Wood ash as a stabilizer for pavement subgrade

Abstract

Soil stabilization techniques have been widely accepted as a measure for enhancing the soil engineering properties. Use of conventional additives such as lime, cement, etc. has been found to have long-term environmental and economic limitations. In this study, wood ash has been experimented as a subgrade stabilizer for sodium bentonite clay, which is a weak pavement subgrade. Chemical composition and index properties of wood ash and bentonite were determined. Bentonite was replaced with 0%, 10%, 20%, 30%, and 40% of wood ash to determine the changes in the engineering properties. Experimental results showed that the maximum values of Optimum Moisture Content (OMC), Maximum Dry Density (MDD), and Unconfined Compressive (UCC) Strength, lie between 20% and 30% dosages of wood ash. Further experiments were conducted with 22%, 24%, 26% and 28% dosages of wood ash in bentonite, which showed optimum strength properties at 24% mix percentage. UCC strength at optimum wood ash dosage at 0 days and 7 days of curing were 122 kPa and 148 kPa respectively. CBR value for soaked specimen at optimum dosage was found as 7.3%. Substantial results prove that wood ash is a successful stabilizer for sodium bentonite as pavement subgrade. This also provides a sustainable solution for disposal of wood ash.