Why does flyash mitigate ASR?

Answer 1

Fly ash mitigates alkali-silica reaction (ASR) in concrete primarily due to its pozzolanic properties, which help to consume alkalis and reduce their availability for reaction with reactive silica in aggregates. Additionally, fly ash contributes to a denser microstructure in the concrete, limiting the permeability and the movement of water and alkalis. This combination of alkali reduction and improved concrete durability helps to minimize the expansion and cracking associated with ASR.