Concrete on the necessary strength cause. Concrete does not freeze: the reasons what to do, how to avoid problems. Dependence on the type of cement and the temperature of hardening
In this article, we will tell about how much time concrete is gaining strength and what ways to control this parameter are available today.
The topic of the article is not accidental, since most of the construction objects from year to year is being built using concrete. The popularity of this material is not reduced, and on the contrary, it increases, despite the widespread introduction of alternative technologies in the construction of objects of various purposes.
That is why the question is so relevant, after what time does Concrete gain strength and how does this affect the timing of construction work?
Average durability
Before answering the question when concrete is gaining 70 strength, we will describe what the number 70 means. In fact, this is the percentage of the vintage parameters. When this parameter is reached, designs and structures conventionally comply with GOST requirements.
It is no secret that in accordance with the assigned brand of concrete, not only the price is determined, but also the maximum load at the calculation of kgf / cm², which can be rendered to the concrete without prejudice to the integrity of the product. That is why, all industrial jubes are manufactured with a vacation strength of 70% of the truck standards in the summer and 90% in the winter.
Since all the industrially produced concrete defaults comply with the requirements of GOST, construction organizations can apply it to the appointment immediately after receiving the ordered product.
Unlike construction organizations that are ordered by the Zhby from the factory, private users of the solution when filling the formwork should have a clear idea of \u200b\u200bwhat time concrete is gaining strength.
In the photo - work with concrete in the cold season
On average, the brand control technologists are carried out after 28 days at the end of the filling of the solution into the formwork. It can be assumed that this is an averaged temporary indicator necessary for a set of optimal hardness parameters.
With warm weather during the first week after laying, an intense set of strength is happening to the material up to the conditional 70% of the varying norm. During this process, cement grains and a liquid medium are reached up to the formation of potassium hydrosilicates.
Important: The hardening process can continue after a set of conditions 70% of the vocational norm.
For example, some concrete concrete brand M 200, after a few years, acquire strength corresponding to materials with the M 400 brand.
Time to remove the formwork
Now, when we decided how many days, the strength of concrete is gaining, we will define when you can proceed to dismantling the formwork.
- If with your own hands, but taking into account the technological requirements and recommendations, then you can start the formulation of the formwork already through three days.
During this time, the optimal parameters of hardness will be achieved, in which it is possible to cut the reinforced concrete diamond circles. But despite this, you can load the design no earlier than in a week. - If the fill of structures and structures is carried out in winter, the growth of strength slows down significantly. Therefore, the formwork can be removed no earlier than in a week. To load the designs of this type and carry out diamond drilling of the holes in the concrete, it is possible not earlier than in 2 weeks.
IMPORTANT: Filling formwork in winter should be carried out using special underflowing materials, since not a covered solution will laugh and does not get the required strength at all.
It should be understood that this instruction is important, since if you make a dismantling ahead of time, the likelihood of cracks in the thickness of the finished design is large. But it is necessary to take into account the fact that the formwork is also undesirable because it prevents the free access of air, as a result of which concrete creates unevenly.
The pace of setting and methods for monitoring these parameters
In the photo - the foundation after the timely dismantling of the formwork
Returning to the time how many concrete is gaining strength, consider the pace of phased hardening:
- For the first three days after laying under normal temperature conditions, the material is gaining about 30% of the varying strength.
- After 7-14 days after laying under normal temperature conditions, the material is gaining over 60% of the vocational norm.
- In 28 days after the end of laying, concrete is capable of gaining 100% of the truck norm.
- For 90 days after laying, the material is capable of gaining up to 120% of the truck norm.
- Further hardening and hardening of structures during moisture access also occurs, but the intensity of the process is an order of magnitude lower.
The strongest rates of hardening cement-containing solutions inhibits the decrease in temperature. As a result of cooling, cement particles less actively interact with water. As a result, chemical reactions proceed extremely slowly.
A decrease in temperature to minus values \u200b\u200bgenerally stop the hardening process. With the subsequent increase in the ambient temperature, the material will be solved, but it does not have to count on the marching set of strength in this case.
In the photo - the result of drying the solution during the gripping process
At the same time, an increase in temperature in the thickness of the material allows you to sharply speed up the pace of hardening. But, increasing the temperature, you should ensure that the solution in the formwork does not dry before the time.
For example, when the concrete is heated with water steam to a temperature of 80 ° C, for a set of 70% of the valuing strength, it will take at least 16 hours. Thus, industrial rank is carried out in the manufacture of piles and a number of other reinforced concrete products.
Important: It is impossible to heat the concrete greater than 90 ° C, since at the water boiling temperature, the chemical reaction at which the cement-containing solution is impossible.
Another point to which special attention should be paid is the fencing of the cement-containing solution is an exothermic process, during the flow, which the concrete highlights heat. As a result, increasing the temperature for a more intense set of strength, you risk over with a concrete, as it will add heat released during the exothermic process to the heating temperature.
Output
Now you know how much the strength of concrete is gaining and what factors determine the intensity of the flow of this process. As a result, you will be able to follow in order to be carried out in the framework of technological recommendations.
You can detect more useful and cognitive information, looking at the video in this article.
About concrete.su / Information / Construction concrete
According to the assigned brand of concrete, you can understand which largest load in kgf / cm 2, a number of way or another. Of course, all reinforced concrete products are produced from production already with vacation strength, which in the summer should be at least 70% of the brand, and in the winter - at least 90%. Therefore, construction organizations can immediately apply the product.
But consumers who buy a ready-made concrete mix for the fill of the foundation or want to make it independently, will be interested to know, for how many days is the strength of concrete And how to achieve it fast?
28 days for brand control
For brand control, the technologists use a period of 28 days. The first week, with warm weather, concrete is intensively gaining its strength, about 70 percent of the actual one. This is due to the interaction of cement grains and water, resulting in potassium hydrosilicates. The process can delay not for one year. For example, some reinforced concrete products, which made a brand of concrete M 200, after a few years the strength reached the concrete of the brand 400.
When to remove the formwork?
If you independently pour the foundation, it is recommended to remove the formwork of the foundation through the three days, but load the concrete structure is better in a week. Under winter conditions, the growth of strength decreases significantly. If the design is not covered, then the concrete can freeze and do not gain strength at all. For the summer period, special care is also required, that is, constant moisturizing and shelter from direct sunlight so as not to cause the contee surface.
Melted processing accelerates concrete strength
After how many days is the strength of concrete, if it is exposed to heat-woof processing? In a few hours. If the temperature chamber is 80-90 degrees in the stereo chamber, the design gains strength up to 60-70 percent of the brand after 12-14 hours. But in such conditions, concrete quickly loses water, and at the same time he begins to dying. Therefore, the best concrete is the one that gained strength in vivo.
For a speedy set of strength, special additives for concrete can be used, which are used during the preparation of the mixture. Dosing is made from the amount of cement. Using additives, concrete can score marching strength in two weeks. Again, if the hardening occurs in the warm season. For the winter, anti-massorous additives are applicable, which are maintained in concrete a positive temperature for the gripping period.
With an independent fill of the ribbon foundation, you can approximately navigate for how many days concrete will type strength - per month. Therefore, try to withstand this interval to prevent unpleasant consequences in the future with the load.
Concrete Strength Schedule
- Stages of hardening solution
- What affects the set of maximum strength
- Acceleration of durability
The key stage of repair and construction work is a drying of concrete. The compound hardened and dials the strength of several weeks. The process is under the supervision of engineers and requires constant control.
Specialists ensure the fulfillment of standards and, if necessary, make adjustments to the schedule. The material is sensitive to temperature fluctuations and has a "seasonality coefficient" - in winter, concrete works are carried out using heating systems. To determine how much concrete dries, various factors take into account.
Stages of hardening solution
Concrete work is part of any construction, from class-cottage to industrial and special. The material is used at various stages of the construction of objects, for the fill of the foundation and carrier structures, the ceiling devices.
Builders successfully use the properties of the cement-sand mixture with the addition of rubble - the ability to take formwork. The strength and durability of the material is valued, the drying time of which is about 28 days.
Depending on the operating conditions and quality of the composition, the estimated service life of objects reaches 250 years, and an average is estimated at 50-100. For modern construction, this solid period - technology is constantly being improved, new materials and constructive solutions appear.
A set of strength is still paying special attention and control each stage:
- Throat. Happens in the first hours of "life" of the composition. To the workshop, the solution is delivered in a concrete mixer or prepared in place to maximize the necessary properties.
Throwing time in summer at temperatures above 20 ° C - about an hour, in the heat - 15-30 minutes. When "Nole" - begins 6-10 hours after the preparation of the mixture and stretches up to 20 hours from the moment of fill;
- Stretching. The main stage takes 7-14 days. During this period, the design is gaining up to 70% of the calculated value, which depends on the brand of concrete;
- Control value according to GOST 18105-86. Standard durability time - 28 days. Specialists compare the result received with the standards of a special table.
Concrete Strength Set - Temperature, Humidity, Hydration
There is a direct relationship between solidification of the solution in various conditions and the achievement of the maximum value.
What affects the set of maximum strength
The absolute majority of concrete works are performed in the open air.
Weather conditions and temperature schedule are key parameters that determine how much the solution is pouring.
In the warm season, the ripening of the mixture and gradual rejection occurs naturally. The process depends on the physicochemical properties of the composition and has small differences associated with the brand of concrete.
In the autumn-winter period, the strength set is provided in two ways:
- Antiorrose additives. Used to preserve the properties of the cooked solution. Special substances do not allow freezing water and loss of quality, facilitate the fill of the structure, alignment of the surface;
- Electrical heating. It is performed by several methods with a common essence - ensuring uniform warming up the thickness of the concrete during the period necessary for a durability.
At low temperatures, the PNSV wires are used or "implanted" into the material of the electrodes, after which the voltage is connected. It is less likely to use the formwork itself as the heating element, cover the surface with special mats.
Works require compliance with the rules of electrical safety and are performed by SNiP 3.03.01-87. If the minimum temperature reaches 0 ° C, and the average per day does not exceed 5 ° C, the concreting initially planned with heating the flooded structures. If necessary, the solution includes PMD.
Acceleration of durability
Concrete formulations are classified depending on the compression strength indicator. Light solutions are used for auxiliary works or structures that do not experience the load.
Basic are considered concretes M-200 - M-400. The compositions are used in the construction of most civil engineering facilities. The class solutions above the M-500 are intended for special objects and structures of increased strength.
The basic rejection rate is calculated on the basis of M-200 - M-300 brands. Indicators are based on the time interval at four weeks. In practice, the required period is reduced under certain conditions:
- Use special additives. These are auxiliary components that are mixed into the solution when preparing. Application Reduces the time of complete pour to 14 days. Such work is carried out in summer - anti-sore supplements do not have a similar property;
- Moisturizing.
With dry hot weather, there is a rapid evaporation of water from the drying composition, which adversely affects the chart of the strength recruitment and the quality of the structure. Continuous moisturizing contributes to the creation of conditions at which they achieve the optimal dynamics of frozen.
After completion of the estimated period, concrete tests and control measurements are carried out. If the indicators meet the standards, proceed to the following steps of work.
In order for the construction to be completed according to the plans, it is recommended to develop detailed project documentation based on the design features. In the calendar chart, concrete works are planning to be planned in the most favorable season.
Return to list
Concreting of the tape and slab foundation of the house is performed according to the long-developed technology. At first glance, nothing complicated in the work, but during the fill, in the process and after curing monolith, there are many issues related to various nuances. Some of them are so important that their non-compliance may well lead to one or another structures. For example, how much time should pass after the fill before removing the formwork and how long do you need to withstand the concrete before the next stage of the work? Among the specialists you can hear different opinions, but the rules still exist.
What threatens untimely removal of formwork
As you know, a cashey-shaped concrete solution is used to fill the ribbon or slab basement of the house. After laying it into the formwork, the processes of cement hydration and gradual hardening of concrete begin. For their correct completion, it is necessary to highlight a certain amount of time required in order for the foundation to be able to stand out and gain project strength.
If the formwork from the design will be removed immediately after grappling cement, then the probability of the layout of the monolith in different directions will appear. The rapid "body" will not only be able to take loads, but also to hold his own form. This is especially true of massive foundations.
If the dismantling of the formwork with a belt foundation will be completed after the cement solution rises, but before it gains certain strength, cracks will appear in the design. For the underground part of the house hosting on itself and distributing all loads on the ground, it threatens to split and complete destruction already during the operation of the house.
How many foundation should stand after the fill? There is no unambiguous answer to this question. The average period of time is determined by 28 days, but in some cases there is enough 15-20 days. In difficult conditions, the deadlines must be renewed.
Professionals assure that the foundation of the house before its download should stand at least a month.
So that the structure does not give a shrinkage, did not twist and not collapsed, it is necessary to strictly comply with the implementation of construction rules and technology for the construction of the underground part of the house.
Concrete - time setting and conformity
The foundation is a support of the building, so does not tolerate the negligence, the inability and lack of elementary knowledge.
How much time the foundation should defend
The deadlines specified in the standards provided for the concrete structure can stand, do not always correspond to real time. They affect foreign factors, such as:
- ambient temperature;
- humidity regime;
- the presence of atmospheric precipitation;
- season;
- ground conditions;
- terrain;
- sizes and type of foundation - tape, slab, columnar;
- design strength of concrete;
- material quality;
- the presence of groundwater on the site;
- construction technology;
- the presence of additives;
- the magnitude of the calculated loads.
In addition to the above moments, situations may arise that affect the period during which the foundation of the house will have to launch before further work. In some cases, the concrete design is left even for the winter so that when tipping the soil it was easier to determine defects and straighten the shrinkage. In this case, the monolith is secure. It is noteworthy that no standard would be able to take into account all the nuances, so the question of how much the foundation of the house will be settled, is solved individually.
When determining the timing, the most worst conditions for the site should be taken. The stock in this case will play a positive role.
How is the foundation of the house
The first time of the concrete structure is allowed to stand immediately after the fill. This period lasts up to seven days, during which the surface is watered with water. Concrete is captured and starts to harden. From above, the foundation is covered with a polyethylene film, but can also be used:
- wedbed fabric;
- sawdust;
- straw.
Polyethylene is lifted before watering, and other materials are wetted from above. They preserve moisture superbly, not giving water to evaporate ahead of time. The duration of solidification of monolith depends on the time of year. About a week later, and in the hot season - after 10-14 days, watering is stopped, but the coating layer is left up to 28-30 days after the end of laying a concrete mix in the formwork. Thus, the primary standing occurs, quite sufficient for foundations installed on the base, beaten below the level of primerization of the soil.
But in practice there is a secondary standing. It concerns situations when on bubbling soils have to build small-brewed foundations. In this case, the hardened concrete structure is left to winter. With the arrival of spring, the progress is recorded, and the base is strengthened by submissions of sand or gravel with a mandatory layer-by-layer tamper.
Experts assure that it will be better if the foundation does not eat without load for a whole year. It turns out that in the first month after the fill, the concrete gains strength to 70-75 percent, and the remaining 25-30 percent in the next 11 months. From this we can conclude that if the construction time allows, then preference should be given a longer time intermediate. If the period of construction is limited to a rigid framework, then the installation of the walls of the house is proceeded in 28 days after the fill of the foundation. With favorable climatic conditions and use in the enclosure structures of lightweight materials - the period can be reduced to two weeks.
08/22/2016 at 13:08
The device of reinforced concrete monolithic foundation requires knowledge and understanding 
many important points.
Before pouring a mixture into a formwork, a non-professional in a construction topic should be prepared theoretically.
It has a considerable value of the disassembly time of the formwork. How to control strength and when can I load the foundation?
How much to wait for the durability
As indicated in p.
How concrete gains strength and how to control these parameters
2.5 SNiP 2.03.01-84, for the construction of foundations, concrete should be applied not lower than M-200. Since BM-100 is used for the preparation device, the body itself is most often performed from concrete M-200. 
The hardness of the solution laid in the formwork is influenced by various factors, including those:
- The correct ratio of the ingredients;
- Air temperature;
- Air humidity;
- Time period from the preparation of the mixture to laying;
- Layer thickness;
- Compliance with technology, etc.
A strength set is a chemical process that requires optimal conditions, heat and humidity are most important. Depending on the ratio of these indicators, the process of achieving regulatory strength characteristics lasts up to 28 days.
If it is overly hot, that is, the air temperature is above 25 degrees, the mixture will crack, the moisture is quickly evaporated from it, necessary for the normal course of the hardening reaction, and at temperatures below +5 degrees, the processes slow down, which adversely affects the frost time.
The optimal temperature of +20 degrees Celsius. Already from the first hours, the strength of the mixture begins to increase: after 2.5 hours the mixture will grab, but the hardness is still too small to hold the concrete. Intensively, the foundation is gaining strength in the first week, reaching 70% of the project. Frozening, hardening continues up to 28 days.
Concrete grasp control
Under the conditions of concrete work, construction companies are carried out by testing concrete samples by the following methods:
- Compression special equipment;
- Cutting the massif by the hammer of Kashkarova;
- Ultrasonic devices (non-destructive method).
For testing in a stationary machine, cubes are prepared: from one portion of the mixture poured samples with a size of 10 × 10 cm in an amount of at least 3, marking the samples themselves, as well as fixing the date and time on them. 
Cubes are transmitted to a special construction laboratory to carry out tests, where on the basis of the load, in which the cubes were collapsed, calculations perform and remove the strength of concrete, given the age of cubes. This method is considered accurate.
The climbing hammer gives approximate results and refers to inaccurate methods. Hammers have different species, and the Kashkarov design device is notable for the fact that the impact force is not reflected in the final readings of the strength. Hammer himself weighs 400-800 g.
The strength indicators are determined in the footsteps remaining on concrete, in accordance with the table shown in the regulatory literature.
Ultrasound devices are based on determining the speed of ultrasound through the thickness of concrete: the more dense concrete, the smaller the speed. In addition to the size of the strength, the ultrasonic method allows you to establish the presence of emptiness, shells in the basement array or other structural element.
Special methods should be applied by professionals with work experience. Laboratories, amateurs will not be able to determine the exact value of the resistance of the material of compression, that is, strength.
In handicraft conditions, the setting check is made like this: simultaneously with the laying of the mixture into the formwork, the form of an arbitrary size is poured separately (the size of 10 × 10 cm) is poured, but preferably the same with the main elevation design.
On day 2, on one side, the formwork needs to be removed and see whether the concrete is holding the form as far as he grabbed. If necessary, follows a day to remove the formwork on another face of the sample and analyze the dynamics of setting. One of the samples can be tried to break up to make sure of its hardness.
It is important to understand that a sample of smaller dimensions than an array of foundation, and in a small volume, concrete is frozen faster. Making sure that the sample grabbed, it is necessary to give an array for an extra time 2-5 days to get the desired result - a hard-hardened, grabbed foundation.
When to remove the formwork
The removal of the formwork can be carried out in an acute need for 3-5 days, but it is better to withstand 7-14 days. 
Well climbed, climbing 30-70% of the strength concrete retains the form, does not give chips sacrificing formwork.
The platform is permissible in the early time if the shields are needed to perform work on another capture or the next object.
In private construction, it is reasonably not in a hurry and give a mixture to type the desired strength indicators, for which it will take 2 weeks.
How much can you load the foundation
To give a load on the foundation means, to perform the next stage of building the building, in the case of the foundation, this is a device of the walls:
The load is acceptable when concrete acquires 100% of design strength indicators. In this case, you can not be afraid of deformations, the destruction of the foundation, since the constructive is already able to perceive the load from the walls, overlap, roofing. 
Such a term occurs after 28-30 days from the moment of filling the concrete to the formwork.
This period can be reduced if you use special means - chemical additives, or technological techniques, like warming during the cold season, watering water or shelter by wet mats in the summer when heat.
If concrete is grabbed in natural conditions, it is better not to hurry and remove the formwork not earlier than one or two weeks, but to build walls aged at least 4 weeks.
There is nothing complicated in the design of the foundation, but it is better when professionals are engaged in this, who have both experience and technical means of monitoring concrete.
If still, the fill of the formwork is performed on its own, it is better to make the platform after 7-14 days, and to expose the load - no earlier than in 28 days from the duty of the fill.
How does Concrete gain strength?
The main characteristic of concrete is its compression strength - this characteristic is reflected in its brand. But the vintage strength is not immediately achieved, concrete is gradually gaining strength for four weeks. Therefore, after the fill of the concrete, it is necessary to wait for a while.
Concrete strength set
The most intense set of strength occurs in the first 5-7 days after the fill - during this time he dials about 70% of its vintage strength. In the future, its strength increases and reaches the brand after 28 days of ripening. Until this time, it is not recommended to load the concrete structure, i.e. If it is a foundation, then you can put a house on it only after it takes its brand strength strength. The minimum strength of concrete is gaining after 7 days, after the expiration of this period you can disassemble the formwork.
The schedule of the concrete strength of the concrete from time is shown in the picture:
Concrete ripening schedule at different temperatures.
The graph shows the dependence of concrete strength from time at various temperatures of its ripening: from 30 to 80 degrees. Strength is shown as a percentage of the brand. However, these are theoretical data obtained in the laboratory conditions, in practice, to withstand such conditions is unreal: the temperature changes over during the day and it will not exactly be constant and equal to 30 degrees. Therefore, during the independent construction of the foundation, it is better to reinforce and give concrete to stand a month, and only then disassemble the formwork and continue the construction.
Cement is used as a binder in concrete, its chemical reaction with water leads to the appearance of solid stony neoplasms, which bind particles of the filler - rubble and sand among themselves. The initial period of this reaction is called a setting, during which the initial relations between the filler particles are formed in the concrete. Then there is a set of strength when these ties are reinforced. In order for this chemical reaction to flow, water is necessary. But since the maturation of concrete is a long-term process, water, originally contained in the concrete mixture, has time to evaporate. In order for this not to take place the surface of the concrete structure is covered with a polyethylene film or rubberoid, as well as watered it with water. It is important that concrete dried uniform throughout the volume.
In the cold season, the water contained in the concrete mix may freeze and maturation concrete will stop. Moreover, freezing, water will increase in volume and will destroy the concrete from the inside. At temperatures below 10 degrees, the strength set is very slow down. Therefore, when pouring a concrete mix at low temperatures throughout the maturation it is necessary to warm it. Of course, with independent construction it is impossible (or at least very difficult), so you need to pour concrete in the summer. The temperature is necessary for its ripening - 20-25 degrees or higher.
The deadline for a set of concrete strength can be reduced using special additives that accelerate this process. Such rapid concrete concretes are gaining strength in two weeks, but with independent construction, their use is difficult, because they not only ripen faster, but they are grapped faster. This means that after the preparation of such a fast-hardening concrete, a mixture of time on its fill will be significantly less. Another way to achieve accelerated maturation of concrete is an increase in temperature: from the graph it is seen that the higher the temperature, the faster the strength is going on. However, with independent construction, creating such conditions is unrealistic.
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Curing
During the ripening of fresh concrete, it takes care: it is necessary to ensure optimum temperature and humidity so that it scores the design strength and not covered with cracks during drying.
Concrete for foundation
Concrete is a stone material that is formed as a result of solidification of the concrete mix. The concrete mixture for filling the monolithic foundation consists of mixed in certain proportions of cement, sand, gravel and water.
Filling the foundation of the house: How to grasp the monolithic foundation?
After you have determined with the type of foundation, the place and the depth of it, they conducted all land works (pulled out the trench for the foundation, made a sandy-gravel pillow), set the formwork, strengthened her walls with backups, gathered the reinforcement frame, installed it in the formwork and It was securely fixed there, it was time for the last and most important stage of the establishment of the foundation - his fillings.
Calculation of the amount of concrete for the foundation
The source data for calculating the amount of concrete for filling the foundation is the foundation type (slab, tape, columnar) and its configuration. The type of foundation and parameters are selected depending on the bearing capacity of the soil and the load on the foundation.
Brand and Class of Concrete
The main characteristics of concrete is its brand and class of strength. The ratio between the brand and class is given in this article.
Publication date: 10/29/2010 15:57:26
Concrete hardness
Concrete strength set (in hours)
| Standing time, clock | |||||||
|---|---|---|---|---|---|---|---|
| 0 ° C. | 5 ° C. | 10 ° C. | 15 ° C. | 20 ° C. | 25 ° C. | 30 ° C. | |
| 4 | 6 | 7 | 8 | 10 | 12 | 13 | 14 |
| 8 | 10 | 12 | 13 | 16 | 18 | 20 | 22 |
| 12 | 13 | 16 | 18 | 21 | 23 | 25 | 27 |
| 16 | 16 | 19 | 22 | 24 | 27 | 30 | 32 |
| 20 | 18 | 21 | 24 | 27 | 31 | 33 | 36 |
| 24 | 20 | 23 | 27 | 30 | 34 | 37 | 39 |
| 28 | 22 | 25 | 29 | 32 | 37 | 30 | 42 |
| 32 | 23 | 27 | 31 | 34 | 38 | 42 | 45 |
| 36 | 24 | 28 | 32 | 36 | 40 | 43 | 47 |
| 40 | 25 | 29 | 33 | 37 | 42 | 44 | 48 |
| 44 | 25 | 29 | 34 | 38 | 43 | 46 | 49 |
| 48 | 26 | 30 | 34 | 39 | 43 | 47 | 50 |
Concrete strength set (in days)
| Standing term, day | The temperature of the hardening of concrete | ||||||
|---|---|---|---|---|---|---|---|
| 0 ° C. | 5 ° C. | 10 ° C. | 15 ° C. | 20 ° C. | 25 ° C. | 30 ° C. | |
| Concrete strength for compression% of 28-day | |||||||
| 1 | 20 | 23 | 27 | 30 | 34 | 37 | 39 |
| 2 | 26 | 30 | 34 | 39 | 43 | 47 | 50 |
| 3 | 30 | 35 | 41 | 45 | 50 | 52 | 56 |
| 4 | 34 | 40 | 46 | 50 | 55 | 58 | 63 |
| 5 | 39 | 44 | 51 | 55 | 60 | 63 | 68 |
| 6 | 42 | 48 | 54 | 59 | 64 | 68 | 72 |
| 7 | 45 | 52 | 58 | 63 | 68 | 72 | 76 |
| 10 | 53 | 60 | 67 | 72 | 77 | 82 | 85 |
| 14 | 60 | 68 | 74 | 81 | 86 | 690 | 95 |
| 21 | 70 | 76 | 83 | 91 | 97 | >100 | >100 |
| 28 | 75 | 83 | 90 | 100 | >100 | >100 | >100 |
The overwhelming majority of amateur builders are considered for not entirely understandable reasons, which by the end of laying in the formwork or the completion of work on the alignment of the tie process of concreting is complete. Meanwhile, the time of setting concrete is much more than the time on its laying. The concrete mix - a living organism in which complex and extended physico-chemical processes associated with the conversion of the solution in the reliable basis of building structures occur at the end of the stacked work.
Before producing a platform and enjoy the results of the applied effort, it is necessary to create the most comfortable conditions for ripening and optimal concrete hydration, without which it is impossible to achieve the required brand strength of monolith. Construction rates and rules contain verified data, which are shown in concrete time tables.
| Concrete temperature, with | The term of hardening concrete, day | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 14 | 28 | |
| Concrete strength,% | |||||||||
| 0 | 20 | 26 | 31 | 35 | 39 | 43 | 46 | 61 | 77 |
| 10 | 27 | 35 | 42 | 48 | 51 | 55 | 59 | 75 | 91 |
| 15 | 30 | 39 | 45 | 52 | 55 | 60 | 64 | 81 | 100 |
| 20 | 34 | 43 | 50 | 56 | 60 | 65 | 69 | 87 | - |
| 30 | 39 | 51 | 57 | 64 | 68 | 73 | 76 | 95 | - |
| 40 | 48 | 57 | 64 | 70 | 75 | 80 | 85 | - | - |
| 50 | 49 | 62 | 70 | 78 | 84 | 90 | 95 | - | - |
| 60 | 54 | 68 | 78 | 86 | 92 | 98 | - | - | - |
| 70 | 60 | 73 | 84 | 96 | - | - | - | - | - |
| 80 | 65 | 80 | 92 | - | - | - | - | - | - |
Care for concrete after fill: Basic goals and methods
The processes associated with the conduct of activities that precede the platform contain several technological methods. The purpose of the implementation of such events is one - the creation of a reinforced concrete structure, which is maximally appropriate in its physico-technical properties of the parameters that are laid in the project. The fundamental event is definitely the departure of the concrete mixture.
Care is to perform a set of measures that are designed to create conditions that are optimally appropriate in the mixture of physicochemical transformations occurring in a mixture during a set of concrete strength. Acquisitive follow-up to the prescribed maintenance technology allows:
- minimal values \u200b\u200bof shrinkage phenomena in the concrete composition of plastic origin;
- ensure the strength and temporal values \u200b\u200bof the concrete structure in the parameters provided for by the project;
- protect the concrete mix from temperature dysfunctions;
- prevent the stuffing hole of the laid concrete mix;
- protect the construction from various origin of the effects of mechanical or chemical genesis.
Care procedures for freshly built reinforced concrete design should be started directly at the end of laying the mixture and continue until 70% of the strength provided by the project is reached. This is provided for by the requirements set forth in clause 2.66 of SNIPA 3.03.01. The platform can be carried out in earlier time, if it is substantiated by the prevailing parametric circumstances.
After the end of laying a concrete mixture should be inspected a formwork design. The purpose of such an inspection is to find out the preservation of geometric parameters, the detection of leakage of the liquid component of the mixture and mechanical damage to the formwork elements. Taking into account how much time concrete is frozen, it is more precise to say - given the time of its setting, the manifested defects need to be eliminated. The average time for which the freshly stated concrete mix can be seized is about 2 hours, depending on the temperature parameters and the portland cement brand. The design must be protected from any mechanical impact in the form of shocks, shakes, vibration manifestations as much as concrete dries.
Concrete Stages Concrete Stages
The concrete mixture of any composition has the property to be captured and obtaining the necessary strength characteristics during the passage of two stages. Compliance with the optimal ratio of temporal, temperature parameters and values \u200b\u200bof the given moisture is determined to obtain a monolithic design with planned properties.
The stadium characteristics of the process are concluded in:
- grapping concrete composition. The preliminary setting time is not large and is approximately 24 hours at an average temperature of +20 CO. The initial gripging processes occur during the first two hours on the mixture of the mixture with water. The final grasp occurs, as a rule, for 3-4 hours. The use of specialized polymer additives allows, under certain conditions, the initial setting period of the mixture is reduced to several tens of minutes, but the feasibility of such an extreme method is justified for the most part during the production of reinforced concrete elements of industrial structures;
- calculated concrete. Concrete gains strength when in its mass flows the hydration process, in other words - removal of water from a concrete mixture. Part of the water during the passage of this process is removed during its evaporation, the other part binds to the molecular level with the mixture of chemical compounds. Hydration can occur with strict observance of the temperature and humidity modification mode. Violation of conditions leads to failures in the passage of physicochemical processes of hydration and, accordingly, to deterioration of the quality of the reinforced concrete structure.
The dependence of the time of a set of strength from the brand of concrete mix
It is logical that the use for the preparation of concrete compositions of different brands of Portland cement leads to a change in the time of the hardening of concrete. The higher the portland cement brand, the less time the mixture is required for a set of strength. But when using any brand, be it a brand of 300 or 400, should not be applied to the reinforced concrete design of a significant mechanical nature of the loader earlier than after 28 days. Although concrete setting time on the tables given in the construction rules may be less. This is especially true of concrete prepared using Portland cement grade 400.
| Brand cement | Time hardening of various brands of concrete | |||||||
|---|---|---|---|---|---|---|---|---|
| for 14 days | for 28 days | |||||||
| 100 | 150 | 100 | 150 | 200 | 250 | 300 | 400 | |
| 300 | 0.65 | 0.6 | 0.75 | 0.65 | 0.55 | 0.5 | 0.4 | - |
| 400 | 0.75 | 0.65 | 0.85 | 0.75 | 0.63 | 0.56 | 0.5 | 0.4 |
| 500 | 0.85 | 0.75 | - | 0.85 | 0.71 | 0.64 | 0.6 | 0.46 |
| 600 | 0.9 | 0.8 | - | 0.95 | 0.75 | 0.68 | 0.63 | 0.5 |
Design, construction and final arrangement of any buildings using reinforced concrete components requires a careful relationship to all stages of construction. But from the thoroughness of the manufacture of concrete components, especially the foundations, the durability and reliability of the entire structure depends largely. Observance of the deadlines, for what time concrete mixes and compositions are collected, it is safe to name the basis of success in any building process.
The following features are characterized for hardening concrete:
- the lower the ambient temperature, the slower the hardening occurs and the strength is increasing;
- at temperatures below 0 ° C, the water required for cement hydration freezes and hardening stops. With a subsequent increase in temperature, the hardening and a set of strength renew;
- all other things being equal in a humid environment, a strength is higher than when hardening in air acquires a certain period of concrete;
- in dry conditions, further hardening slows down and practically stops, due to the lack of moisture necessary for the hydration of cement;
- with an increase in temperature to 70-90 ° C and the maximum humidity, the rate of increase of strength increases significantly. Such conditions create a high pressure steam in autoclaves when steaming concrete.
Note that the speed of a set of concrete strength is a non-permanent value. The hardening has the greatest intensity in the first 7 days from the moment of filling the concrete mix. Under normal conditions of hardening after 7-14 days, concrete is gaining 60-70% of its 28-day strength. In the future, the strength set does not stop, but it happens much slower, and to a three-year-old age, concrete strength can reach 200-250% of the value determined at the age of 28 days.
What depends a set of strength and hardening
The set of concrete strength is influenced by many factors, among them the following can be distinguished:
- the type of cement used in the production of concrete mix;
- the temperature at which concrete is hardening;
- waterproof relationship;
- the degree of compaction of the concrete mix.
The effect of each of the above factors for hardening and the set of strength is given below in the form of a table and graphs.
Dependence on the type of cement and the temperature of hardening:
Below are the data on the set of heavy concrete relative strength depending on the above two parameters (type of cement and the hardening temperature).
|
Hardening time |
Type of cement |
Relative |
|||
|
20 About S. |
10 About S. |
5 About S. |
|||
|
0,45 |
0,42 |
0,26 |
0,16 |
||
|
0,37 |
0,34 |
0,21 |
0,12 |
||
|
0,23 |
0,19 |
0,11 |
0,06 |
||
|
0,58 |
0,58 |
0,37 |
0,22 |
||
|
0,52 |
0,32 |
0,19 |
|||
|
0,38 |
0,34 |
0,21 |
0,12 |
||
|
0,65 |
0,66 |
0,43 |
0,26 |
||
|
0,38 |
0,23 |
||||
|
0,47 |
0,45 |
0,28 |
0,17 |
||
|
0,78 |
0,82 |
0,54 |
0,33 |
||
|
0,75 |
0,78 |
0,51 |
0,31 |
||
|
0,67 |
0,68 |
0,44 |
0,27 |
||
|
0,87 |
0,92 |
0,61 |
0,38 |
||
|
0,85 |
0,37 |
||||
|
0,81 |
0,85 |
0,56 |
0,34 |
||
|
0,93 |
|||||
The construction of the designs of various configurations and destination involves the fill of the foundation. Therefore, many builders, predominantly beginners, are interested in what is the time of a set of concrete strength. It should be immediately noted that this process depends on numerous moments, among which not only environmental conditions, but also the components of the solution used for the fill of the foundation.
In this article we will try to figure out how concrete strength is gaining and there are methods of accelerating this process.
What is the essence of the process?
Conditionally, it is divided into 2 stages:
- Grappling. This stage occurs during the first 24 hours after kneading the base. The time of decisions of the solution depends on the temperature indicators indoors or on the street. And if we provide due conditions, you can accelerate the grasp of concrete mass.
- Stretching. As soon as the base clings, it comes to hardening. Oddly enough, the hardening of the foundation continues within 12-24 months. At the same time, the values \u200b\u200bdeclared by the manufacturer, when providing favorable conditions, is determined on the day 28 after the fill.
Interestingly, in many sources you can find, from which the kinetics of the durability set is dependent, time. Humidity, quality of ingredients. But little where you will find the answer to the question, due to which the concrete is gaining strength? This occurs in the process of cement hydration.
In the dry material there are 4 main elements:
- altitis;
- bELIT;
- threecalcium aluminat;
- fourcalcium aluminorritis.
The first when he missed the reaction to the reaction, but this is the most fragile mineral. Next comes aluminates and alumfererites. The last to the reaction comes the Belith, it also gives the necessary strength. At the same time, it is hydrated gradually, by typing the necessary parameters annually. Even after 50 years, the hydration process goes, respectively, all this time concrete continues to gain strength.
The process of cement hydration begins with the moment of mixing with water and continues for a long time.
As for concrete, its parameters depend on the degree of cement hydration. If we are talking about a low degree, then after 4 weeks it will reach the desired 90%. In high strength, through the same time there will be only half (up to 49%), and in the future, over time it will only increase. On average, for 3-5 years, the increase is about 60%.
What affects the aging foundation
As mentioned earlier, on how much concrete is gaining strength, the whole series of nuances affects, the main of which belongs:
- temperature environmental conditions;
- the level of humidity in the place where the base is pouring;
- cement brand;
- time.
Temperature conditions
A set of concrete strength depending on the ambient temperature, this is an urgent question for most people who are engaged in the fill of the foundation. It is worth remembering one major rule: the colder on the street or indoors where the surface concreting is carried out, the more time the hardening.
At temperatures below 0 ° C, the base strengthen is suspended and, as a result, the duration of the durability increases indefinitely. Sometimes the achievement of the producer of strength characteristics declared by the manufacturer occurs several years. This is when the process takes place in the northern regions. Such a phenomenon is due to the fact that the water existing in the cement mass freezes. And since at the expense of moisture is ensured by the necessary hydration process, then solidification, so to speak, "frozen".
But as soon as the street starts to warm and become higher than the zero mark, the hardening will continue. Etc. This looks like a set of concrete strength depending on temperature.
Warm weather conditions "activate" and accelerate the hardening of the cement base. The velocity of the hardening of concrete depending on the temperature is directly proportional to the increase in environmental performance. So, at 40 ° C, the indicators declared by the manufacturer are achieved in 7-8 days. It is for this reason that many experienced professionals recommend pouring a concrete foundation at the preservation site in hot weather, due to which it takes much less time to organize the entire construction process as a whole, rather than in the case of the fill of the foundation in colder weather.
In winter, as soon as the temperature drops to 0 degrees, the hydration process is completely stopped
But even in this case, the concrete does not need to "push" - while the lower layers are grabbing, the top will take a crack. It does not add any aesthetics or hardness. When working in a hot time, the surface is 2-3 times a day with water and covered with cellophane.
How much does Concrete gain strength in the winter season? In fact, the construction of the foundation in the winter is a time-consuming process that requires the use of special equipment for regular warming up cement mass in order to accelerate its solidification process.
When working with a concrete mass in order to accelerate its solidification, heating over 90 ° C is unacceptable. This can lead to cracking the future surface.
In order to understand how the temperature affects the solidification process, you can learn the schedule for a set of concrete strength. This will allow visually to figure it out in this phenomenon. The recruitment graph consists of lines that are built on the basis of data collected for cement M400 with different mode.
The concrete hardening schedule allows you to determine which percentage ratio from the vintage indicators will be achieved after some time interval. Simply put, on these lines, you can find out how many days the mass is gaining a vintage value of hardness at a time or another.
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Time
In order to determine the optimal, one can even say, the safe period of construction work is often taken into account the durability table. It can easily determine for what time the foundation cooked from a particular cement brand will be frozen. Therefore, experienced specialists always enjoy similar information tables.
|
Brand cement |
Average daily t cement base, ° С |
Deadline for solidification |
||||||
|
Concrete mass hardness indicators for compression (% of the declared) |
||||||||
|
M200-300, kneaded on Portland cement 400-500 |
||||||||
In the event that a regulatory and safe period is set at 50%, then the most optimal period of starting construction work will be 72-80% of the claimed vintage indicators.
Humidity indicators
The reduced indicators of environmental humidity negatively reflect on the process of hardening the foundation base. With the complete absence of moisture, the hydration process is practically not occurring, and the hardness set is inevitably stopped. That is why it is very important to monitor the humidity of the fill with the foundation.
If indoors or on the street, where the fill or laying is the foundation, increased humidity (70-90 °), the rate of increases of strength indicators increases.
Warming up to such a high temperature regime with minimal moist values \u200b\u200bwill necessarily damage the flooded surface and reduce the hardening rate. To avoid such consequences, it is necessary to regularly produce moisturizing. Under such circumstances in hot weather, hardening will occur very quickly.
Video: How much concrete is harden
Cement Composition and Operational Data
If the cement has the ability of heat dissipation and immediately after the fill it quickly hardens, then after freezing in the cement mass of water, the hardening process will always stop. For this reason, during construction work, the cold season is better to give preference to mixtures prepared on the basis of antiorrosal additives.
So, for example, the alummy mass after the fill highlights 7 times more heat than the usual portland cement. Due to this, the construction mixture mixed on the basis of such cement is capable of rapidly gaining strength even at temperatures below 0 ° C. What, in fact, is due to its popularity of use in the cold season.
It is worth noting that the cement brand also affects the fill or masonry hardening. The table presented on the table clearly demonstrates these data.
Here, in fact, everything you need to know about the hardening of the foundation. We hope this information will be used by you in practice and will help you achieve the task in the best way!
Video: How to speed up solidification of concrete
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