Evaluating the Performance of Expansive Soil by Using Rice Husk Ash and Liquid Alkaline Activator

This paper presents the strength, swelling, and microstructure characteristics of the expansive soil (ES) amended with rice husk ash (RHA) and liquid alkaline activator (LAA) for pavement subgrade performance. Sodium metasilicate (Na2SiO3.9H2O) and sodium hydroxide (NaOH) were used to prepare a liquid alkaline activator (LAA). The LAA facilitates the chemical reaction among ES, RHA, and LAA to form cementitious compounds in the treated soil. The effectiveness of the RHA with LAA was determined by performing an unconfined compressive strength (UCS) test, California bearing ratio (CBR) test, and field emission scanning electron microscopy (FESEM) test on the natural and amended ES with the different curing periods of 7, 14, and 28 days. The UCS and CBR of the amended ES specimens were found to be increasing with increase in the RHA content with optimum liquid alkaline activator content (OLAAC) up to a specific limit. After that, it was found to be decreasing with an increase in RHA with OLAAC. The strength increases due to the formation of cementitious compounds. The swelling characteristics of the treated ES with RHA and OLAAC are determined in terms of swelling pressure and percentage swell. It increases with the soaking time, and it decreases with an increase in the RHA content with OLAAC. The thickness of the pavement layers decreases as increase in the RHA with OLAAC at 28 days of the curing period. The construction cost is also reduced as the strength of the pavement subgrade increases. The relationship between compaction characteristics, i.e., maximum bulk density (MBD) and OLAAC, or strength characteristics, i.e., UCS and CBR, has been developed.