: Sediment and Dredged Material Treatment, vol. 2.Elsevier, Amsterdam, Boston.

Brosnan, D., 2008. Shaped Products Made from Elba Island dredge material, FinalReport, Pendleton, SC.

Brownell, W.E., 1976. Structural Clay Products. Springer-Verlag, Wien-New York.BS 1377-2, 1990. Methods of Test for Soils for Civil Engineering Purposes. Classifi-

cation Tests. British Standard Institution.Buxton, J.E., Walker, J.T., Carney, S.D., 2000. Savannah Harbor Disposal Area Sedi-

ment Assessment Report. General Engineering Laboratories, Inc., Charleston SC.Casado-Martínez, M.C., Buceta, J.L., Belzunce, M.J., DelValls, T.A., 2006. Using sedi-

ment quality guidelines for dredged material management in commercial portsfrom Spain. Environ. Int. 32, 388e396.

Chiang, K.Y., Chien, K.L., Hwang, S.J., 2008. Study on the characteristics of buildingbricks produced from reservoir sediment. J. Hazard. Mater. 159, 499e504.

Collins, R.J., 1980. Dredged silt as a raw-material for the construction industry.Resour. Recovery Conserv. 4 (4), 337e362.

Cusidó, J.A., Cremades, L.V., 2012. Environmental effects of using clay bricksproduced with sewage sludge: leachability and toxicity studies. Waste Manage.32, 1202e1208.

Grimshaw, R.W., 1971. The Chemistry and Physics of Clays and Allied CeramicMaterials, fourth ed. Ernest Benn Limited, London.

Hamer, K., Karius, V., 2002. Brick production with dredged harbour sediments. Anindustrial-scale experiment. Waste Manage. 22, 521e530.

Head, K.H., 1980. Manual of soil laboratory testing. In: Soil Classification andCompaction Tests, vol. 1. Halsted Press, New York.

Huang, C., Pan, J.R., Sun, K.-D., Liaw, C.-T., 2001. Reuse of water treatment plant sludgeand dam sediment in brick-making. Water Sci. Technol. 44 (10), 273e277.

Jones, J.T., Berard, M.F., 1993. Ceramics: Industrial Processing and Testing, second ed.Iowa State University Press, Ames, Iowa.

Karius, V., Hamer, K., 2001. pH and grain-size variation in leaching tests with bricksmade of harbour sediments compared to commercial bricks. Sci. Total Environ.278, 73e85.

Karpuzcu, M., Buktel, D., Aydin, Z.S., 1996. The dewaterability, heavy metal releaseand reuse characteristics of Golden Horn surface sediment. Water Sci. Technol.34 (7e8), 365e374.

Kirchhof, G., 2006. Plastic properties. In: Lal, R. (Ed.), Encyclopedia of Soil Science,vol. 2. CRC Press, , Columbus, Ohio, pp. 1311e1313.

Lafhaj, Z., Samara, M., Agostini, F., Boucard, L., Skoczylas, F., Depelsenaire, G.,2008. Polluted river sediments from the North region of France: treatmentwith Novosol process and valorization in clay bricks. Constr. Build. Mater. 22,755e762.

Lee, C.R., 2000. Reclamation and Beneficial Use of Contaminated Dredged Material:Implementation Guidance for Select Options. DOER (The Dredging Operationsand Environmental Research) Technical Notes Collection (TN DOER C-12). U.S.Army Engineer Research and Development Center, Vicksburg, MS.

Liew, A.G., Idris, A., Samad, A.A., Wong, C.H.K., Jaafar, M.S., Baki, A.M., 2004. Reus-ability of sewage sludge in clay bricks. J. Mater. Cycles Waste Manage. 6, 41e47.

Ndiba, P., Axe, L., Boonfueng, T., 2008. Heavy metal immobilization through phos-phate and thermal treatment of dredged sediments. Environ. Sci. Technol. 42(3), 920e926.

Romero, M., Andrés, A., Alonso, R., Viguri, J., Ma Rincón, J., 2008. Sintering behaviourof ceramic bodies from contaminated marine sediments. Ceram. Int. 34, 1917e1924.

Samara, M., Lafhaj, Y., Chapiseau, C., 2009. Valorization of stabilized river sedimentsin fired clay bricks: factory scale experiment. J. Hazard. Mater. 163, 701e710.

Torres, P., Manjate, R.S., Fernandes, H.R., Olhero, S.M., Ferreira, J.M.F., 2009. Incor-poration of river silt in ceramic tiles and bricks. Ind. Ceram. 1, 5e12.

USACE, U.S., Army Corps of Engineers, 2007. Dredged Material Management Plan.Annual Work Plan. Savannah Harbor Navigation Project, Savannah, Georgia.

USDA NRCS, U.S. Department of Agriculture, Natural Resources Conservation Service,2000. Heavymetal soil contamination. Soil Qual.. Urban technical noteNo. 3. Alsoavailable at: ftp://ftp-fc.sc.egov.usda.gov/IL/urbanmnl/appendix/u03.pdf

U.S.EPA, 1995. AP 42 Compilation of Air Pollutant Emission Factors, fifth ed., vol. 1U.S. EPA, 2003. Clean Air Act, Section 63. 40 CFR Part 63. Washington, DC.U.S. EPA, 2010. 40 CFR Section 503, Standards for the Use or Disposal of Sewage

Sludge. Subpart 2: Land Application. Washington DC.Winfield, L.E., Lee, C.R., 1999. Dredged Material Characterization Tests for Beneficial

Use Suitability. Technical note DOER-C2.Worrall, W.E., 1986. Clays and Ceramic Raw Materials, New York. Elsevier, pp.

220e222.Wu, J., Leng, G., Xu, X., Zhang, Y., Lao, X., Li, K., 2012. Preparation and properties of

ceramic facing brick from East-lake sediment. J. Wuhan Univ. Technol. Mater.Sci. Ed. 27 (1), 154e159.