Assessing the Flexural Characteristics of Geofoam using Digital Image Correlation Technique

Geofoam is a popular lightweight fill material block used for the construction of road embankments over soft subsoils. The uneven load distribution and excessive settlement over such embankments can lead to differential stress distribution, leading to the bending of thin geofoam blocks. The assessment of geofoam's ability to withstand bending stresses is commonly conducted by evaluating its flexural strength, which also serves as an indicator of its bond strength resistance. In the present study, flexural characteristics of geofoams of varying densities ranging from 15 kg/m³ to 30 kg/m³ are assessed experimentally. Subsequently, a statistical assessment is conducted to analyse the variations in flexural strength and modulus and their potential relationship with geofoam density. A non-contact full-field strain measurement during the test is conducted using 2D-digital image correlation (DIC). This facilitated the evaluation of strain distribution within the geofoam during the testing. The observed DIC strains at the outer fibre matched precisely with the physically measured strain, validating the analysis method. It is observed that irrespective of the geofoam density; the EPS cell collapse occurred at a constant true strain value, i.e., 17%. Furthermore, it is also noted that more than 55% of the sample area experiences tensile strain during failure, whereas 45% is subjected to compressive strain. It is also determined that the ratio of the area under compression to tension at failure exhibited an increase in correlation with the density of the geofoam.