High-strength anti-cracking dry-mixed plastering mortar and preparation process thereof

Abstract

The invention belongs to the technical field of mortar, and particularly provides high-strength anti-cracking dry-mixed plastering mortar and a preparation process thereof. The high-strength anti-cracking dry-mixed plastering mortar is prepared from the following components: cement, aggregate, basalt fiber, composite hydrophobic powder, a water reducing agent, citric acid and calcium hydroxide. The prepared high-strength anti-cracking dry-mixed plastering mortar has the advantages of being high in waterproofness, high in strength, excellent in anti-cracking performance, low in cost and the like, and is suitable for building wall plastering engineering.

Description

Technical Field

[0001] The present application relates to the field of mortar technology, and more specifically, to a high-strength, crack-resistant dry-mixed plaster mortar and a preparation process thereof. Background Art

[0002] As an indispensable material in construction projects, mortar occupies a crucial position in the field due to its excellent plasticity, adhesion, and durability. Furthermore, mortar boasts low cost and a simple preparation process, facilitating large-scale production and application. It plays an irreplaceable role in masonry, plastering, floor paving, and engineering repairs.

[0003] With the rapid development of the construction industry and the continuous improvement of engineering and technical requirements, ordinary mortar can no longer meet current usage needs, especially the problem of insufficient impermeability, making it difficult to use in construction areas with high waterproofing requirements. At present, the existing mortars on the market have many limitations. Traditional mortars produce cracks due to shrinkage during the hydration process, providing channels for water penetration and seriously weakening the waterproofing effect. Although some technologies improve the impermeability of mortar by adding admixtures such as water reducers and polymers, the irrational use of admixtures may affect the cement hydration process and change the internal structure of the mortar, making it difficult to achieve an effective balance between strength and impermeability. The surface spraying waterproof layer has a more obvious effect, but inherent defects such as difficulty in construction, poor durability, and single function restrict the large-scale promotion of this method.

[0004] The patent application document with application publication number CN110423078A proposes a rigid waterproof mortar and its preparation method. This technology enhances the close packing of the gel material system by adding a variety of powder materials, reduces the pores in the mortar, and enhances the strength of the mortar. However, it still has deficiencies in terms of anti-seepage and crack resistance, and it is difficult to meet the waterproofing requirements in complex environments. In addition, the patent application document with publication number CN119683934A proposes an anti-seepage waterproof dry-mix mortar and its preparation method. This technology prepares a fiber reinforcement used as a raw material for dry-mix mortar by treating glass fiber with hydrogen peroxide and bonding it with modified zinc oxide. The fiber reinforcement can increase its contact surface and friction with the mortar matrix, and to a certain extent improve the mechanical properties of the dry-mix mortar. However, this method only optimizes the interface by increasing the surface roughness of the glass fiber, which is difficult to meet the actual high requirements for mortar waterproofing. Summary of the Invention

[0005] In order to further improve the waterproof and anti-seepage performance of mortar, the present application provides a high-strength crack-resistant dry-mixed plaster mortar and a preparation process thereof.

[0006] In the first aspect, the present application provides a high-strength crack-resistant dry-mix plaster mortar, which adopts the following technical solution: A high-strength, crack-resistant dry-mix plaster mortar comprising the following components: cement, aggregate, basalt fiber, composite hydrophobic powder, water-reducing agent, citric acid, and calcium hydroxide; The composite hydrophobic powder material is prepared by reacting modified polysilazane with composite powder; The composite powder includes diatomaceous earth powder and granite powder.

[0007] Preferably, the preparation method of the composite hydrophobic powder material comprises the following steps: 1) uniformly dispersing the modified polysilazane in anhydrous ethanol to obtain a spray liquid; 2) Spray the spraying liquid evenly on the surface of the composite powder and dry it.

[0008] Preferably, the mass ratio of modified polysilazane to composite powder is 1:(28-32).

[0009] Preferably, in step 1), the preparation method of the modified polysilazane comprises the following steps: The perhydropolysilazane is uniformly dispersed in anhydrous tetrahydrofuran, and the isocyanate derivative A and the isocyanate derivative B are added, mixed evenly, heated to react, and finally the anhydrous tetrahydrofuran is removed to obtain the modified polysilazane.

[0010] Preferably, the preparation method of the isocyanate derivative A comprises the following steps: The isocyanate derivative A is obtained by uniformly dispersing the isocyanate compound in anhydrous tetrahydrofuran, adding a long-chain alkyl compound and a catalyst, mixing evenly, heating to react, and finally removing the anhydrous tetrahydrofuran.

[0011] Preferably, the preparation method of the isocyanate derivative B comprises the following steps: Glycine and m-hydroxybenzaldehyde are added to anhydrous tetrahydrofuran to react to obtain a Schiff base solution; An isocyanate compound and a catalyst are added to the Schiff base solution, the temperature is raised to react, and finally anhydrous tetrahydrofuran is removed to obtain the isocyanate derivative B.

[0012] Preferably, the isocyanate compound is trimethylhexamethylene diisocyanate or polymethylene polyphenyl polyisocyanate.

[0013] Preferably, the composite powder in step 2) is prepared by uniformly mixing diatomaceous earth powder and granite powder, drying the mixture at high temperature, and passing the mixture through a sieve.

[0014] Preferably, the long-chain alkyl compound is n-dodecanol or n-hexadecanol.

[0015] In a second aspect, the present application provides a method for preparing high-strength crack-resistant dry-mix plaster mortar, comprising the following steps: The cement, aggregate, and composite hydrophobic powder are weighed in proportion and dry-mixed at a low speed for 30-90 seconds; basalt fiber is added and dry-mixed at a high speed for 30-90 seconds to obtain a dry-mix mixture; a water reducer, citric acid, and water are uniformly mixed, the mixture is added to the dry-mix mixture, and the mixture is stirred at a high speed for 30-90 seconds to obtain an intermediate A; calcium hydroxide and water are uniformly mixed, the intermediate A is added, and the mixture is stirred at a high speed for 30-90 seconds to obtain a high-strength, crack-resistant dry-mix plaster mortar.

[0016] In summary, this application has the following beneficial effects: 1. The composite hydrophobic powder material prepared in the present application contains hydrophilic-hydrophobic amphiphilic groups. Among them, the hydrophilic groups introduced by the Schiff base reaction can form hydrogen bonds with the hydroxyl groups in the mortar system, which promotes the uniform dispersion of the composite hydrophobic powder material in the mortar, and forms a uniformly distributed hydrophobic network inside the mortar; in the later stage of mortar preparation, the pH is controlled by the "citric acid-calcium hydroxide" method, which can induce the shedding of the hydrophilic groups in the composite hydrophobic powder material without affecting the hydration of the mortar, thereby exposing the hydrophobic groups on the surface of the composite hydrophobic powder material. The detached hydrophilic groups can react with the calcium ions generated in the early stage of cement hydration. Combined with the hydrophilic-hydrophobic amphiphilic groups, they form a stable complex, slowing down the hydration reaction rate and providing more favorable conditions for uniform mixing. In summary, the hydrophilic-hydrophobic amphiphilic groups can not only make the composite hydrophobic powder uniformly dispersed, but also bring excellent waterproof and anti-permeability properties to the mortar, achieving the dual effects of optimizing dispersion and improving waterproof and anti-permeability properties.

[0017] 2. When internal stress builds up in the mortar specimen and cracks appear, the basalt fibers within it can absorb some of the stress and disperse it into the surrounding matrix, preventing excessive stress concentration. This enhances the mortar's toughness while delaying or even preventing the initiation and propagation of cracks. Furthermore, the composite hydrophobic powder acts like a ball bearing, reducing friction between the fiber and the matrix, minimizing fiber aggregation in the mortar and ensuring a more even dispersion of the fibers within the mortar.

[0018] 3. The composite hydrophobic powder material in the high-strength, crack-resistant dry-mixed plaster mortar of the present application uses a mixture of diatomaceous earth powder and granite powder as a base material. When the two are compounded in proportion, they can give full play to the advantages of the flexible buffering of diatomaceous earth powder and the rigid support of granite powder. The fine powder particles can fill the pores of the mortar, increase the density of the mortar, enhance the mechanical strength of ordinary mortar, make the stress distribution of the mortar more uniform when under pressure, and improve the strength and compressive resistance of the mortar. DETAILED DESCRIPTION

[0019] The present application is further described in detail below with reference to the embodiments.

[0020] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0021] Example 1 The high-strength, crack-resistant dry-mix plaster mortar of this embodiment is composed of the following components: 50 kg of cement, 125 kg of aggregate, 0.2 kg of basalt fiber, 6.25 kg of composite hydrophobic powder, 0.5 kg of water reducer, 0.25 kg of citric acid, and 0.15 kg of calcium hydroxide; wherein the cement is 42.5 grade ordinary Portland cement; the aggregate is natural river sand with a particle size range of 0.5 to 1.75 mm, a fineness modulus of 2.61, and a mud content of 0.80%, which meets the requirements of the "Construction Sand" (GB / T14684-2011); the basalt fiber is 3 mm in length.

[0022] The preparation method of the modified polysilazane of this embodiment includes the following steps: 42 g of trimethylhexamethylene diisocyanate and 200 ml of anhydrous tetrahydrofuran were added to a single-necked flask and stirred evenly; 48 g of n-hexadecanol and dibutyltin dilaurate were then added; the reaction temperature was raised to 80°C and reacted at this temperature for 6 h. Finally, anhydrous tetrahydrofuran was removed by rotary evaporation to obtain isocyanate derivative A.

[0023] 15g of glycine, 24.4g of m-hydroxybenzaldehyde, and 200ml of anhydrous tetrahydrofuran were added to a single-necked flask and reacted at 40°C for 2 hours to obtain a Schiff base solution. 42g of trimethylhexamethylene diisocyanate and dibutyltin dilaurate were then added. The reaction temperature was then raised to 60°C and allowed to react for 6 hours. Finally, the anhydrous tetrahydrofuran was removed by rotary evaporation to obtain the product, isocyanate derivative B.

[0024] Add 50g of perhydropolysilazane to 200ml of anhydrous tetrahydrofuran, followed by 2g of isocyanate derivative A and 1g of isocyanate derivative B. Stir thoroughly, then raise the reaction temperature to 50°C and allow to react for 8 hours. Remove the anhydrous tetrahydrofuran from the flask using rotary evaporation to obtain the modified polysilazane.

[0025] The preparation method of the composite hydrophobic powder material of this embodiment includes the following steps: 1) Add 30 g of modified polysilazane to 200 ml of anhydrous ethanol and stir evenly with ultrasonic waves to obtain a spray solution; 2) Mix 600 g of diatomaceous earth powder and 300 g of granite powder and dry them in a constant temperature drying oven at 100°C for 2 h. Then, sieve the mixture to obtain a composite powder. Then, place the composite powder in a mixer equipped with a spraying device. While stirring, spray the spray liquid evenly on the surface of the composite powder. Set the stirring speed to 150 rpm and dry it at 60°C.

[0026] The preparation method of the high-strength crack-resistant dry-mix plaster mortar of this embodiment comprises the following steps: 50 kg of cement, 125 kg of aggregate, and 6.25 kg of composite hydrophobic powder were weighed and dry-mixed at low speed for 60 seconds; 0.2 kg of basalt fiber was added and stirred at high speed for 60 seconds to obtain a dry-mixed mixture; 0.5 kg of water reducer and 0.25 kg of citric acid were added to water and mixed evenly, and then added to the dry-mixed mixture and stirred at high speed for 60 seconds to obtain intermediate A; then 0.15 kg of calcium hydroxide was added to water and mixed evenly, and intermediate A was added and stirred at high speed for 60 seconds to obtain high-strength and crack-resistant dry-mixed plaster mortar.

[0027] Example 2 The high-strength, crack-resistant dry-mix plaster mortar of this embodiment is composed of the following components: 50 kg of cement, 125 kg of aggregate, 0.2 kg of basalt fiber, 6.25 kg of composite hydrophobic powder, 0.5 kg of water reducer, 0.25 kg of citric acid, and 0.15 kg of calcium hydroxide; wherein the cement is 42.5 grade ordinary Portland cement; the aggregate is natural river sand with a particle size range of 0.5 to 1.75 mm, a fineness modulus of 2.61, and a mud content of 0.80%, which meets the requirements of the "Construction Sand" (GB / T14684-2011); the basalt fiber is 3 mm in length.

[0028] The preparation method of the modified polysilazane of this embodiment includes the following steps: 42 g of trimethylhexamethylene diisocyanate and 200 ml of anhydrous tetrahydrofuran were added to a single-necked flask and stirred evenly; 48 g of n-hexadecanol and dibutyltin dilaurate were then added; the reaction temperature was raised to 80°C and reacted at this temperature for 6 h. Finally, anhydrous tetrahydrofuran was removed by rotary evaporation to obtain isocyanate derivative A.

[0029] 15g of glycine, 24.4g of m-hydroxybenzaldehyde, and 200ml of anhydrous tetrahydrofuran were added to a single-necked flask and reacted at 40°C for 2 hours to obtain a Schiff base solution. 42g of trimethylhexamethylene diisocyanate and dibutyltin dilaurate were then added. The reaction temperature was then raised to 60°C and allowed to react for 6 hours. Finally, the anhydrous tetrahydrofuran was removed by rotary evaporation to obtain the product, isocyanate derivative B.

[0030] Add 50g of perhydropolysilazane to 200ml of anhydrous tetrahydrofuran, followed by 2.5g of isocyanate derivative A and 0.5g of isocyanate derivative B. After stirring, raise the reaction temperature to 50°C and allow the reaction to proceed for 8 hours. Remove the anhydrous tetrahydrofuran from the flask using rotary evaporation to obtain the modified polysilazane.

[0031] The preparation method of the composite hydrophobic powder material of this embodiment includes the following steps: 1) Add 30 g of modified polysilazane to 200 ml of anhydrous ethanol and stir evenly with ultrasonic waves to obtain a spray solution; 2) Mix 600 g of diatomaceous earth powder and 300 g of granite powder and dry them in a constant temperature drying oven at 100°C for 2 h. Then, sieve the mixture to obtain a composite powder. Then, place the composite powder in a mixer equipped with a spraying device. While stirring, spray the spray liquid evenly on the surface of the composite powder. Set the stirring speed to 150 rpm and dry it at 60°C.

[0032] The preparation method of the high-strength crack-resistant dry-mix plaster mortar of this embodiment comprises the following steps: 50 kg of cement, 125 kg of aggregate, and 6.25 kg of composite hydrophobic powder were weighed and dry-mixed at low speed for 60 seconds; 0.2 kg of basalt fiber was added and stirred at high speed for 60 seconds to obtain a dry-mixed mixture; 0.5 kg of water reducer and 0.25 kg of citric acid were added to water and mixed evenly, and then added to the dry-mixed mixture and stirred at high speed for 60 seconds to obtain intermediate A; then 0.15 kg of calcium hydroxide was added to water and mixed evenly, and then added to intermediate A and stirred at high speed for 60 seconds to obtain high-strength and crack-resistant dry-mixed plaster mortar.

[0033] Example 3 The high-strength, crack-resistant dry-mix plaster mortar of this embodiment is composed of the following components: 50 kg of cement, 125 kg of aggregate, 0.2 kg of basalt fiber, 6.25 kg of composite hydrophobic powder, 0.5 kg of water reducer, 0.25 kg of citric acid, and 0.15 kg of calcium hydroxide; wherein the cement is 42.5 grade ordinary Portland cement; the aggregate is natural river sand with a particle size range of 0.5 to 1.75 mm, a fineness modulus of 2.61, and a mud content of 0.80%, which meets the requirements of the "Construction Sand" (GB / T14684-2011); the basalt fiber is 3 mm in length.

[0034] The preparation method of the modified polysilazane of this embodiment includes the following steps: 30 g of polymethylene polyphenyl polyisocyanate and 200 ml of anhydrous tetrahydrofuran were added to a single-necked flask and stirred evenly; 37.2 g of n-dodecanol and dibutyltin dilaurate were then added; the reaction temperature was raised to 80°C and reacted at this temperature for 6 h. Finally, anhydrous tetrahydrofuran was removed by rotary evaporation to obtain isocyanate derivative A.

[0035] 15g of glycine, 24.4g of m-hydroxybenzaldehyde, and 200ml of anhydrous tetrahydrofuran were added to a single-necked flask and reacted at 40°C for 2 hours to obtain a Schiff base solution. 30g of polymethylene polyphenyl polyisocyanate and dibutyltin dilaurate were then added. The reaction temperature was then raised to 60°C and allowed to react for 6 hours. Finally, the anhydrous tetrahydrofuran was removed by rotary evaporation to obtain the product, isocyanate derivative B.

[0036] Add 50g of perhydropolysilazane to 200ml of anhydrous tetrahydrofuran, followed by 2g of isocyanate derivative A and 1g of isocyanate derivative B. After stirring, raise the reaction temperature to 50°C and allow the reaction to proceed for 8 hours. Remove the anhydrous tetrahydrofuran from the flask using rotary evaporation to obtain the modified polysilazane.

[0037] The preparation method of the composite hydrophobic powder material of this embodiment includes the following steps: 1) Add 30 g of modified polysilazane to 200 ml of anhydrous ethanol and stir evenly with ultrasonic waves to obtain a spray solution; 2) Mix 560 g of diatomaceous earth powder and 280 g of granite powder and dry them in a constant temperature drying oven at 100°C for 2 h. Then, sieve the mixture to obtain a composite powder. Then, place the composite powder in a mixer equipped with a spraying device and spray the spray liquid evenly on the surface of the composite powder while stirring. Set the stirring speed to 150 rpm and dry the mixture at 60°C.

[0038] The preparation method of the high-strength crack-resistant dry-mix plaster mortar of this embodiment comprises the following steps: 50 kg of cement, 125 kg of aggregate, and 6.25 kg of composite hydrophobic powder were weighed and dry-mixed at low speed for 60 seconds; 0.2 kg of basalt fiber was added and stirred at high speed for 60 seconds to obtain a dry-mixed mixture; 0.5 kg of water reducer and 0.25 kg of citric acid were added to water and mixed evenly, and then added to the dry-mixed mixture and stirred at high speed for 60 seconds to obtain intermediate A; then 0.15 kg of calcium hydroxide was added to water and mixed evenly, and then added to intermediate A and stirred at high speed for 60 seconds to obtain high-strength and crack-resistant dry-mixed plaster mortar.

[0039] Comparative Example 1 The high-strength, crack-resistant dry-mixed plaster mortar in this comparative example is composed of the following components: 50 kg of cement, 125 kg of aggregate, 0.2 kg of basalt fiber, 6.25 kg of composite hydrophobic powder, 0.5 kg of water reducer, 0.25 kg of citric acid, and 0.15 kg of calcium hydroxide; wherein, the cement is 42.5 grade ordinary Portland cement; the aggregate is natural river sand with a particle size range of 0.5~1.75 mm, a fineness modulus of 2.61, and a mud content of 0.80%, which meets the requirements of the specification of "Sand for Construction" (GB / T14684-2011); the length of the basalt fiber is 3 mm.

[0040] The preparation method of the composite hydrophobic powder material of this embodiment includes the following steps: 1) Add 30 g of perhydropolysilazane to 200 ml of anhydrous ethanol and stir evenly with ultrasonic stirring to obtain a spray solution; 2) Mix 640 g of diatomaceous earth powder and 320 g of granite powder and dry them in a constant temperature drying oven at 100°C for 2 h. Then, sieve the mixture to obtain a composite powder. Then, place the composite powder in a mixer equipped with a spraying device and evenly spray the spray liquid on the surface of the composite powder while stirring. Set the stirring speed to 150 rpm and dry the mixture at 60°C.

[0041] The preparation method of the high-strength crack-resistant dry-mix plaster mortar of this embodiment comprises the following steps: 50 kg of cement, 125 kg of aggregate, and 6.25 kg of composite hydrophobic powder were weighed and dry-mixed at low speed for 60 seconds; 0.2 kg of basalt fiber was added and stirred at high speed for 60 seconds to obtain a dry-mixed mixture; 0.5 kg of water reducer and 0.25 kg of citric acid were added to water and mixed evenly, and then added to the dry-mixed mixture and stirred at high speed for 60 seconds to obtain intermediate A; then 0.15 kg of calcium hydroxide was added to water and mixed evenly, and then added to intermediate A and stirred at high speed for 60 seconds to obtain high-strength and crack-resistant dry-mixed plaster mortar.

[0042] Comparative Example 2 The high-strength, crack-resistant dry-mixed plaster mortar in this comparative example is composed of the following components: 50 kg of cement, 125 kg of aggregate, 0.2 kg of basalt fiber, 6.25 kg of composite hydrophobic powder, 0.5 kg of water reducer, 0.25 kg of citric acid, and 0.15 kg of calcium hydroxide; wherein, the cement is 42.5 grade ordinary Portland cement; the aggregate is natural river sand with a particle size range of 0.5~1.75 mm, a fineness modulus of 2.61, and a mud content of 0.80%, which meets the requirements of the specification of "Sand for Construction" (GB / T14684-2011); the length of the basalt fiber is 3 mm.

[0043] The preparation method of the modified polysilazane of this embodiment includes the following steps: 1) Add 42 g of trimethylhexamethylene diisocyanate and 200 ml of anhydrous tetrahydrofuran to a single-necked flask and stir evenly. Then add 48 g of n-hexadecanol and dibutyltin dilaurate. Raise the reaction temperature to 80°C and react at this temperature for 6 hours. Finally, remove the anhydrous tetrahydrofuran by rotary evaporation to obtain isocyanate derivative A.

[0044] 2) Add 15g of glycine, 24.4g of m-hydroxybenzaldehyde, and 200ml of anhydrous tetrahydrofuran to a single-necked flask and react at 40°C for 2h to obtain a Schiff base solution. Then, add 42g of trimethylhexamethylene diisocyanate and dibutyltin dilaurate. The reaction temperature is then raised to 60°C and allowed to react for 6h. Finally, remove the anhydrous tetrahydrofuran by rotary evaporation to obtain the product, isocyanate derivative B.

[0045] 3) Add 50g of perhydropolysilazane to 200ml of anhydrous tetrahydrofuran, followed by 2g of isocyanate derivative A and 1g of isocyanate derivative B. Stir thoroughly, then raise the reaction temperature to 50°C and allow to react for 8h. Remove the anhydrous tetrahydrofuran from the flask using rotary evaporation to obtain modified polysilazane.

[0046] The preparation method of the composite hydrophobic powder material of this embodiment includes the following steps: 1) Add 30 g of modified polysilazane to 200 ml of anhydrous ethanol and stir evenly with ultrasonic waves to obtain a spray solution; 2) Dry 900 g of diatomaceous earth powder in a constant temperature drying oven at 100°C for 2 h, then sieve to obtain a composite powder. Then, place the composite powder in a mixer equipped with a spraying device, and spray the spray liquid evenly on the surface of the composite powder while stirring. Set the stirring speed to 150 rpm and dry at 60°C.

[0047] The preparation method of the high-strength crack-resistant dry-mix plaster mortar of this embodiment comprises the following steps: 50 kg of cement, 125 kg of aggregate, and 6.25 kg of composite hydrophobic powder were weighed and dry-mixed at low speed for 60 seconds; 0.2 kg of basalt fiber was added and stirred at high speed for 60 seconds to obtain a dry-mixed mixture; 0.5 kg of water reducer and 0.25 kg of citric acid were added to water and mixed evenly, and then added to the dry-mixed mixture and stirred at high speed for 60 seconds to obtain intermediate A; then 0.15 kg of calcium hydroxide was added to water and mixed evenly, and then added to intermediate A and stirred at high speed for 60 seconds to obtain high-strength and crack-resistant dry-mixed plaster mortar.

[0048] Performance testing According to JGT / T70-2009 "Standard for Test Methods for Basic Properties of Building Mortar", the compressive strength, flexural strength and impermeability of the specimens of the high-strength, crack-resistant dry-mixed plaster mortar prepared in Examples 1-3 and Comparative Examples 1-2 after 28 days of curing were tested. The average value of three measurements was taken as the final value. The test results are shown in Table 1.

[0049] Table 1 Mortar performance test results Analysis of Examples 1-3 and Comparative Examples 1-2 and combined with Table 1 shows that the mortar to which the composite hydrophobic powder is added has excellent waterproof and anti-permeability properties; in Comparative Example 1, the high-strength anti-cracking dry-mixed plaster mortar prepared is not modified for perhydropolysilazane compared to Examples 1-3, which results in poor waterproof and anti-permeability properties of the prepared mortar; compared to Examples 1-3, the high-strength anti-cracking dry-mixed plaster mortar prepared in Comparative Example 2 does not contain granite powder, which results in more voids inside the mortar, providing a channel for water to enter the mortar, and the overall density of the mortar is reduced, thereby reducing the strength and anti-permeability properties of the high-strength anti-cracking dry-mixed plaster mortar prepared in Comparative Example 2.

[0050] Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A high-strength crack-resistant dry-mix plaster mortar, characterized in that: The invention comprises the following components: cement, aggregate, basalt fiber, composite hydrophobic powder, water reducing agent, citric acid and calcium hydroxide; the composite hydrophobic powder is prepared by reacting modified polysilazane with composite powder; the composite powder comprises diatomaceous earth powder and granite powder.

2. A high-strength crack-resistant dry-mix plaster mortar according to claim 1, characterized in that: The preparation method of the composite hydrophobic powder material comprises the following steps: 1) uniformly dispersing the modified polysilazane in anhydrous ethanol to obtain a spray liquid; 2) Spray the spraying liquid evenly on the surface of the composite powder and dry it.

3. A high-strength crack-resistant dry-mix plaster mortar according to claim 2, characterized in that: The mass ratio of modified polysilazane to composite powder is 1:(28-32).

4. The high-strength crack-resistant dry-mix plaster mortar according to claim 2, characterized in that: In step 1), the preparation method of modified polysilazane comprises the following steps: The perhydropolysilazane is uniformly dispersed in anhydrous tetrahydrofuran, and the isocyanate derivative A and the isocyanate derivative B are added, mixed evenly, heated to react, and finally the anhydrous tetrahydrofuran is removed to obtain the product.

5. The high-strength crack-resistant dry-mix plaster mortar according to claim 4, characterized in that: The preparation method of the isocyanate derivative A comprises the following steps: The isocyanate derivative A is obtained by uniformly dispersing the isocyanate compound in anhydrous tetrahydrofuran, adding a long-chain alkyl compound and a catalyst, mixing evenly, heating to react, and finally removing the anhydrous tetrahydrofuran.

6. The high-strength crack-resistant dry-mix plaster mortar according to claim 4, characterized in that: The preparation method of the isocyanate derivative B comprises the following steps: Glycine and m-hydroxybenzaldehyde are added to anhydrous tetrahydrofuran to react to obtain a Schiff base solution; An isocyanate compound and a catalyst are added to the Schiff base solution, the temperature is raised to react, and finally anhydrous tetrahydrofuran is removed to obtain the isocyanate derivative B.

7. A high-strength crack-resistant dry-mix plaster mortar according to claim 5 or 6, characterized in that: The isocyanate compound is trimethylhexamethylene diisocyanate or polymethylene polyphenyl polyisocyanate.

8. The high-strength crack-resistant dry-mix plaster mortar according to claim 2, characterized in that: The composite powder in step 2) is prepared by uniformly mixing diatomaceous earth powder and granite powder, drying the mixture at high temperature, and passing the mixture through a sieve.

9. The high-strength crack-resistant dry-mix plaster mortar according to claim 5, characterized in that: The long-chain alkyl compound is n-dodecanol or n-hexadecanol.

10. A method for preparing high-strength crack-resistant dry-mix plaster mortar, characterized in that: The steps include: The cement, aggregate, and composite hydrophobic powder are weighed in proportion and dry-mixed at a low speed for 30-90 seconds; basalt fiber is added and dry-mixed at a high speed for 30-90 seconds to obtain a dry-mix mixture; a water reducer, citric acid, and water are uniformly mixed, the mixture is added to the dry-mix mixture, and the mixture is stirred at a high speed for 30-90 seconds to obtain an intermediate A; calcium hydroxide and water are uniformly mixed, the intermediate A is added, and the mixture is stirred at a high speed for 30-90 seconds to obtain a high-strength, crack-resistant dry-mix plaster mortar.

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