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Magnesium oxide expanding agent activity evaluation method

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

Active Publication Date: 2020-04-21
SOUTHEAST UNIV
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  • Claims
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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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  • Magnesium oxide expanding agent activity evaluation method
  • Magnesium oxide expanding agent activity evaluation method
  • Magnesium oxide expanding agent activity evaluation method

Examples

Experimental program
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Effect test

Embodiment 1

[0036] Take the magnesium oxide M1, M2, M3 obtained by calcining different kinds of magnesium carbonate, and calculate the water consumption M of the reference standard 水=10+1*0.94 / 4.18=10.2249. Weigh 10.2249g of deionized water into ampoule B, weigh 10g of deionized water into ampoule A, and weigh 1g 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, use the origin to plot the obtained data, such as figure 1 Shown:

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

Embodiment 2

[0039] Mix the three types of magnesium oxide M1, M2, and M3 in pairs according to the mass percentage of 1:1, and mix them with a three-dimensional motion mixer for 2 minutes, so that the two types of magnesium oxide can be mixed evenly, and number them M12, M13, and M23 respectively. The three kinds of magnesium oxides obtained by mixing are operated in the same way as in Example 1, and the heat of hydration curve obtained by the test is as follows: figure 2 Shown:

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

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Abstract

The invention provides a magnesium oxide expanding agent activity evaluation method. According to the magnesium oxide expanding agent activity evaluation method, an isothermal calorimeter is used fortesting a hydration heat curve of magnesium oxide powder in deionized water and an average heat release amount in unit time to evaluate the hydration activity of an magnesium oxide expanding agent; and indicating that the magnesium oxide is high-activity magnesium oxide if the average heat release amount q in unit time within 24 hours is greater than 25 J / h, indicating that the magnesium oxide ismedium-activity magnesium oxide if q is greater than or equal to 15 J / h and less than or equal to 25 J / h, and indicating that the magnesium oxide is low-activity magnesium oxide if q is less than 15 J / h. According to the magnesium oxide expanding agent activity evaluation method, the hydration process of the magnesium oxide expanding agent can be comprehensively observed according to the hydrationheat curve, and the hydration activity of the magnesium oxide expanding agent can be rapidly and precisely judged by calculating the heat release amount per unit time within 24 hours, thus the magnesium oxide expanding agent activity evaluation method has an precise effect of estimating the expansion performance of the magnesium oxide expanding agent in the cement concrete under the alkaline environment.

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, cracks caused by shrinkage cracking are the main problems faced by many projects. During the hardening process of mass concrete, temperature changes will cause temperature deformation cracks, and the resulting cracks will not only reduce the mechanical properties of the structure, but also become channels for water and harmful substances, reducing the service life of the structure. The appearance of expansion agent effectively solves the crack problem caused by concrete shrinkage, and greatly reduces the risk of concrete cracking and shrinkage. [0003] Magnesium oxide expansion agent is brucite Mg(OH) formed by the reaction of MgO and water 2 A bulking agent that is a bulking sourc...

Claims

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Application Information

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