Properties of lateritic soil replaced by bottom ash for highway material

Abstract

This research aims to study the use of bottom ash which is a by-product from power generation process as a replacement of lateritic soil for base or sub-base. The grain size distributions of lateritic soil were selected as Type B and C based on the subbase standard of Highway Department. The bottom ash was obtained from BLCP power plant, Rayong. The bottom ash replacement ratio is 10, 20, 30, 40 and 50 percent for Type B and that of 10, 20, 30, 40, 50 and 60 percent for Type D. The physical properties, compaction properties and strength using California Bearing Ratio test and Direct Shear test of lateritic soil and lateritic soil replaced with bottom ash were investigated. It is found that the maximum dry density decreased with the increasing of the replacement ratio whereas the optimum water content increased with the increasing of the replacement ratio for both types of soil. For the results of CBR test, it was found that when lateritic soil replaced by bottom ash at 30 percent for type B and 50 percent for type D showed the highest CBR values which passed the subbase condition. Moreover, the bottom ash has little effect on internal friction angle and cohesion, both values slightly decreased with the increasing of replacement ratio. It can be concluded that bottom ash can be used as replacement of lateritic soil for highway material.