Production of lightweight bricks using sustainable materials for saving energy in building constructions

This study investigates the utilization of industrial waste, such as fly ash, to generate lightweight geopolymer concrete (LWGC), which is an environmentally beneficial alternative to typical Portland cement-based lightweight concrete (LWC). Six LWC and six LWGC mixtures were developed, cured, and evaluated for mechanical and physical parameters such as compressive strength, flexural strength, absorption, unit weight, fire resistance, and thermal conductivity. The results revealed that LWGC with 350 kg/m³ of fly ash produced the maximum compressive strength (29.7 MPa uncured, 35.3 MPa cured), exceeding LWC which attained 32.6 MPa. However, increasing polystyrene concentration in LWGC decreased strength. Both varieties have poor flexural strength, making them unsuitable for applications needing significant flexural resistance. LWC absorption rates were greater (up to 7.9%) than LWGC (up to 4.2%). Fire resistance and thermal conductivity tests showed that polystyrene-containing samples had greater insulating qualities, with a temperature differential of 8.75°C compared to 2.85°C for non-polystyrene samples. Overall, LWGC shows promise as a long-term building material with competitive mechanical and thermal performance. The cost research found that 1000 lightweight geopolymer bricks cost roughly 174.9 USD, whereas 1000 lightweight cement bricks cost around 52.1 USD. Geopolymer bricks are more than three times more expensive, but they give major environmental benefits such as lower CO2 emissions, higher fire resistance, and superior thermal insulation, making them a long-term viable solution.