Laboratory determination of mechanical and hydraulic properties of chemically grouted sands

The purpose of this paper is to investigate mechanical and hydraulic properties of sands treated with mineral-based grouts through the results of alaboratory test programme consisting of unconfined compression tests (UCS), triaxial bender element tests (BeT) and constant flow permeability tests10 in triaxial apparatus. An improved apparatus was set up for obtaining high quality, multiple grouted specimens from a single column. Two selectednatural sands having different grain sizes were grouted with two mineral-based silica grouts, resulting in different levels of improvement. Thebehaviour of the sands treated by mineral grouts, in terms of strength, initial stiffness and permeability, was compared with that exhibited by moretraditional silicate grouts. The results of this study indicate that sands treated with mineral grouts result in higher strengths, higher initial shearmodulus and lower permeability values than the sands treated with the silicate solution. The effect of grout type, effective confining pressure, and15 sand particle-size on small-strain shear modulus of grouted sand specimens was evaluated. Based on test results, the small strain shear modulusincrement from treated to untreated specimens has been correlated with the unconfined compressive strength, obtaining a unique relationshipregardless of grout type and grain-size of tested sands.