Experimental feasibility study of ethylene-vinyl acetate copolymer (EVA) as cement stabilized soil curing agent

Loess resources are abundant and widely distributed in the world, but insufficient strength and water-stability cannot meet the requirements of subgrade soil. Ordinary soil reinforcement technology does not apply to loess. This paper provides a theoretical reference for the application of copolymers as soil curing agents in pavement construction and the treatment of loess. The effect of CSS (cement stabilized soil) specimens and CESS (cement-EVA stabilized soil) specimens were studied to evaluate whether cement-EVA stabilized loess can be used as subgrade soil when adding cement and EVA (ethylene-vinyl acetate copolymer) as a soil curing agent to the loess from the perspective of chemically stabilized soil. The performance of cement-EVA stabilized loess was evaluated through the analysis of mechanical properties, damage resistance, water-stability, anti-freezing ability, dry shrinkage and analysis, and micro-morphology of CSS specimens and CESS specimens. The results show that: the addition of EVA significantly improved the properties of cement stabilized loess. The amount of 300 mL/m3 EVA increased the 28 d strength of CESS by about 26.4%, and as the amount of EVA increased, the strength gradually increased, but the growth rate gradually decreased. The addition of EVA made the specimens more resistant to load and water damage. The toughness index VI of the CESS specimens with 600 mL/m3 EVA was increased by 20%–30% compared with the CSS specimens, and the water stability coefficient K was increased by 5%–10%, and the frost resistance coefficient AFA was increased by about 20%–30%. In addition, the addition of EVA slowed down the shrinkage of cement stabilized loess, and the 30 d drying shrinkage of the CESS specimen was reduced by about 30%. It can be seen in the scanning electron microscope test that with the increase of EVA, cement hydration products gradually increased, pores gradually decreased, and the structure was dense. This means adding EVA to cement stabilized loess can cause chemical reactions to form gels, which surround soil particles, eliminates the pore among the soil particles. The price of EVA is lower and the dosage is little, which can reduce the cost of the entire life of the pavement. In general, EVA is an effective curing agent for strengthening loess and its practical application in the pavement can be further studied in the future.