Effect of rock-wool waste on physical, mechanical, and microscopic properties of nonburn solid bricks

Rock wool (RW) possesses excellent thermal and acoustic insulation properties and is widely used for the insulation of building facades and pipes; however, the RW furnace slag (RWFS) produced during RW production is usually treated as a landfill, which causes serious environmental pollution. Herein, nonburn solid bricks were prepared using RWFS as an auxiliary cementitious material and aggregate. Orthogonal experiments were employed to analyze the effect of the raw material ratios on the compressive strength, water absorption, and softening coefficient of the bricks; univariate experiments were employed to investigate the effect of fine-furnace slag-particle content on the properties of these bricks and to characterize the microstructure of the specimens. The results showed that when the fine-furnace slag-particle content was 30%, optimal properties of the nonburn solid bricks with a 28-day compressive strength of 75.82 MPa, water absorption of 3.03%, and softening coefficient of 0.80 were achieved; the improvement of these properties was due to the reaction of the fine-furnace slag particles with Ca(OH)₂ in the slurry, thereby generating a certain amount of hydration products (C–S–H) and improving the pore structure of the nonburn solid bricks.