Improving The Strength Of Expansive Subgrade Soil Using Cement Kiln Dust And Geogrid Material

Abstract

Expansive soil is known as a worldwide problem that posses several challenges for different civil engineering projects. When there is moisture in expansive soils, the volume of soil gets increased and at this time the swelling pressure of soil is greater than the downward pressure of lightweight structures like road hence, such movement causes deformation and cracks on lightweight structures. On the other hand when the soil gets dry the structures face become uneven settlement. Such cyclic movements of soil mass due to moisture variation can cause different structures like road, light weight buildings, and pipeline to have excessive differential settlement and cracks. Therefore, this paper illustrates the use of cement kiln dust and geogrid material to improve the strength of poor expansive subgrade soil which plays an important role in load bearing and supporting different traffic load. In order to commence the above objective, different literatures were reviewed and disturbed soil sample was taken from the specified place and index properties like liquid limit, plastic limit, plasticity index, sieve and hydrometer analysis, free swell and specific gravity tests, and density - moisture tests were determined, based on which the soil was classified as expansive and highly plastic soft soil. Then cement kiln dust material was added varying from 0% to 13% by weight in natural subgrade soil index tests were conducted, the result of which showed that index properties of expansive subgrade soil was significantly improved. Since the second objective of this study is improving the strength of such expansive subgrade soil by using cement kiln dust and geogrid inclusion at the specified layer, CBR and UCS tests were conducted for soil alone, 0% to 13% by weight application of CKD material and reinforcing CBR test by providing PP and HDPE geogrids. The result of the study showed that both cement kiln dust and geogrid inclusion are significantly able to improve the strength of poor subgrade soil. Better improvement was observed when using geogrid inclusion than in the cement kiln dust material. In addition to that, better CBR value was observed when using polypropylene geogrid type rather than high density polyethylene geogrid.