Concreting in winter conditions - what to look for?
The main problem at cold temperatures is to provide the solution with good hardening( but not fast, but it does not have enough strength) for all the requirements of the instruction, and this process should occur in wet and warm weather. In the winter, to achieve this is quite difficult, so the acquisition of the 's critical strength ( that is, the minimum that the structure does not fall apart in the first few minutes without a frame) is associated with minor problems.
In addition to the fact that concrete needs to be given to achieve critical strength, and some designs provide conditions also to achieve branded strength .This inconvenience is accompanied by work with concrete, which must withstand greater dynamic loads in the future, for example, waterproof concrete.
The temperature in the street, of course, does not please, but the numerous precipitations do not lead to a good state of the solution component. Therefore, it is important to ensure that everything is stored in a dry warm place, and before mixing is checked. And to mix components and to prepare concrete it is desirable in a warm premise. Do not allow snow or rain to enter the finished solution, if there is no separate room, then over the cooking area you need to create a canopy.
Concreting in winter conditions - before starting work
The mortar and structures that are poured into it should not be colder than 5 degrees and hotter than 40 degrees Celsius. Therefore, a number of measures are being taken to create this condition. Structures warm and clear of snow, usually done with steam or boiling water. It is impossible, for example, to allow icing of metal structures. Therefore, all cleaning activities are carried out immediately before pouring.
As for the solution, its preparation and transportation is a bit messy, so as not to lose temperature and do not overcool it. Concreting in winter conditions requires that all components of the from which the mixture is prepared are warm .But it is necessary to be cautious with cement, warming up of small-milled material is usually forbidden by safety precautions.
When the solution is ready, it must be delivered to the pouring place, losing as little heat as possible, because the internal heat of the concrete is also needed when hardening, there every degree is on the account. If the finished solution is taken from somewhere, and not cooked directly on the site, the transport should be insulated with insulation.
Another method that helps increase the chances of successful hardening of concrete is the special antifreeze additives .They slow down the hardening of concrete, increasing the time to achieve critical strength. Their number depends on the temperature and the final requirements for the quality of concrete.
Concreting in winter or how to provide heat to hardening concrete
After the concrete is poured, the whole construction is a homemade thermos. It is covered with thermal insulation and a film to create a greenhouse effect and not let the heat from the solution into the environment. Under the influence of this internal heat, curing and accumulation of strength occurs.
If the temperatures in the street are critically cold and the internal heat is not enough to provide the necessary conditions, then the heat is supplied from outside. The structure can be heated by steam, starting it under a thermoshub, which enveloped the structure.
It is also possible to adjust the electrical heating of concrete, however, this will require some technical interventions, but, by passing alternating current through concrete, it is possible to ensure uniform warming of the atmosphere in the near-concrete area.