Spalling of concrete caused by ASR – a review

Abstract

A very well-known fact is that cracks in concrete members can allow water to enter the member, thus jeopardizing the concrete member integrity by changing the chemical composition of concrete and causing the aggregates to expand. This initiates the consequent chemical reactions that may evoke spalling of concrete thus creating a cycle of undesirable occurrences in concrete. As a final result, the concrete member can be deteriorated affecting the serviceability, but sometimes even leading the reduction of its load bearing capacity. An overlooked cause of concrete spalling of a chemical nature is the spalling caused by the Alkali-aggregate reaction. This is colloquially known as “concrete cancer”. It is a specific type of a reaction between alkali hydroxides and specific types of aggregate that occurs in concrete. Two main types of alkali-aggregate reactions are the alkali-silica reaction (ASR) and the alkali-carbonate reaction (ACR). The main goal of this research was to review the alkali-silica reaction in concrete as well as the mechanism of aggregate expansion it causes, which ultimately results in concrete spalling. Finally, the ways of prevention the alkali-silica reaction were reviewed and discussed.