A review of the influence of aluminum phases from cement, SCMs and external aluminum phases on the thaumasite sulfate attack in cement-based materials

Thaumasite sulfate attack (TSA) directly leads to the decomposition of the C-S-H gel and converts the hardened cement paste into a non-cohesive substance. The prevention of TSA damage is of great significance for concrete structures in cold regions worldwide. The aluminum phases probably affect the TSA process of cement-based materials. This paper presents a comprehensive review of the influence of different types of aluminum phases on the TSA process and thaumasite formation of cement-based materials. First, the possible types of aluminum phases in cement-based materials which may affect the TSA process, including the aluminum phases in cement clinkers, supplementary cementitious materials (SCMs, e.g., fly ash, slag, and metakaolin), and other external aluminum phases (i.e., the soluble aluminum phases exist in natural environments such as Al2(SO4)3 or used for experimental purpose such as NaAlO2), are summarized. Then, the effects of these aluminum phases on TSA and thaumasite formation process are introduced and discussed in detail in terms of the surface deterioration, volume deformation and mechanical properties. The mechanism beneath is also discussed and summarized. Finally, the outlook of future work in this filed is proposed.