Strength and Impact of Rice Husk Ash on Expansive Soil by Using Soil Stabilization

Abstract

There are about 20% black cotton soil areas in India. It is one of the most problematic soils with a high tendency to shrink or swell due to water content changes. When it comes into contact with water, the volume of the soil increases and decreases when water evaporates or loses its touch. Because of the unpredictable nature of this soil, it is not easy to construct or use such land properly without proper treatment because it provides different settlements that pose risks to constructed structures. The rice husk is available in abundance, as India has a large rice production. The rice husk is produced from Rice Mills as a by-product. This husk contains some of the volatile matter and is converted to ash, which is produced during the firing of rice husk. The purpose of the present research is to study the impact of rice husk ash on swelling and mechanical characteristics of the black cotton soil. With increase in the contents of RHA into soil up to 20% by dry weight of soils—RHA composite mix starting from 5 to 20% at a rate of increase as 5%, RHA and expansive soil mixtures were prepared in adequate numbers. After three days of curing, differential free swell tests, Atterberg limit tests, shrinkage factor tests, specific gravity tests, light compaction tests, soaked CBR were carried out. The addition of RHA reduces differential free swell, plasticity index, flow index, shrinkage, maximum dry density, angle of internal friction. As the amount of RHA increases CBR, liquid limit, plastic limit, void ratio, porosity, peak deviator stress values of soil increases. In cohesion intercept variation with RHA content, the typical pattern is observed. Cohesion intercept begins to grow with the rise in RHA content, but starts decreasing after 10 percent RHA content. Based on this experimental analysis, it is found that RHA not only reduces the swelling and shrinking behavior of expansive soil but also significantly increases its strength.