A novel prediction model for failure mechanism of foamed concrete

Abstract

In this paper, the effect of pore structure and cement paste characteristics on the mechanical properties of foamed concrete are studied by means of the test and discrete element method (DEM). Firstly, the pore structure of foamed concrete is obtained by X-ray computed tomography (CT), which provides the microstructure parameters for numerical simulation. Then the uniaxial compression and three-point flexural tests are carried out to obtain the stress–strain curves, which are used to calibrate the mesoscopic parameters of DEM. Finally, the numerical models are established based on the determined mesoscopic parameters to simulate the failure process of foamed concrete with different densities at different loading rates. The results show that the ability of cement matrix around the pores to resist tensile failure is weak and the failure of foamed concrete is mainly caused by tensile failure. Moreover, internal pores will be more concentrated and the quantity is more for the low-density foamed concrete, which will cut the cement matrix into the thinner tensile area, resulting in the stress concentration and sharp decrease in mechanical properties. Meanwhile, the high loading rate accelerates the propagation of internal cracks, which makes the cracks tend to propagate directly through the cement matrix along the straight line and exhibit higher strength than the low loading rate. The investigation demonstrates that, once fully calibrated, DEM can be used as a useful tool for practical engineering design based on foamed concrete.