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Alkali- Aggregate Reaction - Control Measures

The following precautions can be taken in order to control the alkali-aggregate reaction.

Fig.1. Alkali-Aggregate Reaction Effect on Concrete Structure



  1. Selection of Non-Reactive Aggregates
  2. Use of Low Alkali Cement
  3. Use of Corrective Admixtures
  4. Controlling Void Space in Concrete
  5. Control of Moisture Content
  6. Temperature
  7. Water

Selection of Non-Reactive Aggregates

Avoiding the use of reactive aggregates is one of the sure method to inhibit the alkali -aggregate reaction in the concrete.

Use of Low Alkali Cement


The restricted value of alkali content in cement should be 0.6%.

Use of Corrective Admixtures


The alkali-aggregate reaction can be controlled by using admixtures like pozzolans, fly ash, stone dust etc.

By controlling the Void Space in Concrete


Reducing the void space in concrete will reduce the alkali-aggregate reaction. To carry out this process, well-graded aggregates are used. Coarse aggregate has more chances to promote the aggregate reaction. So grading is very important.

Control of Moisture Condition


The use of air -entraining agents, the absorption of moisture can be done which result in the control of the reaction. This also controls the expansion due to the reaction which can be reduced by the use of agents.

Temperature 


The temperature should be from 10 to 38-degree celsius.

Water


The growth of silica gel is promoted by continuous availability of water.