Winter foundation: how to fill in, so as not to regret

All features about the construction of the foundation at low temperatures

Among novice developers are of the opinion that the construction of the basement in the winter - it is impossible, or - at best - hardly feasible task. Result - building at a temperature below 0 ° C "Frozen", and construction teams "go to sleep" in anticipation of the new season. Whether such an approach is justified?

To understand this question, we use experienced experts with recommendations Forumhouse, well versed in the modern construction technologies. So, the main questions that will be answered:

• What is the "winter concreting conditions."
• What you need to know before you start building the foundation of the winter.
• Why use antifreeze additives and superplasticizers.
• What methods provide qualitative fill the basement in the winter.

Why can we build a foundation in the winter

Winter conditions of construction - is weather conditions that day the temperature does not exceed 5° C, and at night thermometer falls below 0° C.

Due to climate change, sudden thaws and cold snaps "winter" conditions of construction, depending on the climatic zone, may occur and in September, and in November and even in December. In this case, the snow can not be. In addition, there is the northern regions, where the warm days is not seen, and the average temperature does not exceed 5 ° C. In a typical civil engineering work in the winter and do not stop, and often carried out around the clock.

Sergey Astafjevs

Design Engineer Company Fundamentalno.rf

Modern technologies allow the construction of the foundation to extend the construction season and carry Fill qualitative basis under house at a temperature of up to -15 ° C, and the use of special techniques - to -25 ° C. This will boost the construction time, t. To. The spring can be immediately start erection of walls (if Cottage frame or wood, it can successfully build and winter), which will enter into the house earlier.

The main advantages winter construction foundation relate:

• Seasonal decline in prices for construction materials and work.
• Low utilization of construction brigades.
• Ability Check heavy construction equipment at site t. K. Increases the bearing capacity of soil, usually limp spring.
• Minimizing the risk of collapse of the walls of trenches dug in, as well as flooding groundwater.

Andrew Pashuhin

Construction engineer company Fundamentalno.rf

It is widely believed that the foundation is best to build in the summer. It should be remembered that the weather in this period of time also imposes certain restrictions. For example, can begin long rains, resulting in smearing or complete collapse of trench walls and ditches. Accordingly, it is necessary to dig them again, and this is a waste of time and money. In areas with a high groundwater level need to be taken a range of measures associated with the pumping and discharge of water from the pit.

These measures include digging pits, trenches drainage, drainage pump installation. Additionally, high temperatures - more than 35 ° C, And low humidity also harmful to concrete, a required strength, as well as low temperatures.

Therefore, to sit and wait for the "ideal" weather concreting - unproductive. Indeed, they may never come.

Features of the winter construction of the foundation

Among the features of winter construction of the foundation, to be aware of in advance, can be identified:

• Short daylight hours, which "lengthened" by using additional lighting.
• The need for resettlement insulated cabins, where workers could keep warm and a hot meal.
• Impermissibility freezing base excavated trench or excavation. If you pour the concrete into the icy soil in the spring, when thawing the foundation can give differential settlement.
• The necessity of using special additives, as well as increase the strength of concrete branded. For example, instead of concrete poured M250 M300. This will guarantee the necessary strength to go on in accordance with the project.

Sergey Astafjevs

It should be borne in mind that the process of concreting the foundation directly preceded by a series of preparatory work, requiring time-consuming, and the implementation of which Lower temperatures do not impose significant restrictions.

These works include:

• delivery of construction materials to the site;
• markup portion and a trench digging or excavation strip foundation for the construction of a basement or cellar;
• foundation drainage device;
• construction formwork;
• reinforcement work.

In this video explains in detail about how to build a basement under high groundwater.

Basic principles of construction of the foundation in the winter

Building the foundation of any type winter just as in summer, requires solving a complex task. Negative temperature impose certain restrictions during concreting. To understand how to "work around" these restrictions need to figure out how much hardens filled into the formwork concrete.

Andrew Pashuhin

Construction engineer company Fundamentalno.rf

It is believed that under normal conditions (about +20 ° C and 95-100% humidity) ordinary Portland cement in concrete, filled into the mold without additives, gaining their branded 100% strength in 28 days. A stripping strength (70%) of branded - for 7-10 days.

In winter concreting it decided to allocate a critical strength of concrete (depending on the type of structure and grade of concreteOn average it is 30... 50% of the 100% grade strength). Upon reaching this value, the foundation can "get away in the winter," without further significant changes to its structure. And in the spring, after the thaw, concrete curing process and will continue to set the necessary strength. Ideally, before "sending" foundation "hibernation" should bring the strength of the concrete up to 70% of branded 100%. In this case, the subsequent freezing / thawing of the foundation, the concrete will not have any destructive changes.

Only the foundation, the concrete which gained a certain critical strength, can effectively resist the action of negative temperatures and go for conservation "in the winter."

Andrew Pashuhin

Efficiency of winter concreting is based on a method in which the concrete (defined period of time) to maintain a positive temperature sufficient to set them to desired strength.

It is especially important not to "freeze" the foundation in the first 3-5 days after pouring the concrete into the formwork. It was during this period of time there is a core set of safety.

The rate of hardening of the concrete affected by several factors (water-cement ratio W / C, the mixture, humidity, and so on. D.). But the main factor - is the ambient temperature. For a benchmark in the table shows the averaged set of numbers depending on temperature strength of the concrete.

The higher the temperature of hardening of the concrete mix, the less critical period set foundation strength. At temperatures below 0 ° C hydration process in concrete stops. Water, unable to react with the cement, freezes, which directly affects the strength and durability of the foundation.

Hence, the success of the winter construction of the foundation, it is necessary:

• Maintain a positive temperature already filled concrete mix. For this inclosure is raised, and the temperature therein is raised by thermal guns. Concrete heated by electricity and - summing a voltage to the electrodes in the concrete or reinforcement, or directly to the mold if it is made of metal.

• Use PMD antifreeze additives (inorganic salts, sodium chloride and potassium chloride and so on. D.). Antifreeze additives provide the cement hydration process and concrete hardening (t .k. Water does not freeze) at negative temperatures down to -15 ° C and below.
• Apply early strength Portland cement with the addition of superplasticizers - additives which reduce the W / C. This will reduce the amount of water necessary for the mixing of the concrete mixture and the obtained mixture itself more "rigid".

When using antifreeze additives Carefully read the instructions on their application. Some supplements can not be used for concrete foundations (and other concrete structures), t. To. They cause accelerated corrosion of the steel reinforcement.

Concrete with MIT called "cold". The use of additives allows the mixing water in the concrete mix does not freeze even at low temperatures. When this hydration process is slow. Concrete gradually gaining the necessary strength (the foundation must be properly insulate), which can reach 30% to 50% grade strength within a month. Only after this foundation can be frozen.

When the concrete order PMD passport freezing temperature of the concrete with the additive is taken from the calculation of the average forecast of negative temperature for the month, not the day of casting.

In addition to the warm concrete, construction Tepljakov and combining these methods with the addition of PMD, the method "thermos". For this purpose, the water used for mixing of the concrete mixture was heated up to +60... + 80 ° C. The concrete mix is ​​poured into a well-insulated formwork, which is then added yet harboring film and well insulated on all sides. The chemical reaction that occurs when the concrete hardens, releases heat. It is "working" in tandem with the heat from the already-stacked "heated" mix allows concrete to dial the required grade strength by the time it cooled down to 0 ° C.

The preheated water is added to the mixer in an amount of 50% of the normal amount of mixing water. Then poured rubble, concrete mixer is included in several turns, and only after that added to the cement, sand and water balance. This will prevent concrete "boil". The total amount of time for mixing the solution is increased by 1.5 times in comparison with the warm time of the year. To lower the freezing point of the critical concrete and accelerate its hardening the timing when the method of "thermos" is recommended to additionally use PMD.

The experience of the participants of the portal

Bondik75

user FORUMHOUSE

We poured a monolithic tape foundation In November. Night temperature reached -15 ° C. therefore We are waiting for a "window" with a positive temperature. As soon as the forecast promised warming, poured foundation. When poured foundation was +10 ° C. At night, the temperature dropped to 0 ° C. Concrete was M350 PMD to -20 ° C. The foundation closed after casting film. Inclosure built on top and put a gas gun. Heated to 14 days. The temperature in the inclosure on average was higher than outside, 8-10 ° C. For example, if the street was -2 ° C, then into the plant 6 +... + 8 ° C.

In just two weeks the foundation for heating in new posts took four cylinder with a gas volume of 30 liters. When set to 50% of the strength of the foundation of branding, inclosure removed and disassembled formwork and foundation itself is further warmed and left "hibernate" until spring.

Sergey Astafjevs

This is a good example of the right set of solutions for concreting in winter conditions, namely:

1. Wait for the temperature increase for the concreting works.

2. Used antifreeze additive with a margin on temperature decrease.

3. Teplyakov fulfilled heated device, which resulted in stable acceptable temperatures and exposure to precipitation.

4. The duration of heating in these conditions, there was even more than enough.

As seen in Example forumchanin nothing extraordinary difficult and asked during winter concreting, at low temperatures can be successfully to build the foundations of a different type.

After reading the topic How to pour the concrete for the foundation of the winter, you will learn how to do it right. More about Tepljakov and whether, in principle, bind with winter construction site. In this video it is shown in detail, how to combine three types of foundation in the same house.

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