Innovative approaches for producing unfired bricks: a sustainable construction solution using iron ore mining waste

The construction sector faces constant demand for the reduction of energy and raw material consumption along with green gas emissions. With the constant accumulation of mining waste through the years representing a major environmental hazard. The elaboration of unfired clay bricks stabilized with lime and gypsum using iron mining waste rock from El Ouenza iron mine of Algeria represents an opportunity for the reduction of the environmental impact of construction material and management of mining waste. Bricks were manufactured with varying iron mining waste rock contents ranging from 0 to 25 wt.%. The unfired bricks were evaluated through physical and mechanical tests, including shrinkage, water absorption, porosity, and compressive strength. Additional analyses included thermal conductivity, mineralogical composition, environmental assessment using the Toxicity Characteristic Leaching Procedure (TCLP), as well as microstructural examination by Scanning Electron Microscopy (SEM) and FTIR. Addition of 15–20 wt.% iron waste rock had a positive effect on the physical and mechanical properties of the unfired bricks. Linear shrinkage, water absorption and porosity were reduced, while compressive were increased. Compressive strength reached 10.89 MPa for lime stabilized bricks and 12.45 MPa for gypsum stabilized bricks. Thermal conductivity values ranged from 0.52 to 0.60 W/mK, indicating good insulating properties.