In the quest to reduce carbon emissions and find sustainable uses for industrial byproducts, researchers have made a significant stride in geopolymer technology. A recent study led by Md. Hamidul Islam from RMIT University’s Civil and Infrastructure Engineering department has demonstrated a promising approach to utilizing brown coal fly ash (BCFA) in geopolymer mortar, potentially revolutionizing the construction and energy sectors.
Geopolymer concrete has long been touted as an eco-friendly alternative to traditional Portland cement (PC) concrete, offering reduced carbon emissions and enhanced durability. However, the high curing temperatures required for BCFA-based geopolymers have posed a challenge for commercial adoption. “Most brick manufacturing facilities operate at a maximum of 80 °C, making the previously required 120 °C curing temperature impractical,” explains Islam.
The study, published in *Case Studies in Construction Materials* (translated to English as *Case Studies in Building Materials*), explores the compressive strength and microstructural evolution of blended geopolymer mortar using BCFA and Class F fly ash (FA) at a more commercially viable curing temperature of 80 °C. The research employs various sodium hydroxide-to-sodium silicate activator ratios, with a fixed Na2O dosage of 15% over a range of Alkali Modulus (AM) values.
The findings are promising. The study identifies an optimum alkali activator dosage of 15% Na2O and AM 1.25, achieving a 40% utilization of BCFA with a concrete strength of 39.40 MPa at 7 days and 38.97 MPa at 28 days. Moreover, with a 70% utilization of BCFA, the optimum design attained strengths of 18.92 MPa at 7 days and 23.30 MPa at 28 days, suitable for brick production.
The formation of N-A-S-H and/or C-A-S-H gel combined with the crystalline phases of the optimum mix (70% BCFA and 30% FA) are primarily responsible for achieving these strengths at the reduced curing temperature. “This breakthrough could significantly impact the construction and energy sectors by providing a sustainable solution for BCFA disposal and reducing the carbon footprint of construction materials,” says Islam.
The commercial implications are substantial. The energy sector, particularly coal-fired power plants, generates vast amounts of fly ash as a byproduct. Finding sustainable uses for this material not only reduces landfill storage but also creates value from waste. The construction industry stands to benefit from a more eco-friendly and potentially cost-effective alternative to traditional concrete.
This research could shape future developments in geopolymer technology, encouraging further exploration of blended fly ash systems and optimized curing conditions. As the world increasingly focuses on sustainability and circular economy principles, innovations like this are crucial for driving progress in both the construction and energy sectors.
The study’s findings open new avenues for research and development, potentially leading to more widespread adoption of geopolymer technology in commercial applications. By addressing the challenges of high curing temperatures and high BCFA utilization, this research brings us one step closer to a more sustainable future.