Exploring The Impacts Of Abundantly Available Sustainable By-Product Materials In Australia On Stabilizing Expansive Soils

This paper aims to examine the effects of utilizing readily available sustainable by-product materials in Australia for the purpose of stabilizing expansive soils. Some waste by-products, commonly found in Australia that can be employed for soil stabilisation are cement kiln dust, blast furnace slag, quarry dust, bagasse ash and fibre, rice husk ash, fly ash and bottom ash.

With support of industry a number of materials have been selected for characterisation. Extensive experimental tests utilizing bagasse fibre, bagasse ash, bottom ash, fly ash, and eggshell powder have been conducted at the University of Technology Sydney (UTS) to enhance the engineering properties of expansive soils. These tests have been supplemented by microstructural tests, numerical analysis, and comprehensive discussions. These pozzolanic materials are characterized by significant levels of calcium carbonate, silica, and alumina. Numerous tests have been performed using these by- products to investigate the impact of their composition in conjunction with lime or cement, the curing time, the particle size, the optimal blending ratios, on both treated and untreated soil properties.

Based on research and laboratory investigations, sustainable by-product materials have demonstrated substantial potential for enhanced durability, cost savings and long-term environmental benefits, compared to traditional cementitious agents in treating expansive soils. These materials offer improved soil strength, reduced swelling potential, enhanced soil ductility, and controlled deformation over time. However, the implementation of these sustainable materials in practice is not yet widespread among construction companies and road authorities in Australia. This paper addresses this concern and provides practical recommendations for adoption of these sustainable by-products in weak subgrade of roads.