Mechanical and thermal properties of geopolymers derived from metakaolin with iron mine waste

The construction sector is a major contributor to the increase in energy consumption and CO2 emissions, predominantly through the production of Ordinary Portland Cement (OPC). Recent research has focused on building materials, particularly focusing on amorphous aluminosilicates such as geopolymers, with the objective of alleviating environmental impact by enhancing energy management and embracing more sustainable, cost-effective production techniques while maintaining mechanical and thermal properties. This investigation scrutinizes the mechanical and thermal properties of geopolymers based on metakaolin (MK) and incorporating iron mine waste (Hem), predominantly composed of hematite, across various proportions (ranging from 0% to 50% Hem). Diverse methodologies, including compressive strength testing, bulk density measurement, X-ray diffraction, and thermal conductivity analysis, were utilized to characterize the geopolymers. The results revealed that formulations consisting of 100%MK and 90%MK10%Hem exhibit the highest compressive strengths, measuring at 40 MPa, after a 90-day curing period. However, the most sustainable option, yielding a compressive strength of 37 MPa, is observed in the formulation comprising 60%MK40%Hem, due to its increased use of mine waste. Additionally, geopolymers incorporating higher proportions of mine waste showed reduced thermal conductivity and diffusivity. For instance, the thermal conductivity of the 100%MK geopolymer was recorded at 0.58 W/m•K, with a diffusivity of 0.46 × 10−6 m2/s, whereas the formulation containing 60%MK40%Hem displayed values of 0.46 W/m•K and 0.38 × 10−6 m2/s, respectively. These diminished values signify an enhancement in energy efficiency within buildings employing geopolymers incorporating iron mine waste.