Alkali-Silica Reaction is a type of pavement deterioration caused by _________________.

The Alkali-Silica Reaction (ASR) is a specific type of chemical reaction that occurs in concrete and is a significant contributor to pavement deterioration. This reaction involves the interaction between alkaline substances (such as sodium and potassium hydroxides) present in the cement and reactive silica found in certain aggregates. When these elements come into contact with water, the hydroxyl ions react with the silica, generating a gel-like substance that can expand as it absorbs moisture. This expansion exerts pressure on the surrounding concrete, leading to cracking and structural damage over time.

This understanding highlights the critical nature of material selection in concrete mixtures, as not all aggregates react similarly under these conditions. Proper engineering and testing of aggregates before use are essential to prevent ASR and maintain the integrity of pavement structures. The focus on the reaction between hydroxyl ions and silica is crucial, as it directly addresses the chemical dynamics that result in the adverse effects associated with the Alkali-Silica Reaction.