Stress-strain characteristics of foamed concrete subjected to large deformation under uniaxial and triaxial compressive loading

Large compressive deformation associated with ideal plasticity-like stress plateaus is an extremely important performance characteristic of foamed concrete. However, there have been few investigations concerning the stress-strain characteristics of foamed concrete subjected to axial strain larger than 10% under uniaxial and triaxial compressive loading. In the current study, foamed concrete samples at three densities (250, 450, and 650 kg=m3) were prepared and a series of tests were carried out. Axial stress-strain (s1-e) curves were obtained, and peak stress (compressive strength), elastic modulus, peak strain, and the postpeak stress-strain relationship were analyzed. The experimental results showed that the stress-strain characteristics for foamed concrete at all three densities are similar and each can be ideally simplified into four stages. The compressive strength of foamed concrete increases with density and confining pressure, whereas elastic modulus has a positive correlation only with densities regardless of confining pressure. Additionally, no significant correlation was detected between peak strain and density, but peak strain increases with confining pressure. A linear relationship between residual compressive strength and strain was found for almost all test cases. Based on the experimental results, theoretical models for the prediction of peak stress, elastic modulus, and the postpeak stress-strain relationship were derived incorporating the effects of density and confining pressure.