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Method and equipment for rapidly testing dry shrinkage of cement mortar and concrete

A cement mortar and testing method technology, applied in the direction of measuring devices, instruments, scientific instruments, etc., can solve the problems of not being able to quickly measure drying shrinkage data, reducing work efficiency, etc.

Pending Publication Date: 2021-09-10
SHANDONG LUDA TEST INSTR
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current standard drying shrinkage test method cannot quickly measure the drying shrinkage data of a certain mix ratio, which reduces work efficiency

Method used

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  • Method and equipment for rapidly testing dry shrinkage of cement mortar and concrete
  • Method and equipment for rapidly testing dry shrinkage of cement mortar and concrete
  • Method and equipment for rapidly testing dry shrinkage of cement mortar and concrete

Examples

Experimental program
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Embodiment 1

[0026] A kind of rapid testing method of cement mortar and concrete drying shrinkage that present embodiment relates to, comprises:

[0027] Step 1. Make several groups of concrete or mortar specimens, three specimens in each group, put them into the standard curing room after demoulding, and take out the specimens when they reach the age of 3 days;

[0028] Step 2. Immediately put the test piece into the fixture and put it into the box, start the test system, set the test parameters; reset the deformation data to zero under standard atmospheric pressure, and then run the equipment to reach the preset vacuum degree and temperature, and the equipment maintains this Vacuum degree and temperature, the test system continuously records the data of the shrinkage of the specimen under this vacuum degree with time, and draws the shrinkage-time curve;

[0029] Step 3. The measurement ends after 130 hours. At this time, the total dry shrinkage of the specimen measured by the system repr...

Embodiment 2

[0034] A kind of cement mortar and concrete dry-shrinkage rapid test equipment that this embodiment relates to, comprise cabinet A, described cabinet A comprises box body 1 and pump box 10; Described vacuum pump 2 is positioned at pump box 10, through pipeline 8 ( Such as a hose) is connected with the box body 1; the inner bottom of the box body 1 is provided with a heating device 3, and the top of the heating device 3 is sequentially provided with several layers of partitions 4 for placing test pieces; the side of the box body 1 A refrigeration device 5 is provided; the top of the box body 1 is an upper cover 6, and the upper cover 6 is provided with a reflective coating, which can reflect heat downward to the test piece. The temperature in the box is kept constant by the heating device 3 and the refrigeration device 5, and the air inside the box 1 is drawn out by the vacuum pump 2 to reach a test environment of vacuum degree, and the test temperature is controlled to be highe...

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Abstract

The invention relates to the technical field of material characteristic testing, and in particular, relates to a method for rapidly testing dry shrinkage of cement mortar and concrete, wherein the method comprises the steps: a concrete or mortar test piece is put into a standard curing room for curing; the test piece is put into a clamp, the clamp is put into a box body, a test system is started, and test parameters are set; the deformation data is returned to zero under the standard atmospheric pressure, then the equipment is operated to reach the preset vacuum degree and temperature, the vacuum degree and temperature of the equipment are maintained, the test system continuously records the data of the change of the drying shrinkage of the test piece along with the time under the vacuum degree, and a drying shrinkage-time curve is drawn; and the measurement is finished after 120-150 hours. The invention provides a pore water vacuum boiling rapid dry shrinkage test principle, pore water in mortar or concrete nano micropores can reach a boiling point at a relatively low temperature in a vacuum test environment, so that the water is rapidly evaporated, the mortar and concrete materials are rapidly shrunk, and the long-term dry shrinkage rate of the mortar and concrete materials is measured in a short time.

Description

technical field [0001] The invention relates to the technical field of material characteristic testing, in particular to a rapid testing method for drying shrinkage of cement mortar and concrete. Background technique [0002] The current standard measures the drying shrinkage of cement mortar and concrete under constant temperature and humidity conditions (20°C, 50% RH), and obtains data through long-term (usually 25 days) observations (JC / T603-2004 cement mortar drying shrinkage test method). This is because the drying shrinkage of the cement-based material is caused by the tension caused by the concave liquid surface formed when the pore water in the micropores (pore diameter below 100nm) in the material evaporates. This meniscus tension produces compressive stress on the gelled material, causing the material to shrink on drying. Since the evaporation of pore water in the micropores of cement-based materials (with a pore size below 100nm) is a long-term and slow process,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N25/14
CPCG01N25/14
Inventor 史勇张国宁周俊宇张学利唐兴泉唐乃华杨君李树兰刘圣明杨焕霞
Owner SHANDONG LUDA TEST INSTR