A dam is a physical barrier that restricts the streams of water.
The construction of the dam generally happens across for the reason to control floods, provide water for irrigation and generate electricity.
The dam is usually a giant structure, difficult to cast in a single pour. Also, the other technical disability to single continuous pour is the release of heat in the exothermic reaction between the Lime present in the Cement to Water.
Now, coming to cement, there are more than 13 types of cement practically available in the market with different USP and purpose of the use.
Let’s understand which cement is beneficial for the case of DAM.
The concreting of DAM is a Mass concreting, and the amount of exothermic heat which generates because of the same is tremendous, so the cement shall have low exothermic heat.
At the same time, the DAM is a once in a lifetime kind of structure and is heavy on investment and risk (subjected if failed) so the reinforcement shall not corroded because of the alkalis present in the cement so it needs to be free from alkalis.
Being the Mass structure, the factor of shrinkage/creep has to be considered, (even shrinkage of 1% of total height of 20meter structure would lend to more than 7” which is high for such structure); so the cement shall have an exclusion to development of shrinkage cracks.
Last but not the least the Concrete Design mix also plays the important role in the performance of cement and the relevant type of cement is procured.
Also, the cement shall have minimal water absorption once cured, water generally gets absorbed in the small capillary formed during the curing or process results in poor water retention on the surface.
The structures are generally segmented in two parts, namely:
- Substructure ~ a supporting or underlying structure below the ground level.
- Superstructure ~ an upward extension of an existing structure above ground level.
The substructure part of the dam is poured using of hydrophobic cement & Portland Slag Cement;
whereas the individual or combination of Portland blast furnace with OPC to gain the strength to the construction of the dam, retaining wall & other structures in the periphery.
Hope this adds to the understanding & resolves the query.