Characterization of the concrete deterioration process in an ammonium sulfate environment

expansion, microstructure, and mechanical aspects

Abstract

Ammonium sulfate is an important component in the production of fertilizers. This agricultural input is commonly stored in concrete structures, which can lead to premature deterioration and increased costs associated with structural rehabilitation. In this context, this research aimed to investigate the effects of ammonium sulfate on the cementitious matrix and its degradation mechanism. Concrete and paste specimens were therefore produced with CPV-ARI and were monitored over a period of 365 days through expansion tests, mass variation, tensile and compressive strength tests, and microstructural analyses. Part of the specimens was immersed in an aggressive ammonium sulfate solution with a concentration of 9.3% (NH₄)₂SO₄, while the reference group was immersed in a saturated limewater solution. After 365 days, the specimens exposed to the ammonium sulfate solution exhibited a 58% reduction in compressive strength compared to the reference series, along with cross-sectional loss. Gypsum precipitations were also observed on the surface of the exposed specimens, as well as cracking and spalling. It was concluded that there is a lack of standardized information and procedures regarding the degradation mechanism induced by ammonium sulfate.