Test method and test device for chemical contraction of cement

A technology of chemical shrinkage and testing equipment, which is applied in the direction of measuring equipment, mechanical equipment, instruments, etc., can solve problems such as large testing errors, inability to hydrate cement, and missing volume changes

Inactive Publication Date: 2009-07-15
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For example, first put the cement slurry into a small soft plastic bottle, and then put the soft plastic bottle into the jar, so as to avoid the direct contact between the slurry and the bottle wall after hardening, which will cause friction and affect the test results. Disadvantages, this method has a large test error and is difficult to operate; it is also possible to form a cement hardened body first, then seal the hardened body, and then put the sealed hardened body into a test bottle. This method can choose different water-cement ratios, but the obtained It is the macroscopic volume change of a certain volume of cement hardened body, which cannot be regarded as chemical shrinkage, and misses the volume change of cement paste before hardening, while the chemical shrinkage of cement during this period is relatively large
Generally speaking, various improvement methods are tested with static cement paste, so the cement cannot be completely hydrated, and what is obtained is the partial chemical shrinkage of the cement under various hydration environmental conditions. The test The value is quite different from the theoretical value

Method used

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  • Test method and test device for chemical contraction of cement

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Embodiment 1, the steps are as follows:

[0020] (1) Take 50g of cement and stainless steel beads 4 and put them into the pycnometer 2, add about 50g of water and shake the pycnometer so that the cement and the stainless steel beads 4 are stirred together to form a cement slurry.

[0021] (2) Spread a layer of butter on the outer edge of the measuring tube 1 along the frosted mouth, then insert the buttered end into the mouth of the specific gravity bottle, and then use a lit candle to seal the connection between the measuring tube 1 and the specific gravity bottle 2 with wax tight.

[0022] (3) Fill the pycnometer with water from the other end of the measuring tube 1 to the full scale of the measuring tube 1, and then drop a drop of liquid paraffin on the water surface in the measuring tube to prevent evaporation of water.

[0023] (4) Place the device in a constant temperature curing room at 20°C, turn on the magnetic stirrer 3 to make the stainless steel beads 4 dri...

Embodiment 2

[0025] Embodiment 2, the steps are as follows:

[0026] (1) according to the chemical shrinkage value of the operation test 50g cement of embodiment 1, test the volume of cement after finishing the test, the shrinkage amount tested in each period is converted into volume shrinkage rate, take time as the axis of abscissa, take chemical shrinkage rate As the ordinate axis, draw the curve of time and corresponding chemical shrinkage rate, denoted as A.

[0027] (2) Use the traditional method to do the chemical shrinkage test of the same cement, that is, put 50g of cement into the pycnometer, add about 50g of water and stir evenly, connect the pycnometer with a buttered measuring tube and seal it tightly with wax, and then fill it with water until The measuring tube is full scale, and finally drop a drop of liquid paraffin on the liquid surface and start timing. The operation between adding water and starting timing is also controlled within 10 minutes. After the test is done, me...

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Abstract

The invention relates to a testing method and device of cement chemical shrinkage, composed of a glass burette, a glass pycnometer, a magnetic stirrer and a steel ball. The testing method comprises the following steps: loading the cement sampler to be tested and the steel ball into the glass pycnometer; adding water and uniformly stirring the mixture; closely connecting the burette and pycnometer and adding solution until the full scale of the burette; keeping the cement slurry to be tested rotating using the magnetic stirrer and the steel ball; recording the chemical shrinkage amount at different time based on the liquid level change in burette. The cement chemical shrinkage change can be monitored at real time based on ensuring the cement fully being hydrated.

Description

technical field [0001] The invention relates to a test method and a test device for cement chemical shrinkage. Background technique [0002] During the cement hardening process, the volume reduction due to hydration reaction is called the chemical shrinkage of cement. Theoretically, the total chemical shrinkage produced by 100g of Portland cement completely hydrating is 7-9ml. The chemical shrinkage value is tested by the method, that is, put a certain weight of cement into a glass bottle, add water and stir it, then plug the glass bottle tightly with a stopper with a graduated tube, then fill the glass bottle with water or other liquids to the full scale, and pass The water level changes to indicate the amount of chemical shrinkage. After water is added to the cement and the stirring is stopped, no matter what the water-cement ratio is used, the slurry will always settle and form a hardened body. In the hardened body, pores will be generated due to chemical shrinkage. When...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N19/00
Inventor 朱洪波王培铭张继东
Owner TONGJI UNIV
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