Aggregate Alkali Reaction in Aggregate CONCRETE TECHNOLOGY MODULE 1.3.8

8. Alkali Aggregate reaction

Alkalies in cement are sodium oxide and potassium oxide.



Some of the aggregate contain reactive silica, which reacts with alkalies present in cement i.e sodium oxide and potassium oxide.


When these reaction takes place, alkali silicate gel of unlimited swelling type are formed this starts generating cracks in concrete and may lead to ultimate failure of the structure.





Factor which promote Alkali Aggregate reactions are:


1. Reactive type of aggregate


2. High alkali content in cement


3. Availability of moisture


4. Optimum temperature conditions

1.3.8