Method for testing content of magnesium oxide in magnesium oxide expanding agent

A test method and magnesium oxide technology, applied in the direction of removing a certain component and weighing, etc., can solve problems such as poor correlation, and achieve the effects of good reproducibility, simple experimental method and strong operability.

Active Publication Date: 2013-05-22
JIANGSU SOBUTE NEW MATERIALS +2
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  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0006] In the current standard about magnesia, the "Technical Requirements for the Quality of Light-burned Magnesia Materials in Water Conservancy and Hydropower Projects (Trial)" uses chemical analysis to test the MgO content in light-burned magnesia. Decomposed MgCO 3 and has been moistened with Mg(OH) 2 There is no necessary correlation between the measured MgO content and the expansion performance of the magnesia expansion agent; the hydration method specified in the ferrous metallurgy industry standard YB / T4019-2006 is used to determine light-burned magnesia Medium active magnesia content, although it can exclude undecomposed MgCO in light-burned magnesia 3 and has been moistened with Mg(OH) 2 However, the influence of CaO impurities in the magnesia expansion agent cannot be ruled out, and the reaction environment is quite different from the real hydration environment of the magnesia expansion agent in cement concrete. The measured The correlation between the obtained active magnesium oxide content and the expansion performance of the magnesium oxide expansion agent is poor

Method used

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  • Method for testing content of magnesium oxide in magnesium oxide expanding agent

Examples

Experimental program
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Effect test

Embodiment 1

[0028] Take the magnesium oxide expansion agent provided by a magnesium oxide expansion agent manufacturer, pass the magnesium oxide expansion agent through a 0.08mm standard sieve, place it at 150°C for 2 hours, and place it in a desiccator to cool to room temperature. Weigh 5.0005 g of the pretreated magnesium oxide expansion agent sample, place it in a 200 ml reaction vessel, add 100 ml of prepared buffer solution with a pH value of 13.0, put a stirring bar, and cover with a watch glass. Place the reaction vessel in a water bath of a heat-collecting constant temperature magnetic stirrer. The temperature of the water bath is stabilized at 80°C±1°C. Turn on the magnetic stirrer and keep the speed at 750r / min~800r / min to make the magnesium oxide expansion agent sample and pH The buffer solution with a value of 13.0 was continuously reacted under these conditions for 5 hours, then taken out, filtered, rinsed and filtered with absolute ethanol, and put the rinsed filtered product...

Embodiment 2

[0035] Weigh analytically pure Mg(OH) 2 Sample 5.0011g was placed in a 200ml reaction vessel, and 100ml of buffer solution with a pH value of 13.0 was added, a stirring bar was placed, and a watch glass was covered. Place the reaction vessel in a water bath of a heat-collecting constant temperature magnetic stirrer. The temperature of the water bath is stabilized at 80°C ± 1°C. Turn on the magnetic stirrer and keep the speed at 750r / min to 800r / min to make the Mg(OH) 2 The sample and the buffer solution with a pH value of 13.0 were continuously reacted under these conditions for 5 hours, then taken out and filtered, and the filtered product was rinsed with absolute ethanol, and the rinsed filtered product was put into a porcelain crucible. Dry the porcelain crucible at 150°C to constant weight, place it in a desiccator and cool it to room temperature, weigh and measure the Mg(OH) after reacting with a buffer solution with a pH value of 13.0 2 The mass of the sample is 5.0016g...

Embodiment 3

[0041] High-grade magnesite (mainly composed of MgCO) produced in Haicheng, Liaoning 3 ), ground through a 0.08mm standard sieve, dried at 150°C for 2 hours, and cooled to room temperature in a desiccator. Weigh 5.0006 g of the pretreated magnesite sample, place it in a 200 ml reaction vessel, add 100 ml of prepared buffer solution with a pH value of 13.0, put a stirring bar, and cover with a watch glass. Place the reaction vessel in a water bath of a heat-collecting constant temperature magnetic stirrer. The temperature of the water bath is stable at 80°C±1°C. Turn on the magnetic stirrer and keep the speed at 750r / min-800r / min to make the magnesite sample and pH value The buffer solution with a concentration of 13.0 was continuously reacted under these conditions for 5 hours, then taken out, filtered, and the filtered product was rinsed with absolute ethanol, and the rinsed filtered product was put into a porcelain crucible. Dry the porcelain crucible at a temperature of 15...

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Abstract

The invention provides a method for testing the content of magnesium oxide in a magnesium oxide expanding agent. The method comprises the steps of: enabling a magnesium oxide expanding agent sample to react in a buffer solution with the pH value of 13.0, and detecting the content of the magnesium oxide in the magnesium oxide expanding agent sample, wherein a sodium hydroxide aqueous solution is used as the buffer solution. According to the invention, the influence of a magnesium element in undecomposed magnesite and the magnesium element in generated magnesium hydrate partially absorbing moisture in the magnesium oxide expanding agent can be eliminated, the influence of the calcium oxide in the magnesium oxide expanding agent can be effectively eliminated, and the measured content of the magnesium oxide is the effective content of the magnesium oxide capable of reacting with water; and a test result is capable of truly reflecting the reaction capacity of the magnesium oxide expanding agent in a cement concrete hydration environment, and is closely related to the expansion priority of the magnetism oxide expanding agent in cement concrete.

Description

technical field [0001] The invention relates to the technical field of building material testing, in particular to a method for testing the effective MgO content in a magnesium oxide expansion agent. Background technique [0002] After the concrete is poured, due to the large amount of heat of hydration generated by the hydration of the cement, the temperature of the concrete rises, resulting in volumetric thermal expansion. After reaching the maximum temperature, as the heat dissipates to the external environment, the temperature will drop from the maximum value to a stable or quasi-stable value, and temperature shrinkage stress will be generated. When the shrinkage stress exceeds the ultimate tensile strength of concrete, it will lead to concrete cracking . In the construction of water conservancy and hydropower projects, the temperature shrinkage crack of mass concrete is one of the key factors affecting the quality and durability of the project. Chinese scientists and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N5/04
Inventor 刘加平张守治田倩闫战彪王申进陆安群
Owner JIANGSU SOBUTE NEW MATERIALS
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