Preparation and properties of phase change foamed concrete with waste concrete powder

A novel phase change foamed concrete with enhanced thermal inertia was developed using an alkali-activated recycled waste concrete powder-granulated blast-furnace slag (AARS) binary solid waste system. This study integrates micro-encapsulated phase change material (MPCM) into the AARS foamed concrete, aiming to balance its mechanical properties and thermal performance for sustainable building applications. The effects of MPCM dosage (0–7 wt%) on the compressive strength, dry density, and thermal properties were systematically investigated. Results indicated that increasing MPCM content reduced compressive strength and density while improving thermal insulation. Notably, the specimen with 5% MPCM exhibited a 28-day compressive strength of 1.22 MPa, a dry density of 450 kg/m³, and a low thermal conductivity of 0.085 W/(m·K). Furthermore, thermal tests in a simulated room showed that the 5% MPCM panel significantly delayed temperature rise by 66 min and extended cooling time by 75 min. This work demonstrates that AARS-based phase change foamed concrete is a promising material for regulating indoor temperature fluctuations and enhancing building energy efficiency.