Research Article Comparison of Effects of Using ...Aer sieve analysis, consistency limit experiments...

Research ArticleComparison of Effects of Using Geosynthetics andLime Stabilization to Increase Bearing Capacity ofUnpaved Road Subgrade

Erhan Burak Pancar1 and Muhammet Vefa AkpJnar2

1Department of Architecture Ondokuz Mayıs University Samsun Turkey2Department of Civil Engineering Karadeniz Technical University Trabzon Turkey

Correspondence should be addressed to Erhan Burak Pancar erhanpancarhotmailcom

Received 22 April 2016 Revised 21 July 2016 Accepted 1 August 2016

Academic Editor Jianxi Zhu

Copyright copy 2016 E B Pancar and M V Akpınar This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

So many soil improvement methods have been developed in order to increase bearing capacity of superstructure of the road to beconstructed on the soft clayey road base soils decrease settlements and increase other strength specifications (CBR 119896119872

119877values

etc) In this paper lime stabilization of clayey road base soil with high water content and its improvement with geosynthetics(geocell + geotextile) reinforcement and comparisons of these two different improvement methods were made For this purposeplate loading experimental comparisons of clayey soil which had high water content by 10 increasing the optimumwater contentweremade after it was improvedwith lime at the rates of 3 6 and 12 geotextile reinforcement geocell reinforcement geosyntheticsreinforcement and geosynthetics reinforcement + lime stabilization at various rates It was understood that these improvementmethods will not yield sufficient results on clayey soils with high water content on their own and method of improvement withlime and then reinforcement with geosynthetics yields better results on these types of soils Only one improvement state among tendifferent states examined in this study gave the sufficient results for the soil to be used for unpaved roads

1 Introduction

Subgrade soils may safely withstand the stresses that trafficloads constitute Soft soils have low shear strength and thiscauses excessive consolidation settlement and bearing capac-ity failure when they are used as a road subgrade Bearingcapacity of the soil is generally affected by soil type watercontent and compaction degree The soils shall support highamount of loading without excessive settlement It is requiredto stabilize the subgrade soils that are not appropriate for roadsuperstructure by improving them With the improvementof the soil bearing capacity is increased settlements aredecreased and therefore surfacing thickness is decreasedand surfacing performance is increased A variety of groundimprovement techniques including vertical drains completesoil replacement grouting geosynthetic reinforcement andlime stabilization are used in several structures such as

highways railways airports and embankment to improve theperformance of soils [1ndash6]

Many researchers have reported the ability of lime tochange the plasticity of soils The liquid limit of clay soildecreases when the lime content increases [7] The plasticlimit increases and the plasticity index which is the differencebetween the liquid limit and the plastic limit decreases withlime stabilization [8] The pH becomes about 124 by mixingsoil lime and water [9] It is desired to get this pH valueby adding lime to the soil and there is a minimum limitfor lime content to achieve this goal The strength of soilincreases if the amount of lime added to the soil increases[10] Dash andHussain [2] determined that the optimum limecontent was 9 for expansive soils and 5 for residual soil-rich specimens

Dash and Hussain [2] also stated that when the amountof lime added to the soil increases the swell potential of soils

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2016 Article ID 7129356 8 pageshttpdxdoiorg10115520167129356

2 Advances in Materials Science and Engineering

decreases at first and then starts to increase after a certainlimit of lime content This content is 5 for fine-grainedsoils and 9 for coarse-grained soils It is also known thatexcessive lime treatments decrease the soil strength Becauseof that calculating the optimum amount of lime is veryimportant for lime stabilization

Dash and Hussain [11] detected that the effect of limeon reducing the shrinkage potential of high plastic expansivesoils is more than low plastic residual soilThe optimum limecontent to get minimum shrinkage was calculated as 5

In the studies Kavak et al [12] reviewed performance oflime stabilization of clay with high plasticity on the base soilof the real road The necessary lime ratio was determinedas 5 Implementation was done on total 40 cm part of thesoil The lime stabilization was applied in 2 layers as 20 cmfor each CBR (California Bearing Ratio) values increasedfrom 11 to 56 after lime stabilization At the plate loadingexperimentsmaximumsettlement decreased to 36mm from222mm 8 times increases occurred on dry CBR values of thematerial to which 5 lime was mixed at the end of 56 daysand up to 34 times increases occurred on its wet CBR valuescompared to the natural material

Geosynthetic reinforcement has been more used amongsoil improvement techniques It gives an advantage of rapidconstruction at low costs Zhou and Wen [13] have deter-mined the mechanisms of geosynthetic reinforcement byexplaining the confinement pocket effect raft foundationeffect and stress dispersion effect in their study

Latha and Somwanshi [14] demonstrated that the geocellis the most advantageous form of geosynthetic reinforce-ment (ie geocell planar layers and randomly distributedmesh elements) Moghaddas Tafreshi and Dawson [4] andDash et al [15] also determined that geocell reinforcementis more desirable than planar reinforcement MoghaddasTafreshi andDawson [4] stated that the geocell reinforcementimproves the bearing capacity of soil more than 200 andreduces the settlement by 75

Zhou andWen [13] indicated that subgrade reaction coef-ficient 119896

30can be improved by 3000 and the deformation

can be reduced by 44 by using geocell-reinforced sandcushion Sireesh et al [16] and Dash et al [15] stated thatif a planar geogrid is added at the base of the geocell thebearing capacity of the foundation also increases Dash et al[17] detected that this increasing can be 30 more than withgeocell aloneThe effect of planar reinforcement layer reducesby increasing the height of the geocell mattress

The overall goal of this study was to demonstrate thebenefits of geosynthetics reinforcement and lime stabilizationfor clayey pavement subgrade with high water content withthe detailed objective of this study being to compare the per-formance of geocell reinforcement geotextile reinforcementand lime stabilization by using these treatments solely andtogether This comparison has not been made before in otherstudies

2 Cellular Confinement Systems

As seen in Figure 1 cellular confinement systems (geocellgeoweb neoweb etc) are a network having a high resistance

Figure 1 Application of geocell in the field

Tensile force

LoadsWall of geocell

FrictionalresistanceT

Lateralrestriction

Lateralrestriction

Subgrade reaction

of geocell T

Figure 2 Lateral resistance effect of geocell reinforcement

that was developed with the aim of stabilizing the soil bytaking it under control and formed from three-dimensionalcells interconnected with nodes in the shape of a honeycombmade from polyethylene The cellular load bearing systemsexpand in the construction field and are filled with soilThe filling material completely covers the cell walls andconfined the entire environment in the soil Therefore itincreases load-deformation behavior and resistance of thesoil by taking vertical loading stresses at the cell walls and soilresistance at the adjacent cells [18]

Zhao et al [19] stated the working principle of geocelllayer by explaining its three effects lateral resistance effectvertical stress dispersion effect and membrane effect Zhanget al [6] explained these aspects in their study Figure 2shows the ldquolateral resistance effectrdquo of geocell reinforcementThe soil above and below the geocell increases the lateralconfinement and lower lateral strain

Figure 3 shows the ldquovertical stress dispersion effectrdquoof geocell reinforcement Footing load is distributed overa wider area and the soil pressure decreases on the softsubgrade [6]

Figure 4 shows the ldquomembrane effectrdquo of geocell rein-forcement The loads deflect the geocell and it causes tensionforcesThe vertical component of the tension force is upwardand it reduces the load and pressure on the subgrade soil[6]

In their study Zhang et al [6] determined that ldquoverticalstress dispersion effectrdquo and ldquomembrane effectrdquo are effectiveon increasing the bearing capacity of subgrade soil whileldquolateral resistance effectrdquo of geocell reinforcement has no

Advances in Materials Science and Engineering 3

Uniform load

Footing load due to the vertical stressdispersion effect

Dispersion angle

Hei

ght o

f the

geo

cell-

rein

forc

ed cu

shio

n

Figure 3 Vertical stress dispersion effect of geocell reinforcement

Tension TensionLoad

Figure 4 Membrane effect of geocell reinforcement

significant effect In that study it is also observed that whenthe settlement is small ldquovertical stress dispersion effectrdquois more effective than ldquomembrane effectrdquo and ldquomembraneeffectrdquo is accepted as almost zero

In that study a different method from Koernerrsquos methodwas used to draw bearing capacity increment-settlement(Δ119901-119904) curves It was stated that Δ119901-119904 curve from thepresented method in that study was more realistic than thatfrom Koernerrsquos method when the embankment settlementwas larger than 5mm This is because the influence oftension membrane effect of the reinforcement is not takeninto account in Koernerrsquos method It was detected thatdispersion angle has very significant effects on the calculatedΔ119901-119904 curve and geocell size infill material properties andgeocell tensional strength are effective on dispersion angle[6] although Dash et al [17] stated that the tensile strengthof the grid used to fabricate geocell mattress is not effectiveon geocell

Dash et al [17] stated that the footing width is importantfor pressure-settlement curve and this curve is almost linearup to settlement of half of the footing width In their studyMoghaddasTafreshi andDawson [4] noted that inmost of theresearches settlement limit criterion is not taken into accountand only bearing capacity is considered while dealing withthe performance of footing But settlement is very importantin practical design of shallow foundations The improvementin bearing capacity is estimated to be unreal in some studies[15 17 20] because of not considering the acceptable range ofsettlement The footing settlement (119904) must not be more than12 of the footing width (119861) Using geotextile is very effectiveon reduction in footing settlement for higher settlements(119904119861 gt 6) [4]

3 Material and Method

31 Method In this paper experimental studies were con-ducted on clayey soil After sieve analysis consistency limitexperiments and hydrometer analyses respectively weredone on this material which was classified according toAASHTO and unified soil classification system In orderto determine optimum water content and dry unit weightof the clay material also modified proctor experimentswere conducted The experiments that were conducted upto here were done with the aim of determining class andspecifications of the soil In this paper the experiment modelthat was mainly wanted to be conducted was plate loadingexperiment With this aim model plate loading experimentswere conducted on the mixtures that were prepared fromhigh water content (10 more than optimum water content)In these experiments the stabilization was done by the waythe soil was reinforced with geocell and geotextile withoutadding anything to the clayey soil and lime was mixed to dryweight of the soil at the rates of 3 6 and 12 and high watercontent in other words natural water content of the soil wasincreased 10

32 Materials Used for the Testing

321 Soil Used as a Subgrade and Sand Used as an InfillMaterial for Geocell The sieve analysis of soil samples isshown in Table 1

With the aim of classifying the material consistencylimits are given in Table 2 Measurements were made after 3daysrsquo curing period of lime

As per ASTMD2487 [21] the soil used as a subgrade wasclassified as clay with high plasticity (Class CH)

The sand used as an infill material for geocell in thisinvestigation was dry It was used as a base layer forunreinforced test section The effective particle size (119863

10)

was 12mm coefficient of uniformity (Cu) was 225 specificgravity was 264 and coefficient of curvature (Cc) was 105 Itis classified as poorly graded sand (SP) according to unifiedsoil classification system [21] The void ratio of the sand was042 and internal friction angle was 37∘

322 Geosynthetics The geocell and planar reinforcementused in this study were both made and supplied by thesame company The type of geotextile was nonwoven Theengineering properties of this geotextile as listed by themanufacturer are in Table 3

The engineering properties of the geocell as listed by themanufacturer are in Table 4 There were also drainage holeshaving 10mm diameter at geocell cell walls

323 Lime The chemical analysis information belonging tothe lime used in this study is given in Table 5

33 Model Plate Loading Experiment

331 Experiment Tool Laboratory model loading tests wereconducted to compare the influence of geocell and geotextile


Table 1 Wet sieve analysis

Sieve analysisSieve number Sieve diameter (mm) Residue of sieving (gr) Sieved (gr) Sieved percent 3810158401015840 953 0 420 1004 476 413 3787 9010 2 296 3491 8340 042 194 3297 79100 152 3145 75200 0074 127 3018 72Pan 3018

Table 2 Liquid limit and plastic limit experiments for natural soiland lime state

Atterbeg (consistency) limitsLiquid limit Plastic limit Plasticity index

Natural 57 27 303 lime 54 32 226 lime 51 35 1612 lime 50 39 11

Table 3 Technical properties of nonwoven geotextile

Properties ValuesUnit weight (grm2) 500Thickness (mm) 4Tensile strength (kNm) 27ndash29Breaking elongation () 50ndash80Static puncture resistance (N) 5500Dynamical puncture resistance (mm) 3Water permeability (msn) 0025Characteristic aperture size (mm) 01

Table 4 Technical properties of geocell

Properties ValuesDensity (grcm3) 094Welding size (cm) 40Cell length (mm) 300Cell width (mm) 250Thickness (mm) 2Cell depth (cm) 20

reinforcement and lime stabilization on increasing the bear-ing capacity of clayey soil in a steel box The overall innerdimensions of the box were 12m length 12m width and12m height as seen in Figure 5 Unpaved road test sectionswere constructed inside the box

The pocket size (119889) of the geocell is taken as the diameterof an equivalent circular area of the pocket opening Thisdiameter was 25 cm in this study Pocket diameterfootingwidth (119889119861) is reported by Dash et al [15] to be around 08times the footingwidthwhich is found to be the one that gives

Table 5 Chemical analysis of the lime ()

Chemical analysis Ca(OH)

280ndash85

Active CaO 60ndash65Total CaO + MgO 85ndash95MgO 1ndash3Density (grlt) 375ndash500

Hydraulic hose

Hydraulic actuator

LVDT

Piston

Circular footing (loading plate)

Steel test box

Loading frame

Geocell reinforcement

Clayey soilsubgrade

Geotextile

Pressurecell

Straingage

12m

12m

15cm

15cm

D = 30 cm

12m times 12m times 1m

Figure 5 Schematic diagram for the set-up of the plate loading test

maximumperformance improvementDue to this reason thediameter of circular footing was determined as 30 cm in thisexperimental tool

The footing was loaded with a hydraulic actuator andthe circular footing was 30 cm in diameter and 3 cm thick1 cm thick rubber pad was attached to the bottom of theloading plate to ensure full contact and minimize stressconcentrations at the edge of the plate Dash et al [17]detected that very good improvement in the footing per-formance can be obtained even with geocell mattress ofwidth equal to the width of the footing and the optimumwidth of the geocell layer is around 4 times the footingwidth Moghaddas Tafreshi and Dawson [4] determined that


increasing the reinforcement width more than 42 timesthe footing width for the geocell would not provide muchadditional improvement in bearing pressure and additionalreduction in footing settlement Sireesh et al [16] and Dashet al [15] detected the efficient width of the geocell as 49 and5 respectively In this experiment geocell layer was chosenas 4 times the footing width The peak load was selected tosimulate a single wheel load of 40 kN (equivalent to an axleload of 80 kN and a tire contact pressure of 550 kPa)

The testing procedures in the experiment are as followsThe subgrade clayey soil was prepared by increasing theoptimumwater content of the clayey soil by 10 and bringingit to 35 outside the test deviceThe soil was mixed homoge-nously and represented a soil whose bearing capacity was lowThe soil also stabilized by lime in proportions of 3 6 and12 by total weight of dry soil The test box was filled withthis soil at the depth of 75 cm as a subgrade The subgradesoil was placed in 3 layers with 25 cm thickness for each layerThe placed layers were compacted in lifts inside a box using avibratory plate compactorThe top of geocell mattress shouldbe at a depth of 01 times the footingwidth from the bottomofthe footing to obtain maximum benefit [4 17] In this studythe top of geocell mattress was at a depth of 3 cm from thebottom of the footing

After preparing the subgrade three strain gages wereinstalled on the top of the subgrade Five pressure cells wereinstalled on the surface of the subgrade at the center and15 cm and 30 cm away from the center of the loading platerespectively A linear variable differential transducer (LVDT)was also placed on the footing model to provide the value offooting settlement during the loading (Figure 5)

Ten unpaved road test sections were prepared in thetest box Experiments were conducted on one (naturalsubgrade and unreinforced base) one (natural subgradeand geotextile reinforced base) one (natural subgrade andgeocell-reinforced base) one (natural subgrade and geocell +geotextile reinforced base) three (3 6 and 12 lime stabilizedsubgrades and unreinforced bases) and three (3 6 and 12lime stabilized subgrades and geocell + geotextile reinforcedbases) sections respectively Reinforced and unreinforcedbases were all 23 cm thick Unreinforced bases consisted ofclayey soil After installation of pressure cells and strain gagesa layer of geotextile was placed on top of the subgrade andthe geocells were placed on top of geotextile for reinforcedsectionsThe geocell used in this experiment was 20 cm thicktop of the geocell mattress was at a depth of 3 cm from thebottom of the footing and the geocell width was 118m asMoghaddas Tafreshi and Dawson [4] and Dash et al [17]detected the ratios between footing width geocell height andgeocell width to get optimum test results

4 Results and Discussion

41 Load-Deformation Findings and Review Comparisonbetween the improvement of clayey unpaved road subgradewith geosynthetics and lime stabilization was made in thelaboratory Ten different alternatives for road sections were

3 limeGeotextile6 lime12 lime

Natural (35water content)Geocell

Geosynthetics (geocelland geotextile)

minus50

minus40

minus30

minus20

minus 10

0

Settl

emen

t (m

m)

0 275 550Plate loading pressure (kPa)

Geosynthetics + 12 limeGeosynthetics + 6 limeGeosynthetics + 3 lime

Figure 6 Loading-settlement curve

examined in this study The loading-settlement relation atdifferent states is in Figure 6While the maximum settlementin natural state at 550 kPa pressurewas 45mm this settlementwas decreased to 41mm when soil was stabilized with3 lime 36mm when soil was reinforced with geotextile35mm when soil was stabilized with 6 lime 29mm whensoil was stabilized with 12 lime 24mm when soil wasreinforced with geocell 16mm when soil was reinforcedwith geosynthetics (geocell + geotextile) 13mm when soilwas reinforced with geosynthetics (geocell + geotextile) andsubgrade was stabilized with 3 lime 11mm when soilwas reinforced with geosynthetics (geocell + geotextile) andsubgrade was stabilized with 6 lime and 8mm when soilwas reinforced with geosynthetics (geocell + geotextile) andsubgrade was stabilized with 12 lime It was observedthat the effects of geotextile (placed 23 cm under the topsurface of the soil) and lime stabilization of soil with 6lime were similar to each other The settlement at geotextilereinforcement state was 15 times the geocell reinforcementstate and 21 times the geosynthetics reinforcement under550 kPa loading The settlement at natural state was 6 timesthe settlement at geosynthetics + 12 lime state underthe same loading The authors in [4] stated that the valueof footing settlement that equals 12 of footing width isconsidered absolute upper limit It was observed that fourstates (natural 3 lime geotextile and 6 lime) among tenstates examined in this study did notmeet the requirements ofsettlement

42 Modulus of Subgrade Reaction Themost popular modelin determining the modulus of subgrade reaction (119896) isWinkler model In this model the subgrade soil is assumedto behave like infinite number of linear elastic springs suchthat the stiffness of the spring is named as the modulus


Table 6 Modulus of subgrade reaction

States Modulus of subgradereaction (119896) (kNm3)

Natural 67653 lime 96776 lime 12000Geotextile 1260812 lime 15000Geocell 18330Geosynthetics 26000Geosynthetics + 3 lime 42000Geosynthetics + 6 lime 48300Geosynthetics + 12 lime 70000

of subgrade reaction The direct method to estimate themodulus of subgrade reaction is plate load test that isdone with 30ndash100 cm diameter circular plate or equivalentrectangular plate

Modulus of subgrade reaction values was calculated withthe help of Figure 6 by determining the inclinations ofloading-settlement curves These values are listed in Table 6

As seen in Table 6 ldquo119896rdquo value was 6765 kNm3 for naturalstate of the soil which had 35 water content and thisvalue was 70000 kNm3 for soils reinforced with geocell +geotextile and 12 lime stabilized According to HighwaysTechnical Specifications in Turkey this value is to be noless than 55000 kNm3 and ldquogeosynthetics + 12 limerdquowas the only state that met the requirement of HighwayTechnical Specifications It was seen that lime stabilizationor reinforcement with geosynthetics solely did not meet therequirement of modulus of subgrade reaction in this studyThe only acceptable situation was making geosyntheticsreinforcement after stabilizing soil with 12 lime AlthoughDash and Hussain [2] determined that for expansive soildominant samples the optimum lime content was 9 inthis study 12 lime content was the better proportion among3 6 and 12 lime treatments In Figure 7 the relationbetween the modulus of subgrade reaction and ratio oflime used to stabilize the soil is seen In Figure 8 therelation between the modulus of subgrade reaction andgeosynthetics reinforcement with lime content in the soil isseen

43 Vertical Stress Vertical stresses occurring on the sub-grade soil were measured by the help of pressure cells usedin the experiment These values were measured at 23 cmlower than the bottom of the loading plate and they are seenin Figure 9 It is detected that geosynthetics reinforcementis more effective than 12 lime stabilization 12 limestabilization + geosynthetics reinforcement is much moreeffective than the other states The stress value 23 cm lowerand at the center of the plate of natural soil is about 25times the stress value obtained at 12 lime stabilization +geosynthetics reinforcement

R2 = 09206

y = 74658e00635x

5 10 150Lime content ()

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

Figure 7Modulus of subgrade reactionwith respect to lime contentin the soil

5 10 150Geosynthetics reinforcement with lime content ()

R2 = 09301

0

10000

20000

30000

40000

50000

60000

70000

80000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

y = 29245e00771x

Figure 8 Modulus of subgrade reaction with respect to geosynthet-ics (geocell + geotextile) reinforcement with lime content in the soil

5 Conclusion

In this paper the effects of lime stabilization geotextilereinforcement geocell reinforcement geosynthetics (geo-cell + geotextile) reinforcement and lime stabilization +geosynthetics reinforcement were researched for unpavedroad which has clayey subgrade with high water contentModel plate loading experiments were done in the laboratoryfor this purpose Comparisons of these soil improvementmethods were madeThese comparisons have not been madebefore in the literature for ten different states examined inthis study This study is important to detect the optimumsoil improvement method among lime stabilization geocelland geotextile reinforcement for unpaved roads with clayeysubgrade which has high water content Plate loading test wasmade by considering optimum dimensions obtained fromother studies


minus15minus30 0 15 30 45minus45

Distance from plate center (cm)

0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa

P = applied pressure

Unreinforced soil12 lime stabilized12 lime + geotextile +

geocell reinforcement

Geotextile + geocell reinforcement

Figure 9 The vertical stress values on subgrade

As a result of plate loading test lime stabilization achievesdecrease in soil settlement 12 lime stabilization gave betterresults among 3 6 and 12 lime treatments for reductionof settlements Although lime stabilization or geotextilereinforcement decreases settlements natural clayey soil withhigh water content (10 more than optimum content)3 and 6 lime stabilization and geotextile reinforcementdid not meet the settlement requirement which must beat most 12 of the width of footing 12 lime stabiliza-tion geocell reinforcement geosynthetics reinforcement andgeosynthetics reinforcement + lime stabilization gave thesufficient values for settlement among ten states in this studyGeosynthetics reinforcement + 12 lime stabilization wasthe best treatment to get lowest settlement and it was 56times the settlement at natural state under 550 kPa loadingpressure The stress value measured at 23 cm lower than thebottom of the loading plate for natural state was 25 times thestress value obtained at 12 lime stabilization + geosyntheticsreinforcement

Lime stabilization and geosynthetics reinforcements allincreased themodulus of subgrade reaction (119896) But when thenatural clayey soil which has 35water content by increasingthe optimum water content of the clayey soil by 10 has ldquo119896rdquovalue of 6765 kNm3 only one state (geosynthetics + 12 limestabilization) among 10 states applied to improve the soil inthis experiment met the Highways Technical Specificationswith a value of 70000 kNm3

When clayey soil with high plasticity (Class CH) with10 more water content than optimum water content isused as an unpaved road base it does not meet the bearingcapacity and modulus of subgrade reaction requirementsLime stabilization or geosynthetics reinforcements are notenough on their own for this purpose It is recommended tostabilize the soil with 12 lime content and then reinforce itwith geotextile and geocell to improve these types of soils tobe used for unpaved roads

Competing Interests

The authors declare that they have no competing interests

References

[1] A Wilkinson A Haque J Kodikara J Adamson and DChristie ldquoImprovement of problematic soils by lime slurrypressure injection case studyrdquo Journal of Geotechnical andGeoenvironmental Engineering vol 136 no 10 pp 1459ndash14682010

[2] S K Dash and M Hussain ldquoLime stabilization of soilsreappraisalrdquo Journal of Materials in Civil Engineering vol 24no 6 pp 707ndash714 2012

[3] N R Krishnaswamy K Rajagopal and G Madhavi LathaldquoModel studies on geocell supported embankments constructedover a soft clay foundationrdquoGeotechnical Testing Journal vol 23no 1 pp 45ndash54 2000

[4] S N Moghaddas Tafreshi and A R Dawson ldquoComparison ofbearing capacity of a strip footing on sand with geocell andwith planar forms of geotextile reinforcementrdquo Geotextiles andGeomembranes vol 28 no 1 pp 72ndash84 2010

[5] S Y Liu J Han D W Zhang and Z S Hong ldquoA combinedDJM-PVD method for soft ground improvementrdquo Geosynthet-ics International vol 15 no 1 pp 43ndash54 2008

[6] L Zhang M Zhao C Shi and H Zhao ldquoBearing capacity ofgeocell reinforcement in embankment engineeringrdquoGeotextilesand Geomembranes vol 28 no 5 pp 475ndash482 2010

[7] F G Bell ldquoLime stabilization of clay minerals and soilsrdquoEngineering Geology vol 42 no 4 pp 223ndash237 1996

[8] J E Barker C D F Rogers and D I Boardman ldquoPhysio-chemical changes in clay caused by ion migration from limepilesrdquo Journal of Materials in Civil Engineering vol 18 no 2 pp182ndash189 2006

[9] J KMithchell and K Soga Fundamentals of Soil Behavior JohnWiley amp Sons Hoboken NJ USA 3rd edition 2005

[10] N C Consoli L Lopes Jr P Prietto L Festugato and RCruz ldquoVariables controlling stiffness and strength of lime-stabilized soilsrdquo Journal of Geotechnical and GeoenvironmentalEngineering vol 137 no 6 pp 628ndash632 2011

[11] S K Dash and M Hussain ldquoInfluence of lime on shrinkagebehavior of soilsrdquo Journal of Materials in Civil Engineering vol27 no 12 Article ID 04015041 pp 1ndash9 2015

[12] A Kavak A G Gungor C Avsar B Atbas and A AkyarlıldquoA lime stabilization application on a divided road projectrdquoin Zemin Mekanigi ve Temel Muhendisligi Onikinci UlusalKongresi Selcuk University Konya Turkey October 2008

[13] H Zhou and X Wen ldquoModel studies on geogrid- or geocell-reinforced sand cushion on soft soilrdquo Geotextiles and Geomem-branes vol 26 no 3 pp 231ndash238 2008

[14] G M Latha and A Somwanshi ldquoEffect of reinforcement formon the bearing capacity of square footings on sandrdquo Geotextilesand Geomembranes vol 27 no 6 pp 409ndash422 2009

[15] S K Dash S Sireesh and T G Sitharam ldquoModel studies oncircular footing supported on geocell reinforced sand underlainby soft clayrdquo Geotextiles and Geomembranes vol 21 no 4 pp197ndash219 2003

[16] S Sireesh T G Sitharam and S K Dash ldquoBearing capacityof circular footing on geocell-sand mattress overlying clay bedwith voidrdquoGeotextiles and Geomembranes vol 27 no 2 pp 89ndash98 2009


[17] S K Dash N R Krishnaswamy and K Rajagopal ldquoBearingcapacity of strip footings supported on geocell-reinforced sandrdquoGeotextiles and Geomembranes vol 19 no 4 pp 235ndash256 2001

[18] A Emersleben and N Meyer ldquoBearing capacity improvementof gravel base layers in road constructions using geocellsrdquo inProceedings of the 12th International Conference of InternationalAssociation for ComputerMethods and Advances in Geomechan-ics (IACMAG rsquo08) pp 3538ndash3545 Goa India October 2008

[19] M-H Zhao L Zhang X-J Zou and H Zhao ldquoResearchprogress in two-direction reinforced composite foundationformed by geocell reinforced mattress and gravel pilesrdquo ChinaJournal of Highway and Transport vol 22 no 1 pp 1ndash10 2009

[20] S GThallak S Saride and S K Dash ldquoPerformance of surfacefooting on geocell-reinforced soft clay bedsrdquo Geotechnical andGeological Engineering vol 25 no 5 pp 509ndash524 2007

[21] ASTM ldquoStandard practice for classification of soils for engi-neering purposes (unified soil classification system)rdquo Tech RepD2487 ASTM West Conshohocken Pa USA 2006

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decreases at first and then starts to increase after a certainlimit of lime content This content is 5 for fine-grainedsoils and 9 for coarse-grained soils It is also known thatexcessive lime treatments decrease the soil strength Becauseof that calculating the optimum amount of lime is veryimportant for lime stabilization

Dash and Hussain [11] detected that the effect of limeon reducing the shrinkage potential of high plastic expansivesoils is more than low plastic residual soilThe optimum limecontent to get minimum shrinkage was calculated as 5

In the studies Kavak et al [12] reviewed performance oflime stabilization of clay with high plasticity on the base soilof the real road The necessary lime ratio was determinedas 5 Implementation was done on total 40 cm part of thesoil The lime stabilization was applied in 2 layers as 20 cmfor each CBR (California Bearing Ratio) values increasedfrom 11 to 56 after lime stabilization At the plate loadingexperimentsmaximumsettlement decreased to 36mm from222mm 8 times increases occurred on dry CBR values of thematerial to which 5 lime was mixed at the end of 56 daysand up to 34 times increases occurred on its wet CBR valuescompared to the natural material

Geosynthetic reinforcement has been more used amongsoil improvement techniques It gives an advantage of rapidconstruction at low costs Zhou and Wen [13] have deter-mined the mechanisms of geosynthetic reinforcement byexplaining the confinement pocket effect raft foundationeffect and stress dispersion effect in their study

Latha and Somwanshi [14] demonstrated that the geocellis the most advantageous form of geosynthetic reinforce-ment (ie geocell planar layers and randomly distributedmesh elements) Moghaddas Tafreshi and Dawson [4] andDash et al [15] also determined that geocell reinforcementis more desirable than planar reinforcement MoghaddasTafreshi andDawson [4] stated that the geocell reinforcementimproves the bearing capacity of soil more than 200 andreduces the settlement by 75

Zhou andWen [13] indicated that subgrade reaction coef-ficient 119896

30can be improved by 3000 and the deformation

can be reduced by 44 by using geocell-reinforced sandcushion Sireesh et al [16] and Dash et al [15] stated thatif a planar geogrid is added at the base of the geocell thebearing capacity of the foundation also increases Dash et al[17] detected that this increasing can be 30 more than withgeocell aloneThe effect of planar reinforcement layer reducesby increasing the height of the geocell mattress

The overall goal of this study was to demonstrate thebenefits of geosynthetics reinforcement and lime stabilizationfor clayey pavement subgrade with high water content withthe detailed objective of this study being to compare the per-formance of geocell reinforcement geotextile reinforcementand lime stabilization by using these treatments solely andtogether This comparison has not been made before in otherstudies

2 Cellular Confinement Systems

As seen in Figure 1 cellular confinement systems (geocellgeoweb neoweb etc) are a network having a high resistance

Figure 1 Application of geocell in the field

Tensile force

LoadsWall of geocell

FrictionalresistanceT

Lateralrestriction

Lateralrestriction

Subgrade reaction

of geocell T

Figure 2 Lateral resistance effect of geocell reinforcement

that was developed with the aim of stabilizing the soil bytaking it under control and formed from three-dimensionalcells interconnected with nodes in the shape of a honeycombmade from polyethylene The cellular load bearing systemsexpand in the construction field and are filled with soilThe filling material completely covers the cell walls andconfined the entire environment in the soil Therefore itincreases load-deformation behavior and resistance of thesoil by taking vertical loading stresses at the cell walls and soilresistance at the adjacent cells [18]

Zhao et al [19] stated the working principle of geocelllayer by explaining its three effects lateral resistance effectvertical stress dispersion effect and membrane effect Zhanget al [6] explained these aspects in their study Figure 2shows the ldquolateral resistance effectrdquo of geocell reinforcementThe soil above and below the geocell increases the lateralconfinement and lower lateral strain

Figure 3 shows the ldquovertical stress dispersion effectrdquoof geocell reinforcement Footing load is distributed overa wider area and the soil pressure decreases on the softsubgrade [6]

Figure 4 shows the ldquomembrane effectrdquo of geocell rein-forcement The loads deflect the geocell and it causes tensionforcesThe vertical component of the tension force is upwardand it reduces the load and pressure on the subgrade soil[6]

In their study Zhang et al [6] determined that ldquoverticalstress dispersion effectrdquo and ldquomembrane effectrdquo are effectiveon increasing the bearing capacity of subgrade soil whileldquolateral resistance effectrdquo of geocell reinforcement has no


Uniform load


Dispersion angle

Hei

ght o

f the

geo

cell-

rein

forc

ed cu

shio

n


Tension TensionLoad












10)





















280ndash85


Hydraulic hose

Hydraulic actuator

LVDT

Piston


Steel test box

Loading frame


Clayey soilsubgrade

Geotextile

Pressurecell

Straingage

12m

12m

15cm

15cm

D = 30 cm















minus50

minus40

minus30

minus20

minus 10

0

Settl

emen

t (m

m)














R2 = 09206

y = 74658e00635x


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )



R2 = 09301

0

10000

20000

30000

40000

50000

60000

70000

80000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

y = 29245e00771x


5 Conclusion





0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa









Competing Interests


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Uniform load


Dispersion angle

Hei

ght o

f the

geo

cell-

rein

forc

ed cu

shio

n


Tension TensionLoad












10)





















280ndash85


Hydraulic hose

Hydraulic actuator

LVDT

Piston


Steel test box

Loading frame


Clayey soilsubgrade

Geotextile

Pressurecell

Straingage

12m

12m

15cm

15cm

D = 30 cm















minus50

minus40

minus30

minus20

minus 10

0

Settl

emen

t (m

m)














R2 = 09206

y = 74658e00635x


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )



R2 = 09301

0

10000

20000

30000

40000

50000

60000

70000

80000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

y = 29245e00771x


5 Conclusion





0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa









Competing Interests


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials

















280ndash85


Hydraulic hose

Hydraulic actuator

LVDT

Piston


Steel test box

Loading frame


Clayey soilsubgrade

Geotextile

Pressurecell

Straingage

12m

12m

15cm

15cm

D = 30 cm















minus50

minus40

minus30

minus20

minus 10

0

Settl

emen

t (m

m)














R2 = 09206

y = 74658e00635x


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )



R2 = 09301

0

10000

20000

30000

40000

50000

60000

70000

80000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

y = 29245e00771x


5 Conclusion





0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa









Competing Interests


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials













minus50

minus40

minus30

minus20

minus 10

0

Settl

emen

t (m

m)














R2 = 09206

y = 74658e00635x


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )



R2 = 09301

0

10000

20000

30000

40000

50000

60000

70000

80000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

y = 29245e00771x


5 Conclusion





0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa









Competing Interests


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials











R2 = 09206

y = 74658e00635x


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )



R2 = 09301

0

10000

20000

30000

40000

50000

60000

70000

80000

Mod

ulus

of s

ubgr

ade r

eact

ionk

(kN

m3 )

y = 29245e00771x


5 Conclusion





0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa









Competing Interests


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






0

30

60

90

120

150

180

Vert

ical

stre

ss (k

Pa)

P = 550kPa









Competing Interests


References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Research Article Comparison of Effects of Using ...Aer sieve analysis, consistency limit experiments...

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Transcript of Research Article Comparison of Effects of Using ...Aer sieve analysis, consistency limit experiments...