Experimental Study on Mechanical Behavior of Sand Improved by Polyurethane Foam

So far, many studies have been completed on the traditional soil stabilisation using cement or lime, however, very limited literatures pay attention to the mechanical behavior of stabilised soil with new materials. The main objective of the current study was to investigate the mechanical behavior of stabilised soil with polyurethane (PU) foam. For this purpose, a series of direct shear tests were performed on soil specimens which were stabilised by PU foam. The study revealed that adding PU foam to sand resulted in a remarkable increase in the shear strength parameters (c and ϕ), which the increase of cohesion was more pronounced than the increase of angle of internal friction. The strength of PU foam-stabilised specimens increased gradually as the PU foam content increased from 0 to 10% and then decreased for additional PU foam content. The interaction between the sand particles and PU foam was investigated by optical micrograph analysis. Finally, a new model was developed to predict the shear strength of PU foam-stabilised specimens. Results indicated a satisfactory performance of the proposed model where the Pearson correlation coefficient was 0.94.