Experimental study on compressive behaviors and meso-scale structure of SFRFC based on CT scanning technique

Due to the excellent characteristic of lightweight, foam concrete shows great potential in civil and mining en-gineering fields, such as prefabricated roofs and supportive materials for tunnels. However, inherent porosity not only reduces the density of foam concrete but also the strength, which greatly limits its application in engi-neering structures. In this study, the foam concrete reinforced by steel fibers (SFRFC) is proposed, and a detailed experimental study is conducted to investigate the influence of steel fibers and porosities on the physical and mechanical properties of SFRFC. Firstly, 17 groups of SFRFC specimens with different steel fiber content (0, 0.5, 1, 1.5, 2 and 2.5%) and different foam content (0, 40, 50, 60, 70, 80%) are fabricated, and the mechanical properties under uniaxial compressive loading are tested. Secondly, CT scanning technique is adopted to investigate the distribution of steel fiber and pores in the prepared specimens at the meso-scale level and clarifies their interaction at the meso-scale level; Thirdly, the formula which takes porosity and steel fiber content as variables, is established to predict the compressive strength of SFRFC and provides references for the design and engineering application of SFRFC. According to the results of uniaxial compressive test, it can be concluded that steel fibers play an important role in improving the compressive properties of SFRFC, especially the compressive strength and energy absorption. The increase of Steel fibers will reduce the proportion of foam pores in SFRFC and make the pore size distributions polarized according to the X-CT test results. Based on the empirical models commonly used for different materials, we obtain the best formulas for predicting the porosity and compressive strength of SFRFC.