In the bustling world of construction materials, a groundbreaking study led by Zehao Lei from the Department of Civil, Structural & Environmental Engineering at Trinity College Dublin, has opened new avenues for sustainable and robust geopolymers. The research, published in ‘Case Studies in Construction Materials’ (translated to English as ‘Case Studies in Construction Materials’), focuses on the potential of spent fluid catalytic cracking catalyst (FCC) in creating high-performance geopolymers, with significant implications for the energy sector.
FCC, a waste product from oil refineries, has long been a challenge for the industry. However, Lei’s team has turned this liability into an asset by incorporating it into geopolymers, a class of materials known for their low carbon footprint and excellent mechanical properties. The study explores the optimal composition of activators and the ratio of FCC to ground-granulated-blast-furnace slag (GGBS) and fly ash (FA) to create geopolymers with exceptional performance.
The FCC-GGBS system, in particular, has shown remarkable robustness. “The FCC-GGBS system exhibits exceptional robustness, performing well across a range of activators and producing outstanding strength,” Lei explains. The geopolymers created from this system demonstrated compressive strengths ranging from 45 to 57 MPa at 28 days, which is a testament to their durability and potential for use in high-strength applications.
One of the most compelling aspects of this research is the potential to lower costs and embodied carbon. The study found that low sodium ([Na+]) and SiO2/Na2O ratios can be safely used to fabricate FCC-GGBS geopolymers, making the process more economical and environmentally friendly. This is a significant development for the energy sector, where reducing costs and carbon emissions are critical goals.
The research also delves into the high-temperature resistance of these geopolymers. While the FCC-GGBS system showed excellent performance at ambient temperatures, high-temperature exposure led to devitrification and the transformation of cementitious phases into aluminosilicates, resulting in significant strength reduction. This insight is crucial for applications where materials may be exposed to extreme temperatures, such as in energy production facilities.
The study utilized advanced analytical techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), and scanning electron microscopy (SEM/EDX), to understand the microstructure and chemical composition of the geopolymers. These analyses revealed that the zeolite in FCC dissolves and participates in polymerization reactions, forming a dense matrix with no unreacted particles. This dense structure contributes to the superior strength of the FCC-GGBS geopolymer.
In contrast, the FCC-FA system showed high sensitivity to activator composition, with deviations from the optimal composition impairing strength. This highlights the importance of precise formulation in achieving the desired properties of geopolymers.
The implications of this research are far-reaching. By utilizing waste materials like FCC, the construction industry can move towards more sustainable practices, reducing reliance on virgin materials and lowering carbon emissions. For the energy sector, this means more durable and cost-effective materials for infrastructure, which can withstand the rigors of energy production and transmission.
As the world continues to seek sustainable solutions, research like Lei’s offers a glimpse into a future where waste is transformed into valuable resources, and construction materials are not only strong but also environmentally responsible. This study, published in ‘Case Studies in Construction Materials’, sets a new benchmark for geopolymer research and paves the way for innovative applications in the construction and energy sectors.
