Behavior of zero cement reinforced concrete slabs under monotonic and impact loads: Experimental and numerical investigations

Currently, there is a shift toward the use of low-carbon construction materials to reduce global carbon dioxide emissions. Zero-cement concrete (ZCC) synthesized from alkaline activated fly ash (FA) is a promising alternative for Portland cement in the construction industry to reduce global CO 2 emissions, increase the consumption of waste materials, and save energy. A substantial amount of research on the impact load behavior of ordinary reinforced concrete (RC) structural components has been conducted. However, investigations on the behavior of zero cement concrete (ZCC) ZCC ) slabs under impact loads have not been reported. In this work, twenty simply supported two-way flat reinforced fly ash ZCC slabs (including two normal concrete (NC) NC ) slabs as reference samples) were tested under monotonic and impact loads. The test samples were categorized into eight groups on the basis of various parameters. Twelve RC slabs (1 NC and 11 ZCCs) ) were prepared for repeated impact tests, and eight slabs (1 NC and 7 ZCCs) ) were prepared for monotonic loading tests. Various parameters were investigated herein, including slab thickness, bar spacing, molarity concentration of alkali activators, hammer height, and hammer mass. Nonlinear finite element models were also developed and validated by using ABAQUS software for additional parametric study purposes. The results revealed that the behavior of ZCC slabs is approximately similar to that of NC slabs. The results also revealed that an increase in the ZCC slab thickness, reinforcement ratio, hammer height, and hammer mass has a noticeable effect on the dynamic response of the slab. However, increasing the molarity concentration of alkali activators has clearly a slight influence on the impact load-time - time history. When the slab thickness was increased or the bar spacing was reduced, the static and impact energy absorption capacities were increased by 1.5 and 2.0 times, respectively. For impact load tests, the damage degree, penetration, and cracking pattern at failure were approximately typical for all test samples at the first hit except when the hammer mass and impact height were changed. For the samples subjected to monotonic loading, a flexural response was observed for almost all the slab samples at the first loading stage, and cracking started from the midpoint of the slab and propagated toward the slab edges; ultimately, punching shear failure was observed.