Alkali-activated concrete for the production of building blocks: research achievements and future challenges

Abstract

Several global challenges identified by the UN Sustainable Development Goals are either directly or indirectly linked to the construction sector. The need for decent and affordable houses is an urgent problem for many developing countries, whereas the concerns about the carbon emissions related to the manufacture of Portland cement are growing worldwide. A number of possible solutions are currently offered by the research, which has been investigating the recycling of waste/by-products into sustainable building materials during the last decades. This paper discusses the experience gathered in the manufacture of building blocks using alkali-activated concrete produced from waste streams such as fly ash, slag, or cement kiln dust. Laboratory investigations on binder development, concrete mix proportioning, and building block sample production, as well as full size factory trials with industrial equipment, were carried out for assessing the potential and the challenges of this technology. Obtained results demonstrated the technical feasibility of manufacturing building blocks with alkali-activated concrete, and highlighted the challenges for a viable and sustainable application of this technology.