Graph of concrete strength set: features, types, technology and key indicators

One of the important indicators of the quality of concrete is strength. If you read the requirements of government standards, you can find information that the strength can vary from M50 to 800. However, the most popular brands are the concrete from M100 to 500.

Strength graph

Concrete solution for a certain time after pouring will acquire the required performance properties. This time interval is called the aging period, after which a protective layer can be applied. The graph of the strength of concrete reflects the time during which the material will reach the highest level of strength. If normal conditions persist, then it will take 28 days.

The first five days is the time during which intense hardening will occur. But in 7 days after completion of the work the material will reach 70% of strength. It is recommended to begin further construction work after achieving a 100% strength, which will happen in 28 days. The graph of the concrete strength set by time may differ for individual cases. In order to determine the time, control tests are carried out on the samples.

What else do I need to know?

If work on monolithic housing construction is carried out in a warm time, then to optimize the process of maintaining the mixture and gaining physical and mechanical properties it will be necessary to sustain the structure in the formwork and leave it to ripen after the fence has been dismantled. The schedule of concrete strength set in cold weather will be different. In order to achieve vintage strength, it is necessary to provide concrete heating and waterproofing. This is due to the fact that lower temperatures help to slow the polymerization.

To ensure that the strength set occurred as quickly as possible, and the time keeping of the concrete was minimized, sand concrete must be added to the ingredients, in which the water percentage ratio is minimal. If cement and water are added in a proportion of four to one, then the terms will be reduced by half. To obtain this result, the formulation must be supplemented with plasticizers. The mixture can ripen faster if it is artificially increased its temperature.

Strength control

In order to ensure that the schedule for the strength of concrete has been met, for some time - up to a week - it is necessary to carry out measures that provide conditions for holding the solution. It must be heated, moistened, and covered with moisture and heat insulating materials.

To do this, often used heat guns. Special attention is paid to surface moistening. 7 days after completion of pouring, under such conditions, if the temperature of the environment changes from 25 to 30 ° C, the structure can be loaded.

Classification of concretes

If cement is used in the process of mixing the mortar and traditional dense aggregates, which allow obtaining heavy compositions, these blends are classified as M50-M800. If you have concrete of the brand M50-M450, then for its preparation porous aggregates were used, which make it possible to obtain light compositions. Concrete has a mark within the M50-M150 if it is particularly light or light, and also cellular.

The design brand of concrete should be determined even at the stage of compiling documentation for the erection of the object. This characteristic is given, based on the resistance to axial compression in the sample cubes. In the constructions under construction, the main is the axial extension, the cement brand is determined from it.

The strength set of concrete (the time schedule for stretching) will last longer when the stamp on compressive strength increases. But in the case of high-strength materials, the increase in tensile strength slows down. Depending on the composition and area of use of the mixture, the class and brand are determined by strength.

The most durable are materials with the following brands:

• M50.
• M75.
• M100.

They are used in the construction of critical structures. When buildings and buildings that require great strength are erected, concrete M300 is used. But with the arrangement of the screed, it is best to use the M200 grade. The strongest are cements, the brand of which begins with M500.

Temperature strength versus temperature

If you intend to use mortar in construction, then you should be aware of the graph of the dependence of the strength of concrete on temperature. As mentioned above, setting occurs within the first few days after mixing the solution. But to complete the first stage will be necessary time, which affects the temperature of the environment.

For example, when the thermometer's column is held at 20 ° C or higher, it takes an hour to grasp. The process begins 2 hours after the mixture has been cooked and will be finished in 3 hours. The time and the completion of the stage will be shifted by cooling, it will take more than 24 hours to grasp. When the thermometer is held at zero, the process begins 6-10 hours after the solution is prepared, and lasts up to 20 hours after pouring.

It is important to know also about the decrease in viscosity. In the first stage, the solution remains mobile. During this period, it can be mechanically affected, giving the structure the desired shape. The setting step can be extended using a thixotropy mechanism, exerting a mechanical effect on the mixture. Stirring of the solution in the concrete mixer ensures the extension of the first stage.

Percentage strength of concrete from vintage depending on temperature and time

Beginning builders are usually interested in a schedule of concrete strength set at 25 ° C. In this case, everything will depend on the brand of concrete and the time of hardening. If used for mixing portland cement brand within M 400 to 500, eventually will be able to get concrete M200-300. After a day at this temperature, its percentage of compressive strength from the brand will be 23. After two, three days, this figure will increase to 40 and 50%, respectively.

After 5, 7 and 14 days the percentage of brand strength will be equal to 65, 75 and 90% respectively. The graph of the concrete strength set at 30 ° C varies slightly. In a day and two strengths will be 35 and 55% of branded, respectively. In three, five and seven days strength will be equal to 65, 80 and 90% respectively. It is important to remember that the normative-safe period is 50%, whereas it is possible to start work only when the strength of concrete has reached 72% of the brand value.

Critical strength of concrete depending on brand: Overview

Immediately after pouring the solution will gain strength due to heat release, but after the water freezes the process will stop. If the work is supposed to be done in winter or autumn, it is important to add antifreeze mixtures to the solution. After laying, alumina cement releases more heat 7 times than conventional Portland cement. This indicates that the mixture prepared on its basis will gain strength even at low temperatures.

The speed of the process is also influenced by the brand. The lower it is, the higher the critical strength. The graph of concrete strength set, reviewed in the article, indicates that the critical strength for concrete grades from M15 to 150 is 50%. For pre-stressed concrete structures from M200 to 300, this value is 40% of the branded. Concrete grades from M400 to 500 have a critical strength of 30%.

Hardening of concrete in perspective

The schedule of concrete strength set (SNiP 52-01-2003) is not limited to a month. It may take several years to complete the strength-setting process. But you can determine the brand of concrete in 4 weeks. The strength of the design will be typed at different speeds. This process takes place most intensively in the first week. After 3 months strength will increase by 20%, after the process slows down, but does not stop. The indicator can double in three years, this process will be affected by:

• time;
• humidity;
• temperature;
• Brand of concrete.

Quite often, novice builders ask themselves a question in which GOST the schedule of strength strength of concrete can be found. If you look in GOST 18105-2010, you can learn more about this in more detail. These documents mention that the temperature directly affects the duration of the process. For example, at 40 ° C the brand value is reached in a week. Therefore, winter work is not recommended. After all, it is problematic to heat concrete by yourself, for this you need to use special equipment and get acquainted with the technology. But to heat the mixture more than 90 ° C and is completely unacceptable.

Conclusion

Having become acquainted with the schedule of durability, you can understand that the decking is carried out when the structural strength exceeds 50% of the brand value. But if the temperature of the external environment has dropped below 10 ° C, then the brand value will not be reached after 2 weeks. Such weather conditions suggest the need for heating the solution to be poured.