Durability of concrete

Reasons for Disintegration and Decay of concrete

Durability of concrete is defined as the property of concrete by virtue of which it is capable of resisting its disintegration and decay.
Disintegration and decay of concrete may be due to following reasons:

1. Use of unsound cement
2. Use of less durable aggregate
3. Entry of harmful gases and salts
4. Freezing and throwing of water sucked through the cracks or crevices
5. Expansion and contraction resulting from temperature changes

Water required for chemical reaction is about 25% of the weight of cement. For durable concrete, water cement ratio should e as small as possible to get a workable mix. A well compacted concrete has less voids and pores and has more durability. Thus for good structure, the concrete should be durable with proper regard to the various weathering conditions such as action of atmospheric gases, moisture changes, temperature variations.