Assessing the flexural characteristics of geofoam using digital image correlation technique

IMAGE BASED FLEXURAL CHARACTERISATION OF GEOFOAM

Abstract

Geofoam is a popular lightweight fill material used for the construction of road embankments over soft subsoils. The elastic modulus of geofoam is the primary parameter used in designing and modelling such applications. The uneven load distribution over such embankments can lead to differential settlement and is likely to cause cracks in the blocks. The bond strength of the moulded blocks is evaluated based on flexural strength, which varies depending on the density of the geofoam. In the present study, flexural characteristics of geofoams of varying densities were evaluated, followed by statistical evaluation and correlation analysis. Full-field strain measurement in conjunction with physical measurement facilitates strain evaluation over a wide range of time and area. To this end, 2D-digital image correlation (DIC) was adopted to characterise the strain localization within the geofoam block during the testing. The observed DIC strains match precisely with the nominal strain, validating the analysis method. It is observed that irrespective of the geofoam density, the bead collapse occurred at a constant true strain value. In addition, the ratios of the area under compression and tension, during the failure were also determined for varying geofoam densities.