## Summary

**Water to Cement Ratio** - The water to cement ratio is the ratio of the weight of water to the weight of cement in a fresh concrete mix.

## Technical Information

Increasing the water to cement ratio in a fresh concrete mix will have the following major effects:

- Improve the workability of the fresh concrete.
- Decrease the strength of the hardened concrete.

Whilst increasing the water to cement ratio of a fresh concrete mix is the easiest way to improve workability it is not recommended as it has negative effects on the properties of the finished concrete. This can include additional shrinkage as the excess water leaves the concrete.

The theoretical minimum water to cement ratio required to fully hydrate the cement is around 0.25. However, more water is required in order for the mix to integrate properly and for the concrete to be fluid enough to be placed. In general construction it is sensible to use a ratio of 0.4-0.6 depending on workability and strength requirements. In the construction of floors this is often reduced to help minimise unwanted dry shrinkage.

An alternative way of improving the workability of fresh concrete is to use a superplasticiser or certain other admixtures.

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