Experimental Study and 3-D Meso-Scale Discrete Element Modeling on the Compressive Behavior of Foamed Concrete

Abstract

The relationships between the mechanical properties of foam concrete and its pore structure and cement slurry properties have been confirmed, but these relationships cannot be directly reflected just through experimental research. Thus, experiments and the discrete element method (DEM) were used to reveal the relationship between pore structure, cement slurry characteristics, and mechanical properties in foam concrete in this paper. In order to ensure the authenticity and accuracy of numerical simulation, tests of foam concrete were carried out first, such as X-ray computed tomography (CT), the uniaxial compression test, and the three-point flexural test. On this basis, the failure process of foamed concrete was reflected by numerical simulation. The results show that the bearing capacity of foam concrete increases significantly with its increased density. In 750 kg/m3 foam concrete, the stress is mainly borne by the cement matrix. The ability of the cement matrix around the pores to resist tensile failure is weak, and the failure of foamed concrete is mainly caused by tensile failure. Moreover, when the loading rate is low, it takes a long time for the foamed concrete to break, and the cracks generated by the force expand along the weakest area around the pores to form a rough failure section. At higher loading rates, cracks tend to develop directly through the cement matrix along a straight line. The crack development process inside foam concrete is accurately presented by DEM. The density of foam concrete increases, the number of internal cracks decreases, and the cracks are dispersed. The crack development of foam concrete can be divided into the following stages: First, the microcracks are generated near the supports. Following that, the cracks are caused by tensile stress and gradually extend with increasing loading until the foamed concrete fails. Under full calibration, the engineering design of foam concrete can be completed by DEM.