Technical and commercial progress in the adoption of geopolymer cement

If formulated optimally, geopolymer cement made from fly ash, metallurgical slags and natural pozzolans could reduce by 80% the CO2 emissions associated with the manufacturing of cement. 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 100+ 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 geopolymerisation of aluminosilicates constitutes a radical change in construction materials chemistry and synthesis pathways compared with the calcium silicate hydrate chemistry which underpins Portland cement. Consequently, there are regulatory, supply chain, product confidence and technical barriers which 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 commercialise 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 continues to be the key driver for the short term adoption of geopolymer cement. In the absence of an in-service track record comparable in scale and longevity to Portland cement, research is essential to validate durability testing methodology and improve geopolymer cement technology. Colloid and interface science, gel chemistry, phase formation, reaction kinetics, transport phenomena, comminution, particle packing and rheology, which are familiar concepts to minerals engineers, are also 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.

CO2 emissions of various cement binders as a function of OPC content.Figure optionsDownload as PowerPoint slideHighlights
► Alkali activated slag and ash cement has 80% less CO2 emissions than OPC cement.
► Geopolymers face regulatory, supply chain, product trust and technical barriers.
► Projects using geopolymers compensate partially for lack of 100+ year track record.
► Relationship between geopolymer microstructure and durability shown by research.
► Colloid science, particle technology and rheology are key to geopolymer knowledge.