Sustainable stabilisation of expansive clay subgrades using ethylene-vinyl acetate copolymer emulsion: A comprehensive laboratory evaluation

Expansive clay soil is known to cause damage to pavements due to its volume fluctuations with changes in moisture content, a phenomenon observed globally in many countries. Implementing suitable stabilisation treatments is crucial for improving the mechanical and hydraulic properties of the expansive clay subgrade. While cement and lime have traditionally been widely used as soil stabilisers, there is a growing emphasis on sustainable engineering due to increased awareness of global warming. Seeking alternative green and sustainable materials for soil stabilisation is demanded now, and one such alternative is using ethylene-vinyl acetate (EVA) copolymer emulsion. However, the use of EVA copolymer emulsion for stabilising expansive clay has been relatively underexplored in existing studies. This study evaluates the feasibility of utilising EVA copolymer emulsion for stabilising expansive clay subgrade through comprehensive laboratory tests to assess the mechanical (compaction, unconfined compressive strength, California bearing ratio, resilient modulus, and direct shear), hydraulic (soil-water retention curve and swell-shrinkage), and micro-chemical (thermogravimetric analyses and scanning electron microscopic) performance of the soil. The experimental results indicate that the inclusion of 1 % EVA copolymer emulsion into the expansive clay provided the highest mechanical properties, resulting in an increase in the unconfined compressive strength, soaked California bearing ratio, resilient modulus, and cohesion by 8.8 %, 177.8 %, 35.8 % and 19.4 %, respectively. Swell-shrinkage behaviour was also improved with the addition of EVA copolymer, with 1 % EVA copolymer presenting the lowest swell-shrinkage index of 3.19 %/pF (14 % decrease in shrink-swell potential compared to the untreated clay).