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Method for measuring tensile strength and fracture toughness of cement mortar or concrete

A technology of concrete strength and cement mortar, which is applied in the direction of applying stable tension/pressure to test material strength, preparation of test samples, and measurement devices, etc., to achieve the effect of reducing difficulty, reducing workload, and sufficient accuracy

Inactive Publication Date: 2016-08-03
NORTH CHINA UNIV OF WATER RESOURCES & ELECTRIC POWER
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Problems solved by technology

And with the same test method and sample, the method for determining cement mortar and concrete tensile strength and fracture toughness has not been reported yet.

Method used

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  • Method for measuring tensile strength and fracture toughness of cement mortar or concrete
  • Method for measuring tensile strength and fracture toughness of cement mortar or concrete
  • Method for measuring tensile strength and fracture toughness of cement mortar or concrete

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Embodiment 1

[0045] Embodiment 1: The maximum particle size d of the cement mortar aggregate used in the test of this embodiment 1 max = 2.5 mm. There are two series: the first series L×B×W=400×50×100mm, the initial seam height ratio α=a 0 / W=0.03~0.72,W / d max =40. The second series L×B×W=240×50×60mm, initial seam height ratio α=a 0 / W=0.04~0.68,W / d max =24.

[0046] see figure 1 , considering that cement mortar is a quasi-brittle material, the stress distribution at peak load is as follows figure 1 As shown, the corresponding crack propagation amount Δa fic = γ·d max . Based on the following formula (2), the measured peak load P max , the nominal strength σ of each specimen can be calculated n :

[0047]

[0048] Considering γ=1.0 from a statistical point of view, the average value of the tensile strength and fracture toughness of cement mortar can be calculated, see figure 2 a. Considering the discretization of the cement mortar test results and solving it accurately, γ...

Embodiment 2

[0061] Embodiment 2: the maximum particle size of the concrete aggregate used in the experiment of this embodiment 2 d max =19mm. Specimen size L×B×W=1143×76.2×305mm, initial seam height ratio α=a 0 / W=0.36~0.68,W / d max =16.

[0062] The stress distribution of the specimen at peak load is as follows: figure 1 As shown, the corresponding crack propagation amount Δa fic = γ·d max . Based on formula (2), the nominal strength σ of each specimen can be calculated from the measured peak load n .

[0063] Considering γ=1.0 from a statistical point of view, the average value of concrete tensile strength and fracture toughness can be calculated. Considering the discretization of the concrete test results and solving it accurately, then make γ=0.6,0.8...2.0, and calculate the exact values ​​of concrete tensile strength and fracture toughness.

[0064] The equivalent crack length a of each specimen e Can be calculated by formula (3a) ~ (3d).

[0065] get different σ n with a ...

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Abstract

The invention discloses a method for measuring tensile strength and fracture toughness of cement mortar or concrete. The method comprises the steps of pouring test pieces, cutting cracks, static loading, recording peak loads, calculating a nominal intensity (Sigma)n, calculating an equivalent crack length ae, and finally obtaining the tensile strength ft and the fracture toughness KIC of cement mortar or concrete simultaneously through regression analysis. The method provided by the invention is simple in form, easy to operate tests, sufficient in accuracy and easy to judge the reasonableness of results; the tensile strength ft and fracture toughness KIC of cement mortar or concrete can be determined simultaneously just by peak loads of small-size test pieces.

Description

technical field [0001] The invention relates to the technical field of civil engineering and hydraulic engineering material properties, in particular to a method for simultaneously measuring the tensile strength and fracture toughness of cement mortar or concrete. Background technique [0002] A large number of studies have shown that there is an obvious size effect on the strength and fracture toughness of cement mortar and concrete. To obtain real material parameters independent of the size of the specimen, it is necessary to cast a larger size specimen. Therefore, the test results of small-scale cement mortar specimens cannot be directly used to evaluate the real material properties of cement mortar and concrete. [0003] At present, the tensile strength of cement mortar and concrete generally needs to be tested with axial tensile specimens, and the fabrication and testing of axial tensile specimens are relatively difficult. Due to the heterogeneity of cement mortar and...

Claims

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Application Information

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IPC IPC(8): G01N3/08G01N1/28
CPCG01N3/08G01N1/286G01N2001/2873
Inventor 管俊峰姚贤华胡晓智白卫峰王强谢超鹏钱国双赵顺波
Owner NORTH CHINA UNIV OF WATER RESOURCES & ELECTRIC POWER
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