LEGEND OF CIVIL

Alkali silica reaction (ASR) commonly known as ‘concrete cancer’ is a swelling reaction that happens due to highly soluble alkalies cement paste and non-crystalline silica(siliceous minerals) that are generally found in aggregate. Why it is called concrete cancer? As we know concrete is permeable and water percolates in concrete and ASR reaction are happed in the presence of water.  In ASR, aggregates containing certain forms of silica will react with alkali hydroxide( NaOH / KOH) in concrete to form a gel that swells as it absorbs water from the surrounding cement paste or the environment. These  Viscous  gels can induce enough expansive pressure to damage concrete . there is sodium silicate   (Na 2 SiO 3  •  n H 2 O), also noted Na 2 H 2 SiO 4  •  n H 2 O or N-S-H ( sodium silicate hydrate ) form in Gel. The conditions required for ASR to occur are: •A sufficiently high alkali content of th...