In a groundbreaking development that could revolutionize sustainable construction materials, researchers have successfully created engineered geopolymer composites incorporating recycled waste rubber as a full replacement for fine aggregates. This innovation, led by Feihong Wan from Shenzhen International Graduate School, Tsinghua University, China, opens new avenues for the construction industry to enhance ductility and sustainability simultaneously.
Traditionally, the use of recycled waste rubber in construction materials has been limited to low replacement ratios due to concerns about strength reduction. However, Wan and her team have pushed the boundaries by developing rubberized engineered geopolymer composites (RU-EGCs) with rubber replacement ratios ranging from 0% to 100%. “We aimed to improve ductility and sustainability by replacing fine silica sand with high volumes of rubber,” explains Wan. The results are promising, with the fully rubberized mixture achieving a tensile strain of 7.7% and maintaining a compressive strength of 47 MPa.
The study, published in the Journal of Materials Research and Technology (Revista Iberoamericana de Tecnología de los Materiales), involved a comprehensive experimental evaluation, including mechanical testing, microstructural characterization, and life cycle assessment (LCA). The findings reveal that increasing the rubber replacement ratio reduces compressive strength but significantly improves ductility and crack control. X-ray computed tomography (X-CT) and backscattered electron (BSE) imaging analyses showed increased porosity and a wider interfacial transition zone (ITZ) with rubber incorporation, which facilitate early crack initiation. However, strong fiber/matrix bonding ensures sufficient bridging stress and energy dissipation, promoting high ductility.
From a sustainability perspective, the LCA results demonstrate notable environmental benefits. Compared to typical engineered cementitious composites (ECC), the developed RU-EGCs achieve more than a 40% reduction in both embodied carbon and material cost. This research lays down an approach for designing sustainable ultra-high-ductility EGC through high-volume rubber utilization, offering strong potential for practical application.
The commercial implications for the energy sector are substantial. As the demand for sustainable and resilient construction materials grows, the adoption of RU-EGCs could lead to significant cost savings and environmental benefits. “This innovation not only addresses the pressing need for sustainable construction materials but also provides a viable solution for recycling waste rubber, which is a major environmental challenge,” says Wan.
The findings of this study are expected to shape future developments in the field, encouraging further research and commercialization of rubberized engineered geopolymer composites. As the construction industry continues to seek sustainable alternatives, the work of Wan and her team offers a promising path forward, demonstrating that high-volume rubber utilization can indeed enhance both performance and environmental sustainability.