Resistance of self-consolidating concrete to ammonium sulphate attack

With the growing use of self-consolidating concrete (SCC) in various infrastructure applications, it has become necessary to establish reliable data on its long-term durability since its mixture design, rheology and consolidation are different than that of normal concrete. Several applications of SCC involve its exposure to chemical attack, particularly to sulphate-rich media such as wastewater treatment facilities, industrial and agricultural zones which also encompass ammonium cations. Thereby, this study aims at investigating the resistance of a wide scope of SCC mixture designs to ammonium sulphate attack. Specimens from 23 SCC mixtures were continuously immersed in a high concentration ammonium sulphate solution with controlled pH (6.0–8.0) up to 54 weeks. The main test variables included the type of binder (single, binary, ternary and quaternary), air-entrainment, sand-to-total aggregates mass ratio, and the inclusion of fibre reinforcement (single and hybrid). The SCC specimens showed variable degrees of deterioration after 54 weeks, indicating different modes of degradation. The study highlights the role of ternary and quaternary binders in improving the resistance of SCC to ammonium sulphate attack. It is also emphasized that multiple performance indicators are needed to achieve a reliable assessment of cement-based materials under ammonium sulphate attack.

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