Concreting in cold weather requires special rules and regulations. If you do not pay attention to the principles of engineering when concreting in cold weather, you should expect severe stress in the concrete ventricle.
Tensions that can easily cause concrete to crack.
Concreting do's and don'ts in cold weather
Concrete is one of the most durable materials in modern construction. A material that can last for years without the slightest defect with significant strength.
Of course, this hard-to-build building material requires special care at the very beginning when it needs to be formed. In any case, concrete is a material that will be created by mixing water, cement and sand next to sand.
Any irregularity or imbalance in this mixing can negatively affect the final quality of the concrete. Sometimes these negative effects are so unacceptable that we have to block the concrete produced.
One of these sensitivities to concreting is when we experience a sharp drop in temperature. Concreting in cold weather requires special rules and regulations.
If you do not pay attention to the principles of engineering when concreting in cold weather, you should expect severe stress in the concrete ventricle. Tensions that can easily cause concrete to crack.
In construction activities, these activities cannot really be kept dependent on the hot days of the year. It's a fact that building is a time-consuming operation, and whether you like it or not, it's likely that you'll need to keep working during the cold season.
In this case, concreting in cold weather will be inevitable. Therefore, it is necessary for every technician to achieve a standard and strong structure in their building, learn the principles of concreting in cold weather and do it properly.
What are the problems of concreting in cold weather?
Before we get into the general rules of engineering in concreting operations with power trowels or any other tool in cold weather, it's a good idea to talk a little bit about why this sensitivity is present.
What can be so troublesome in cold weather is that special rules and regulations need to be developed to get rid of it.
Cold concrete concreting problems show up when you know that about one-third of the weight of concrete at the time of mixing is water.
Water is a key element in the creation of concrete, and any irregularities in its ideal conditions will lead to the risk of disrupting the desired structure of the concrete.
The story will be critical when we know that water is a highly sensitive element to temperature, and at low temperatures it completely loses its physical nature.
It just freezes. Freezing of water during concreting will prevent the desired mixing and as a result, concrete with a very poor quality level will be obtained.
Concreting with a power trowel or any other tool in cold weather, if not in accordance with the rules, will lead to water freezing and eventually cracks in the surface and depth of concrete.
The resulting concrete will be in the form of scales and in a short time the erosive effects will be well visible.
This possibility of losing the quality of concreting in cold weather has led to the development of some laws. Rules that are sometimes recommended and sometimes strongly emphasized.
For example, if possible, it is recommended to avoid concreting in cold weather at temperatures below 5. C. There is no legal prohibition on this recommendation; However, it is stated that if it is necessary to concrete in cold temperatures at temperatures below 5. C, you should be able to set the temperature of the concrete body at temperatures above 5. C in all concreting steps.
Principles of concreting in cold weather
As mentioned, it is recommended not to concrete in cold weather for temperatures below 5 C; Unless all types of steps can be built to keep the concrete distribution even higher than 5 degrees Celsius.
The reason for these sensitivities is the lack of reaction of cement hydration with cold water at very low temperatures. Apart from the category of water freezing, cement cannot have the necessary reactions with water at low temperatures.
Even if the water used is completely smooth and free of any frost. This is why concreting in cold weather ultimately leads to the creation of concrete that is easily crushed.
An engineering and completely scientific way to deal with this problem could be to use concrete antifreeze. However, the use of concrete antifreeze will prevent the water from freezing in all stages of concreting in cold weather; But this concrete antifreeze will not be able to keep the water temperature high.
The fact that the water does not freeze is not a reason for the desired temperature. When using concrete antifreeze, we will only lower the freezing temperature of the water so that the ice does not freeze; But the risk of the cement not reacting well with water at temperatures below 5.
C during concreting operations in cold weather will still threaten the whole story. Therefore, a solution should be considered to deal with the principle of concrete temperature drop in critical conditions.
Conflicts that have only begun in the use of concrete antifreeze will be pursued after concreting operations in cold weather.
Engineered operations against concrete temperature drop
In concrete construction, when we want to have concreting operations in cold weather, in the concrete construction stage, the risk of water freezing can be eliminated by using concrete antifreeze; But to accelerate the chemical reactions of cement, it is necessary to process the concrete as soon as possible.
For example, if concrete is to be leveled at the work surface by a power trowel, or if trowel ingots are required, these operations must be carried out quickly.
On the other hand, along with spot heating, you should try to keep the total temperature of the concrete in a space above 5 degrees Celsius.
Speed of operation to perform tasks such as concrete vibration or the use of power trowels, concrete screed ingots are essential to complete cold-air concreting operations.
These operations must be accompanied by spot heating that can keep the total concrete temperature above 5 degrees.
However, after the operation of devices such as power trowels or concrete screeds that will almost complete the concreting work, the concrete cannot be left alone.
Spot heating must be in operation for at least 24 hours after concreting in cold weather; So, if there is a risk that this heating will not be able to be provided for a long time and in a completely principled way, it is necessary to ensure that the concrete does not freeze for the next 24 hours after concreting operations.
Concreting problems in cold weather
One of the major problems of concreting in cold weather is the lack of quality concrete antifreeze. Unfortunately, we are witnessing the production of this sensitive and strategic material in the underground market.
Products that are out of the standard and completely miscellaneous with a low price in the market and will endanger the strength of a structure every time they are used.
Another problem with the use of concrete antifreeze is the use of food salt compounds as concrete antifreeze. Salt, however, can cause the water inside the concrete to freeze well; but it will eventually erode the remaining rebars in reinforced concrete.
Because the salt takes the water from the concrete in an electrolytic state and the rebars left in the concrete will become one side of this electrolyte.
High quality concrete antifreeze is prepared on the basis of alcoholic and nitrite compounds to complete concreting operations in cold weather. Compositions that will be free of any damage to the concrete and rebars left in it.
Preliminary instructions for concreting in cold weather
Use of type 3 or quick-setting cements to increase the rate of concrete formation.
Use high quality concrete antifreeze.
Keep warm the surface of molds, reinforcement and free them from snow and ice.
Fully cover the concrete at the end of the work with tarpaulin or nylon
Failure to store materials in cold weather or in the face of wind and winter humidity
Keep in mind that complying with any of these principles alone will not be sufficient for cold weather concreting. Concreting in cold weather requires a well-designed and well-engineered program. A program that anticipates all aspects of work with high sensitivity.