In the quest for sustainable construction materials, a groundbreaking study led by Luca Tefa from the Department of Environment, Land, and Infrastructure Engineering at Politecnico di Torino has shed new light on the potential of alternative binders to stabilize recycled aggregates. The research, published in Cleaner Materials, explores the mechanical properties, environmental impact, and economic viability of these binders, offering a compelling narrative for the construction and energy sectors.
The study compares three low-clinker cements with varying proportions of pozzolana and three alkali-activated (AA) binders derived from construction and demolition waste fines, municipal incinerator bottom ash, and waste clay. These alternatives are pitted against the industry standard, Portland limestone cement, to assess their potential as sustainable binders for road pavements.
The findings reveal that pozzolanic cements are viable alternatives to Portland cement, offering comparable mechanical strength. However, the story takes an intriguing turn with alkali-activated binders. “The crystallinity of alkali-activated silica- and alumina-rich waste precursors was responsible for their limited strength,” Tefa explains. This crystallinity poses a challenge, as it limits the strength of the binders, making them less competitive in terms of performance.
Environmentally, the story is more promising. The life cycle assessment indicates that replacing clinker with pozzolana significantly reduces the environmental impact. For AA binders, the environmental benefits are contingent on the quantity of alkaline solution used. If more binder is added to compensate for lower strength, the environmental and economic advantages diminish. Tefa notes, “The option of using AA binders would be further strengthened with the production of environmentally friendly alkaline solutions and greater local availability of amorphous precursors.”
The economic landscape is equally nuanced. Currently, cements are cheaper due to massive production and widespread availability. However, the potential for cost reduction with AA binders exists, especially if the production of alkaline solutions becomes more environmentally friendly and cost-effective.
This research has significant implications for the energy sector, particularly in reducing the carbon footprint of construction materials. As the demand for sustainable infrastructure grows, the findings could influence future developments in road layer stabilization and the use of recycled aggregates. The construction industry stands at a crossroads, where the choice of binders could redefine sustainability and economic viability.
As the construction industry continues to evolve, the insights from Tefa’s research could catalyze a shift towards more sustainable practices. The study, published in Cleaner Materials, provides a roadmap for future developments, highlighting the need for innovation in binder technology and the potential for significant environmental and economic gains.
