Cement-Based Stabilization of Black Cotton Soil Using Rice Husk ash and Promoter

Abstract

Black cotton soils exhibit high swelling and shrinkage on the absorption or depletion of moisture and are the main cause of the many problems such as pavement failure, foundation cracks, and excessive settlement associated with the soil. Although poor and undesirable for engineering purposes, black cotton soil could be improved to meet engineering specifications by stabilization processes. The aim of this paper is to evaluate the effect of RHA and promoter on the compressive strength of black cotton soil. Natural black cotton soil was stabilized with 0% cement, 0% RHA, 0% promoter; 0% cement, 1% RHA, 0.3% promoter; 0% cement; 2% RHA, 0.6% promoter; 0% cement, 3% RHA, 1% promoter continuously up to 1% and 2% cement replacement and cured for a period of 1, 7, 14, 28, and 60 days. To evaluate the strength of the natural soil, various tests were carried out in the laboratory such as moisture content, sieve analysis, Atterberg limit, specific gravity and compaction (OMC and MDD). The experimental results showed that unconfined compressive strength (UCS) values increased with higher compactive effort, RHA and promoter content. The UCS increased from 340KN/m2 to a maximum strength value of 582kN/m2 at 3% cement, 3% RHA and 1% promoter for specimens compacted at the West Africa Standard energy level at 60 days curing period, which implies that stabilization of black cotton soil can be improved with increased amount of RHA and promoter.