RU2739415C1 - Method of determining durability of dowel-nest immersion into tested concrete - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to investigation of strength properties of concrete and can be used to control strength of concrete structures. Summary: determining the dowel-nail immersion durability in the tested concrete when the perforator is exposed to it without rotational mode or a hammer.

EFFECT: technical result: higher safety when determining strength of concrete.

6 cl

Description

Technology area

The invention relates to the study of the strength properties of concrete and can be used to control the strength of concrete structures.

State of the art

Close in technical essence is the method implemented using the device according to the USSR patent for invention No. 50279, which was published on January 31, 1937, according to the class 42k, 29, 28, including the immersion of the working body in the concrete of the structure under study and where the funnel left by the working body determine the strength of concrete in comparison with reference samples.

The disadvantages of the above method include low safety in determining the strength.

The closest in technical essence is the method, according to the RF patent for invention No. 2706390, which was published on November 18, 2019, according to IPC G01N 3/48, including the immersion of the working body into the concrete of the structure under study and where, according to the depth of immersion of the dowel-nail, the concrete strength is determined by comparison with reference samples.

The disadvantages of the above method include low safety in determining the strength.

Disclosure of invention

The objective of the invention is to improve safety in determining the strength of concrete.

The technical result of the invention is an increase in safety in determining the strength of concrete.

The use of a construction gun or its analogue with chucks when driving in dowels-nails is obviously less safe in comparison with driving with a hammer or perforator operating in hammer mode. On the other hand, concrete is a composite structure with varying strengths of the ingredients included. The immersion of the dowel-nail into concrete for a period of time, due to impulses leading to immersion, is actually an integral characteristic of strength, i.e. resistance to immersion. It should be noted that the time (local from a single impact) of immersion of the dowel-nail into concrete is, in fact, a function that depends on the magnitude and direction of the transmitted impulse, the geometric parameters of the dowel-nail, the depth of the submerged part of the dowel-nail and the strength parameters of concrete, and the time (integral) - the sum of the periods of time of movement of the dowel-nail in concrete from the transmitted impulse, preparation of the mechanism for transmitting the next impulse to the dowel-nail and, in case of downtime of the mechanism, the downtime of the mechanism. To determine the strength of concrete, the downtime of the impact mechanism should be excluded from the factors taken into account. Also, at the stage of dowel-nail immersion, at least to the depth in which it will not lose alignment with the impulses leading to its immersion, it is safe to use the jig.

The technical result is achieved by the fact that the strength is determined by the time the dowel-nail is immersed in the tested concrete when exposed to it with a perforator without rotation mode or a jackhammer.

In the method for determining the strength, the immersion time of the dowel-nail can be the sum of the periods of time of movement of the dowel-nail in concrete from the transmitted impulses.

In the method for determining the strength, the dependence, or in another formulation, the graph, of the time of immersion of the dowel-nail in concrete samples of various strengths can be determined.

In the method for determining the strength for plotting the dependence of the dowel-nail immersion time when determining the strength, dowel-nails of the same hardness, the same diameter and the same length for the same mechanical impact mechanisms can be used.

A jig can be used in the method for determining the strength when immersing a dowel-nail.

In the method for determining the strength, at least one washer can be put on the cylindrical part of the dowel-nail before it is immersed in concrete.

Implementation of inventions

Twin samples of various strengths are made and tested by the proposed method and the standard, or samples are cut out of the structure and tested by the standard method. The dependences of the strength of concrete on the time of immersion of the dowel-nail using a specific type of mechanical impact mechanism, for example, a perforator or a jackhammer, and the characteristics of dowels-nails (of the same hardness, the same diameter and the same length) are plotted.

According to a certain dependence, or in another formulation of the graph, the time of immersion of a dowel-nail of a specific type and size in concrete samples of different strengths by comparing the immersion time in the tested concrete and the immersion time in concrete samples of different strengths of a specific type of mechanical impact mechanism, the strength of the tested concrete is determined. Of course, for an accurate and repeatable determination of the strength of concrete, it is necessary to use impact mechanisms with stable characteristics of generating a mechanical effect on the dowel-nail.

The submerged dowel-nail is made, for example, of steel with a hardness of at least 51.5 HRC, standard diameter and length.

A jig for a dowel-nail, when exposed to it with a perforator without rotation mode or a jackhammer for immersion in concrete being tested for strength, can contain a cylindrical guide sleeve, in which the diameter of the inner part applied to the test concrete corresponds to the outer diameter of the dowel-nail washer. In the jig, the diameter of the inner part opposite to that applied to the concrete to be tested may correspond to the outer diameter of the impacting part of the rock drill without rotation or a jackhammer.

The jig for the dowel-nail can be made by known methods from known materials.

You can put a washer on the cylindrical part closer to the tip of the submerged dowel-nail, insert the dowel-nail with the washer into the conductor and attach the working element of the percussion mechanism from the side of the head of the dowel-nail.

For the proposed method, the jig can be used both with full immersion of the dowel-nail in the tested concrete, and with partial immersion of the dowel-nail in the tested concrete, and further immersion of the dowel-nail in the tested concrete until complete can be carried out without using the jig. It is safe to use the jig when the dowel-nail is immersed to a depth where it will not lose alignment with the impulses leading to immersion. Then the immersion impact of the impulses on the dowel-nail can be stopped for a while, the conductor can be removed and the immersion impact of the impulses on the dowel-nail can be continued. In this case, the time at which the immersion impact of impulses on the dowel-nail is not carried out is not taken into account in the offset of the time for determining the strength.

The method also makes it possible to first carry out tests on the time of immersion of the dowel-nails into a specific structure, and then, using known methods, determine the dependence of the strength of concrete on the time of immersion of the dowel-nails of a particular type and draw conclusions about the strength of the tested structure.

Claims (6)

1. A method for determining the strength of the tested concrete by the time of immersion of the dowel-nail when exposed to it with a perforator without rotation mode or a jackhammer. 2. The method according to claim 1, characterized in that the immersion time of the dowel-nail is the sum of the periods of time of movement of the dowel-nail in concrete from the transmitted impulses. 3. The method according to claim 1, characterized in that the dependence of the time of immersion of the dowel-nail in concrete samples of various strengths is plotted. 4. The method according to claim 5, characterized in that to plot the time dependence of the dowel-nail immersion when determining the strength, the dowel-nails of the same hardness, the same diameter and the same length are used for the same mechanical impact mechanisms. 5. The method according to claim 1, characterized in that a conductor is used when the dowel-nail is immersed. 6. The method according to claim 1, characterized in that at least one washer is put on the cylindrical part of the dowel-nail before it is immersed in concrete.