Evaluating moduli of triaxial geogrid-stabilised sandy soil with lightweight deflectometer

Abstract

Geogrid-stabilised soil has been widely adopted to enhance performance in transportation and infrastructure sectors. In this study, the performance of unstabilised and triaxial-geogrid-stabilised sandy soils in terms of dynamic deformation modulus and elastic modulus was measured using lightweight deflectometer (LWD) and plate load tests (PLTs), respectively. The objective of the study was to evaluate: (a) dynamic deformation modulus of sandy soils with different relative compactions from deflectometer testing and compare with the elastic modulus of sandy soils from PLTs for a given relative compaction of 97%; (b) modulus improvement factors (MIFs) of triaxial-geogrid-stabilised sandy soils through extensive laboratory testing and (c) compaction quality control of well-graded gravel using deflectometer testing through a field study. The triaxial-geogrid-stabilised sandy soil layer showed MIFs of 1.51 and 1.37 obtained from deflectometer and plate load tests corresponding to an embedded depth of 50 mm, respectively. The percentage differences in these values are in the range of 4–9% for all the embedded depths. Hence, an LWD can be used instead of a PLT as a quick and low-cost alternative for determining the MIF of geogrid-stabilised sand soil, both in the laboratory and in the field.