Control of alkali aggregate reaction in hardened concrete

Alkali-aggregate reaction causes significant damage to concrete structures worldwide particularly to hydraulic structures such as dams, barrages etc. This harmful reaction can occur if the alkali content of the cement and the presence of reactive minerals in the aggregate are high and enough moisture is present to sustain the reaction. Under some conditions, the reaction may result in slow but progressive expansion and cracking of the concrete.

This paper presents the studies to control the alkali aggregate reaction in hardened concrete in their service life for Water Resources Projects. As we are aware that the alkali aggregate reaction in concrete is just like a cancer and it is very difficult to control it once started. The pozzolans and other materials can be used to control the alkali aggregate reaction in concrete. Studies have been conducted using the reactive aggregate, water proofing agents, geomembrane, pozzolans etc. to control the alkali aggregate reaction in concrete and their effects have been examined. Results of the study showed that the water proofing agent by crystallization technique noticeably reduces the residual alkali aggregate reaction in the hardened concrete than the other measures.