Added water

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The water that has to be added when mixing and processing concrete , mortar or plaster of paris, for example , to make the material workable and to get the setting process going is referred to as added water (outdated also mixing water ) . The total amount of water in the mixture is made up of the amount that got into the mixture with the aggregate material (sand, gravel) and the added water.

composition

In general, any naturally occurring water can be used as additive water as long as it is not heavily contaminated. Water containing oils , fats , salts , acids or sugar , as well as sea water or moor water, are not suitable . These ingredients can interfere with the curing process or in reinforced concrete to increased corrosion of reinforcement lead. The desired strength is not achieved and damage can occur.

According to the DIN EN 1008 standard, it is permissible to use residual water from concrete production and concrete recycling . The fine material concentration contained in the residual water must be taken into account.

amount

Water is only added in such an amount that the consistency required for processing is achieved and the strength of the set material is not impaired too much. The excess water escapes during the setting process. The water required for the setting process is chemically bound. Both processes lead to a volume reduction ( shrinkage ) of the component.

Too much added water can lead to "bleeding" and / or segregation.

Influence of temperature

In warm temperatures as well as in drafts, components must be protected against the water escaping too quickly, as this can bring the setting process to a standstill ( burning ). Subsequent moistening of the dried-out component does not restart the setting process.

In winter, when there is frost, there is a risk that the water that has not yet bound freezes will cause damage from ice pressure . Since only liquid water enables the setting process, it is interrupted in the event of frost. However, the process continues after the water has become liquid again.