Thermal Curing and Environmental Impact of Alkali-Activated Cementitious Materials

Abstract

During the production of ordinary Portland cement (OPC) clinker a lot of carbon dioxide (CO2) is emitted. To improve the sustainability of concrete production, many studies were carried out to evaluate alternative binders for OPC. The use of alkali-activated cementitious materials (AAMs) reduces the amount of Portland cement clinker and a larger volume of industrial by-products such as fly ash (FA) and blast furnace slag (BFS) can be applied. The combination of an aluminosilicate precursor and an alkali activator is characterised by a slower early age strength development compared to OPC. Thermal curing of the concrete is a successful technique to overcome this drawback. Although, thermal curing promotes the early age strength development of OPC-based concrete, the strength at 28 days often is relatively lower. In terms of environmental impact of AAMs, a significant reduction in production-related CO2-emissions is possible by replacing OPC by FA and/or BFS. With a relatively small activator dosage, it was found that the CO2-emissions can be decreased by up to 85% for AAMs compared to OPC-based mixtures. In this research, the effect of the mix design and curing temperature on the early age strength development and the environmental impact of AAMs was investigated.