Ultra high performance and high strength geopolymer concrete

Alkali-activated materials and geopolymer concrete refer to a group of aluminosilicate-containing materials activated by a highly alkaline solution that has major benefits when compared to ordinary concrete, including the potential to develop superior thermo-mechanical and durability properties with lower environmental footprints. For them to be used as ultra high performance and high strength geopolymer concrete, a compressive strength of around or above 120 and 60 MPa, should, respectively, be developed. To develop such strength in conventional ultra high-performance concrete, generally a very low water to binder ratio (~ 0.2), through the use of admixtures, with a high quantity of steel fibers, fine sand (e.g., quartz sand) and silica fume is used. Yet, since the production of geopolymer and its polymerization and microstructural formation is somewhat different from ordinary practices, its performance and strength development follow a somewhat different path. As a result, with the potential to be used as an optimized concrete that can effectively reduce the costs and CO2 emissions associated with the production of conventional ultra high-performance concrete, this article provides a state-of-the-art review on ultra high performance and high strength geopolymer concrete introduced and developed more recently, and the reported thermo-mechanical and durability properties by recent studies. Based on the results of this review, it is found that ultra high performance and high strength geopolymer concrete has a better thermal performance while it relies more significantly on the mixture ingredients, such as silica fume, quartz sand and steel fiber for fresh, compressive and flexural strength properties, respectively.