Research Article Effect of Strength Enhancement of Soil ...downloads.hindawi.com/journals/tswj/2014/526491.pdf · calcium carbonate to enhance the strength of so ground. However,

Research ArticleEffect of Strength Enhancement of Soil Treated withEnvironment-Friendly Calcium Carbonate Powder

Kyungho Park Sangju Jun and Daehyeon Kim

Department of Civil Engineering Chosun University Gwangju 501-759 Republic of Korea

Correspondence should be addressed to Daehyeon Kim dkimgeochosunackr

Received 30 August 2013 Accepted 1 December 2013 Published 4 February 2014

Academic Editors E Lui and I B Topcu

Copyright copy 2014 Kyungho Park et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

This study aims to investigate the effects of the strength improvement of soft ground (sand) by producing calcium carbonate powderthrough microbial reactions To analyze the cementation effect of calcium carbonate produced through microbial reaction fordifferent weight ratios four different types of specimens (untreated calcium carbonate cement and calcium carbonate + cement)with different weight ratios (2 4 6 and 8) were produced and cured for a period of 3 days 7 days 14 days 21 days and 28days to test themThe uniaxial compression strength of specimens was measured and the components in the specimen dependingon the curing periodwere analyzed bymeans of XRD analysisThe result revealed that higher weight ratios and longer curing periodcontributed to increased strength of calcium carbonate cement and calcium carbonate + cement specimensThe calcium carbonateand the calcium carbonate + cement specimens in the same condition showed the tendency of decreased strength approximately 3times and two times in comparison with the 8 cement specimens cured for 28 days but the tendency of increased strength wasapproximately 4 times and 6 times in comparison with the untreated specimen

1 Introduction

11 Background and Objective Recent increasing cost of rawmaterials scarcity of natural materials and lack of con-struction materials result in difficulty in developing the con-struction industry Fast industrial development contributesto qualitative and quantitative expansion of the national keyindustry so Korea experiences difficulty in securing sitesin comparison with other countries with large land areasThis leads to Korearsquos interest in methods of improving softground of loose sandy soil or weak silt which has not beenconsidered as a construction site for efficient use of landMany construction companies have taken a lot of overseasorders from Middle East countries to work there and it isthus needed to develop a new method of or new material forimproving soft ground

The Korea Cement Association (2005) says that thevolume of cement produced in Korea in 2006 amounts toapproximately 48 million tons which is the 7th place inthe global volume of produced cement and carbon dioxidedischarged in producing 1 ton of cement is approximately 09tons Because carbon dioxide discharged through cement is a

major cause of greenhouse gas various studies are currentlyunderway to develop substitutes for reducing cement toaddress the environmental issue

In this study the effect of the strength improvement ofsoft ground was analyzed when calcium carbonate producedby microbes was applied to loose sandy soil which is weakground To this end the calcium carbonate was producedas powder like cement to compare it with cement Foranalyzing and comparing their applicability with cementcalcium carbonate + cement specimens were produced toanalyze their strength through the uniaxial compression testafter curing them for 3 days 7 days 14 days 21 days and28 days The XRD analysis was carried out in order toexamine chemical reaction and to analyze components ofeach specimen depending on longer curing period

12 Previous Studies Various substitutes have been studiedfor reducing consumed cement Some Korean and overseasresearchers have studied how to use cement created throughbiological and chemical reactions ofB pasteurii (KCTC 3558)which is one type of numerousmicrobes under the ground to

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 526491 11 pageshttpdxdoiorg1011552014526491

2 The Scientific World Journal

cement soft ground Kim et al [1] [2ndash8] K H Park et al [9]K H Park and D H Park [3 10]

Kim et al [1] are the first Korean researchers who havestudied how to use microbes in order to enhance the strengthof soft ground They developed a method of increasingprecipitation of cement by means of the microbial conditionof high concentration They now own a patent of microbialcementation registered in the Korean Intellectual PatentOffice and titled ldquoMethod of Cementing Soft Ground byUsing Microbesrdquo [11] Microbial cementation of soft groundwas identified through a test of mixing an untreated speci-men a high concentration-treated specimen and a normalconcentration-treated specimen [12]

Park et al [2] intended to cement the ground by usinga plant extract with a component of urease to precipitatecalcium carbonate They found that the strength of the spec-imen using the plant extract was increased to about 300 kPaapproximately 3 times higher than that of the untreatedspecimen However the process of getting the primary andthe secondary liquid from the plant extract is not simple andmaximum 5 of cement is obtained after 4 days Thereforeit takes several days to have the maximum amount of cementeven after mixing the extract with the reaction solution

In other countries some researchers including Paassenet al [7] (2008) and DeJong et al [5 6] have studiedmicrobial cementation DeJong et al [5] achieved a desiredstrength through triaxial compression strength by continuousinjection but the process is very complicated Whiffin et al[8] obtained a great value of 10MPa for the specimen strengthbut estimated the strengthwith presumed values not throughquantitative analysis Paassen et al (2008) carried out a test ina model soil tank The test results revealed that the strengthincreased along the surface and the part where air is availableenough but slight strength increase was observed in thecentral part which did not have enough air

Paassen et al [7] (2008) DeJong et al [5 6] Whiffinet al [8] and Park et al [2] used an aqueous solution ofcalcium carbonate to enhance the strength of soft groundHowever calculation of strength by means of estimates isnot highly reliable and the aqueous solution of calciumcarbonate lowers strength and it is not easy to handle thesupernatant liquid if much of the solution is injected Thecalcium carbonate used in this study is produced throughthe reaction between a microbial solution and an aqueoussolution of calcium chloride It is produced as powder likecement which is widely used as a construction material andit is possible to identify the effect of increased quantitativestrength unlike prior studies

2 Method of Producing Specimens

21 Materials Used in the Test

211 Sand and Cement The sample sand was collected fromthe riverside of the Seomjingang River Sangdong-myonNamwon Jeollabuk-do Sieve analysis was performed for thecollected sample to use the sample mixed in the ratio of1 1 1 with the sample remaining in the sieves 60 (025mm)

0

10

20

30

40

50

60

70

80

90

100

00100100100010000100000

Perc

ent fi

ner b

y w

eigh

t (

)

Sieve (mm)

Figure 1 Particle size of the sample test results

100 (015mm) and 200 (0075mm) in order to produceself-standing specimens to measure strength through theuniaxial compression test Figure 1 shows the result of soilanalysis for the sand sample used in this study Here theresult of calculation of the coefficient of uniformity and thecurvature with the particle-size distribution curve is 263 forthe coefficient of uniformity (119862

119906) and 094 for the coefficient

of curvature (119862119892) which means SP sample of nonuniform

particle sizeThe cement was Portland cement from a Koreancompany

212 Calcium Carbonate Produced through Microbial Reac-tion B pasteurii (KCTC 3558) used in this study was pur-chased for bacterial culture from the Korean Collection forType Culture of Korea Research Institute of Bioscience andBiotechnologyThe culture medium for culturing B pasteuriiwasNutrient Broth 8 gLUrea 20 gL It wasmixedwith 1 literof distilled water and B pasteurii was cultured in a shakingincubator of 180 RPM at 30∘C Equation (1) is for the reactionbetween microbes and urea Growing microbes react withurea to be hydrolyzed into a carbonate ion (CO

3

2minus) and twoammonium ions (NH

4

+)

CO(NH2)2+ 2H2O Urease reaction997888997888997888997888997888997888997888997888997888997888997888rarr CO

3

2minus

+ 2NH4

+

(1)

Calcium carbonate (CaCO3) is produced by the reaction

between carbonate ions (CO3

2minus) produced through whichB pasteurii takes urea and the calcium ions (Ca2+) in theaqueous solution of calcium chloride (CaCl

2) Equation (2)

is for the precipitation reaction of calcium carbonate

CO3

2minus

+ Ca2+ 997888rarr CaCO3 (2)

The calcium carbonate (CaCO3) is produced through

microbial reaction in the process described above Figure 2shows the process of producing calcium carbonate and thecycle of precipitating soil particles in each equation

213 Powdering Calcium Carbonate The calcium carbonateused in this study was produced through microbial reactionand then powdered like cement unlike prior studies forwhich an aqueous solution of calcium carbonate was used

The Scientific World Journal 3

Particle

+ H2O 2NH3 + CO2

Ca2+

Ca2+

attractedto

2NH3 + 2H2O

CO2 + OHminus

Ca2+

CaCO3 + H2O

CaCO3

CaCO3CaCO3

H2O

H2O

H2O

H2O

Net urea hydrolysis reaction

Net pH increase [OHminus] generated from

HCO3minus

+ HCO3minus+ OHminus

2NH4++ HCO3

minus+ OHminus

cellminus2NH4

++ 2OHminus

NH2mdashCOmdashNH2

NH2mdashCOmdashNH2

+ 3H2O

NH4+production ≫ [Ca2+

]

NH 3

CO2

Bacteria cell Sporosarcina pasteurii

Figure 2 Process of producing calcium carbonate [6]

(a) (b) (c)

(d) (e) (f)

(g) (h) (i)

Figure 3 Extracting and producing calcium carbonate


The microbial reaction was done by adding calcium chlorideinto bacteria solution The powdered calcium carbonateenabled the supernatant liquid to be handled and quantita-tive strength to be measured which was an issue in priorstudies Figure 3 shows the process of extracting drying andpowdering calcium carbonate from the microbial solutionand the aqueous solution of calcium chloride In the methoddescribed below the calcium carbonate produced throughmicrobial reaction was used as a cementation agent

Figure 3 shows (a) a medium for microbes (1L) (b)mixing the aqueous solution of calcium chloride (1L) (c)precipitating calcium carbonate in the reaction solution(d) filtering the reaction solution (e) extracting calciumcarbonate (f) drying calcium carbonate at 40∘C for 24 hours(h) powdering calcium carbonate

22 Producing Specimens Specimens of which the ratio ofheight to the diameter were produced to be 1 2 in theratio of the diameter (D) 5 cm to the height (H) 10 cm asshown in Figure 4 in conformity with the Korea IndustrialStandard KS F2314 This aimed to measure the uniaxialcompression strength of the specimens of calcium carbonate(produced throughmicrobial reaction) cement and calciumcarbonate + cement The process applied was (a) to measurethe weight of the sample material the cement and the waterrespectively (b) to hand-mix the sample material (c) toproduce specimens in a mold through 3-layer compaction(d) to cure the specimens at 40∘C (e) to remove the curedspecimen mold and (f) to measure the uniaxial compressionstrength of the specimens

The 65 produced specimens were divided into 4 cases of5 untreated specimens 20 calcium carbonate specimens 20cement specimens and 20 calcium carbonate + cement speci-mensThe untreated specimenswere produced to correspondto 3 days 7 days 14 days 21 days and 28 days Five specimensfor each of calcium carbonate cement and calcium carbonate+ cement were produced to have the weight ratios of 24 6 and 8 to measure the strength depending on thecuring period (3 days 7 days 14 days 21 days and 28 days)Table 1 shows the mixing ratio of the specimens untreatedcalcium carbonate cement and calcium carbonate + cementwith which 5 specimens were produced respectively

3 Analysis of Test Results

31 Uniaxial Compression Test Result of Untreated SpecimensTheuniaxial compression strength test was carried out for thespecimens at a shearing speed of 1min Table 2 and Figure 5show the results of uniaxial compression strength test for theuntreated specimens after curing them for 3 days 7 days 14days 21 days and 28 days

The untreated sand specimens to which the cementationagent was not added stood for themselves as a circularcylinder by means of apparent cohesion and the uniaxialcompression strength thereof was 5342 kPa for the initialcuring (3 days) which is shown in Table 2 For curing for 28days the result was 6410 kPa which increased approximately

12 times This increase is due to the drying moisture in thespecimens

32 Results of Uniaxial Compression Test for Calcium Carbon-ate Specimens The calcium carbonate specimens were testedat the shearing speed of 1min in the same method as theuniaxial compression strength test for untreated specimensThe result of the uniaxial compression test for the calciumcarbonate specimens after curing them for 3 days 7 days 14days 21 days and 28 days is shown in Table 3 and Figure 6As shown in Table 3 the initial strength (3 days) of thecalcium carbonate specimens was 8457ndash19995 kPa whichexhibits increased strength approximately 24 times with theincreasedweight ratio It is thought that the increased amountof calcium carbonate affects the increased strength of the sandground The strength increased approximately 26-27 timeswith the increased weight ratio for the curing period of 7days 14 days 21 days and 28 days The calcium carbonatespecimens also exhibited increased strength with the longercuring period like the untreated specimens

As shown in Figure 7 it is thought that the uniaxialcompression strength of the calcium carbonate specimensincreased with the longer curing period While the calciumcarbonate powder was mixed with water and then driedaround the sand particles in producing the specimensevaporating water contributed to shrinking for holding sandparticles The strength of the calcium carbonate specimensincreased approximately minimum 16 times for the curingperiod of 3 days in comparisonwith the untreated specimens

33 Results of Uniaxial Compression Test of Cement Speci-mens The uniaxial compression test was carried out for thecement specimens in the same method as the one for theuntreated and the calcium carbonate specimens describedabove Table 4 and Figure 8 show the result of the uniaxialcompression strength test for the cement specimens aftercuring them for the period of 3 days 7 days 14 days21 days and 28 days The initial strength (3 days) of thecement specimens was 12845ndash87606 kPa which increasedapproximately 68 times with the increased ratio even higherthan the strength of the untreated and the calcium carbon-ate specimens previously tested This proves the effect ofenhanced strength of ordinary cement specimens

It was seen that the cement specimens also exhibitedincreased strength approximately 70-80 times with theincreased weight ratio for the curing period of 7 days 14days 21 days and 28 days It is thought that the reaction ofhydration and the Pozzolanic reaction of cement contributedto the effect of even enhanced strength with longer curingperiod than the enhanced strength of the untreated and thecalcium carbonate specimens previously tested The effect ofenhanced strength is shown in Figure 9 The strength of thecement specimens increased approximately 164ndash188 times incomparison with the untreated specimens

34 Results of Uniaxial Compression Test of Calcium Carbon-ate + Cement Specimens The uniaxial compression strengthof the calcium carbonate + cement specimens was tested at a


(a) (b) (c)

(d) (e) (f)

Figure 4 Mixing sample materials and producing specimens

Table 1 Mixing the sample material

Test ID Cementation material Soil (g) Water (g) Weight ratio () Calcium carbonate (g) Cement (g) QuantityUntreated mdash 275 50 mdash mdash mdash 5C-2

Calcium carbonate

275 50 2 55 mdash 5C-4 275 50 4 11 mdash 5C-6 275 50 6 165 mdash 5C-8 275 50 8 22 mdash 5S-2

Cement

275 50 2 mdash 55 5S-4 275 50 4 mdash 11 5S-6 275 50 6 mdash 165 5S-8 275 50 8 mdash 22 5CS-2

Calcium carbonate + cement

275 50 2 225 225 5CS-4 275 50 4 55 55 5CS-6 275 50 6 11 11 5CS-8 275 50 8 165 165 5

Table 2 Curing period to compare strength of untreated specimens (unit kPa)

Specimen Curing period to compare strength of untreated specimens3 days 7 days 14 days 21 days 28 days

Untreated 5342 5442 5917 6032 641

Table 3 Curing period to compare the strength of calcium carbonate specimens (unit kPa)

Test ID Curing period to compare the strength of calcium carbonate specimens3 days 7 days 14 days 21 days 28 days

Untreated 5342 5442 5917 6032 6410C-2 8457 9244 9835 10334 13988C-4 12069 14210 15960 16816 20578C-6 15248 15888 17312 23724 24908C-8 19995 25143 25420 28171 37886


Table 4 Curing period to compare the strength of cement specimens (unit kPa)

Test ID Curing period to compare the strength of cement specimens3 days 7 days 14 days 21 days 28 days

Untreated 5342 5542 5917 6032 6410S-2 12845 13417 13758 16141 17099S-4 26847 33015 34226 45678 45906S-6 61813 64179 66699 69576 73854S-8 87606 105073 11114 118469 120669

0

100

200

300

400

3 7

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

Untreated

2114 28

Figure 5 Curing period to compare strength of untreated speci-mens

shearing speed of 1min in the same method as the one forthe previous specimens The uniaxial compression strengthtest of the calcium carbonate + cement specimens was carriedout by mixing calcium carbonate with cement to determinecompatibility as an admixture Table 5 and Figure 10 show theresult of uniaxial compression test for the calcium carbonate+ cement specimens after curing them for 3 days 7 days14 days 21 days and 28 days The initial strength (3 days)of the calcium carbonate + cement specimens was 3680ndash36778 kPa which increased approximately 10 times with theincreased amount of calcium carbonate + cement in thespecimens This strength is higher than the initial strength ofthe previous specimens

The specimens produced by curing calcium carbonate +cement with 2 of the weight ratio for 3 days exhibited 14times lower uniaxial compression strength than the strengthof the untreated specimens This is quite different from whatwe expected It is thought that this resulted from the fact thata small amount of calcium carbonate and cement was not

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

C-2C-4

C-6C-8

3 7 14 21 28

Curing time (day)

Untreated

Figure 6 Curing period to compare the strength of calciumcarbonate specimens

fully dried to inhibit cohesion to result in lowered strengthHowever the increasedweight ratio contributed to increasingthe strength approximately 67ndash86 times with respect to thecuring periods of 7 days 14 days 21 days and 28 days It wasidentified that the strength that increased approximately 13ndash30 timeswas attributable to longer curing periodThe 2and4 calcium carbonate (lowweight ratio) + cement specimensshowed similar tendency to the increased strength of theuntreated specimens with longer curing period However the6 and 8 calcium carbonate (high weight ratio) + cementspecimens showed higher strength than that of the cementspecimens The tendency showed that the calcium carbonate+ cement specimens had a less effect of cement in the lowweight ratio and in the early stage of curing but showedincreased strength because of more cement contents in thespecimens as the weight ratio increased It is thought that thiswill contribute to a highly strong and environmentally safeadmixture by studying the mixture of environment-friendlycalcium carbonate produced through the reaction betweencement and net microbes


CaCO3 + H2OCaCO3 + H2O

CaCO3 + H2O

(Combination) (Vaporization)

(Dry)

Figure 7 Effect of enhancing strength of calcium carbonate specimens

Table 5 Curing period to compare the strength of calcium carbonate + cement specimens (unit kPa)

Test ID Curing period to compare the strength of calcium carbonate + cement specimens3 days 7 days 14 days 21 days 28 days

Untreated 5342 5542 5917 6032 6410CS-2 3680 6112 6279 6783 7645CS-4 5693 9478 11881 14019 16956CS-6 27526 33396 33570 33875 35278CS-8 36778 40714 43660 49994 65427

35 Results of Uniaxial Compression Test The uniaxial com-pression strength of the calcium carbonate cement andcalcium carbonate + cement specimens analyzed above wascompared with respect to the different weight ratios (2 46 and 8) This was intended to compare and analyze thechange of the uniaxial compression strength of calcium car-bonate cement and calcium carbonate + cement specimenswith respect to the sameweight ratios Figure 8 shows analysisand comparison for the effect of enhanced strength in theweak sandy soil ground by each cementation agent

Figures 11(a)ndash11(d) show the result of each specimencorresponding to (a) weight ratio 2 (b) weight ratio 4 (c)weight ratio 6 and (d) weight ratio 8 for comparing thestrength of each specimen depending on the weight ratio

Figure 11(a) shows the result of weight ratio 2 Forweight ratio 2 higher strength wasmeasured in the order ofuntreated calcium carbonate cement and calcium carbonate+ cement specimens but most specimens showed a similartendency to the untreated specimens It is thought that a smallamount of the cementation agent does not significantly affectthe enhancement of strength

Figure 11(b) shows the result of weight ratio 4 Forweight ratio 4 higher strength was measured in the orderof untreated calcium carbonate + cement calcium carbon-ate and cement specimens The cement specimens showed22ndash27 times higher strength than the calcium carbonatespecimens The calcium carbonate specimens showed 11ndash21 times higher strength than the calcium carbonate +cement specimens but a similar tendency was shown It is

thought that because the cement contents of the calciumcarbonate + cement specimens are smaller than those ofthe cement specimens the calcium carbonate + cementspecimens showed lower uniaxial compression strength thanthat of the calcium carbonate specimens

Figure 11(c) shows the result of weight ratio 6 Forweight ratio 6 higher strength of the specimens was mea-sured in the order of untreated calcium carbonate calciumcarbonate + cement and cement specimens unlike theuniaxial compression strength of the 2 and 4 specimensThe cement specimens showed 38ndash40 times higher uniaxialcompression strength than that of the calcium carbonatespecimens The calcium carbonate + cement specimensshowed 14ndash20 times higher uniaxial compression strengththan that of the calcium carbonate specimens

Figure 11(d) shows the result of weight ratio 8 Forweight ratio 8 higher strength of the specimens wasmeasured in the order of weight ratio 6 The cementspecimens showed 32ndash44 times higher uniaxial compressionstrength than that of the calcium carbonate specimens Thecalcium carbonate + cement specimens showed 16ndash18 timeshigher uniaxial compression strength than that of the calciumcarbonate specimens The uniaxial compression strength ofthe highest weight ratio 8 specimens gradually increased asthe amount of the cementation agent increased with the sandweight in a given specimen

The analysis of the graph for the calcium carbonateand calcium carbonate + cement specimens reveals thatthe increase of the uniaxial compression strength with the


0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated

Figure 8 Curing period to compare the strength of cementspecimens

Pozzolanicreaction

Reaction ofhydration

Stre

ngth

Time

Figure 9 Enhanced strength through ground improvement withcement

increased weight ratio is not significant like the cement speci-mens However because longer period for curing the calciumcarbonate and calcium carbonate + cement specimens tendsto contribute to enhanced strength it is thought that theeffect of enhancing strength in the weak sand ground will beimplemented

36 Results of X-Ray Diffraction Analysis (XRD) XRD analy-sis was carried out to identify ores created in the calcium car-bonate produced bymeans of microbes cement and calciumcarbonate + cement specimens Each sample was reduced tofine powder and the diffraction angle of X-rays was set as

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated

Figure 10 Curing period to compare the strength of calciumcarbonate + cement specimens

5ndash70∘ for 2 For the calcium carbonate specimens the resultof identified silica (SiO

2) and calcium carbonate (CaCO

3)

was described to compare the result of identification in thecement specimens Silica (SiO

2) which is a representative

ore of cement and aluminum oxide (Al2O3) was identified

in the cement specimens The result of identification in thecalcium carbonate + cement specimens includes silica (SiO

2)

aluminum oxide (Al2O3) and calcium carbonate (CaCO

3)

Table 5 shows the result of XRD analysis for each specimenwhich includes right minerals in each specimen Note thatthe percentage of calcium carbonate is larger in the specimenwith calcium carbonate than the specimen with calciumcarbonate+cement

4 Summary and Conclusions

This study aims to identify the effect of enhanced strength bycalcium carbonate produced through microbial reaction inthe sandy soil ground by means of the uniaxial compressiontest

Specimens with weight ratios 2 4 6 and 8 wereproduced to measure the uniaxial compression strength forthe curing periods of 3 days 7 days 14 days 21 days and28 days and to identify the type of minerals contained in thespecimens by means of XRD analysis (Table 6)

(1) The uniaxial compression strength was measured tobe 8457ndash37886 kPa after curing the calcium carbon-ate specimens for each weight ratio for 3 days 7days 14 days 21 days and 28 days It was identifiedthat the strength of calcium carbonate produced bymeans of microbial reaction increased approximately


0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)

Figure 11 Strength of specimens by weight ratios

15 times with the increased period of curing incomparison with initial curing As the amount of cal-ciumcarbonate in specimens increased their strengthalso increased It is thought that shrinking for sandparticles holding together due to water evaporation inthe specimens contributed to increased uniaxial com-pression strength with the longer period of curing

(2) The strength of cement specimens was measured tobe 12845ndash120669 kPa for each weight ratio after

curing them for 3 days 7 days 14 days 21 days and28 days The analysis revealed that the reaction ofhydration and the increased strength of the sandysoil were attributable to the reaction of hydration andPozzolanic reaction as the amount of cement and theperiod of curing increased

(3) Theuniaxial compression strength of calciumcarbon-ate + cement specimens was measured to be 12845ndash65427 kPa for each weight ratio after curing them


Table 6 Specimen curing period in accordance with the results ofXRD analysis

Test ID Formula Scale factor Score

C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11

for 3 days 7 days 21 days and 28 days The mixtureratio of 1 1 of calcium carbonate produced by meansof microbial reaction with cement resulted in lesseffect of cement in low weight ratio 2ndash4 specimensHowever it is thought that the enhanced strength ofweight ratio 6sim8 specimens is attributable to morecement contents in the specimens It is expected thatthis will be an environment-friendly admixture tocombine the environment-friendly calciumcarbonateproduced by means of net microbial reaction withcement

It is thought that the strength of calcium carbonatecement and calciumcarbonate + cement specimens increasesfor the sandy soil ground with the increased weight ratio

and with longer period of curing them For weight ratio 2calcium carbonate achieved better effect in terms of strengththan calcium carbonate + cement However for weight ratio4ndash6 calcium carbonate + cement achieved more strengthenhancement than calcium carbonate for the sandy soilground It is thought that this results from the fact that theincreased weight ratio contributed to the increased amountof cement in the specimens to enhance strength by means ofinitial strength and the reaction of hydration It is necessaryto further study how to ideally mix calcium carbonateproduced by means of microbes with cement to achievehigher strength of calcium carbonate + cement Successfulstudy will contribute to reducing the environmental costs forcarbon dioxide emissions and excavation of lime

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

This research was supported by Basic Science ResearchProgram through theNational Research Foundation of Korea(NRF) funded by the Ministry of Science ICT and FuturePlanning (NRF-2013R1A1A105010106)

References

[1] D H Kim H C Kim and K H Park ldquoCementation of soft soilusing bacteriardquo Certificate of Patent 10-1030761 2012

[2] S S Park S K Choi and I H Nam ldquoDevelopment of groundcement using plant extractrdquo Journal of Korean GeotechnicalSociety vol 28 no 3 pp 67ndash75 2012

[3] K H Park and D H Kim ldquoIdentification of calcium carbonatefor silt and sand treated with bacteriardquo Journal of KoreanGeotechnical Society vol 28 no 6 pp 53ndash61 2012

[4] J K Mitchell and J C Santamarina ldquoBiological considera-tions in geotechnical engineeringrdquo Journal of Geotechnical andGeoenvironmental Engineering vol 131 no 10 pp 1222ndash12332005

[5] J T DeJong M B Fritzges and K Nusslein ldquoMicrobiallyinduced cementation to control sand response to undrainedshearrdquo Journal of Geotechnical and Geoenvironmental Engineer-ing vol 132 no 11 pp 1381ndash1392 2006

[6] J T DeJong BMMortensen B CMartinez andD C NelsonldquoBio-mediated soil improvementrdquo Ecological Engineering vol36 no 2 pp 197ndash210 2010

[7] L A Paassen M P Harkes G A Zwieten W H Zon WR L Star and M C M Loosdrecht ldquoScale up of biogrouta biological ground reinforcement methodrdquo in Proceedingsof the 17th International Conference on Soil Mechanics andGeotechnical Engineering pp 2328ndash2333 2009

[8] V S Whiffin L A van Paassen and M P Harkes ldquoMicro-bial carbonate precipitation as a soil improvement techniquerdquoGeomicrobiology Journal vol 24 no 5 pp 417ndash423 2007

[9] K H Park Strength improvement of soft soil using soft soil [MSthesis] Chosun University Gwangju Korea 2011


[10] K H Park and D H Kim ldquoEffect of strength and injectionfor the sand treated bacteriardquo Journal of Korean GeotechnicalSociety vol 29 no 2 pp 65ndash73 2013

[11] D H Kim K H Park and Y H Lee ldquoEffects of microbialtreatment on biogroutrdquo Journal of Korean Geotechnical Environ-mental Society vol 13 no 5 pp 51ndash67 2012

[12] H C Kim Characteristics of cementation of soil using bacteria[MS thesis] Chosun University Gwangju Korea 2011

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

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Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



cement soft ground Kim et al [1] [2ndash8] K H Park et al [9]K H Park and D H Park [3 10]

Kim et al [1] are the first Korean researchers who havestudied how to use microbes in order to enhance the strengthof soft ground They developed a method of increasingprecipitation of cement by means of the microbial conditionof high concentration They now own a patent of microbialcementation registered in the Korean Intellectual PatentOffice and titled ldquoMethod of Cementing Soft Ground byUsing Microbesrdquo [11] Microbial cementation of soft groundwas identified through a test of mixing an untreated speci-men a high concentration-treated specimen and a normalconcentration-treated specimen [12]

Park et al [2] intended to cement the ground by usinga plant extract with a component of urease to precipitatecalcium carbonate They found that the strength of the spec-imen using the plant extract was increased to about 300 kPaapproximately 3 times higher than that of the untreatedspecimen However the process of getting the primary andthe secondary liquid from the plant extract is not simple andmaximum 5 of cement is obtained after 4 days Thereforeit takes several days to have the maximum amount of cementeven after mixing the extract with the reaction solution

In other countries some researchers including Paassenet al [7] (2008) and DeJong et al [5 6] have studiedmicrobial cementation DeJong et al [5] achieved a desiredstrength through triaxial compression strength by continuousinjection but the process is very complicated Whiffin et al[8] obtained a great value of 10MPa for the specimen strengthbut estimated the strengthwith presumed values not throughquantitative analysis Paassen et al (2008) carried out a test ina model soil tank The test results revealed that the strengthincreased along the surface and the part where air is availableenough but slight strength increase was observed in thecentral part which did not have enough air

Paassen et al [7] (2008) DeJong et al [5 6] Whiffinet al [8] and Park et al [2] used an aqueous solution ofcalcium carbonate to enhance the strength of soft groundHowever calculation of strength by means of estimates isnot highly reliable and the aqueous solution of calciumcarbonate lowers strength and it is not easy to handle thesupernatant liquid if much of the solution is injected Thecalcium carbonate used in this study is produced throughthe reaction between a microbial solution and an aqueoussolution of calcium chloride It is produced as powder likecement which is widely used as a construction material andit is possible to identify the effect of increased quantitativestrength unlike prior studies

2 Method of Producing Specimens

21 Materials Used in the Test

211 Sand and Cement The sample sand was collected fromthe riverside of the Seomjingang River Sangdong-myonNamwon Jeollabuk-do Sieve analysis was performed for thecollected sample to use the sample mixed in the ratio of1 1 1 with the sample remaining in the sieves 60 (025mm)

0

10

20

30

40

50

60

70

80

90

100

00100100100010000100000

Perc

ent fi

ner b

y w

eigh

t (

)

Sieve (mm)

Figure 1 Particle size of the sample test results

100 (015mm) and 200 (0075mm) in order to produceself-standing specimens to measure strength through theuniaxial compression test Figure 1 shows the result of soilanalysis for the sand sample used in this study Here theresult of calculation of the coefficient of uniformity and thecurvature with the particle-size distribution curve is 263 forthe coefficient of uniformity (119862

119906) and 094 for the coefficient

of curvature (119862119892) which means SP sample of nonuniform

particle sizeThe cement was Portland cement from a Koreancompany

212 Calcium Carbonate Produced through Microbial Reac-tion B pasteurii (KCTC 3558) used in this study was pur-chased for bacterial culture from the Korean Collection forType Culture of Korea Research Institute of Bioscience andBiotechnologyThe culture medium for culturing B pasteuriiwasNutrient Broth 8 gLUrea 20 gL It wasmixedwith 1 literof distilled water and B pasteurii was cultured in a shakingincubator of 180 RPM at 30∘C Equation (1) is for the reactionbetween microbes and urea Growing microbes react withurea to be hydrolyzed into a carbonate ion (CO

3

2minus) and twoammonium ions (NH

4

+)

CO(NH2)2+ 2H2O Urease reaction997888997888997888997888997888997888997888997888997888997888997888rarr CO

3

2minus

+ 2NH4

+

(1)

Calcium carbonate (CaCO3) is produced by the reaction

between carbonate ions (CO3

2minus) produced through whichB pasteurii takes urea and the calcium ions (Ca2+) in theaqueous solution of calcium chloride (CaCl

2) Equation (2)

is for the precipitation reaction of calcium carbonate

CO3

2minus

+ Ca2+ 997888rarr CaCO3 (2)

The calcium carbonate (CaCO3) is produced through

microbial reaction in the process described above Figure 2shows the process of producing calcium carbonate and thecycle of precipitating soil particles in each equation

213 Powdering Calcium Carbonate The calcium carbonateused in this study was produced through microbial reactionand then powdered like cement unlike prior studies forwhich an aqueous solution of calcium carbonate was used


Particle

+ H2O 2NH3 + CO2

Ca2+

Ca2+

attractedto

2NH3 + 2H2O

CO2 + OHminus

Ca2+

CaCO3 + H2O

CaCO3

CaCO3CaCO3

H2O

H2O

H2O

H2O



HCO3minus


2NH4++ HCO3

minus+ OHminus

cellminus2NH4

++ 2OHminus

NH2mdashCOmdashNH2

NH2mdashCOmdashNH2

+ 3H2O


]

NH 3

CO2



(a) (b) (c)

(d) (e) (f)

(g) (h) (i)

















(a) (b) (c)

(d) (e) (f)




Calcium carbonate


Cement



275 50 2 225 225 5CS-4 275 50 4 55 55 5CS-6 275 50 6 11 11 5CS-8 275 50 8 165 165 5



Untreated 5342 5442 5917 6032 641



Untreated 5342 5442 5917 6032 6410C-2 8457 9244 9835 10334 13988C-4 12069 14210 15960 16816 20578C-6 15248 15888 17312 23724 24908C-8 19995 25143 25420 28171 37886




Untreated 5342 5542 5917 6032 6410S-2 12845 13417 13758 16141 17099S-4 26847 33015 34226 45678 45906S-6 61813 64179 66699 69576 73854S-8 87606 105073 11114 118469 120669

0

100

200

300

400

3 7

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

Untreated

2114 28




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

C-2C-4

C-6C-8

3 7 14 21 28

Curing time (day)

Untreated





CaCO3 + H2O


(Dry)














0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Particle

+ H2O 2NH3 + CO2

Ca2+

Ca2+

attractedto

2NH3 + 2H2O

CO2 + OHminus

Ca2+

CaCO3 + H2O

CaCO3

CaCO3CaCO3

H2O

H2O

H2O

H2O



HCO3minus


2NH4++ HCO3

minus+ OHminus

cellminus2NH4

++ 2OHminus

NH2mdashCOmdashNH2

NH2mdashCOmdashNH2

+ 3H2O


]

NH 3

CO2



(a) (b) (c)

(d) (e) (f)

(g) (h) (i)

















(a) (b) (c)

(d) (e) (f)




Calcium carbonate


Cement



275 50 2 225 225 5CS-4 275 50 4 55 55 5CS-6 275 50 6 11 11 5CS-8 275 50 8 165 165 5



Untreated 5342 5442 5917 6032 641



Untreated 5342 5442 5917 6032 6410C-2 8457 9244 9835 10334 13988C-4 12069 14210 15960 16816 20578C-6 15248 15888 17312 23724 24908C-8 19995 25143 25420 28171 37886




Untreated 5342 5542 5917 6032 6410S-2 12845 13417 13758 16141 17099S-4 26847 33015 34226 45678 45906S-6 61813 64179 66699 69576 73854S-8 87606 105073 11114 118469 120669

0

100

200

300

400

3 7

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

Untreated

2114 28




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

C-2C-4

C-6C-8

3 7 14 21 28

Curing time (day)

Untreated





CaCO3 + H2O


(Dry)














0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation
























(a) (b) (c)

(d) (e) (f)




Calcium carbonate


Cement



275 50 2 225 225 5CS-4 275 50 4 55 55 5CS-6 275 50 6 11 11 5CS-8 275 50 8 165 165 5



Untreated 5342 5442 5917 6032 641



Untreated 5342 5442 5917 6032 6410C-2 8457 9244 9835 10334 13988C-4 12069 14210 15960 16816 20578C-6 15248 15888 17312 23724 24908C-8 19995 25143 25420 28171 37886




Untreated 5342 5542 5917 6032 6410S-2 12845 13417 13758 16141 17099S-4 26847 33015 34226 45678 45906S-6 61813 64179 66699 69576 73854S-8 87606 105073 11114 118469 120669

0

100

200

300

400

3 7

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

Untreated

2114 28




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

C-2C-4

C-6C-8

3 7 14 21 28

Curing time (day)

Untreated





CaCO3 + H2O


(Dry)














0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(a) (b) (c)

(d) (e) (f)




Calcium carbonate


Cement



275 50 2 225 225 5CS-4 275 50 4 55 55 5CS-6 275 50 6 11 11 5CS-8 275 50 8 165 165 5



Untreated 5342 5442 5917 6032 641



Untreated 5342 5442 5917 6032 6410C-2 8457 9244 9835 10334 13988C-4 12069 14210 15960 16816 20578C-6 15248 15888 17312 23724 24908C-8 19995 25143 25420 28171 37886




Untreated 5342 5542 5917 6032 6410S-2 12845 13417 13758 16141 17099S-4 26847 33015 34226 45678 45906S-6 61813 64179 66699 69576 73854S-8 87606 105073 11114 118469 120669

0

100

200

300

400

3 7

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

Untreated

2114 28




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

C-2C-4

C-6C-8

3 7 14 21 28

Curing time (day)

Untreated





CaCO3 + H2O


(Dry)














0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Untreated 5342 5542 5917 6032 6410S-2 12845 13417 13758 16141 17099S-4 26847 33015 34226 45678 45906S-6 61813 64179 66699 69576 73854S-8 87606 105073 11114 118469 120669

0

100

200

300

400

3 7

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

Untreated

2114 28




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

C-2C-4

C-6C-8

3 7 14 21 28

Curing time (day)

Untreated





CaCO3 + H2O


(Dry)














0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











CaCO3 + H2O


(Dry)














0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

200

400

600

800

1000

1200

3 7 14 21 28

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

Curing time (day)

S-2S-4

S-6S-8

Untreated


Pozzolanicreaction


Stre

ngth

Time




0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)CS-2CS-4

CS-6CS-8

3 7 14 21 28

Curing time (day)

Untreated




3)





2)


3)







0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-2Untreated S-2

CS-2

(a)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-4Untreated S-4

CS-4

(b)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-6Untreated S-6

CS-6

(c)

0

200

400

600

800

1000

1200

Unc

onfin

ed co

mpr

essiv

e stre

ngth

(kPa

)

3 7 14 21 28

Curing time (day)

C-8Untreated S-8

CS-8

(d)









C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












C3-4 SiO2 0308 54CaCO3 0124 12

C7-4 SiO2 0326 63CaCO3 0286 34

C14-4 SiO2 0352 70CaCO3 0354 12

C21-4 SiO2 0404 80CaCO3 0450 10

C28-4 SiO2 0411 78CaCO3 0556 12

S3-4 SiO2 0773 72Al2O3 0097 22

S7-4 SiO2 1024 65Al2O3 0271 21

S14-4 SiO2 1530 61Al2O3 0278 11

S21-4 SiO2 2635 72Al2O3 0301 17

S28-4 SiO2 2523 61Al2O3 0329 7

CS3-4SiO2 0962 73Al2O3 0052 26CaCO3 0152 11

CS7-4SiO2 0995 79Al2O3 0062 10CaCO3 0152 16

CS14-4SiO2 0999 67Al2O3 0077 12CaCO3 0162 10

CS21-4SiO2 1010 50Al2O3 0084 19CaCO3 0172 8

CS28-4SiO2 1100 72Al2O3 0089 21CaCO3 0175 11






Acknowledgment


References
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article Effect of Strength Enhancement of Soil ...downloads.hindawi.com/journals/tswj/2014/526491.pdf · calcium carbonate to enhance the strength of so ground. However,