Mechanical properties of recycled brick powder engineering cementitious composites under freeze-thaw cycling environment

With the continuous advancement of urbanization construction, the number of discarded red bricks caused by construction demolition is impressive because of the characteristics of construction materials in the early stage of our country. This study used the recycled brick powder produced in crushing red waste bricks to partially or wholly replace quartz sand, combined with different doses of PVA fiber to prepare green recycled brick powder engineering cementitious composites (ECC). First, the strain hardening and multiple cracking behaviors of recycled brick powder ECC with different fitting ratios were verified using four-point bending tests. Then, a rapid freeze-thaw experiment was conducted to study the effects of different fitting ratios on the quality failure rate, phase dynamic elastic modulus, and compressive flexural resistance of recycled brick powder ECC. Based on the evaluation parameters of compressive strength loss rate and frost resistance, the ECC freeze-thaw prediction model of recycled brick powder was established by the Monte Carlo method to expand the number of samples. The research results show the best frost resistance of recycled brick powder ECC with a 25% recycled brick powder ratio and 1% PVA fiber. Scanning electron microscopy was used to observe raw materials and cement-based materials, and the reasons of macroscopic phenomena were explained from a microscopic perspective.