Development of Limestone Calcined Clay Cement-Based Lightweight Bricks Incorporating Waste Rockwool: A Step into Leading the Way in Low-Carbon Bricks

Abstract

This study aimed to develop eco-friendly limestone calcined clay cement (LC3)-based lightweight bricks by reusing waste rockwool (RW) with the improvement of technical performances such as thermo-physical and mechanical, including fire-resistance performances. LC3 binder was blended with expanded clay (EC) aggregates at a ratio of binder-to-aggregate of 1:1.5 (vol%). EC was substituted by waste RW at different percentages, ranging from 5 to 15 vol%. Several technical properties such as density, compressive strength, total porosity, water absorption, thermal conductivity, and thermal diffusivity were investigated after 7 days of curing. The fire-resistance performance of the developed bricks was determined by assessing the residual compressive strength after exposure to standard fire for up to an hour. With dry bulk densities ranging from 1200 to 1360 kg/m3 and compressive strengths (>8.60 MPa), the developed brick met the acceptance criteria for non-load-bearing applications. Even at the highest dosage of RW, the results demonstrated a thermal conductivity as low as 0.36 W/mK, indicating that the developed brick is suitable for hot weather zones, as it reduces the heat flow into buildings. The partial replacement of EC by RW is very beneficial in enhancing the fire-resistance performance, and a residual strength of about 89.7% has been maintained by the bricks incorporating 5% waste RW after 1 h of fire exposure (employing a maximum applied temperature of 927 °C). Lifecycle assessment results indicated that up to 13% lower carbon emissions are associated with LC3-based lightweight bricks designed to reuse a higher amount of waste RW.