A kind of magnesium oxide expansion agent activity evaluation method

An evaluation method, magnesium oxide technology, applied in the direction of material thermal development, etc., can solve the problem that the low active components of magnesium oxide expansion agent do not reflect the hydration activity of magnesium oxide expansion agent, and achieve the effect of predicting the expansion effect

Active Publication Date: 2022-07-15
SOUTHEAST UNIV
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Problems solved by technology

[0018] Technical problem: In view of the above-mentioned problem that the low active components of the magnesium oxide expansion agent cannot be detected and the hydration activity of the magnesium oxide expansion agent in an alkaline environment is not reflected, the present invention proposes to use the magnesium oxide expansion agent in deionized water The heat of hydration can be used to quickly determine the hydration activity of the magnesia expansion agent

Method used

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  • A kind of magnesium oxide expansion agent activity evaluation method
  • A kind of magnesium oxide expansion agent activity evaluation method
  • A kind of magnesium oxide expansion agent activity evaluation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Take the magnesium oxide M1, M2, M3 obtained by calcining different varieties of magnesium carbonate, and calculate the reference standard water consumption M 水=10+1*0.94 / 4.18=10.2249. Weigh 10.2249 g of deionized water into ampoule B, weigh 10 g of deionized water into ampoule A, and weigh 1 g of M1 magnesium oxide powder sample with weighing paper. Mix bottle A with magnesium oxide powder and shake well, open the software, click "Mark", then put bottle B and bottle A at a time to start the test. The same operation test M1, M2, M3 magnesium oxide expansion agent powder samples. After 24 hours, the obtained data is plotted with origin, such as figure 1 shown:

[0037] Take the hydration heat release of three different magnesia expansion agents at t=24h. Q1=908.74J, Q2=625.79J, Q3=319.33J, so the average heat release per unit time in 24h is q1=37.86(J / h), q2=26.07(J / h), q3=13.3(J / h) Therefore, three types of magnesium oxide are divided into: type 1 magnesium oxide e...

Embodiment 2

[0039] The three kinds of magnesium oxides M1, M2 and M3 were mixed in 1:1 mass percentage, and mixed for 2 minutes with a three-dimensional motion mixer, so that the two kinds of magnesium oxides could be mixed uniformly, and were numbered M12, M13, M23 respectively. The three kinds of magnesium oxides obtained by mixing are operated in the same manner as in Example 1, and the hydration heat curve obtained by the test is as follows: figure 2 shown:

[0040] Take the hydration heat release of three different magnesia expansion agents at t=24h. Q12=750.88J, Q13=617.33J, Q3=487.43J, so the average heat release per unit time in 24h is q12=31.29(J / h), q13=25.72(J / h), q23=20.3(J / h) Therefore, the three types of magnesium oxide after mixing are divided into: 12 types of mixed expansion agent are high-activity magnesium oxide, and types 13 and 23 are mixed with medium-activity magnesium oxide.

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Abstract

The invention provides a method for evaluating the hydration activity of magnesium oxide expansion agent; the method is to use an isothermal calorimeter to test the hydration heat curve of magnesium oxide powder in deionized water and the average heat release per unit time to evaluate Hydration activity of magnesia expansion agent; if the average heat release per unit time q in 24h > 25J / h, it is high activity magnesia, if 15J / h≤q≤25J / h, it is medium activity magnesia, if q<15J / h, it is low-activity magnesium oxide; the method of the present invention can comprehensively observe the hydration history of the magnesium oxide expansion agent according to the hydration heat curve, and determine the magnesium oxide expansion agent quickly and accurately by calculating the heat release per unit time within 24h. The hydration activity of magnesium oxide expansion agent has a more accurate effect on predicting the expansion performance of magnesia expansion agent in the alkaline environment of cement concrete.

Description

technical field [0001] The invention relates to the technical field of performance testing of building materials, in particular to a method for testing and evaluating the hydration activity of a magnesium oxide expansion agent. Background technique [0002] With the increase of building volume, shrinkage cracking leads to cracks, which is the main problem faced by many projects. During the hardening process of mass concrete, temperature changes will cause temperature deformation cracks, and the cracks will not only reduce the mechanical properties of the structure, but also become the channel of water and harmful substances, reducing the service life of the structure. The appearance of expansion agent effectively solves the problem of cracks caused by concrete shrinkage, and greatly reduces the risk of concrete cracking and shrinkage. [0003] Magnesium oxide expansion agent is brucite Mg(OH) produced by the reaction of MgO and water 2 A swelling agent that is a source of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N25/48
CPCG01N25/48
Inventor 冯攀邵丽静陆晋媛
Owner SOUTHEAST UNIV
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