How to pour concrete in the winter: the technology of
Concreting is considered one of the most time consuming and highly costly types of work in the construction industry. In addition, until recently, this type of work was also difficult in the cold regions of the country, or rather, completely impossible for quite understandable reasons.
Many works related to concreting were turned down to the arrival of cold weather, when the temperature in the daytime dropped below +5 degrees, and at night it could often drop to a critical unacceptable level.
Until recently, when there were no such technologies as now, concreting in the winter was a very problematic event. The water used for the preparation of the solution, as is known, at a temperature below zero, crystallizes and thus does not allow for activities to pour concrete at the proper level.
It is for this reason that with the onset of cold weather, quite often in October, all works were rolled up before the onset of favorable conditions under which the mortar could remain unchanged during the process of concreting and subsequent drying.
This could not continue for long, given the short period of warm time in our country in most regions and the emergence of new technologies in the construction industry. Thus, methodologies have been developed that have shown their effectiveness in practical testing.
Let us take a closer look at what methods of winter concreting exist and how to dry up concrete in winter, so that in future it will not lose its quality characteristics during operation.
Features of work in the winter
During the construction of concrete foundations, a concrete solution is used as a starting material, which, when cured, forms a solid monolith that can withstand heavy physical loads.
In a solution of concrete, ordinary water acts as a diluent, which, under the influence of negative temperature, quickly crystallizes, turning into ice. Ice, in turn, is able to increase the volume of water by 5–10% and thereby prevent the normal drying process of the entire concrete mass to flow.
Thus, the concrete poured in the winter time would have the lowest strength characteristics, and in general would be unsuitable for use.
Material hydration
Being mixed, the components: fractional sand and gravel, the cement of the appropriate brand and diluent, that is, the water from the liquid phase, when dried, gradually passes into a solid state.
At temperatures from +10 degrees and at a certain humidity in the setting solution, the following processes take place:
- In the first hours after pouring the concrete mass, processes occur during which a film of hydrosilicate begins to form on the surface layer.;
- After the formation of the surface shell and the evaporation of a certain amount of moisture, the upper layer consisting, as a rule, of large particles of rubble and sand for concrete, gradually begins to set;
- Thus, already deeper layers dry up and seize up to the moment until all the moisture evaporates and the structure gains adequate strength.. Typically, these processes occur in a relatively short period of not more than 1 month, but here everything depends on the volume of the structure, temperature and air humidity.
Possible ways of pouring concrete
Many private developers are constantly faced with the questions of how to properly pour and how to dry concrete in winter.
This comment can be heard a variety of opinions, but for the most part it all depends on factors such as:
- The composition of the concrete mix solution, as well as the proportional ratio of the components;
- Overall parameters also play an important role;
- Cement quality and brand;
- Weather conditions in particular and climatic in general;
- It is important to have the technical possibility of heating the diluent and aggregate.
The process of hydration involves the release of a certain amount of thermal energy, but, as a rule, it is not enough in cold time to fully set the material. To increase the reaction rate of substances in some cases, a very finely ground binder is used.
This measure allows you to slightly increase the heat, as the substance reacts faster with a diluent. In addition, to maintain heat before mixing, it is recommended to heat the water and aggregate.
Important: The technology categorically prohibits the cement from being heated as it will instantly lose the binding effect and becomes completely unusable.
Builders recommend increasing by approximately 20–30% the mixing time of the concrete mass in order to give it increased flowability, which will provide the solution with a more uniform and rapid acceptance of the required form. In addition, it is recommended to use only fine-ground cement.
If there is a question how to make concrete in the winter with your own hands, then it is extremely important to adhere to the above recommendations.
Concrete heating
It should be noted that the heating of concrete by the above methods, as well as the use of gas guns, etc. It is unlikely to be useful if the ambient temperature begins to fall below zero, more than 2–3 degrees at night.
As soon as the composition is poured into a previously prepared form, it must be protected from heat loss and exposure to cold air by covering it with special insulating films on a polymer base and preferably a high density. Under such a tent, you can install electric heaters of sufficient power, as well as in the absence of electricity gas guns in compliance with safety measures.
The use of the mixture with modifiers
When working on concreting under conditions of significant sub-zero temperatures, a special type of concrete mortar with modifying additives that prevent the rapid weathering of heat and contribute to an accelerated setting of the mortar comes to the rescue.
Plants in the manufacture of mortar take into account all the features of real climatic conditions, so if large-scale work on concreting is planned in the cold winter months, it is advisable to use the integrated services of the manufacturing plant.
Rules and recommendations for work in the cold
The main thing that needs to be considered when pouring a concrete solution in the winter, is that in no case should we try to partially work. In the case of concreting activities during the winter period, it is necessary to be ready even for round-the-clock work until it is fully completed.
Laying the material should be carried out in small volumes, instantly overlapping one filled layer with another, in order to avoid heat losses, which will certainly reduce the adhesion of the layers between themselves.
It happens that it is not possible to cover the layer in time in such cases, make sure that a helium film did not form on the surface of the composition, which prevents sufficient adhesion (adhesion) of the material, otherwise remove it immediately and only then overlap with fresh solution.
Properly prepared object - half the success
Before concreting the foundation, it is necessary to perform a number of preparatory activities, namely:
- A prepared pit must be cleaned of all kinds of rubbish, snow, and in the event of ice on the bottom or on the rebar, it must be chipped and completely removed. It is recommended to protect the bottom from freezing by placing the straw after the backfill of the sand cushion has been completed.
- It is strictly forbidden to pour concrete solution directly onto the frozen base, this will lead to a gradual subsidence of the material, as the soil under the mass of concrete begins to melt.
- The space around the formwork should be free, that is, access from all sides should not be blocked.
Draw conclusions
Now you know how to make winter concrete with your own hands and what rules must be followed in order not to be disappointed in the work done and not to waste time and money. Instruction and technology must be strictly observed in accordance with technical regulations.
For a complete understanding of how concrete is poured during cold weather - watch the video in this article.