How to calculate the flexural strength of concrete

Test data: Because the ratio of the difference between the third and second specimens to the second specimen is greater than 15%, that is, the minimum and maximum are rounded off to the median value, and the result is.

If you don't understand it, you can take a look at the formula and understand it.

1. The flexural strength of concrete FCF is calculated according to the following formula (accurate to MPA): FCF=FL BH2

where f—failure load, n; l—support spacing, 450mm; b—specimen cross-sectional width, 150mm; h—cross-sectional height of the specimen, 150mm.

2. When the fracture surface of the specimen is located in the middle of the two indenters, the test result is valid, and when it is located on the outside of the two indenters, the test result is invalid. When one specimen is invalid, the average of the other two is taken. When two specimens are invalid, the test results of that group are invalid.

3. The arithmetic mean value of the measured value of 3 specimens.

as the flexural strength value of the specimens in this group. When the difference between the maximum or minimum value and the median value of the three measured values exceeds 15% of the median value, the maximum and minimum values are rounded together, and the median value is taken as the flexural strength value of the group of specimens. If the difference between the two measured values and the median value is more than 15% of the median value, the test results of the group of specimens are invalid.

Concrete bending resistance to be obtained through the test, specimen specifications 150 * 150 * 150 standard curing 28 days of strength, a group of 3 specimens, respectively, to do the test to obtain the bending value, take the average value to obtain a group of strength. Each specimen must be greater than the design value (more than 10 groups). For details, please refer to the engineering test regulations.

The data can be processed according to the calculation formula provided by the concrete structure test specification.

The flexural strength of concrete is calculated using the formula f fi bh.

Where: f--ultimate load (n);

l--distance between bearings, l 450mm;

b--Specimen width (mm);

h--Specimen height (mm).

The influence of construction factors on the flexural strength of cement concrete pavement is eliminated.

1) The influence of mixing conditions on the strength of concrete.

It mainly includes mixing equipment, mixing environment, mixing process, etc. The quality of the mixed concrete is also different due to the different equipment, environment and process. In particular, the mixing time and temperature have a great influence on the strength of concrete.

Therefore, the quality of concrete should be stable, the strength should be guaranteed, the mixing conditions must be improved, the mixing time must be strictly controlled, and the mixing should be uniform.

2) The influence of transportation conditions on the strength of concrete.

The transportation time should not be too long, so as to avoid premature condensation and hardening of concrete, which will affect the construction. Generally, it can be determined according to the initial setting time of cement and the construction climate.

3) In the pouring of concrete, whether the vibration is sufficient also directly affects the formation of concrete strength.

Therefore, after concrete paving, it should be vibrated in time and strive to be sufficient. In order to improve the vibration effect, plug-in and plate vibrators can be used to work together to improve the compactness and strength of concrete.

The flexural strength of concrete is calculated using the formula f fi bh. A set of three specimens.

The calculation and determination of the flexural strength test results are carried out according to the following methods:

1 If the fracture position of the lower edge of the specimen is between two lines of action of concentrated load, the flexural strength f (MPa) of the specimen is calculated as follows:

2. The determination of the flexural strength value shall comply with the following provisions:

1) should take the arithmetic mean value of 3 specimens as the flexural strength value of this group of specimens, should be refined to;

2) When the difference between one of the maximum or minimum values and the intermediate value of the three measured values exceeds 15% of the intermediate value, the maximum value and the minimum value should be rounded together, and the intermediate value should be taken as the flexural strength value of the group of specimens;

3) When the difference between the maximum and minimum values and the median value is more than 15% of the median value, the test results of this group of specimens are invalid.

3 When one of the three specimens is located outside the two concentrated loads, the concrete flexural strength value should be calculated according to the test results of the other two specimens. When the difference between these two measured values is not greater than 15% of the smaller value of these two measured values, the flexural strength value of the group of specimens should be calculated according to the average value of these two measured values, otherwise the test of the group of specimens is invalid. When the fracture position of the lower edge of two specimens is outside the two concentrated load lines, the test of this group of specimens is invalid.

4. When the size of the specimen is 100mm 100mm 4 00mm non-standard specimen, it should be multiplied by the size conversion factor; When the concrete strength grade is not less than C60, it is advisable to use standard specimens; When non-standard specimens are used, the size conversion factor should be determined by the test.

The pressed data can be divided directly.

Concrete is mainly used for compressive strength, the compressive strength of concrete.

It is obtained through experiments, and China uses a cube with a side length of 150mm.

As a standard size specimen for the compressive strength of concrete. Specify the temperature and relative humidity of a cube with a side length of 150 mm in (20 3).

Cured in more than 90% humid air for 28 days, the compressive strength with 95% guarantee rate measured according to the standard experimental method is used as the concrete strength grade.

According to China's "Code for Design of Highway Cement Concrete Pavement" (JTJ012-94), the calculated flexural strength of cement concrete with different traffic volume classifications is shown in Table 4-14. The conversion relationship between flexural strength and compressive strength of road cement concrete is shown in Table 4-15. Table 4-14 Calculation of flexural strength of pavement cement concrete Traffic volume classification:

Calculation of flexural strength (mpa.) for extra-heavy, heavy and medium-light concrete0 Table 4-15 Relationship between flexural strength and compressive strength of road cement concrete, flexural strength (mpa.)5. Compressive strength (mpa.)

Summary. There is no inevitable correspondence between flexural strength and compressive strength, of course, the compressive strength is high, and the flexural strength is also high, but the same compressive strength, due to the different proportions and materials used, the flexural strength is not the same, and it is best to do a test to determine. Generally, the flexural strength is only about 10% of the compressive strength.

Is there a relationship between the compressive strength and flexural strength of ordinary concrete?

There is no inevitable correspondence between flexural strength and compressive strength, of course, the compressive strength is high, the flexural strength is also high, but the same compressive strength, due to the ratio, the materials used, the flexural strength is not the same, it is best to do a test to determine. Generally, the flexural strength is only about 10% of the compressive strength.

There is no inevitable correspondence between flexural strength and compressive strength, of course, the compressive strength is high, the flexural strength is also high, but the same compressive strength, due to the ratio, the materials used, the flexural strength is not the same, it is best to do a test to determine. Generally, the flexural strength is only about 10% of the compressive strength.

Compressive strength. The bottom area of the test block is 150*150 1000 strength (mpa) force area.

That is, the press reading

Flexural strength: RB=PL BH2=(450 15*152)=P*2 is squared, L is the support spacing, B is the test width, H is the height of the specimen, P is the load.

The strength p* is also the press reading*

I don't know if you can see it and help you.

Flexural Strength Calculation Formula:

ff=pl/（bh2）

The flexural strength of concrete is equal to the product of the failure load and the spacing of the support, divided by the product of the square of the cross-section height of the specimen and the cross-section width.

First of all, the formula for calculating the compressive strength of concrete is as shown below.