Strength Development in Soil Cement Column and Soil Fly ash - Cement Column in Soft BangkokClay Deposit

Abstract

This study investigated the effect of using fly ash (FA) to replace cement on the strength development in deep mixing columns in soft Bangkok clay deposit. In total, 3 columns were installed and their strengths were investigated. The first column was soil-cement column, made up at the water to cement ratio of 1, while the second and third columns were soil-cement-FA column with 15 percent FA replacement, made up at the water to binder ratios of 1 and 1.2, respectively. It was found that the unconfined compressive strengths of soil-cement column were similar to those of the soil–cement-FA column at water to binder ratio of 1 for all the tested curing times of 14, 28 and 60 days. The strength ratios of the soil–cement-FA columns between water to binder ratios of 1 and 1.2 were 1.3, 1.24 and1.24 for14, 28 and60 days of curing, respectively.The 15 percent FA replacement can save cement cost up to12.75 percent.