Stabilization Of Expansive Sub-Grade Soils Using Rice Husk Ash Blend With Gypsum

Expansive soil problem is a serious problem due to damage to civil engineering infrastructure and it also affects the expansion of infrastructure construction in the World and China as well.Previously,different stabilizers such as cement,lime,fly ash,bitumen used to stabilize the expansive sub-grade soil,but it takes high costs to reduce this problem.In the present day,in the soil stabilisation and alteration cycle or soil strengthening focus is imposed on full use of the local& waste materials.The main reason behind this phenomenon is the excessive production of industrial and agricultural waste(agricultural bi-products)such as coffee husk ash,plastics,rice husk(coat)ash(RHA),which is not only harmful but also causes problems with deposition.The use of some of these agricultural bi-products in construction would significantly reduce the problem,and construction costs can be reduced.Gypsum also used as a stabilizer,but due to the availability,cost,applicability for other purpose requires high cost.This research aims to compare the effects and reduce the amount of gypsum required for stabilization of expansive soil through partially replace of RH ash.In this regard,an attempt was made to evaluate the impact of RHA blend with gypsum as a stabilizer on the geotechnical property of the expansive clay soils in a stabilised form especially in terms of strength characteristics and workability.Therefore,a series of laboratory tests such as Atterberg limits and Direct shear tests of natural and treated specimens were performed.Following the completion of this required laboratory analysis for the stabilization of Rice Husk Ash & Gypsum in cumulative value(30%)with different ratios: 1:1,1:2,1:3 and 1:4(G: RH ash),the results show noticeable enhancement on the geotechnical properties of RHA mix with gypsum stabilized soil.The additive agent appreciably reduces plastic index of expansive soil.Shear strength parameters significantly increase with rice husk ash and gypsum additive in a mixture.