Principles of Origin and Methods of Determination of Alkali-Silica Reaction (ASR)
The alkali-silica reaction (ASR) is the chemical reaction between alkali and hydroxyl ions in the solution of hydrated cement paste and certain reactive silica phases in aggregates in concrete. ASR decreases the tensile strength of the concrete (formation of micro-cracks in the concrete structure) and consequently macro-cracks occur, decreasing the compressive strength of the concrete. Concrete decomposition is the final stage of the reaction. The paper presents experience with diagnostics of ASR in concrete. Colorimetric assays and microscopic detection were used to determine ASR products in concrete. The tests were carried out on core bore samples from the highway. On the core bore samples, colorimetric tests were performed using saturated aqueous solutions of rhodamine B and sodium hexanitrocobaltate.