Structural implications of internal swelling reactions in concrete: review and research needs

Abstract

The chemical and physical processes associated with alkali–aggregate reaction and delayed ettringite formation, otherwise known as internal swelling reactions (ISRs), have been the subject of considerable research spanning several decades, yet the implications for affected structures are still open to debate. A major knowledge gap currently exists between the diagnosis and prognosis of ISR mechanisms, and the quantification and management of risk associated with ISR expansion in structures. This lack of understanding of the effects of ISRs on structural behaviour may be attributed to the fact that parameters such as confinement, boundary conditions, anisotropy and loading conditions are complex and vary greatly in existing structures. Furthermore, the correlation between the results of microscopic/macroscopic analyses on concrete core samples and the in situ performance of large-scale structures is still not well understood, even at a fundamental level. The aim of this paper is to summarise current knowledge of the structural implications of ISR mechanisms in concrete structures and stimulate a discussion of the importance of pursuing multi-scale experimental testing programs for the assessment of ageing infrastructure. A parametric analysis is included using the software VecTor2.