CN115504760A - A kind of early-strength magnesium phosphate cement repair material and preparation method thereof - Google Patents

Abstract

The invention provides an early-strength magnesium phosphate cement repairing material and a preparation method thereof, wherein the early-strength magnesium phosphate cement repairing material comprises the following components: 30-35 parts of dead burned magnesium oxide, 15-20 parts of monopotassium phosphate, 5-10 parts of ammonium dihydrogen phosphate, 2-3 parts of borax, 7-10 parts of fly ash, 0.5-1.5 parts of redispersible latex powder, 0.02-0.05 part of triethanolamine and 15-25 parts of water. Compared with the prior art, the potassium dihydrogen phosphate and the ammonium dihydrogen phosphate are compounded, so that the coagulation hardening strength is higher; the borax can improve the water resistance and the hardened strength of the material; the redispersible latex powder is not easy to wet, so that the water resistance of the redispersible latex powder is greatly enhanced; the triethanolamine can not only increase the fluidity of the slurry and reduce the porosity of the hardened slurry so as to improve the strength, but also increase the interfacial bonding force between the redispersed latex powder and the hardened slurry. The invention has the effects of high strength and good water resistance under the condition of ensuring the sufficient setting time, namely the construction time.

Description

A kind of early-strength magnesium phosphate cement repair material and preparation method thereof

technical field

The invention belongs to the technical field of building materials, and in particular relates to an early-strength magnesium phosphate cement repair material and a preparation method thereof.

Background technique

Magnesium phosphate cement generally uses phosphate, dead-burned magnesia, and retarder as the main components. It has the characteristics of fast setting, early strength and low shrinkage. It is often used as a repair material for the rapid repair of highways, bridges and other projects. In recent years There are also applications in the medical field.

Magnesium phosphate cement has the characteristics of rapid hardening and early strength. The lower the water-cement ratio, the higher the compressive strength. The molar ratio of magnesium oxide and phosphate will also affect the hydration process and products. The type of phosphate will affect the hydration products and structure. , The addition of fly ash, bentonite, etc. will also affect the hydration of phosphate cement. Due to its excellent adhesion, it has been developed as a new application such as steel anchor glue and steel protective coating.

Due to the fast setting time of repair materials such as phosphate cement, based on the actual workability requirements of the project, most of them introduce retarders such as borax to make the setting time adjustable within a certain range. According to actual performance requirements, magnesium phosphate cement will also be modified, such as adding silica fume to improve impermeability, adding steel slag to improve later strength, adding glass beads to enhance fluidity, and introducing fibers to strengthen cohesion, etc.

The patent with the publication number CN114409371A published on April 29, 2022 discloses a water-resistant phosphate cement-based repair material. The material disclosed in the patent is prepared from the following raw materials: modified magnesium oxide, potassium dihydrogen phosphate, phosphorus Aluminate cement, silica fume, potassium chloride, and admixture are water-resistant phosphate cement-based repair materials, which can be applied to the rapid repair of buildings in long-term humid environments and coastal environments. They have early strength, high strength and good water stability. The modified magnesium oxide is prepared according to the following steps: (1) Add ethanol to the wet ball mill, then add calcium chloride, potassium carbonate and triethanolamine to the wet ball mill in parts by weight 1:1:20-200 and mix evenly, solid-liquid The ratio is 10-50%; (2) The slurry is obtained by centrifugal filtration after wet grinding, and the temperature of the outer wall of the ball mill is controlled by water cooling or liquid nitrogen during the wet grinding process; (3) Magnesium oxide and slurry are mixed in parts by mass :50 is fully mixed and granulated to obtain modified magnesium oxide; wherein, the magnesium oxide is crushed from dead-burned magnesium oxide, and the specific surface area is 238-322m ² /kg.

The patent with the publication number CN113149491A published on July 23, 2021 discloses a high water-resistant magnesium potassium phosphate repair material and its preparation method. The preparation raw materials include: magnesium oxide, potassium dihydrogen phosphate, borax, water, and latex powder. The preparation method is to take magnesium oxide, potassium dihydrogen phosphate, borax and latex powder according to the weight components and place them in a cement mortar mixer, stir and mix evenly to obtain a mixed powder; add water to the mixed powder, stir and put it into a mold After a certain period of time, after 15-20 minutes, the mold is demoulded to obtain the high water-resistant magnesium potassium phosphate repair material. The invention has better water resistance, and improves the natural defect of phosphate cement not being water resistant to a certain extent.

Due to its rapid hardening and early strength characteristics, magnesium phosphate cement has considerable development potential in special engineering scenarios, but the natural defect of water resistance limits its application in engineering to a certain extent.

In recent years, the technology of magnesium phosphate cement repair materials has mostly focused on improving its water resistance, but there are more or less defects in previous studies. The above-mentioned technologies either introduce admixtures or surface active materials into the mature magnesium phosphate cement system. Adding agent to improve water resistance by increasing the density of the hardened slurry; or adding high molecular polymers to improve the surface properties and reduce the wettability of the material surface. The technology of simply introducing admixtures or surfactants has no effect on the strength of magnesium phosphate cement, but its water resistance is not improved enough, and it will still be structurally damaged in a long-term water erosion environment; simply adding polymers The technology to improve the surface properties can greatly improve the water resistance of magnesium phosphate cement, but this technology will reduce the strength of magnesium phosphate cement with potassium dihydrogen phosphate and magnesium oxide as cementitious materials.

Contents of the invention

The object of the present invention is to provide a kind of early-strength magnesium phosphate cement repair material and its preparation method, which can prepare magnesium phosphate cement with higher early strength, improve its water resistance at the same time, ensure that its strength does not lose, and have lower porosity Rate.

Concrete technical scheme of the present invention is as follows:

An early-strength magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

30-35 parts of dead-burned magnesium oxide, 15-20 parts of potassium dihydrogen phosphate, 5-10 parts of ammonium dihydrogen phosphate, 2-3 parts of borax, 7-10 parts of fly ash, 0.5-1.5 parts of redispersible latex powder , 0.02-0.05 parts of triethanolamine, 15-25 parts of water.

Preferably, the early-strength magnesium phosphate cement repair material includes the following raw materials in parts by mass:

32 parts of dead-burned magnesium oxide, 19 parts of potassium dihydrogen phosphate, 7 parts of ammonium dihydrogen phosphate, 3 parts of borax, 8 parts of fly ash, 1.5 parts of redispersible latex powder, 0.05 parts of triethanolamine, and 17 parts of water.

The dead-burned magnesia is obtained by calcining magnesite powder at a high temperature above 1400°C.

The potassium dihydrogen phosphate is chemical analysis pure KH ₂ PO ₄ .

The ammonium dihydrogen phosphate is chemical analysis pure NH ₄ H ₂ PO ₄ .

The borax is chemical analysis pure Na ₂ B ₄ O ₇ ·10H ₂ O.

The fly ash is class F first class fly ash.

The redispersible latex powder is PVA redispersible latex powder.

The triethanolamine is chemical analysis pure C ₆ H ₁₅ NO ₃ .

A kind of preparation method of early-strength magnesium phosphate cement repair material provided by the invention comprises the following steps:

1) According to the formula, measure dead-burned magnesium oxide, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, borax, fly ash, and redispersible latex powder, stir and mix at a low speed to obtain premixed powder;

2) Take triethanolamine and water according to the formula and add them to the mixer, then add the pre-mixed powder and start the mixer, after stirring evenly, the magnesium phosphate cement repair material slurry is obtained;

3) Pour out the magnesium phosphate cement repair material slurry, put it into a mold, and demould, and obtain the early-strength magnesium phosphate cement repair material.

Stir at a low speed as described in step 1), the stirring rate is 140-150r/min, and the stirring time is 30-45s.

Stirring described in step 2), the stirring rate is 250-300r/min, and the stirring time is 30s-45s;

In step 3), put it into the mold and demould after 15-20min.

The present invention involves thinking as follows:

The present invention uses potassium dihydrogen phosphate and ammonium dihydrogen phosphate to compound in a certain ratio, and compared with the previous magnesium phosphate cement repair material that only uses potassium dihydrogen phosphate, the present invention has higher coagulation hardening strength. The addition of fly ash can fill the micro pores generated by the reaction of ammonium dihydrogen phosphate, ensuring the compactness of the repair material.

The redispersible latex powder in the present invention can well improve the surface wettability of the magnesium phosphate cement repair material after forming a film, hinder water penetration, and improve the water resistance of the repair material.

The invention adds a small amount of triethanolamine to improve the fluidity of the slurry and reduce the porosity of the hardened repair material. At the same time, as a nonionic surfactant, it can improve the interfacial adhesion between the redispersible latex powder and the hydration product of magnesium phosphate. Bond performance, improve the strength of magnesium phosphate cement repair materials.

Compared with the prior art, the invention can effectively improve the water resistance of the magnesium phosphate cement while maintaining its strength without loss, and has lower porosity. The combination of potassium dihydrogen phosphate and ammonium dihydrogen phosphate reduces the intensity of the reaction, increases the construction time of the slurry in a flowing state, and facilitates engineering applications; Ammonium dihydrogen and magnesium oxide form a magnesium phosphate hydrate product with higher strength, and the material itself has higher strength than the prior art. Borax acts as a setting retarder, not only adjusting the setting time, but also the fly ash fills the pores during the hardening process of the slurry, increases the structural density, and improves the water resistance and the strength of the material after hardening. The redispersible latex powder is evenly dispersed throughout the slurry after stirring, which increases the surface tension of the magnesium phosphate cement repair material, makes it difficult to wet, and greatly enhances its water resistance. Triethanolamine is used as a non-ionic surfactant, which can not only increase the fluidity of the slurry, reduce the porosity of the slurry after hardening, and then increase the strength, but also improve the interface properties between the redispersible latex powder and the hardened slurry, and increase the interface bonding. force. The invention can prepare the magnesium phosphate cement repair material with high strength and good water resistance under the condition that the setting time is ensured, that is, the construction time is sufficient.

detailed description

The present invention is further described below in conjunction with embodiment.

Example 1

An early-strength magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

32 parts of dead-burned magnesium oxide, 19 parts of potassium dihydrogen phosphate, 7 parts of ammonium dihydrogen phosphate, 3 parts of borax, 8 parts of fly ash, 1.5 parts of redispersible latex powder, 0.05 parts of triethanolamine, and 17 parts of water.

Example 2

An early-strength magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

30 parts of dead-burned magnesium oxide, 15 parts of potassium dihydrogen phosphate, 5 parts of ammonium dihydrogen phosphate, 2 parts of borax, 7 parts of fly ash, 0.5 part of redispersible latex powder, 0.02 part of triethanolamine, and 15 parts of water.

Example 3

An early-strength magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

35 parts of dead-burned magnesium oxide, 20 parts of potassium dihydrogen phosphate, 10 parts of ammonium dihydrogen phosphate, 3 parts of borax, 10 parts of fly ash, 1.5 parts of redispersible latex powder, 0.05 parts of triethanolamine, and 25 parts of water.

Example 4

An early-strength magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

34 parts of dead-burned magnesium oxide, 16 parts of potassium dihydrogen phosphate, 6 parts of ammonium dihydrogen phosphate, 2.5 parts of borax, 9 parts of fly ash, 0.8 parts of redispersible latex powder, 0.03 parts of triethanolamine, and 21 parts of water.

Example 5

An early-strength magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

30 parts of dead-burned magnesium oxide, 20 parts of potassium dihydrogen phosphate, 10 parts of ammonium dihydrogen phosphate, 2.5 parts of borax, 8 parts of fly ash, 1.3 parts of redispersible latex powder, 0.04 parts of triethanolamine, and 20 parts of water.

Comparative example 1

A magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

The difference between Comparative Example 1 and Example 1 is only that no fly ash is used in Comparative Example 1, and all the other components are consistent with Example 1, that is, Comparative Example 1 includes the following components in parts by weight:

32 parts of dead-burned magnesium oxide, 19 parts of potassium dihydrogen phosphate, 7 parts of ammonium dihydrogen phosphate, 3 parts of borax, 1.5 parts of redispersible latex powder, 0.05 part of triethanolamine, and 17 parts of water.

Comparative example 2

A magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

The difference between Comparative Example 2 and Example 1 is only that redispersible latex powder and fly ash are not used in Comparative Example 1, and all the other components are consistent with Example 1, that is, Comparative Example 2 is calculated in parts by weight, including The following components:

32 parts of dead-burned magnesium oxide, 19 parts of potassium dihydrogen phosphate, 7 parts of ammonium dihydrogen phosphate, 3 parts of borax, 0.05 part of triethanolamine, and 17 parts of water.

Comparative example 3

A magnesium phosphate cement repair material, comprising the following raw materials in parts by mass:

The difference between Comparative Example 3 and Example 1 is that in Comparative Example 1, ammonium dihydrogen phosphate is replaced by potassium dihydrogen phosphate of the same molar amount, and the rest of the components are consistent with Example 1, in parts by weight, including the following Components:

32 parts of dead-burned magnesium oxide, 27 parts of potassium dihydrogen phosphate, 3 parts of borax, 8 parts of fly ash, 1.5 parts of redispersible latex powder, 0.05 parts of triethanolamine, and 17 parts of water.

The preparation method of above embodiment 1-5 and comparative example 1-3 magnesium phosphate cement repair material may further comprise the steps:

1) Weigh each powder component except triethanolamine and water according to the formula quantity, and then put it in a cement mortar mixer, stir and mix evenly at a low speed, the stirring speed is 140r/min, and the stirring time is 35s, to obtain the ready-mixed powder;

2) Weigh triethanolamine and water according to the parts by weight, add the pre-mixed powder together and start the mixer at a stirring rate of 285r/min, pour it out after 40s of stirring evenly and put it into the mold, demould after 18min to obtain test block.

The early-strength magnesium phosphate cement repair material of embodiment 1-5, the magnesium phosphate cement repair material of comparative example 1-3 carry out the compressive strength of different ages and compressive strength test after soaking in water for 28d, according to GB/T 17671 -2021 cement mortar strength test method (ISO method), the test results are shown in Table 1.

Each embodiment of table 1 and comparative example compressive strength test result

As can be clearly seen from the data in Table 1, a kind of early-strength type magnesium phosphate cement repair material provided by the present invention has had higher compressive strength in 2h, has good early-strength characteristic, simultaneously in 3d, 7d, 28d All ages can guarantee high compressive strength, and after soaking in water for 28 days, the compressive strength is significantly higher than that of the comparative example, and has good water resistance.

Judging from the compressive strength data of Example 1 and Comparative Example 1, fly ash can not only improve the water resistance of the repair material, but also improve the compressive strength of the repair material. According to the compressive strength data of Example 1 and Comparative Example 2, the impact of redispersible latex powder on strength is negligible, but it can significantly improve the water resistance of repair materials. According to the compressive strength data of Example 1 and Comparative Example 3, the strength of the magnesium phosphate cement repair material compounded by potassium dihydrogen phosphate and ammonium dihydrogen phosphate is greater than that of the magnesium phosphate cement repair prepared by potassium dihydrogen phosphate alone Material.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (9)

1. an early-strength type magnesium phosphate cement patching material, is characterized in that, described early-strength type magnesium phosphate cement patching material comprises following mass parts raw material: 30-35 parts of dead-burned magnesium oxide, 15-20 parts of potassium dihydrogen phosphate, 5-10 parts of ammonium dihydrogen phosphate, 2-3 parts of borax, 7-10 parts of fly ash, 0.5-1.5 parts of redispersible latex powder , 0.02-0.05 parts of triethanolamine, 15-25 parts of water. 2. early strength type magnesium phosphate cement repair material according to claim 1, is characterized in that, described early strength type magnesium phosphate cement repair material comprises following mass parts raw material: 32 parts of dead-burned magnesium oxide, 19 parts of potassium dihydrogen phosphate, 7 parts of ammonium dihydrogen phosphate, 3 parts of borax, 8 parts of fly ash, 1.5 parts of redispersible latex powder, 0.05 parts of triethanolamine, and 17 parts of water. 3. The early-strength magnesium phosphate cement repair material according to claim 1, wherein the dead-burned magnesium oxide is obtained by calcining magnesite powder at a high temperature above 1400°C. 4. The early-strength magnesium phosphate cement repair material according to claim 1, characterized in that, the fly ash is F class first-class fly ash. 5. early strength type magnesium phosphate cement repair material according to claim 1, is characterized in that, described redispersible latex powder is PVA redispersible latex powder. 6. a preparation method of the early-strength magnesium phosphate cement repair material described in any one of claim 1-5, is characterized in that, described preparation method comprises the following steps: 1) According to the formula, measure dead-burned magnesium oxide, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, borax, fly ash, and redispersible latex powder, stir and mix at a low speed to obtain premixed powder; 2) Take triethanolamine and water according to the formula and add them to the mixer, then add the pre-mixed powder and start the mixer, after stirring evenly, the magnesium phosphate cement repair material slurry is obtained; 3) Pour out the magnesium phosphate cement repair material slurry, put it into a mold, and demould, and obtain the early-strength magnesium phosphate cement repair material. 7. The preparation method according to claim 6, characterized in that, the low-speed stirring described in step 1), the stirring rate is 140-150r/min, and the stirring time is 30-45s. 8. The preparation method according to claim 6, characterized in that, for the stirring described in step 2), the stirring rate is 250-300r/min, and the stirring time is 30s-45s. 9. The preparation method according to claim 6, characterized in that, in step 3), it is loaded into a mold and demoulded after 15-20min.