Influence of Rice Husk Ash on Sub-Grade Bearing Strength in Stabilization of Expansive Soils for Low Volume Roads in Kenya

Catherine Mugai ,Benedette Sabuni ,Edward Neyole ,Faith Mugai

doi:10.7176/cer/12-11-04

Abstract

The cost of cement and lime used in stabilizing soils can be reduced by using locally available rice husk ash which is known to contain pozzolanic properties. This paper studies the variations in sub-grade bearing strength of clay when rice husk ash (RHA), lime and cement are added in varying proportions. Chemical analysis was first carried out to establish the silica content in the RHA. CBR test was conducted to establish the strength properties of the various soil mixes. RHA was used as the main stabilizing agent added at varying proportions of 0%, 5%, 10%, 15% and 20%. Lime and cement proportions were constant in each batch but varied across the six batches as 0%, 2% lime, 4% lime, 6% lime, 1.5% cement and 2% cement. The test results show that RHA in combination with lime can be used as an economic and eco friendly stabilizing agent giving a significant improvement in the sub-grade bearing strength of cotton soil. Keywords: key words, Rice Husk Ash (RHA), California Bearing Ratio (CBR), Sub-grade, Lime, Cement DOI: 10.7176/CER/12-11-04 Publication date: November 30 th 2020

Highlights

The cost of cement and lime used in stabilizing soils in Kenya can be reduced by using locally available rice husk ash which is known to contain pozzolanic properties
The sub-grade bearing strength class of cotton soil increased from soil class S1 (2-5% California Bearing Ratio (CBR)) to S3 (7-13% CBR) using two combinations with the least additives; 2%lime mixed with 5% rice husk ash (RHA) and 4% lime alone
The water to be added when mixing was determined which is the product of the total dry mass and difference of optimum moisture content (OMC) and present moisture content (PMC) vi

Summary

Introduction

The cost of cement and lime used in stabilizing soils in Kenya can be reduced by using locally available rice husk ash which is known to contain pozzolanic properties. Many studies have been done on the use of rice husk ash in stabilizing soil there are no studies specific to low volume road construction. The results obtained from this study can be used as a guideline in stabilizing materials for the sub-grade layers on low volume roads in Kenya. The findings of this research can form a basis for further research on other applications of rice husk ash in the construction industry in Kenya with the aim of finding economical solutions and preservation of non-renewable resources such as soils and rocks

Methods

Results

Conclusion