CN111943549A - Magnesium oxide composite expanding agent and preparation method thereof - Google Patents
Magnesium oxide composite expanding agent and preparation method thereof Download PDFInfo
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- CN111943549A CN111943549A CN202010705815.5A CN202010705815A CN111943549A CN 111943549 A CN111943549 A CN 111943549A CN 202010705815 A CN202010705815 A CN 202010705815A CN 111943549 A CN111943549 A CN 111943549A
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- magnesium oxide
- expanding agent
- oxide composite
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- gypsum
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
Abstract
The invention discloses a magnesium oxide composite expanding agent and a preparation method thereof, wherein the magnesium oxide composite expanding agent comprises the following components in percentage by weight: 25-35 parts of magnesite, 15-20 parts of dolomite, 18-27 parts of bauxite, 21-33 parts of gypsum and 4-8 parts of limestone. The preparation method of the magnesium oxide composite expanding agent comprises the following steps: uniformly mixing magnesite, dolomite and limestone, then putting the mixture into a muffle furnace, calcining the mixture for 60min at the temperature of 850-1050 ℃, then taking the calcined mixture out, cooling the calcined mixture, bauxite and gypsum, crushing the calcined mixture, bauxite and gypsum into specified fineness by a ball mill, and uniformly mixing the pulverized mixture to obtain the magnesium oxide composite expanding agent. According to the magnesium oxide composite expanding agent, the bauxite and the gypsum are doped into the magnesium oxide expanding agent, so that the early expansion effect is improved, and the magnesium oxide expanding agent is relatively late in expansion time, so that cracks caused by later-stage drying shrinkage of concrete are prevented, and the expansion effect is improved.
Description
Technical Field
The invention relates to the technical field of concrete admixtures, in particular to a magnesium oxide composite expanding agent and a preparation method thereof.
Background
The concrete material is composed of cement, sand, stone and water, and is a building material which is most widely used. With the development and improvement of the technology, the understanding and use of concrete materials are deepened, and the influence of shrinkage and cracking on the durability and quality of concrete becomes a research hotspot, which is caused by the cracking and shrinkage of concrete due to the dehydration, temperature and humidity change in the cement setting process, so that the durability and strength of concrete are reduced.
The expanding agent is a material which can cause volume expansion through physical and chemical reactions, and the volume expansion can be applied to a plurality of fields such as material production, silent blasting and the like.
The concrete expanding agent and the refractory material expanding agent are common and are mainly used for compensating the shrinkage of the material in the hardening process and preventing cracking. In recent years, static blasting agents have also been developed, based on the material properties, which destroy the structural structure mainly by volume expansion of the material.
The expanding agent material is mainly applied to material production, and is commonly used as a concrete expanding agent and a refractory material expanding agent. During the hardening process of concrete and unshaped refractory materials, cracking is often caused by the shrinkage characteristics of the raw materials. The expanding agent is introduced to introduce quantitative volume expansion, compensate the shrinkage value of the material, and prevent the material from shrinkage cracking to influence the structure, function and appearance of the material. In recent years, as composite materials are widely researched and developed, expansion materials are also emphasized by various industries and are widely applied to production and manufacturing of materials.
At present, the expansion agent used at home and abroad mainly comprises calcium sulphoaluminate type, calcium oxide type, magnesium oxide type, compound type and the like, the principle is different, and certain prestress is provided by an expansive substance generated by the reaction of the expansion agent with water or hydration products in the hydration process of cement, so that gaps in concrete are filled, and the water loss of the concrete or the drying shrinkage caused by temperature are resisted.
Disclosure of Invention
The invention aims to provide a magnesium oxide composite expanding agent which can simultaneously realize early expansion and later compensation shrinkage of the magnesium oxide expanding agent and a preparation method thereof.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the magnesium oxide composite expanding agent is characterized in that: comprises the following components in percentage by weight: magnesite: 25-35 parts of dolomite: 15-20 parts of bauxite: 18-27 parts of gypsum: 21-33 parts of limestone: 4-8 parts.
As a preferred embodiment of the present invention, the magnesium oxide content of the magnesite is more than 40%.
As a preferred embodiment of the invention, the content of magnesium oxide in said dolomite is more than 15%.
In a preferred embodiment of the present invention, the bauxite is primary bauxite.
As a preferred embodiment of the present invention, the gypsum is anhydrite or hemihydrate gypsum.
The other purpose of the invention is to provide a preparation method of the magnesium oxide composite expanding agent, which comprises the steps of firstly uniformly mixing magnesite, dolomite and limestone, then putting the mixture into a muffle furnace, calcining the mixture at 850-1050 ℃ for 60min, then taking the calcined mixture out, cooling the calcined mixture, bauxite and gypsum, crushing the calcined mixture into 200 meshes by a ball mill, and uniformly mixing the crushed mixture, the bauxite and the gypsum to obtain the magnesium oxide composite expanding agent, wherein the screen residue is less than or equal to 5 parts.
By adopting the technical scheme, compared with the prior art, the invention has the characteristics that the composite expansion material is used, the magnesite which is fired at high temperature has perfect crystal form and slow hydration speed, so the expansion can not be generated at the early hardening stage of cement, and the composite doping of gypsum and bauxite can cause the partial expansion of concrete at the early setting stage. Meanwhile, the expansion size and temperature of the magnesite which is fired at high temperature have a great relationship, bauxite and gypsum provide expansion in the early stage, the temperature of concrete rises, and magnesium oxide begins to generate an expansion effect when the temperature drops in the later stage, so that the cracking of the concrete caused by overlarge expansion is avoided.
Detailed Description
The following examples further illustrate embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example one
The invention provides a magnesium oxide composite expanding agent and a preparation method thereof, and the invention is further explained by the following examples:
the magnesium oxide composite expanding agent comprises the following components in percentage by weight: 31 parts of magnesite, 19 parts of dolomite, 20 parts of bauxite, 24 parts of gypsum and 6 parts of limestone.
Wherein, magnesite with the content of magnesium oxide more than 40% is selected.
The dolomite is dolomite with magnesium oxide content more than 15%.
The bauxite is first-grade bauxite.
The gypsum is anhydrous gypsum or semi-hydrated gypsum.
The preparation method comprises the following steps:
(1) uniformly mixing magnesite, dolomite and limestone;
(2) putting the mixed magnesite, dolomite and limestone into a muffle furnace, calcining for 60min at the temperature of 850-1050 ℃, and taking out;
(3) cooling, and grinding the fired mixture, bauxite and gypsum by a ball mill to obtain powder with a 200-mesh sieve residue of less than or equal to 5%;
(4) and homogenizing to obtain the magnesium oxide composite expanding agent.
Table 1 shows the measurement indexes of the magnesium oxide composite swelling agent prepared according to the first example:
example two
The invention provides a magnesium oxide composite expanding agent and a preparation method thereof, and the invention is further explained by the following examples:
the magnesium oxide composite expanding agent comprises the following components in percentage by weight: 28.4 parts of magnesite, 19 parts of dolomite, 21 parts of bauxite, 27.6 parts of gypsum and 4 parts of limestone.
Wherein, magnesite with the content of magnesium oxide more than 40% is selected.
The dolomite is dolomite with magnesium oxide content more than 15%.
The bauxite is first-grade bauxite.
The gypsum is anhydrous gypsum or semi-hydrated gypsum.
The preparation method comprises the following steps:
(1) uniformly mixing magnesite, dolomite and limestone;
(2) putting the mixed magnesite, dolomite and limestone into a muffle furnace, calcining for 60min at the temperature of 850-1050 ℃, and taking out;
(3) cooling, and grinding the fired mixture, bauxite and gypsum by a ball mill to obtain powder with a 200-mesh sieve residue of less than or equal to 5%;
(4) and homogenizing to obtain the magnesium oxide composite expanding agent.
Table 2 shows the measurement indexes of the magnesium oxide composite swelling agent prepared according to example two:
EXAMPLE III
The invention provides a magnesium oxide composite expanding agent and a preparation method thereof, and the invention is further explained by the following examples:
the magnesium oxide composite expanding agent comprises the following components in percentage by weight: 34.7 parts of magnesite, 16 parts of dolomite, 17.3 parts of bauxite, 25 parts of gypsum and 7 parts of limestone.
Wherein, magnesite with the content of magnesium oxide more than 40% is selected.
The dolomite is dolomite with magnesium oxide content more than 15%.
The bauxite is first-grade bauxite.
The gypsum is anhydrous gypsum or semi-hydrated gypsum.
The preparation method comprises the following steps:
(1) uniformly mixing magnesite, dolomite and limestone;
(2) putting the mixed magnesite, dolomite and limestone into a muffle furnace, calcining for 60min at the temperature of 850-1050 ℃, and taking out;
(3) cooling, and grinding the fired mixture, bauxite and gypsum by a ball mill to obtain powder with a 200-mesh sieve residue of less than or equal to 5%;
(4) and homogenizing to obtain the magnesium oxide composite expanding agent.
Table 3 shows the measurement indexes of the magnesium oxide composite swelling agent prepared according to the third example:
the detection indexes used in the above embodiments one to three are as follows
(1) The fineness is represented by specific surface area and screen residue of 1.255 screen or 0.88 screen residue;
(2) the total alkali amount, magnesium oxide is carried out according to GB/T176;
(3) the water content is carried out according to JC 744;
(4) chloride ion proceeds according to JC/T420;
(5) the setting time is carried out according to GB/T1346;
(6) the compressive strength and the rupture strength are carried out according to GB/T17671;
(7) the limiting expansion ratio is calculated according to industry standards.
The magnesium oxide composite expanding agent and the preparation method thereof provided by the first embodiment to the third embodiment meet the standard, and the composite expanding material is used, the magnesite which is fired at high temperature has perfect crystal form and slow hydration speed, so that the expansion cannot be generated in the early hardening stage of cement, and the composite mixed gypsum and bauxite can enable concrete to generate partial expansion in the early setting stage. Meanwhile, the expansion size and the temperature of the magnesite which is fired at high temperature are in direct proportion, bauxite and gypsum provide expansion in the early stage, the temperature of the concrete rises, and the magnesium oxide starts to generate an expansion effect when the temperature drops in the later stage, so that the cracking of the concrete caused by overlarge expansion is avoided.
The embodiments of the present invention have been described in detail with reference to the examples, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.
Claims (6)
1. The magnesium oxide composite expanding agent is characterized in that: comprises the following components in percentage by weight: magnesite: 25-35 parts of dolomite: 15-20 parts of bauxite: 18-27 parts of gypsum: 21-33 parts of limestone: 4-8 parts.
2. The magnesium oxide composite expander according to claim 1, wherein: the content of magnesium oxide in the magnesite is more than 40%.
3. The magnesium oxide composite expander according to claim 1, wherein: the content of magnesium oxide in the dolomite is more than 15 percent.
4. The magnesium oxide composite expander according to claim 1, wherein: the bauxite is first-grade bauxite.
5. The magnesium oxide composite expander according to claim 1, wherein: the gypsum is anhydrous gypsum or semi-hydrated gypsum.
6. A method for preparing the magnesium oxide composite expanding agent according to claims 1 to 5, wherein: the method comprises the following steps: firstly, uniformly mixing magnesite, dolomite and limestone, then putting the mixture into a muffle furnace, calcining the mixture for 60min at the temperature of 850-1050 ℃, then taking the mixture out, cooling the mixture, crushing the mixture after firing, bauxite and gypsum by using a ball mill, uniformly mixing the mixture after firing and the bauxite with the crushing fineness of the gypsum of 200 meshes to obtain the magnesium oxide composite expanding agent, wherein the screen residue is less than or equal to 5 parts.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114230216A (en) * | 2022-01-11 | 2022-03-25 | 中建材中研益科技有限公司 | Steel slag-based oil well cement expanding agent and application thereof in oil well cement |
| CN115925316A (en) * | 2022-10-31 | 2023-04-07 | 海南瑞泽双林建材有限公司 | Additive for improving cracking resistance of concrete and preparation method thereof |
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| JP2006151772A (en) * | 2004-11-30 | 2006-06-15 | Taiheiyo Material Kk | Liquid expansive admixture |
| CN101481605A (en) * | 2005-09-28 | 2009-07-15 | 江苏海特曼新材料有限公司 | Oil well cement crystal expansion agent and preparation thereof |
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| CN104909596A (en) * | 2015-04-03 | 2015-09-16 | 中国建筑股份有限公司 | High efficiency composite expanding agent for high-strength self-stressing concrete filled steel tube and preparation method thereof |
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2020
- 2020-07-21 CN CN202010705815.5A patent/CN111943549A/en active Pending
Patent Citations (6)
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|---|---|---|---|---|
| SU686610A3 (en) * | 1975-05-09 | 1979-09-15 | Емеза Аг (Фирма) | Expanding additive to concrete |
| CN1412144A (en) * | 2002-09-27 | 2003-04-23 | 贵州赛迪高峡科技开发有限责任公司 | Magnesium oxide composite expanding agent |
| JP2006151772A (en) * | 2004-11-30 | 2006-06-15 | Taiheiyo Material Kk | Liquid expansive admixture |
| CN101481605A (en) * | 2005-09-28 | 2009-07-15 | 江苏海特曼新材料有限公司 | Oil well cement crystal expansion agent and preparation thereof |
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| CN104909596A (en) * | 2015-04-03 | 2015-09-16 | 中国建筑股份有限公司 | High efficiency composite expanding agent for high-strength self-stressing concrete filled steel tube and preparation method thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114230216A (en) * | 2022-01-11 | 2022-03-25 | 中建材中研益科技有限公司 | Steel slag-based oil well cement expanding agent and application thereof in oil well cement |
| CN114230216B (en) * | 2022-01-11 | 2023-02-17 | 中建材中研益科技有限公司 | Steel slag-based oil well cement expanding agent and application thereof in oil well cement |
| CN115925316A (en) * | 2022-10-31 | 2023-04-07 | 海南瑞泽双林建材有限公司 | Additive for improving cracking resistance of concrete and preparation method thereof |
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