Method for determining early-stage concrete crack resistance by adopting elliptical ring test specimen

Abstract

The invention belongs to the field of research for early-stage concrete crack resistance, and relates to a method for determining the early-stage concrete crack resistance by adopting an elliptical ring test specimen. The method comprises the following steps: putting an internal steel ring with the thickness of 12.5mm into the inner side of an elliptical concrete ring with the thickness of 37.5mm, wherein the concrete ring closely attaches to the internal steel ring, the concrete ring and the internal steel ring have the heights of 75mm, the ratio of a long axis to a short axis of the outer ring of the elliptical internal steel ring is a / b=2, a=150mm, and b=75mm; putting strain gauges respectively at the part which is 50mm away from the long axis end of the inner ring of the internal steel ring horizontally, wherein the strain gauges are positioned on the same height of the internal steel ring, the height is at the middle part of the internal steel ring; connecting the strain gauges with a collecting system, and sealing the upper surface and the lower surface of the concrete ring with aluminum bands. According to the invention, compared with a circular ring testing method, not only is the crack time advanced, but also the crack position is more regular and is close to the long shaft of the elliptical ring, which is beneficial to the research for the early-stage concrete crack under limited contraction condition.

Description

technical field [0001] The invention belongs to the field of fracture research of early-age concrete, and relates to an experimental method for measuring the crack resistance of early-age concrete by adopting an elliptical ring geometric parameter model, in particular to measuring the crack resistance of early-age concrete under the condition of limited shrinkage by using an elliptical ring specimen sex. Background technique [0002] Concrete is prone to cracks due to shrinkage at an early age. These cracks seriously affect the safety, durability and applicability of the structure. While reducing the service life of the structure, it also increases the maintenance cost and becomes one of the main diseases of the concrete structure. . How to evaluate the crack resistance of concrete is very important. Over the past few decades, engineering and academia have been working hard to find a simple and effective method to evaluate the crack resistance of concrete. Although the fr...

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Problems solved by technology

But the above is just speculation, and there is no scientific basis to support the above remarks, and there is no experiment comparing the elliptical ring with the circular ring, and no specific geometric parameters are given for the elliptical ring

Therefore, for elliptical ring specimens, the current research is limited to assuming that the major axis may generate stress concentration and shorten the cracking time, without proposing specific geometric parameters of the elliptical ring.

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