This is a recorded webinar from October 6, 2015.
When the alkalis in cement react with susceptible aggregate particles, a reaction rim of alkali-silica or alkali-carbonate gel is formed around the aggregate (AAR). If this gel is exposed to moisture, it expands, causing an increase in volume of the concrete. In mass concrete structures, the expansion can cause wide cracks and major operation and maintenance problems, such as inoperable gates and misalignment of hydropower generators. Maintenance and repair ranges from monitoring the AAR-affected concrete to complete removal and replacement, but mitigation methods are also available. Crack injection, post-tensioning, and slot-cutting can be implemented to reduce the impact of the AAR on the structure. Effective maintenance can accommodate continuing expansion, thus allowing most structures to achieve a long service life.
Table of Contents
1. Understand the mechanisms of deterioration and prevention of AAR in new construction.
2. Describe the methods of identifying AAR in existing mass concrete structures
3. Identify the repair techniques for mass concrete structures damaged by AAR.
4. Explain the ongoing process of monitoring of mass concrete structures after repair.
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