Pouring concrete under special conditions

Many had to deal with the problem of making concrete screed, especially in the winter. Pouring concrete in winter differs significantly from similar work that is performed in the summer, and requires knowledge of certain features.

Even from school physics lessons , it is known that water at negative temperatures takes the form of a solid, that is, it passes into ice, which several times becomes larger than the volume of water. Thus, when pouring concrete in winter in the usual way, the water that enters the solution freezes, which stops the solidification processes and forms breaks in the bundle.

Especially harmful for concrete are temperature changes. Of course, we can not say that there is no grasping, but with repeated thawing and freezing, pouring concrete into the formwork can give zero result.

How to produce concrete works in cold weather?

Working with solutions to create a screed, first of all you should follow the general rules that exist in the construction. There are two requirements. Firstly, to create a screed, it is necessary to prepare a high-quality concrete that meets the standards. When delivering it to a place it is better to use a concrete pump. In addition, the builder takes full responsibility for the preparation of the future place for pouring and for the further care of concrete.

In order for the solution to harden well, which will provide about 75 percent of its strength, conditions should be created to maintain the temperature regime. And for a high-quality strong screed, concrete casting should be performed at a temperature of 10 degrees above zero. Therefore, work on the production of screeds should be carried out in warm rooms that have walls, roof and heating.

When the concrete is poured in a place with a temperature regime of 5 degrees (this is the minimum figure at which it is possible to work with cement, however, the time of the recruitment increases several times), the following actions should be taken. Firstly, additives for concrete or chemical additives (not recommended for screeding) are used to stop the freezing processes. Concrete must be poured into the formwork, which must first be insulated. Formwork can be covered with tar, mineral wool, straw, reeds, and between the boards to fill slag, sawdust or fill the space with foam. You can use infrared heat sources for heating. In addition, the fillers are heated: water, sand or crushed stone.

From this it follows that the best way to ensure the normal hardening of the solution and the necessary microclimate is the use of a heat curtain, as well as the use of a heat generator, if necessary the inclusion of electric or gas heat guns.

It is necessary to remember the rules of using heating equipment. Incorrectly installed heat gun will do more harm, one part of the screed can dry up, and the second - it will freeze.

If concrete pouring is carried out under conditions and with constant support (about 4-5 days) of the thermal regime, then its quality can not be worried.

Sometimes it happens that the concrete freezes. Its solidification can be restored by creating a positive temperature (at least 10 degrees). This often happens during the autumn frosts. But in this case it is possible not to worry, such colds will not bring significant harm to concrete. Only the upper thin layer can be destroyed.

If the screed has frozen, then urgently it is necessary to cover it with a polyethylene thick film so that frosts and thaws do not destroy the concrete. In this case, the strength will be somewhat lower, but this applies only to the upper layer.