SUBGRADE STABILIZATION USING ALKALI ACTIVATED RICE HUSK ASH

Abstract

The pavement performance is determined by the behaviour of the subgrade soil and its bearing capacity. Expansive subgrade soil is problematic to the pavement and other types of construction activities due to its excessive swelling and shrinkage, necessitating stability with various materials. Soil stabilization using different chemicals have been used to improve the soil property to make them suitable for the desired engineering purpose. Expansive subgrade can be stabilized using alkali activated slag, fly ash and other waste materials and this also helps in solving disposal difficulties. The purpose of the current work is to strengthen Black Cotton Soil (BCS) with alkali activated Rice Husk Ash (RHA) and to design flexible pavement using IITPAVE software (based on IRC 37-2018). This research explains the behaviour of the modified expansive soil for highway subgrade with liquid alkaline activator stabilizer and RHA. A combination of sodium hydroxide and sodium silicate was utilized as the liquid alkaline activators. Sodium oxide (Na2O) and silica modulus (Ms) are the activator parameters selected for the investigation and were varied in different proportions. Unconfined Compression Strength test and Durability test were used to study the effect of different proportions of alkali activated RHA and activator parameters at different curing durations. CBR test, Swelling test and Flexural strength test were done on samples that have passed the Durability test and Unconfined Compressive Strength (UCS) with the highest compressive strength. This soil treatment enhanced the CBR, UCS, durability and flexural strength of the BCS. The swelling was also significantly reduced.