1) Mechanism and interaction with existing materials.The basic functioninvolvedinadditionof geo-synthetics intothe pavement improves itsfunction and structure in many ways. Geo-synthetic materials can help the road in reinforcementincrease itscapacity, canactasasealant in road, helpsin filtration process,drainage and inseparationoflayers. Geo-syntheticmaterialscanalsobenefit thepavement bystoppingsub-grade soil to get mix with aggregate of designed base or sub-base. o, in general geo-syntheticscan be very useful for pavement design, function and structure. !einforcement "or reinforcement geo-synthetic material layer is either introduced between base and sub-base orbetween sub-base and sub-grade.The following figure explains the loading condition of pavement is improved by the addition ofgeo-synthetic reinforcement.#ddition of geo-synthetic material in road improves its strength by three different mechanism. $ateral restrain %ncreased bearing capacity Tension membrane effect"ollowing mechanisms are explained as& $ateral restrain&$ateral restrain in the pavement is obtained due to friction between geo-synthetic layer andthe aggregate of the pavement.'henpavement is under loading theaggregatetendstomovedownbecauseof loadingbut theduetointroductionof geo-synthetic material it saves the pavement from moving down laterally. %nteraction betweenaggregate and the geo-synthetic layer allows transferring the shear load on the baseaggregate due to loading to the tensile load in geo-synthetic. The friction and interloc(ingfunction of geo-synthetic materials increases the strength of the pavement. %ncreased bearing capacity&)uetoadditionof geo-syntheticmaterial alternativefailuresurfaceisdeveloped which tends to increases bearing capacity of the soil. The new failure plane isdeveloped is tend to increase the bearing capacity of the soil. *y addition of geo-syntheticlayer in the pavement the punching failure changes into general failure. Tension membrane effect&Geo-synthetic material also act as tension member and support wheel load.The membrane provides the vertical force+reaction to the applied wheel load. This verticalsupport helps to reduce the load on the sub-grade because of loading. eparation&%n many cases fines from under laying sub-grade can enter the base layeranddisturbthe existingprofile. ,ontaminationof base layer canreduce the efficiencyofpavement in many ways. %t may reduce the strength of the pavement or the stiffness of pavementmay suffer. )ifferent studies have shown that up to -.fines will not affect the road.,ontainment due to fines can also cause frost heaving in the base layer. The addition of geo-synthetic layer between base and sub-grade will save the base layer on the time of constructionalso at the time of functioning of the road. # properly designed separator can help base coarse toremain clean so that it will wor( properly in terms of strength and drainage./nli(e reinforcement strength and modulus of geo-synthetic material is importantfor survival of the material. The addition of separator seem to improve the strength of the baseand helps to continue as load carrying part but the separator will not contribute to the structuralsupport 0ust li(e in reinforcement. "iltration&'hen geo-synthetic layer act as a filtration material it filter out fines fine whichare present in pore water. #s water flows from sub-grade to base the filtration mechanism doesnot allow fines to travel through and contaminate the base. 'hen the traffic move, due to loadingpore water pressure is generated which and thus water due to pressure starts flowing upwardcarrying the fines with it. o the basic function of geo-synthetic material to the filter the fineswithout getting clogged. The best filter in geo-synthetic found by studies is heavy woven geo-textile. The passage of fine and the functioning of filter mainly depend upon the si1e of openingof the geo-textile. )rainage&%nproperdrainagecandecreasethelifeoftheroad. %fsameroadisproperlydesigned for drainage then its life may extent up to two or three time which is muchsignificant. This shows the importance of well designed drainage in pavementconstruction. *y adding geo-synthetic for drainage it acts as a medium to transfers thewater to edges of the pavement. %n addition tothis, geo-synthetic especiallygeo-composites also help to mitigate frost heaving in soils which are prone to frosting.2) ,onstruction re3uirementsccording to M!T-45 the construction re3uirements are as under&Thesurfaceor thesub-gradeonwhichthegeo-syntheticlayer is laidshouldbecleananduniformsothat it canfunctionproperly.6owthelayerislaidandshould be uniform and clean and free from wrin(les. The geo-synthetic layer shall overlapfor788mmminimuminthelongitudinaldirection. %fthesub-gradelayerissoft, greateroverlap is re3uired. %n some cases geo-synthetic material is 0oined with ties and cable so thatit may not lose its shape or orientation due to presence of softer under laying sub-grade.*efore place the layer the layer should be examined properly so that any fault or damage inthat it should be replaced because it will not allow the geo-synthetic layer to wor( properly.Thegeo-syntheticsectionshall not overlapduringconstruction. Thetrac(constructione3uipment which is generally used shall not be used for geo-synthetic pavementconstruction. #ny deformation or rutting occurs during placing and fill shall be addressed3uic(ly. The recommended value for overlap of woven textile is 1888 mm in all directionspecified by M!T 45.Moreover the cost is alsoanimportant issuetoaddress duringuseof geo-synthetic material.7) Testssessment of geo-synthetic materials is based on field test, laboratory test andnumerical simulations. $aboratorytest arecheaperthanfieldinvestigationandcanbedone in controlled conditions but achieving the actual behavior of pavement by laboratorytesting is a difficult tas(. "inally numerical based calculation will be done to testify theresults by both test methods. "ield test&"ield tests are performed on actual roadways. "ield test is very time consumingprocess as we have to gather actual information. %n flexible pavements two main failures of theroad are to be examined crac(ing and surface deflection. ,rac(ing include longitudinal crac(ing,transversecrac(ingas well as fatigue. urfacedeflectionis themost commoncriteriaformeasuring the ability of the road.)eflectionmeasurement is usuallydonebynon-destructivetesting. Themostwidely used device for surface deflection is "alling 'eight )eflectometer. %n this method seriesof impulses are applied on the pavement using trailer mounted device. $oading plate is loweredhydraulically to the pavement surface and then impulse is applied to the pavement by droppingweight fromthe(nownheight ontotheloadingplate. Thenmagnitudeandtheamount ofdeflection is measured which gives the result of the deflection compared to (nown impulse.9ther e3uipment used for measuring surface crac(ing is rolling )ynamic)eflectometer. %t performs continuous deflectingmeasurements thandiscrete. :enceresultsobtained by this are more accurate and actual. $aboratory test&There are number of laboratory tests to measure the performance of geo-syntheticreinforcement in flexible pavements. Two main tests are performed to measure the performanceof pavement are& /nconfined test ,onfined testMoreover field conditions are to be adopted for better results. %n unconfined testgeo-synthetic properties are measured in air while in confined test properties are measured inconfinement of soil. /nconfined tests mentionedearlier unconfinedtest performedongeo-syntheticmaterial inisolation. These tests are easy to run and re3uire less period of time as compared to fieldtests."or (nowing the performance of reinforcement in pavement unconfined tests includewide-widthtensile test, biaxial loading test, 0unctionefficiency test and torsional rigiditytest. 'ide-width tensile test can be performed on any type of geo-material while other testsare only specified for geo-grids. Tensile test is considered to be most important when geo-synthetic material is used as reinforcement in pavement construction.The geo-synthetic behavior observed in laboratory is from unconfined test is thencompared and correlated with field test which have different loading and boundarycondition. %t isverydifficult toreplicateactual fieldconditionsinlaboratorytestingsounconfined test are only used for index parameters rather than actual design properties forreinforcement. ,onfined test&Geo-synthetic reinforcement which is used under base and is sub0ected to trafficloading comes under confinement. To study its behavior unconfined tests are not applicable.Geo-synthetic soil confinement does not only depend upon physical structure and propertiesof geo-synthetic material but also on the properties of soil as well as interaction between soiland geo-synthetic material. There are number of test performed for measuring the strengthand behavior of geo-synthetic material out of which most common used laboratory tests arecyclicplateloadtest, cyclicpullout test, bendingstiffness test andmodifiedpavementanaly1er test.9verall confined test results and approaches is considered to be more appropriateand better but they are very time consuming and expensive in comparison with unconfinedtests. :owever thereareother drawbac(sli(ecost andtimeisthat theyneedspeciale3uipment and re3uirement for the performance. 6umerical studies&)esignof flexiblepavement withgeo-syntheticreinforcement involves manyaspects for its strength and performance. Most important of them is the interaction betweendifferent materials used in construction of pavement. These materials are asphalt, base, sub-base and sub-grade. The most important of which is addition of geo-synthetic material andits interaction with others materials. 6umerical studies do not gives the actual informationon the road profile it 0ust gives us the empirical results due to limitations of parameters andunavailability of tools to ma(e a real time situation. The most commonly tests method are";M