The Effects of Waste Materials on the Thermo-mechanical Properties of Eco-Friendly Bricks

The world is now obliged to produce sustainable, green and environmentally friendly construction materials to improve thermal comfort in buildings, reduce energy costs, and alleviate the effects of both greenhouse gas emissions and global warming. In this study, the researcher produced cost-effective eco-friendly construction materials with higher effective thermal conductivity using two alkaline activators (AA), sodium hydroxide (NaOH) and sodium silicate (Na2SiO3), in combination with waste materials including a regional volcanic rock Diyarbakir Karacadag Red Scoria (KS) and Karacadag rice husk ash (RHA). First, the researcher analysed the raw materials through Particle Size analysis, XRF, XRD, TGA/DTA, SEM, and EDS to determine their characteristics. Then, they were mixed at different rates to form mixtures (clay: 65 %, 60 %, 55 %, 55 %, and 50 %; KS: 30 % (fixed); RHA: 5 %, 10 %, 15 %, and 20 %; AA: 5 %, 10 %, and 15 %). Rectangular samples for mechanical tests and cylindrical samples for thermal tests were made and fired at 950 degrees C. Next, SEM, EDS and XRD analyses were carried out on the fractured bricks after they were tested for compressive strength. Then, the researcher analysed the fired bricks for their bulk density, apparent porosity, water absorption, compressive strength, loss on ignition, effective thermal conductivity, and microstructures. Experimental results demonstrated that porosity, water absorption, and loss on ignition increased. However, density, compressive strength, and effective thermal conductivity decreased as the rates of RHA and NaOH + Na2SiO3 increased with Karacadag scoria at a fixed rate. The addition of waste RHA, KS, and AA in the brick yielded in a significant improvement in thermal performance (by 0.263 W center dot mK-1) compared to the control bricks (1.043 W center dot mK-1), while the compressive strength dropped from 32.5 MPa to 7.2 MPa. Even though the compressive strength decreased due to the micropores forming as a result of the addition of these materials in the brick, it was greater than 7MP, as stated in the literature. The findings of this study indicated that the fired clay bricks produced are potential materials for construction applications that require an appropriate thermal insulation and mechanical strength, as well as internal structural applications.