CN109721272B - Magnesium oxide retarder based on composite vitamins, composite magnesium oxide and application - Google Patents
Magnesium oxide retarder based on composite vitamins, composite magnesium oxide and application Download PDFInfo
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- CN109721272B CN109721272B CN201910004174.8A CN201910004174A CN109721272B CN 109721272 B CN109721272 B CN 109721272B CN 201910004174 A CN201910004174 A CN 201910004174A CN 109721272 B CN109721272 B CN 109721272B
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Abstract
The invention discloses a light-burned magnesia retarder based on compound vitamins, which comprises the following components: 40-70 parts of vitamin C and 10-20 parts of vitamin B110-20 parts of vitamin B2And 10-20 parts of vitamin B6The preparation method comprises the following steps: 1) grinding the vitamin tablets into powder; 2) and uniformly mixing the powder at normal temperature according to a proportion to obtain the required magnesium oxide retarder. The vitamin magnesium oxide retarder provides a new idea for the preparation of cement-based material additives from the perspective of biological medicines, is simple in preparation process, safe and nontoxic, and can remarkably prolong the initial and final setting time.
Description
Technical Field
The invention belongs to the technical field of cement-based material additives, and particularly relates to a magnesium oxide retarder based on compound vitamins, compound magnesium oxide and application thereof.
Background
The lightly-calcined magnesia, known as magnesia and commonly called magnesite, is obtained by calcining magnesite at 700-1000 ℃, and the volume of the magnesite after hydration obviously expands. In the cement-based material with large volume, the temperature drop process exists in the later stage of cement hydration heat release, and shrinkage cracks are generated. The magnesium oxide is doped to effectively compensate temperature drop shrinkage and enable the whole system to generate micro-expansion. The light-burned magnesia has large specific surface area and high reaction speed, overcomes the defects of low activity and slow reaction of the heavy-burned magnesia, and is an ideal material for compensating the shrinkage of cement.
However, at the same time, the reaction rate of the lightly calcined magnesia is greatly affected by the temperature. In a high-temperature environment in summer, the hydration speed of magnesium oxide is high, and magnesium hydroxide generated by hydration can bring huge expansion when temperature reduction shrinkage is not generated in the cement-based material with large volume, so that cracks are generated in the cement-based material. In the prior art, the cooling is usually carried out by means of laying a condenser pipe, pre-cooling aggregate and the like, and extra cost is required. The retarder is an additive which can reduce hydration speed and hydration heat and prolong the setting time. The retarder is used for regulating and controlling the hydration speed of the magnesium oxide, so that the construction quality of the project can be ensured, and the cost is saved. Therefore, from the practical engineering consideration, in a high-temperature environment, the retarder needs to slow down the hydration speed of the magnesium oxide. The commonly used retarder at present mainly comprises lignosulphonate and derivatives thereof, cellulose derivatives, hydroxycarboxylic acid and salts thereof, inorganic substances and the like according to the structure, wherein part of the retarder has retarding effect on cement but does not play a role in hydration of magnesium oxide.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a magnesium oxide retarder based on composite vitamins, which can obviously prolong the setting time of magnesium oxide and slow down the hydration speed of magnesium oxide. The invention also provides a composition synthesized by the retarder and magnesium oxide.
The technical scheme is as follows: the invention relates to a magnesium oxide retarder based on multivitamins, which comprises the following components in parts by weight: 40-70 parts of vitamin C and 10-20 parts of vitamin B110-20 parts of vitamin B2And 10-20 parts of vitamin B6。
Preferably, the retarder comprises the following components in parts by weight: 40-55 parts of vitamin C and 15-20 parts of vitamin B115-20 parts of vitamin B2And 15-20 parts of vitamin B6。
The preparation method of the retarder comprises the following steps: mixing vitamin C and vitamin B1Vitamin B2And vitamin B6And (3) mashing the raw materials, grinding the raw materials into powder, weighing the powder according to a proportion, and uniformly mixing to obtain the required magnesium oxide retarder.
The retarder is used for preparing a magnesium oxide compound, the magnesium oxide compound comprises magnesium oxide and the retarder, and the mass percentage of the retarder to the magnesium oxide is 0.1-0.2%.
Preferably, the magnesium oxide composite is prepared by the following method: mixing magnesium oxide, retarder and proper amount of water to obtain magnesium oxide compound; the magnesium oxide is light-burned magnesium oxide.
Preferably, the temperature of the mixture of the magnesium oxide, the retarder and the water is controlled to be 0-50 ℃.
The action mechanism of the retarder for delaying the hydration of the magnesium oxide is as follows: vitamin C and vitamin B6The polyhydroxy structure can obviously reduce the hydration speed of the magnesium oxide, and has a delayed coagulation effect; the vitamins are easy to oxidize and decompose in an alkaline environment to generate substances such as a carboxyl structure, sulfite and the like, and have a hydroxyl retarding effect; the absorption of the compound vitamin and the reaction product thereof on the magnesium oxide and the magnesium hydroxide changes the rate of crystal embryo generation in the saturated solution, thereby slowing down the hydration rate of the magnesium oxide and playing a good retarding effect.
The retarder and the magnesium oxide are premixed, the obtained magnesium oxide compound can obviously reduce the hydration speed of the magnesium oxide, particularly under the high-temperature environment, the light-burned magnesium oxide is quickly hydrated under the condition of not adding the retarder, magnesium hydroxide generated by hydration can bring huge expansion when temperature reduction shrinkage is not generated in the cement-based material with large volume, and the cement-based material can generate cracks.
Furthermore, the magnesium oxide compound is applied to the cement-based material, so that the formation of cracks on the cement-based material due to the high hydration speed of magnesium oxide can be remarkably reduced.
The concrete application steps of the retarder in the cement-based material are as follows:
(1) adding water into the retarder and the magnesium oxide for pre-mixing to obtain a pre-mixed compound; the mass ratio of the water adding amount of the pre-mixing to the magnesium oxide is the same as the water cement ratio of cement in the cement-based material;
(2) and (2) doping the ready-mixed compound obtained in the step (1) into a cement-based material.
Preferably, in the step (1), the temperature of the pre-mixing is 0 ℃ to 50 ℃, and the storage temperature of the pre-mixed compound obtained after the pre-mixing is-10 ℃ to 30 ℃.
The cement-based material comprises the retarder and magnesium oxide as raw materials.
Preferably, the mass percentage of the retarder to the magnesium oxide is 0.1-0.2%, and the magnesium oxide is light-burned magnesium oxide.
Has the advantages that: (1) the invention adopts common vitamins as effective components to serve as additives, and the vitamins and oxidation products thereof are adsorbed on the surface of magnesium oxide after reacting with the magnesium oxide, thereby preventing further hydration and effectively reducing the hydration speed; (2) the retarder can obviously prolong the initial and final setting time of light-burned magnesium oxide, and is suitable for being used in a high-temperature environment in summer; (3) the retarder is easy to obtain raw materials, simple and feasible in preparation process, safe, non-toxic, innovative in thought and easy to popularize.
Drawings
FIG. 1 is a graph showing the effect of the retarder of the present invention on the early drying shrinkage of a MgO-doped cement paste at 60 ℃.
Detailed Description
Raw material sources and experimental conditions
1.1 the magnesium oxide in the invention adopts light-burned magnesium oxide, and the calcination temperature is 700-1000 ℃.
1.2 vitamin C and vitamin B used in the invention1Vitamin B2And vitamin B6Is derived from vitamin tablets, wherein the content of active ingredients is more than 80 percent.
1.3 the ambient temperature in the examples was 25 ℃, the mass ratio of water to magnesium oxide was 195: 500.
second, sample preparation
2.1 preparation method of retarder
Mixing vitamin C and vitamin B1Vitamin B2And vitamin B6And (3) mashing the raw materials, grinding the raw materials into powder, weighing the powder according to a proportion, and uniformly mixing to obtain the required magnesium oxide retarder.
Example 1: grinding vitamin tablet into powder according to part 2.1 method, and collecting 40 parts by weight of vitamin C and 20 parts by weight of vitamin B120 portions of vitamin B220 portions of vitamin B6And uniformly mixing to obtain the retarder.
Dissolving a retarder with the mass of 0.1% of magnesium oxide in water, adding magnesium oxide, mixing to prepare a standard test piece 1, measuring the setting time, and recording in table 1.
Example 2: grinding the vitamin tablets into powder according to the method of part 2.1, and taking 55 parts by weight of vitamin C and 15 parts by weight of vitamin B115 portions of vitamin B215 portions of vitamin B6And uniformly mixing to obtain the retarder.
Dissolving a retarder with the mass of 0.1% of magnesium oxide in water, adding magnesium oxide, mixing to prepare a standard test piece 2, measuring the setting time, and recording in table 1.
Example 3: grinding the vitamin tablets into powder according to the method of part 2.1, and taking 55 parts by weight of vitamin C and 15 parts by weight of vitamin B115 portions of vitamin B215 portions of vitamin B6And uniformly mixing to obtain the retarder.
Dissolving a retarder with the mass of 0.2% of magnesium oxide in water, adding magnesium oxide, mixing to prepare a standard test piece 3, measuring the setting time, and recording in table 1.
Control 1: no retarder was added and magnesium oxide was mixed with water to prepare a control specimen 1, and the setting time was measured and recorded in Table 1.
The method for testing the setting time of the magnesium oxide is carried out by referring to a method of GB/T1346-2011 inspection method for water consumption, setting time and stability of standard consistency of cement.
TABLE 1 comparison of setting times for test pieces and control groups incorporating the retarder magnesium oxide
From the results in Table 1, it can be seen that when the amount of retarder doped in magnesium oxide is 0.2%, the vitamin retarder significantly extended the setting time of the sample, the initial setting time was 80.7% and the final setting time was 41.8% as compared to control 1. The retarder prepared by the invention obviously prolongs the initial and final setting time of magnesium oxide, has a good retarding effect, and provides guarantee for construction requirements of delaying the hydration speed of magnesium oxide.
Third, the application effect in the cement-based material
Example 4: referring to JC _ T603-2004 cement mortar dry shrinkage test method, the magnesium oxide retarder in example 2 is taken, and the mixing ratio is cement: water: magnesium oxide 1: 0.45: 0.05 cement paste was prepared into 25mm by 285mm test pieces, one of which was doped with 0.1% by mass of magnesium oxide of the vitamin retarder prepared in example 2, and the magnesium oxide was modified, while the other was not modified and used as a control group, both ends of which were buried in copper heads, and after demolding, the test pieces were put into a curing oven at 20 ℃ and 95% relative humidity for curing for 2 days, and then put into a dry curing oven at 60 ℃ for curing, and the early drying shrinkage was measured and recorded in fig. 1. As can be seen from FIG. 1, the test piece doped with the vitamin retarder has a smaller expansion amount at 1d than the control group and a smaller drying shrinkage at 2d than the control group, which indicates that the vitamin retarder delays the expansion behavior of magnesium oxide at 60 ℃ to generate more effective expansion.
Claims (10)
1. The magnesium oxide retarder based on the compound vitamins is characterized by comprising the following components in parts by weight: 40-70 parts of vitamin C and 10-20 parts of vitamin B110-20 parts of vitamin B2And 10-20 parts of vitamin B6。
2. The multi-vitamin magnesium oxide retarder of claim 1, wherein the retarder comprises the following components in parts by weight: 40-55 parts of vitamin C and 15-20 parts of vitamin B115-20 parts of vitamin B2And 15-20 parts of vitamin B6。
3. The magnesium oxide compound is characterized in that the preparation raw material of the magnesium oxide compound comprises magnesium oxide and the retarder according to claim 1 or 2, wherein the retarder is 0.1-0.2% of the mass of the magnesium oxide.
4. The magnesium oxide composite according to claim 3, wherein the magnesium oxide composite is prepared by a method comprising: mixing magnesium oxide, retarder and proper amount of water to obtain magnesium oxide compound; the magnesium oxide is light-burned magnesium oxide.
5. Use of a retarder according to any of claims 1 or 2 or a magnesium oxide composite according to any of claims 3 or 4 in a cement-based material.
6. The application according to claim 5, characterized in that it comprises the following steps:
(1) adding water into the retarder and the magnesium oxide for pre-mixing to obtain a pre-mixed compound; the mass ratio of the water adding amount of the pre-mixing to the magnesium oxide is the same as the water cement ratio of cement in the cement-based material;
(2) and (2) doping the ready-mixed compound obtained in the step (1) into a cement-based material.
7. The use of claim 6, wherein in step (1), the pre-blending temperature is from 0 ℃ to 50 ℃, and the storage temperature of the pre-blend obtained after pre-blending is from-10 ℃ to 30 ℃.
8. A cementitious material comprising a set retarder as claimed in any one of claims 1 or 2 and magnesium oxide.
9. The cement-based material according to claim 8, wherein the retarder is 0.1-0.2% by mass of magnesium oxide.
10. The cementitious binder of claim 8, wherein the magnesium oxide is light-burned magnesium oxide.
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| CN105198268A (en) * | 2014-06-30 | 2015-12-30 | 沈阳联合化学科技有限公司 | Retarding water reducer and preparation method thereof |
| CN107840929A (en) * | 2017-11-30 | 2018-03-27 | 鹿寨鸿志建材有限公司 | The preparation method of polycarboxylate water-reducer |
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| CN105198268A (en) * | 2014-06-30 | 2015-12-30 | 沈阳联合化学科技有限公司 | Retarding water reducer and preparation method thereof |
| CN107840929A (en) * | 2017-11-30 | 2018-03-27 | 鹿寨鸿志建材有限公司 | The preparation method of polycarboxylate water-reducer |
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