Influence of expanded polystyrene size on deformation characteristics of light weight soil

HOU Tian-shun(侯天顺)

(College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, China)

Abstract:Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests. The results show that the confined stress？strain relation curve is in S shape, which has a good homologous relation with e？p curve and e？lgp curve, and three types of curves reflect obvious structural characteristics of light weight soil. When cement mixed ratio and EPS volume ratio are the same for different specimens, structural strength decreases with the increase of EPS size, but compressibility indexes basically keep unchanged within the structural strength. The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement. It has no obvious rheology property, and 90% of total consolidation deformation can be finished in 1 min. Settlement？time relation of light weight soil can be predicted by the hyperbolic model. S？lgt curve of light weight soil is not in anti-S shape. It is proved that there is no secondary consolidation section, so consolidation coefficient cannot be obtained by time logarithm method. Structural strength and unit price decrease with the increase of EPS size, but the reducing rate of the structural strength is lower than that of the unit price, so the cost of mixed soil can be reduced by increasing the EPS size. The EPS beads with 3？5 mm in diameter are suggested to be used in the construction process, and the prescription of mixed soil can be optimized.

Key words:light weight soil; expanded polystyrene (EPS); size effect; one-dimensional consolidation theory; compressibility index; structural strength; consolidation test