Investigation of the mechanical behaviour of concrete with severe delayed ettringite formation expansion focusing on internal damage propagation under various compressive loading patterns

• Published in: Cement & concrete composites 2022-04, Vol.128, p.104433, Article 104433
• Main Authors: Joshi, Nirmal Raj, Matsumoto, Ayumu, Asamoto, Shingo, Miura, Taito, Kawabata, Yuichiro
• Format: Article
• Language: English
• Subjects: Compression test; Delayed ettringite formation (DEF); Image analysis; X-ray CT
• ISSN: 0958-9465; 1873-393X
• DOI: 10.1016/j.cemconcomp.2022.104433

Expansion due to delayed ettringite formation (DEF) can cause severe concrete strength deterioration; the failure process related to internal damage remains unclear. In this study, the influence of pre-existing DEF cracks on the compressive failure process was demonstrated. Concrete specimens with DEF expansions greater than 2% were tested under monotonic, step, cyclic, and sustained loading patterns, providing stress–strain relationships. Internal crack propagation due to loading was quantified using X-ray CT images. Large plastic strains occurred, even at low stress levels. Peak stress and strain at failure were almost independent of the loading history. Gaps formed around the aggregate with increased loading were closed and opened in the loading and perpendicular directions, respectively, contributing to plastic strain accumulation. Gradual interconnection of cracks along the aggregate interfaces at high stress levels led to specimen failure. Gradual gap closing under cyclic or sustained loading reduced additional plastic deformation under the same stress.