Analysis of early-age properties of geopolymers with various waste materials

Abstract

As the demand for concrete increases to meet the expanding need, the environmental impact of its production cannot be ignored. The use of ordinary Portland cement (OPC) is known to deplete natural resources and release large amounts of CO2 into the atmosphere. Geopolymer concrete (GPC), made from waste and industrial by-products, has shown the potential to overcome the environmental issues associated with OPC-based concrete. In addition to being a sustainable alternative, GPC has properties comparable to or superior to those of OPC-based concrete. This research aims to investigate the early-age properties of GPC and the influence of incorporating alternative waste materials on these properties. Samples of GPC were examined for their mechanical properties and mineralogy in the early stages of curing. By partially integrating alternative waste sources (such as waste wood ash, recycled aggregates and seawater), the influence on these early-age properties were analysed. The results of this research indicate that the majority of strength gain is developed within the first few hours of elevated curing, with the final strength being achieved after approximately ten hours. The strength development during these first ten hours can be approached by a logarithmic function and beyond this point no significant increase in strength is observed. Additionally, the observed changes in mineralogy and microstructure indicate an initial correlation with the development of mechanical properties. An effect on early-age properties was observed by integrating various alternative waste sources. Each different waste source indicated at least some effect on the fresh or hardened properties, the rate at which they developed, and the mineralogy. Some mechanical properties were improved by the use of these alternative waste sources in combination with significant changes in mineralogy. Initial observations encourage further research and show the potential benefits of using alternative waste materials in geopolymers, not only in terms of performance but also for a more sustainable future in construction.