State-of-the-art review of geopolymer concrete carbonation: From impact analysis to model establishment

Geopolymer concrete (GPC) is a relatively new, innovative and sustainable green civil engineering material, which has many advantages similar to ordinary Portland Cement (OPC). Through the investigations and analyses of published literature, this review paper summarizes the state-of-the-art research progress with respect to the carbonization performances of GPC from the following aspects. First of all, the advantages, carbonization mechanism, and carbonization identification methods of GPC are introduced. Second, the carbonization properties between GPC and OPC are compared, as well as the influences of different factors on the carbonization performance of GPC are analyzed, such as admixtures, additives, environment, etc. Finally, a series of models to evaluate the degree of carbonization are listed, and the future prospect of GPC carbonization research is also put forward. Based on the literature summaries, existing researchers still have great controversy about the research results on the anti-carbonization properties of geopolymer gelling materials, mainly because of the diversity of raw materials in the geopolymer system, resulting in large differences in the hydration products and microstructure of various geopolymer pulps, so there are differences in their anti-carbon performance. It is significant that the influential factors will be of great importance to determine the carbonization performances of GPC, which can also be extended to the anti-carbonization properties of GPC, such as the filling effect of nanoparticles, changing the proportion of silicon and aluminum substances, and improving the mechanical properties and durability of GPC. In addition, more types of numerical models for the carbonization of GPC should be established, considering more impact factors, to ensure the applicability and accuracy, and the integration of the models needs be more strengthened to serve for the complex engineering practices. Overall, the carbonization model establishment will contribute to analyzing the durability of GPC and provide some clues for prolonging its life.