RU1803776C - Method of determining concrete strength - Google Patents

Abstract

The invention relates to testing equipment and can be used to assess the strength of concrete under the action of shear and tensile-compressive stresses. The aim of the invention is to increase the information content of tests by determining the strength of concrete on a single sample, not only when shearing, stretching and joint normal tensile and tangential stresses, but also under compression and the combined action of normal compressive and tangential stresses with the construction of a complete11 concrete strength diagram. The test sample is made in the form of a cylinder having two symmetrical L-shaped slots, the edges of which are located in two mutually perpendicular planes, and four slots 3 extending along the cylindrical surface to the plane of the working sections of the perpendicular cylinder. The loading of the sample is carried out in five stages, sequentially separating parts 4-8 from the sample in the corresponding sections of the working sections. The stages of loading correspond to the five types of stress state of concrete in which its strength is determined. According to the test results, a concrete strength diagram is constructed in coordinates a - T. 5 silt. ate

Description

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The invention relates to a test technique and can be used to evaluate the strength of concrete under shear and compressive stresses.

The aim of the invention is to increase the information content of tests by determining the strength of concrete on one specimen, not only when shearing, stretching and the combined action of normal tensile and shear stresses, but also when compressing and the combined action of normal compressive and tangential stresses with building a complete concrete strength diagram.

1, a sample is shown; figure 2 is a section aa in figure 1; in Fig.Z - section bB in Fig.2; Fig. 4 is a diagram of sample loading during testing; figure 5 is a diagram of the strength of the material, built according to test data of the sample.

The test sample is made in the form of a cylinder having two .centrically symmetric L-shaped slots 1,2, the edges of which are located in two mutually perpendicular diametrical planes, and four slots 3 extending from the cylindrical surface to the plane of the working sections perpendicularly forming cylinder. The loading of the sample is carried out in five stages, sequentially separating parts 4-8 from the sample in the corresponding sections of the working sections. The stages of loading correspond to the five types of stress state of concrete in which its strength is determined. At the first stage, the sample is installed between the press plates, the plane of the working sections is combined with the plane of the load and the forces are loaded by PI (Fig. 4) until the separation of part 4 by the working section, the breaking load of Pipaap is measured and the concrete strength is determined from its value slice.

Similarly, the tests of the sample are carried out in the following four stages, applying PI forces to the sample (Fig. 4), and before the second, fourth and fifth

in steps, the sample is rotated 45 ° about its axis. The measured strengths of Pipaap determine the strength of concrete under the combined action of normal tensile and shear stresses (step 2), tensile (step 3), compression (step 4) and the combined action of normal compressive and tangential stresses (step 5).

According to the test results, a concrete strength diagram is constructed in coordinates a - t (Fig. 5). A line 9 connecting the experimental points limits the region of stresses within which the strength of the material is maintained.

Claims (1)

SUMMARY OF THE INVENTION A method for determining the strength of concrete by which through the slots and carry out the phased loading of the parts of the sample located between the slots until they are separated from the sample by working sections located between the edges of the slots, characterized in that that, in order to increase the information content of tests by determining the strength of concrete on one specimen, not only when shearing, stretching and the combined action of normal tensile and tangential stresses, but also under compression and the combined action of normal compressive and tangential stresses with the construction of a full concrete strength diagram, the sample is made in the form of a cylinder, the edge of two centrally symmetric L-shaped slots are arranged in two mutually perpendicular diametrical planes, four slots extending from the cylindrical surface to the plane of the workers sections, perpendicular to the cylinder, and loading is carried out in five stages, in the first of which the plane of the working sections is combined with the plane of loading, and before each in the next step, the sample is rotated through an angle of 45 ° around its axis. Figz