Performance of concrete with demolition waste and PCM under high temperature ranges

Abstract

Concrete is considered an incombustible material, however, the investigation of the strength behavior under high-temperature (fire) conditions is crucial for assessing the safety impact on structures. Additionally, pure paraffin (PP), as the most common phase change material (PCM), was used in construction materials. In this work, the functionalization of demolition waste (DW) was prepared through absorption of PP. Subsequently, the functionalized DW, as an innovative aggregate, was used into concrete to enhance the thermal performance of building envelopes. Furthermore, based on 42.5 R Portland cement, the performance of concrete containing different proportions of DW (0 %, 25 %, 50 %, 75 % and 100 %) and functionalized DW (25 %, 50 %, 75 %, and 100 %) were investigated at various temperatures (20 ◦ C, 200 ◦ C, 400 ◦ C, and 600 ◦C). Through microstructural observations, TGA test, and analysis of concrete’s physical and mechanical properties, it was found that PP can fill the concrete and DW pores, but at 200 ℃, the evaporation of PP causes the increase of the internal pores of concrete, which further reduces the mechanical properties of concrete.