Thursday, March 3, 2011

Alkali Aggregate Reaction

For a long time aggregates are considered to be inert.But now it is proven that they are not inert totally. Some aggregates contain reactive silica which reacts with alkalies,i.e, sodium or potassium present in cement.
The reaction starts by attacking on silicous mineral by alkaline hydroxide derived from alkali. Hence silicate gel of unlimited swelling form inside concrete. This swelling cause pattern of cracks and eventual failure of concrete structure.

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