Chapter 10 - Progress in the Adoption of Geopolymer Cement

Abstract

If formulated correctly, geopolymer cement made from fly ash, metallurgical slags, and natural pozzolans could reduce the CO2 emissions associated with the manufacturing of cement by at least 80%. However, almost all standards and design codes governing the use of cementitious binders and concrete in construction are based on the use of Portland cement. The 150 + year track record of in-service application of Portland cement is inherently assumed to validate the protocols used for accelerated durability testing. Moreover, the entire supply chain associated with cementitious materials is based on the production of Portland cement. The geopolymerization of calcium aluminosilicates constitutes a radical change in construction-materials chemistry and synthesis pathways compared with the calcium silicate hydrate chemistry that underpins Portland cement reactions. Consequently, there are regulatory, supply chain, product confidence, and technical barriers that must be overcome before geopolymer cement could be widely adopted. High-profile demonstration projects in Australia have highlighted the complex regulatory, asset management, liability, and industry-stakeholder engagement process required to commercialize geopolymer cement. While the scale-up from the laboratory to the real world is technically challenging, the core challenge is the scale-up of industry participation and acceptance of geopolymer cement. Demand pull by a carbon-conscious market has been the key driver for adoption of geopolymer cement in Australia, although valorization of waste, improved technical properties, and cost reduction may become drivers for adoption in other markets. In the absence of an in-service track record comparable in scale and longevity to Portland cement, research remains essential to validate durability-testing methodology and improve geopolymer cement technology. Colloid and interface science, gel chemistry, phase formation, reaction kinetics, transport phenomena, particle packing, and rheology are key building blocks in the development of geopolymer knowledge. Analysis of the nanostructure of geopolymer gels has enabled the tailored selection of geopolymer precursors and the design of alkali-activator composition, aiding in establishing the relationship between geopolymer gel microstructure and durability.