The Effect of Lime and Cement on Rice Husk Ash-Based Peat Stabilization: A Sustainable Ground Improvement Technique
摘要
Most construction sites have implemented chemical treatments over peat to improve its strength and stability adequately as it is a vulnerable geomaterial with poor engineering properties. While rice husk ash (RHA) can be utilized as a sustainable pozzolanic material for soil stabilization, solitary application of it is not sufficient to attain the required strength for construction. Though several studies have explored the potential of using RHA with cement and lime as stabilizers, they are confined to short-term effects and have not systematically compared the effectiveness of both methods. Hence, this study investigates the feasibility of using Portland Composite Cement (PCC) and lime as a partial replacement material for RHA to improve the mechanical properties in the peat stabilization process through conducting extensive laboratory tests. Samples are prepared by varying lime to RHA ratio and PCC to RHA ratio, maintaining a constant peat-to-stabilizer (RHA with PCC or RHA with lime) ratio of 4:1, and cured under fully submerged conditions with a 1.25 kN/m2 surcharge load to maintain in-situ conditions. The performance of stabilized soil is evaluated by considering undrained shear strength, elastic modulus, structure and pore distribution, and chemical properties and compared with the properties of natural peat. The results reveal that PCC mixed with RHA is superior out of the two conventional stabilization agent considered; where, using cement as the partial stabilizer for peat significantly enhances the engineering properties of peat yielding a sufficient strength for typical geotechnical constructions. However, the peat stabilized with RHA and lime shows a gradual decline of its mechanical properties with time, questioning its mechanical integrity in the long run. In general, the current findings conclude that, to align with the circular economy concept for a sustainable future, the most suitable method to achieve required strength and stiffness is peat mixed with 15% PCC + 5% RHA, followed by curing for 60 days under the submerged condition with surcharge.