Device and method for measuring linear expansion coefficient of cement-based material

Abstract

A cement-based material linear expansion coefficient measuring device comprises a heat insulation box, a plurality of cement-based material test pieces are arranged in the heat insulation box at intervals in the width direction, and the cement-based material test pieces are horizontally arranged in the length direction of the heat insulation box; an invar pedestal is supported at the bottom of the cement-based material test piece, and the bottom of the invar pedestal is arranged on the bottom surface of the inner side of the heat insulation box; an anti-freezing solution is injected into the heat insulation box, and the liquid level of the anti-freezing solution is higher than the top of the cement-based material test piece; two ends of the cement-based material test piece are respectively provided with a non-rebound displacement sensor made of invar steel, a first thermocouple is arranged in the heat insulation box, a second thermocouple is arranged in the cement-based material test piece, and the displacement sensors, the first thermocouple and the second thermocouple are electrically connected with a data acquisition instrument. The test process is carried out in the anti-freezing solution, the specific heat capacity of the solution is large, the temperature of a test piece is increased and decreased more easily than that in air, the overall temperature is more uniform, the test time is shortened, and the linear expansion coefficient of a preset age can be obtained.

Description

technical field [0001] The invention relates to the technical field of civil engineering, in particular to a device and method for measuring the linear expansion coefficient of cement-based materials. Background technique [0002] As one of the basic indexes to describe the physical properties of materials, the linear expansion coefficient is an important prerequisite for comprehensively evaluating the volume change of cement-based materials under the action of composite factors. In the construction process, the linear expansion coefficient of cement-based materials is a necessary parameter for calculating temperature deformation and temperature stress. It is necessary to understand the real development law of the early linear expansion coefficient of cement-based materials to accurately evaluate the temperature deformation and restraint stress of cement-based materials. . The measurement of the linear expansion coefficient of cement-based materials is relatively complicate...

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Problems solved by technology

[0003] For patents CN 102435631 A, CN 102608152A, CN 111122646 A, and CN 103293179 A, ​​the methods described do not consider the temperature deformation of the displacement sensor itself; for patents CN 102435631 A, CN111122646 A, the methods described are all directly within the device. Forming, device wrapping or semi-wrapping the specimen, can not test the coefficient of linear expansion of concrete under dry curing conditions; for patents CN 103293179 A, ​​CN 214224994 U, the heating and cooling method of the method described will cause the overall temperature of the specimen to change unevenly , affect the experimental results; for patents CN 111122646A and CN 107894440 A, the contact surface between the test piece and the device described in the method is relatively large, which will generate a large friction force and restrain the deformation of the test piece; for patents CN 111487278 A and CN 204514837 U, According to the method, the heating and cooling device is located inside the test piece, which will constrain the temperature deformation of the test piece; for the patent CN 101482526 A, when the test piece is placed vertically during the test, the gravity will affect the deformation of the test piece, and It is necessary to check the temperature deformation generated by the displacement sensor, but the temperature distribution of the displacement sensor is not uniform, and the correction is difficult and complicated; for patents CN 111487278 A and CN 111638240 A, the method described uses the mold as a bellows. If you want to prepare For specimens containing large aggregates, the aggregates are easy to get stuck in the groove of the bellows, limiting the deformation of the specimen

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