A model to measure compressive strength of compressed earth blocks with the ‘3 points bending test’

Abstract

This article proposes a modelling of the ‘3 points bending test’ on compressed earth blocks (CEB) which will give their compressive strength. This test is already used in situ for CEB quality control. Conventional bending modelling gives the tensile stress at failure using three of the principal assumptions of the Strength of Materials theory, which are in fact not respected here. This is why it is proposed in this paper to model the arch behaviour in compression, which is of primary importance for aspect ratios less than three. Considering a proposed lattice, a behaviour at failure is obtained, close to that of a CEB during a 3 points bending test. The compressive stress at failure is obtained by using this lattice. The validation of the model is given using experimental data. Then the model gives information on the CEB structure such as isotropy, dry density gradient within the CEB, and effect of friction with the experimental direct compression test device, leading to confinement of the sample.