Method for measuring whole-process autogenous volume deformation of concrete

Abstract

A method for measuring whole-process autogenous volume deformation of concrete comprises the following steps: stirring raw materials of the concrete according to the corresponding ratio, pouring the concrete in accommodating space to form a test specimen, and covering with a temperature template upper cover; inserting temperature sensors in trisection points of the middle of the test specimen andin a temperature measuring hole of an environment box; mounting a displacement sensor in the middle of the test specimen, and fixing the displacement sensor with a positioning tool to maintain the position of the displacement sensor constant; setting the corresponding temperature templates and a temperature course curve of the environment box in the software testing interface; and after initial setting of the concrete, disassembling the positioning tool, beginning to test, and measuring shrinkage data of a free concrete test specimen. Total strain of the concrete is directly measured throughchange of the length of the test specimen in a testing machine, coefficients of thermal expansion are known, temperature change of the test specimen is measured directly, and autogenous volume deformation of the concrete can be obtained according to a formula. The whole-process autogenous volume deformation under the condition of temperature change and development of the concrete is tested, and basis is provided for mastering of mechanical property of concrete and prevention of concrete cracks.

Description

technical field [0001] The invention belongs to the technical field of water conservancy and hydropower engineering, in particular to a method for measuring autogenous volume deformation in the whole process of concrete. Background technique [0002] The problem of cracks in mass concrete has always been an important problem in engineering circles at home and abroad. The appearance of concrete cracks not only affects the appearance quality of the structure, but also seriously affects the service life and safety of the project, which in turn threatens people's lives and property. Therefore, how to avoid or reduce the possibility of cracks has become a concern of project builders, especially in large-volume concrete structures, where temperature cracks are the main form of cracks. Up to now, the prevention of temperature cracks in mass concrete mainly starts from the following three aspects: (1) optimize the concrete structure and improve the mechanical characteristics; (2) im...

AI Technical Summary

Problems solved by technology

Up to now, the determination of concrete self-generated volume deformation is mainly through a sealed specimen bucket, under the condition of constant temperature and humidity and no load, through the differential resistance strain gauge, measuring the resistance and resistance ratio change of the strain gauge, and calculating according to the formula Autogenous volume deformation of concrete However, this experimental device and method also has the following objective disadvantages: concrete can only be carried out in a constant temperature room with constant temperature and humidity, and cannot be tested under the condition of the temperature change of the concrete itself. The self-generated volume deformation of the temperature history; the self-generated volume deformation is calculated through a series of formulas, affected by empirical formulas and many intermediate parameters (strain gauge sensitivity, resistance ratio, resistance ratio reference value, temperature compensation coefficient, etc.), the calculated It is difficult to reflect the actual situation of the project, which seriously affects the decision-making of the project builders; the autogenous volume deformation calculated by the formula is also the autogenous volume deformation of several ages, not the whole process of the autogenous volume deformation process

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