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Improved test method for determining crack resistance of concrete under condition of restrained shrinkage

A technology of anti-cracking performance and test method, applied in the direction of material inspection products, etc., can solve the problems of unrealized anti-cracking performance of concrete materials at an early age, the effect of shrinkage cracking restraint is not obvious, and testing, etc. Shorten, reduce test costs, eliminate the effect of driving

Pending Publication Date: 2019-06-21
DALIAN UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the results of the study show that the method has little effect on the confinement of shrinkage cracking
According to the applicant's investigation, there is still no mature test method to effectively reduce the self-constraint in the ring test, and the test of the crack resistance of early-age concrete materials only under the condition of limited shrinkage has not yet been realized

Method used

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  • Improved test method for determining crack resistance of concrete under condition of restrained shrinkage
  • Improved test method for determining crack resistance of concrete under condition of restrained shrinkage
  • Improved test method for determining crack resistance of concrete under condition of restrained shrinkage

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Embodiment Construction

[0014] The specific implementation manners of the present invention will be further described below in conjunction with the accompanying drawings and technical solutions.

[0015] (1) Test preparation

[0016] Inner diameter R of steel ring 2 1 137.5mm, outer diameter R 2 150mm, thickness R 2 -R 1 =12.5mm, the height is 75mm. The prefabricated crack is made of steel, with a height of 85 mm and a cross-section of an isosceles triangle with a base of 3 mm and a height of 6 mm, see Figure 1(c). Before the experiment, use 502 glue to evenly paste 4 prefabricated cracks on the surface of the outer ring of the steel ring 2 at intervals of 90°. The bottom of the prefabricated cracks is flush with the bottom of the test piece, and the top is 10 mm higher than the test piece. For details, see attached drawing 1 (a ), (b).

[0017] (2) Test piece production

[0018] C30 concrete with a water-cement ratio of 0.5 was used to pour the constrained ring-shaped specimen. After pouring,...

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Abstract

The invention, which belongs to the technical field of crack resistance research of early-age concrete, provides an improved test method for determining the crack resistance of concrete under the condition of restrained shrinkage. On the basis of reasonable improvement of the restrained ring test recommended by the American Society for Testing and Materials, the influence on the shrinkage crackingby the own constraining effect is reduced and the crack resistance of early-age concrete under restricted shrinkage condition is accurately evaluated. A corresponding initial crack is formed at the annular inner side of concrete by pasting a pre-fabricating crack at the outer side of a steel ring. The bottom of the pre-fabricating crack is flush with the bottom of a ring-shaped test piece in a height direction; and the top of the pre-fabricating crack is higher than the top of the test piece by no less than 10mm. With consideration of the influence of the dispersion on the concrete material,the numbers of the initial cracks is set to be 3 to 5 and the initial cracks are distributed uniformly at the annular inner side of the concrete. No strain gauge needs to be pasted at the inner side of the steel ring and the crack time of the test piece can be determined clearly by observing the expansion of the outer ring surface at the initial crack position of the concrete.

Description

technical field [0001] The invention belongs to the technical field of research on the anti-crack performance of early-age concrete, and relates to an improved test method for measuring the anti-crack performance of concrete under the condition of limited shrinkage Background technique [0002] Early shrinkage cracking of concrete is common in flat concrete structures such as floor slabs, pavements, and bridge decks. The appearance of cracks provides a transmission channel for the intrusion of external substances. Water and inorganic salt ions in the environment enter the interior of the concrete through shrinkage cracks, accelerating the corrosion of internal steel bars and the deterioration of concrete. The American Society for Testing Materials (ASTMC1581 / C1581M-09a) recommended a standard constrained ring test to evaluate the crack resistance of early-age concrete under the condition of limited shrinkage. The thickness of the concrete ring and the steel ring are 37.5mm a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N33/38
Inventor 董伟袁文岩周向明赵晓瑜李杰
Owner DALIAN UNIV OF TECH
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