Investigation on the Suitability of High Clay Lateritic Soils Stabilized with Cement and Rice Husk Ash for Use in Road Base Construction: A Case Study of Juja Town

Abstract

- The problem being addressed in this study is the lack of suitable material for road base applications in areas with high clay lateritic soil. The study aims to investigate if a mixture of Ordinary Portland Cement (OPC) and Rice Husk Ash (RHA) can be used to improve the mechanical properties of this type of soil, making it suitable for road base construction. The natural soil is first characterized through tests such as Atterberg limits, compaction test, Californian Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS). After that, the soil sample is mixed with cement at a gradually varying content of 4– 10 % of the dry weight of the soil sample at 2 % intervals, and the optimum cement content necessary to achieve the targeted strength properties (UCS) with regard to standards is selected. The optimum cement proportion is 8%, and the treated soil's UCS and soaked CBR values are 1.83 MPa and 142%, respectively. Following that, the soil is treated with a cement-RHA mixture, with RHA gradually replacing cement content from the optimum proportion selected to full replacement at 1% intervals. Atterberg limits, compaction, CBR, and UCS testing are performed on all treated samples. The mechanical performances of the treated specimens with a cement-RHA combination containing no more than 3% RHA meet the requirements for the desired use. All specimens with RHA content greater than 3% have lower and insufficient strength values. In conclusion, an optimal mixture of 5% cement+3% RHA is chosen, with soaked CBR and UCS values of 115 and 1.72, respectively.