Utilization of waste foam concrete with MPCM as a substitution material for cement in mortars

Abstract

Given the rising popularity of foam concrete (FC) for both structural and insulating purposes, evaluating the feasibility of recycling after its lifespan is crucial in the context of the growing emphasis on sustainable building practices. One approach to recycling FC incorporating microencapsulated phase change material (MPCM) involves utilizing recycled foam concrete powder (RFCP) as an additive in cement composites. This article aims to investigate the impact of RFCP without and with MPCM when employed as a partial replacement for cement in mortars. Furthermore, the study verifies various processing methods such as crushing, grinding, and heat treatment for RFCP. The results reveal that introducing RFCP, regardless of the MPCM presence and processing method, significantly affects the properties of both cement and mortar. The presence of MPCM in RFCP negatively influences the flowability of fresh mortars, delays the setting time, and reduces the hydration heat within the first 48 h. However, the presence of MPCM does not significantly affect mortars' strength and water absorption but simultaneously it increases shrinkage and decreases thermal conductivity. Grinding RFCP mitigates the adverse effects of MPCM, while thermal processing removes MPCM from RFCP, albeit with an associated increase in water demand. A noteworthy finding is that mortars having 20 % RFCP, with or without MPCM, exhibit compressive strengths exceeding 16 MPa and 42.5 MPa after 2 and 28 days, respectively. These results meet the requirements outlined in EN-196-1 for cement of class 42.5, highlighting the potential to produce CEM II/A-F 42.5 using RFCP with MPCM.