Device and method for testing concrete self-constriction under condition of temperature changing

Abstract

The invention discloses a device and method for testing concrete self-constriction under the condition of temperature changing. The device comprises a magnetic chuck, a non-contact displacement sensor, a bellows mold, a test stand, a quartz glass rod, a bellows packaging end socket, a hanger, a pressure relief air bag, a plastic tube, and a rubber plug. The device employs the specially-produced bellows mold and package end socket as the molding tool for self-constriction deformation testing, and solves a problem that a mode does not cooperate with the deformation of a test piece. The device isprovided with the pressure relief air bag, thereby avoiding the impact caused by the internal air pressure of a bellows to the early testing. The device is provided with the hanger, thereby solving afriction problem of the mold and the test stand, and truly achieving the zero friction between the test piece and the stand. The device is provided with the quartz glass rod, thereby avoiding the impact on testing from the self-deformation of the test support. The device achieves the accurate testing of the self-constriction deformation under the condition of temperature changing, and the testingmethod is stable, scientific and reliable.

Description

technical field [0001] The invention relates to the technical field of concrete testing, in particular to a device and method for testing concrete self-shrinkage under variable temperature conditions. Background technique [0002] Cement-based materials such as cement paste, mortar, concrete, etc. will produce autogenous shrinkage deformation due to their own characteristics. Therefore, autogenous shrinkage deformation has become an important parameter in the research and application of cement-based materials, and its testing devices and testing methods are also various. , but the currently generally accepted technical methods are the deformation amount or deformation rate that characterizes the overall deformation through the deformation in the length direction. [0003] With the development of concrete science and technology, especially the gradual deepening of practical application research, the test results in the usual laboratory at 20°C have little guiding significance...

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Problems solved by technology

[0004] Although there are many technical methods for self-shrinkage deformation testing, in the field of scientific research, the bellows method is widely recognized as a relatively reasonable test method in terms of operability and realizability. One of the inventors of the present invention, Tian In 2009, Qian Zeng and JENSEN Ole Mejlhede of the Danish University of Science and Technology published "Using bellows to test the early self-shrinkage method of cement-based materials" in the "Journal of Silicates", discussing the reliability and theoretical basis of the bellows method. In the same year, this test method was adopted by the American standard ASTM C1698. Tian Qian and others also applied for the patent "CN200610038892.X concrete self-deformation test method and device in the early stage". This patent technology realizes the self-drying shrinkage of concrete condensation and concrete initial setting test; Zhang Jianliang, one of the inventors of the present invention, further improved the test device of the bellows method, and obtained the patent "CN201420842970.1 Bellows packaging end, and cement-based material self-shrinkage measurement device using it", However, there are still problems such as early deformation, especially during the period from initial setting to final setting, poor test repeatability, and large data fluctuations. One of the reasons for this problem is the friction between the specimen mold and the bracket, including the current Similar problems exist in the non-contact method of concrete shrinkage and deformation in the national standard GB / T 50082-2009 "Standard for Test Methods for Long-Term Performance and Durability of Ordinary Concrete". The method is still somewhat controversial

When the bellows mold is used, the inside of the bellows is sealed. When the temperature rises, some of the gas inside the bellows will expand, resulting in an increase in the air pressure in the bellows, and when the volume of the concrete itself deforms, it will also cause changes in the internal pressure, thus Cause early test results to deviate from true values

Under variable temperature conditions, the test bracket itself will also experience thermal expansion and contraction, and the resulting errors, especially in the case of a large temperature span, have a serious impact on the test data

[0005] In summary, none of the existing technical methods can accurately and reliably test the self-shrinkage deformation of concrete under variable temperature conditions. Therefore, the present invention proposes a device and method for testing concrete self-shrinkage under variable temperature conditions. solved this series of problems

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