New M.Tech. Thesis Submitted from Civil-Geo

IMPROVEMENT IN CBR AND UCS VALUE OF CLAYEY SOIL USING RICE HUSK ASH AND GEO-GRID by Joginder Singh 

Abstract

Soil stabilization is widely used now days due to decrease in sites and increasing construction structures and to counter the swell-shrink characteristics of the clayey soil. The performance of pavement is very dependent upon the characteristics of the soil sub-grade, which provides base for whole pavement structure. Also, million tons of waste is produced from agricultural fields and industries making environment polluted. Accumulation of waste is a serious threat to our environment. Various problems are faced by engineers in their disposal. Therefore, practice of using waste materials is commonly opted. The main objective of this research is focused at improving the CBR and UCS values of clayey soil with addition of RHA as stabilizer along with geo-grid as reinforcement in layers. The soil used for the research purpose was collected from village Lohat Badhi, near Ludhiana. Samples were prepared by mixing with the different proportions of RHA as 5%, 10%, 15% and 20%. The effect of RHA on Atterberg’s limits (LL, PL and PI), Compaction parameters, CBR and UCS values was observed. It was observed that Atterberg’s limit and value of Maximum Dry Density show reduction in their values as compared with that of unmolded clayey soil with increase in RHA content while OMC showed some increase in its value. Maximum value of CBR was observed at 15% RHA with value of 5.83 (unsoaked) and 4.01 (soaked) and UCS value of 190.12kN/m2. Further soil was stabilized with single layer of geo-grid with plan dimensions of CBR mould was placed at distance of 25mm, 50mm, 75mm and 100mm. With each arrangement of geo-grid, the CBR values are calculated and compared with the results of CBR values obtained earlier without geo-grids. It was concluded that maximum CBR value attained when single geo-grid was placed at distance of 25mm from top of CBR mould. Further for two layered geo-grid reinforcement, maximum CBR value was attained with two layer geogrid at 50mm and 100mm. CBR increased with increase in number of layers increasing to 14.96 (unsoaked) and 11.67 (soaked) with four layer reinforcement. Hence, use of Rice Husk Ash along with geo-grid reinforcement proved to be effective method for stabilizing soil.