Effectiveness of geopolymer-treated soil plasticity characteristics: A road pavement material

Abstract

High- and low-expansivity are common in all expansive soils. Most roads are constructed on high- and low-plastic soils that can be enhanced by means of fly ash-based geopolymer, a “green cement”. This paper describes the effectiveness of fly ash-based geopolymer for construction of road subgrade through laboratory experimentation, considering free swell behaviour, shrinkage behaviour, unconfined compression test, California bearing ratio, and resilient modulus. The effectiveness and feasibility of the material were characterized in terms of reduction in swelling and shrinkage and improvement in strength behaviour of soil mass. The optimized fly ash and geopolymer mixes were noted at 25 %, as observed through the microstructural analysis of soil samples. Soil plasticity plays an important role, governing the strength of soil. Low-plastic soil shows high mechanical strength compared to high-plastic soil. Fly ash geopolymer-treated soil material was found to be more suitable for construction of the sub-grade or sub-base layer of flexible pavement, help to reduce conventional stabilizer, and lead to a sustainable solution.