Wednesday, August 24, 2016

New M.Tech. Thesis Submitted from Civil-Geo

Effect of RBI Grade 81 and Fly ash on CBR value of clayey and expansive soil by Virajan Verma

In a developing country like India, roads are being constructed at a very fast rate. Traffic is increasing day by day and therefore we require a pavement that can safely take the loads and transfer them to the sub grade soil. Sometimes the soil does-not have enough strength and stability to carry the loads coming from the pavement. In such a case either we can replace the soil or we can stabilize it. Stabilization provides an economical solution. In the present study soil is stabilized by using RBI Grade 81 and fly ash. More precisely, a comparison is done on the effect of RBI Grade 81 and fly ash on the CBR value of clayey soil and Expansive soil. The different percentages of RBI used were 1%, 3% and 5%, whereas fly ash was used at 10%, 20% and 30% respectively. The clayey soil used was not expansive in nature and therefore 15% bentonite powder was added to it to make it expansive. The various tests performed in the laboratory were standard proctor test and CBR test. OMC increased and MDD decreased using both RBI and fly ash on both soils. With the addition of 1%, 3% and 5% RBI, the OMC was found to be 16.5, 17 and 18% respectively. The OMC of virgin soil came out to be 16%. The MDD of virgin soil was 1.61g/cc. The MDD was found to be 1.6, 1.59 and 1.58g/cc respectively upon adding 1%, 3% and 5% RBI. The soaked CBR value of virgin soil was 1.75%. This value increased to 3.75, 6.86 and 9.63% respectively with the addition of 1%, 3% and 5% RBI. The optimum combination was found to be 75:20:5 (Soil: Fly ash: RBI) for both the soils. It was also seen that the percentage increase in CBR value for clayey soil was more as compared to expansive soil in all cases.