I agree with Abdul Hai, but have some things to add. Even in low slump concrete, there is far more water present than is needed for hydration of the cement particles. That excess water is required to have a workable concrete that can be handled, placed, and compacted. Water can be reduced and workability can be increased through the use of proper use of superplasticisers, which reduce the surface tension of the water in the mix and greatly increase slump. Expert mix designers are required to produce appropriate mix designs.

A W/C ratio of maximum 0.45 is usually required for very durable concrete mixes, and those in turn usually need superplasticisers to aid handling, placement and compaction.

Once the concrete has been placed, compacted and finished, proper curing of the concrete for at least 7 days is required, to reduce the rate of water evaporation from the concrete matrix, which in turn reduces the risk of shrinkage cracking and which increases durability of the surface.

Curing can be done by covering with water, using misting sprays, misting with water and then completely covering with weighted down polythene, or suitable curing compounds applied to the surface. Each methods has advantages and disadvantages.