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Method for measuring thermal expansion coefficient of concrete

A technology of thermal expansion coefficient and measurement method, applied in the direction of material thermal expansion coefficient, etc., can solve the problems of large uncertainty and low accuracy, achieve good repeatability, meet the accuracy requirements, and simple operation process

Inactive Publication Date: 2010-05-05
SOUTHEAST UNIV
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] Aiming at the problems of low accuracy and large uncertainty in the above measurement methods, the present invention provides a method for measuring the coefficient of thermal expansion of concrete, the measurement process is simple to operate, and the measurement accuracy is high

Method used

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  • Method for measuring thermal expansion coefficient of concrete
  • Method for measuring thermal expansion coefficient of concrete
  • Method for measuring thermal expansion coefficient of concrete

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) Form 100mm×100mm×400mm prismatic concrete specimens, form 3 specimens for each concrete mix ratio, and pre-embed 4 copper heads parallel to the surface of the specimen during molding on each specimen as the end point of the measurement length Such as figure 1 As shown, the distance between the two copper heads along the length of the specimen is about 250mm. The concrete specimens were demolished one day after forming, placed in a standard curing room for curing, and the coefficient of thermal expansion was measured at the predetermined age.

[0028] (2) When the set curing age is reached, first put the concrete specimen into 20°C water and soak it completely. Put the handheld strain gauge into the standard curing room half an hour before the measurement, so that the specimen and the handheld strain gauge have the same temperature. After the concrete specimen is fully immersed in water for 1.5h, measure and record the length between the corresponding two copper he...

Embodiment 2

[0047] Under the experimental conditions of slurry water-binder ratio of 0.42, fly ash replacement amount of 25%wt, and sand ratio of 38%wt, the volume fraction V of slurry in concrete is 20%, 30%, and 40% respectively. Respectively form 3 test pieces under the condition, after forming, according to the method for embodiment 1, measure the coefficient of thermal expansion of concrete at different ages, test result is as follows image 3 shown. Because the thermal expansion coefficient of the hardened cement paste is higher than that of the aggregate, as the volume fraction of the paste increases, so does the thermal expansion coefficient of the concrete. This is the same as image 3 The trend of the detection results shown is consistent.

Embodiment 3

[0049] The total amount of cementitious material is 400kg / m 3 , the water-binder ratio is 0.42, the sand rate is 38%wt, and the mass fraction of fly ash in the slurry is 0, 0.1, 0.2, 0.3, 0.4 respectively. After standard curing 28d, test the thermal expansion coefficient of different dosage fly ash concrete according to the method for embodiment 1, as Figure 4 shown. In the case of the same amount of cementitious material, as the amount of fly ash increases, the porosity of cement stone increases, resulting in a decrease in the thermal expansion coefficient of concrete. This is the same as Figure 4 The trend of the detection results shown is consistent.

[0050] It can be seen from the examples that the measuring method is simple, the repeatability of the measuring results is good, and the error is also small.

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Abstract

The invention discloses a method for measuring the thermal expansion coefficient of concrete, which comprises the steps of: proportioning each concrete to form into 3 test pieces; previously embedding 4 copper heads which are taken as ends for measuring the length on the surface of the each test piece when forming the each test piece; removing modules after 1 day of forming the test pieces; putting the test pieces into a standard curing room to cure; when reaching a preset curing age, putting the concrete test pieces into water with temperature of T0 to immerse, and measuring the length 1 (T0) among each two corresponding copper heads on the surface of the each test piece; moving the concrete test pieces into a thermostatic water tank with temperature of T to immerse, measuring the length 1 (T) among each two corresponding copper heads on the surface of the each test piece, and recording; measuring the distance among the same pair of the copper heads on the surface of the same test piece under each temperature for many times, taking the average value as effective data; and according to the measured length among the two copper heads on the surface of the each test piece under the different temperatures, counting the thermal expansion coefficient of concrete according to formula (1).

Description

technical field [0001] The invention belongs to the technical field of concrete performance analysis and relates to a method for measuring the thermal expansion coefficient of concrete. Background technique [0002] The thermal expansion coefficient of concrete refers to the change in length or volume of concrete per unit length or volume under unit temperature change when it is not disturbed by the outside world and is only affected by its own properties. It is one of the main physical characteristic parameters of the material. Characterized by the coefficient of linear thermal expansion. Due to the existence of cement hydration heat and the influence of solar radiation and other environmental heat sources, large temperature gradients are generated in concrete structures, especially in large-volume and super-long concrete structures, resulting in large uneven temperature deformation of the structure. In turn, a large temperature stress is generated. When the temperature st...

Claims

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Application Information

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IPC IPC(8): G01N25/16
Inventor 钱春香高桂波巴明芳
Owner SOUTHEAST UNIV
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