Winter concrete: technology of work and features of the
Modern construction rates require year-round work of companies, but not all materials are able to withstand low temperatures. This article will talk about how to prepare the winter concrete with their own hands, and also it will be told about its characteristics, differences from the usual.
What is winter conditions
In this case, the "winter conditions" are somewhat different from the calendar ones. This is due to the average daily temperature, the value of which is fixed at + 5 ° C, which sometimes gives a drop in the temperature of the thermometer during the day below 0 ° C.
The danger is that under such conditions, water that did not have time to react with cement turns into ice, and therefore cannot react with it in a chemical reaction. As a result, the hydration reaction stops, and the concrete in the winter time ceases to gain hardness.
At the same time, the material increases the internal pressure due to ice, so that with its early freezing the structure, which has not yet gained strength, begins to gradually collapse. Although after thawing, the frozen water again becomes liquid and the hydration process resumes, it is not possible to completely restore the damaged bonds.
If reinforcement is present in the concrete, ice films will also start to appear around it, which will squeeze it out of the cement paste.
All this leads to the fact that:
- the strength of concrete is significantly reduced;
- coupling with fittings is broken;
- material density decreases;
- resistance decreases;
- reduced its use.
Light: if you manage to make it so that, before freezing, the concrete will be able to gain the initial strength specified in the work regulations, negative processes will not adversely affect it.
Technology "winter" work
The composition of the winter concrete must necessarily include heated water, while the base itself, which will be laid, should not be frozen. At the end of the process, the mixture must be insulated.
But these events sometimes may not be enough to get the material of good quality.
In this case, you should pay attention to the winter additives in concrete, with which:
- manages to accelerate the setting;
- time for achievement of necessary strength by concrete is reduced;
- increases the grade of the material without reducing its plasticity;
- it is possible to complete the work under adverse conditions.
Additional ingredients can be added to the dry cement mix or directly while mixing the mortar. Although the price of work after the introduction of components will increase, but the mixture itself will acquire the necessary properties, giving the opportunity to conduct construction continuously.
| Requirements for winter work | 1. If electric heating or a “thermos” method is used, use a heated filler. You can add filler cold, but without frozen lumps and ice, if you use antifreeze additives. |
| Recommendations of specialists | 1. It is best to prepare concrete in the winter on central concrete nodes under the control of a laboratory technician. Indoors must be the necessary humidity and heating.3. It is necessary to constantly monitor the temperature of the components and adjust the amount of additives. 4. Remove the insulation and formwork for concrete should be before the temperature of the material drops to 5? C, otherwise it will freeze to the formwork. 5. It is allowed to use flexible heaters which will give the chance to warm separate elements. |
Process
For the preparation of concrete for use at low temperatures, it is necessary to approach responsibly to the choice of devices for protection against cold and initial components. For example, make sure that there is no snow on the sand, cement and gravel. Heat water to the temperature required for the work, but not more than +80? С.
Tip: Do not use water heated to a boil.
Instructions for preparing the solution:
- Pour crushed stone and 50% of the calculated amount of heated water into the mixer at the same time.
- Add cement, sand and remaining water after 5-10 turns of the device.
Remember, the temperature of the concrete mix in the winter should ensure a uniform setting.
Features of the technique
In this case, we will focus on the "thermos" method.
The key to success will be high-quality preparation of raw materials:
- Check cement, sand and crushed stone for compliance. They should not be:
- frozen lumps;
- snow;
- foreign components.
- Bring sand and rubble to the desired temperature (no more than +60? C). You can mix all the ingredients and heat them together. It happens that it is more convenient to carry out heating of each component separately, after which the optimum water temperature is selected.
- Mix together all the constituents of concrete in a concrete mixer. At the same time you should be interested in the temperature at the entrance and exit from the device.
- Prepare the formwork and warm the surface for laying to improve the adhesion of the mortar with it..
Tip: the reinforcement mesh should be dry, then excess moisture will not get into the mixture.
It may be advisable to cover the fittings with oilcloth, tarpaulin and other available materials. Before laying the material should be dried with compressed air.
After casting is completed, cover the structure tightly with insulating materials and leave for a while to set the concrete.
Conclusion
Winter conditions were previously considered unfavorable for construction. Today, however, companies offer to add special anti-frost additives to the mix, which make it possible to ignore the weather conditions. There are also developed methods for laying concrete at low temperatures. The video in this article will help you find additional information on this topic.