ASR
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ASR ✩
Application Note
Introduction
The Problem
Alkali-silica reaction (ASR) is a chemical reaction that occurs between the high silicate content in certain aggregates and the alkaline environment in concrete. The reaction produces an alkali-silica gel, which absorbs water and swells, generating internal pressure that causes cracking in the concrete. ASR manifests as distinctive map cracking or aggregate popping from the surface, compromising the concrete's durability. If left untreated, ASR can lead to long-term structural deterioration.
The necessary conditions for ASR to occur are:
Presence of reactive silica in aggregates (e.g., quartz or volcanic material).
Availability of alkali compounds (sodium, potassium, calcium hydroxide) from the cement phase.
Sufficient moisture to activate the ASR process.
Mitigation Strategy
Surtreat’s ASR control system is designed to address the core issues driving ASR by:
1.Neutralizing Reactive Aggregates: Reducing the chemical reactivity of the aggregate surface.
2.Inhibiting Alkali-Silica Gel Expansion: Modifying the gel to a non-expansive form.
3.Strengthening the Concrete Matrix: Increasing tensile strength and reducing porosity.
4.Reducing Moisture Content: Limiting water ingress to inhibit further ASR activity.
5.Sealing Cracks: Repairing surface cracks and preventing further crack growth.