Nanometer material-based composite dry-mixed waterproof mortar, preparation method and application thereof

Abstract

The application belongs to the technical field of mortar, and specifically provides a composite dry-mixed waterproof mortar based on nanomaterials, a preparation method and application thereof, which comprises the following raw materials: ordinary Portland cement, machine-made sand, modified nanomaterials, redispersible latex powder, hydrophobic agent, water-retaining thickener and water-reducing agent; the modified nanomaterials are prepared by wrapping modified nanosilica with poly-N-isopropyl acrylamide / polyvinyl alcohol gel; the modified nanomaterials improve the performance of the mortar by improving the dispersibility of nanosilica in the mortar. The dry-mixed waterproof mortar prepared by the application has the advantages of anti-permeation and strong durability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mortar, and particularly relates to a composite dry-mixed waterproof mortar based on nanomaterials and a preparation method and application thereof. BACKGROUND

[0002] Waterproof mortar is a key line of defense for building waterproofing, and is often used in basement, kitchen and bathroom and other parts prone to leakage. However, in actual use, ordinary waterproof mortar produces a large number of pores in the hydration process of cement due to the difficulty in forming a close packing between products, further forming capillary channel, so that water can enter the building interior through these channels, threatening the safety of the building structure. On the other hand, in a relatively humid environment for a long time, the erosive medium can also enter the interior of the mortar through the pores, causing cracking, peeling and other phenomena, reducing the service life of the building.

[0003] The use of nanomaterials such as nano-silicon dioxide in waterproof mortar can improve the performance of the mortar in many ways. First, the extremely small particle size of nano-silicon dioxide can fill the small pores inside the mortar and the capillary channels generated during hydration, and its filling pore size and optimized microstructure also enhance the ability of the mortar to resist erosion. Second, nano-silicon dioxide has high activity and can promote cement hydration and improve the early strength of the mortar. However, due to its small particle size and large specific surface area, nano-silicon dioxide particles are prone to agglomeration, and the agglomerated nano-silicon dioxide cannot fully exert its nano effect and easily forms structural defects by occupying the internal space of the mortar.

[0004] The patent application with the publication number CN112661461A discloses a kind of nano-SiO2 high-strength waterproof anti-permeable mortar and its preparation method. In this invention, nano-silicon dioxide is made into a dispersion liquid with polyvinyl alcohol, and is stirred with cement, sand and other materials to obtain mortar. This invention uses the filling effect and hydration reaction promotion of nano-silicon dioxide to improve the performance of the mortar. To some extent, this method can alleviate the agglomeration problem of nano-silicon dioxide. However, in the system of nano-silicon dioxide and polyvinyl alcohol, no chemical grafting modification method is used, and only physical dispersion method is used, which has poor dispersion stability. Physical dispersion does not change the surface properties of nano-silicon dioxide, which still has high surface energy. With the passage of time, nano-particles are easy to overcome the state maintained by physical dispersion and re-agglomerate. Moreover, polyvinyl alcohol and nano-silicon dioxide mainly adsorb each other through hydrogen bonds and van der Waals forces, which have weak adsorption capacity. Nano-silicon dioxide has high polarity, which preferentially forms hydrogen bonds with water molecules in the solution and is easy to fall off and quickly agglomerate. SUMMARY

[0005] To further improve the dispersibility of nano-silicon dioxide and improve the anti-permeability and mechanical properties of the mortar, the application provides a composite dry-mixed waterproof mortar based on nanomaterials.

[0006] The application provides a composite dry-mixed waterproof mortar based on nanomaterials, which is prepared from the following raw materials: ordinary portland cement, machine-made sand, modified nanomaterials, re-dispersible latex powder, hydrophobic agent, water-retaining thickening agent and water-reducing agent.

[0007] The modified nanomaterials are obtained by treating modified nanosilica with poly N-isopropyl acrylamide / polyvinyl alcohol gel.

[0008] The modified nanosilica is obtained by grafting modified cyclodextrin onto the surface of nanosilica.

[0009] Further, the mass ratio of the modified cyclodextrin to nanosilica is 1:(7-9).

[0010] Further, the preparation method of the modified cyclodextrin comprises the following steps: S1, reacting cyclodextrin with p-toluenesulfonyl chloride to generate p-toluenesulfonylated cyclodextrin; S2, reacting linear alkyl alcohol with p-toluenesulfonyl chloride to generate p-toluenesulfonic alkyl ester; S3, reacting p-toluenesulfonylated cyclodextrin with a diamine compound to generate a cyclodextrin derivative; and S4, reacting the cyclodextrin derivative with the p-toluenesulfonic alkyl ester, filtering and drying to obtain the modified cyclodextrin.

[0011] Further, in the step S2, the linear alkyl alcohol is one of n-dodecanol, n-tetradecanol and n-hexadecanol.

[0012] And / or, in the step S3, the diamine compound is one of ethylenediamine, 1,3-propanediamine and 1,4-butanediamine.

[0013] Further, in the step S4, the mass ratio of the cyclodextrin derivative to the p-toluenesulfonic alkyl ester is (1.5-2):1.

[0014] Further, the preparation method of the modified nanomaterials comprises the following steps: dissolving polyvinyl alcohol in deionized water, then adding the modified nanosilica and N-isopropyl acrylamide, uniformly mixing, adding ammonium persulfate and tetramethyl ethylenediamine for polymerization, and freeze-drying.

[0015] Further, the mass ratio of the polyvinyl alcohol, N-isopropyl acrylamide and modified nanosilica is 5:10:(1-1.5).

[0016] Further, the cement is ordinary portland cement with a strength grade of 42.5.

[0017] Further, the machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4, and a stone powder content of ≤10%.

[0018] Further, the redispersible latex powder is at least one of polyvinyl acetate, polyvinyl acetate-ethylene, polyvinyl acetate-tert-carbonate, and polyacrylate-styrene.

[0019] Further, the hydrophobic agent is a silicone-based hydrophobic agent.

[0020] Further, the water-retaining thickening material is at least one of hydroxypropyl methyl cellulose, methyl cellulose, and hydroxyethyl methyl cellulose.

[0021] The application further provides a preparation method of the composite dry-mixed waterproof mortar based on nanomaterials, including the following steps: premixing cement, machine-made sand, and modified nanomaterials; adding redispersible latex powder, a hydrophobic agent, and a water-retaining thickening agent for mixing; adding polycarboxylic acid water reducing agent for stirring to obtain dry-powdered dry-mixed waterproof mortar.

[0022] The application further provides an application of the composite dry-mixed waterproof mortar based on nanomaterials in building waterproofing, water conservancy projects, and industrial facilities.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] 1. The modified nanomaterial prepared by the application is prepared by wrapping modified nanosilica with poly N-isopropyl acrylamide / polyvinyl alcohol gel. After the three-dimensional network structure of the gel wraps the modified nanosilica, the physical barrier formed by the gel molecular chain effectively prevents the agglomeration of the modified nanosilica, thereby improving the dispersibility of the modified nanosilica in water.

[0025] 2、Poly N-isopropyl acrylamide / polyvinyl alcohol gel molecular chain contains hydroxyl, amide bond, can form hydrogen bond with the hydroxyl in the β-cyclodextrin in the modified nano-silica structure, form more stable fixed in the gel network, enhance the stability of the whole gel. At the same time, poly N-isopropyl acrylamide / polyvinyl alcohol gel has a unique lower critical solution temperature, when the mortar hydration process, the temperature is higher than the lower critical solution temperature, the gel from the swelling state to the shrinkage state, release the stored water molecules and with cement particles hydration reaction, accelerate the hydration speed, hydration product and poly-N-isopropyl acrylamide crosslinking interpenetration, improve the mortar density. With the hydration, poly-N-isopropyl acrylamide polymer into a film network structure, bridge the cement hydration product, dispersion and stress, improve the mortar flexural strength. Polyvinyl alcohol exists in the unhydrolyzed vinyl acetate chain, hydrolysis in cement to generate acetate, acetate and calcium ion in cement complexation, prolong the time of calcium ion to supersaturation state, reduce the amount of calcium hydroxide, improve the durability of cement, improve the mechanical properties.

[0026] 3、The steric hindrance effect of the hydrophobic long chain in the modified nano-silica reduces the agglomeration of nano-silica, and after dispersion, the nano-particles fill the mortar capillary pores, reduce the porosity of the mortar, the reduction of the pores makes the stress distribution in the mortar more uniform, improves the mechanical indexes such as compressive strength and flexural strength. In addition, the hydrophobic alkyl long chain connected by the modified nano-silica has a lower surface energy, repels water molecules from penetrating, and improves the impermeability of cement. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The infrared spectrum of the modified β-cyclodextrin and β-cyclodextrin prepared in Example 3 of the application.

[0028] Figure 2 The scanning electron microscope image of the nano-silica of Comparative Example 1 of the application.

[0029] Figure 3 The scanning electron microscope image of the modified nano-silica prepared in Example 3 of the application. DETAILED DESCRIPTION

[0030] The application will be further described in detail below in combination with examples.

[0031] The raw materials of the examples and comparative examples of the application are all ordinary commercial products unless otherwise specified.

[0032] Example 1

[0033] The nanomaterial-based composite dry-mixed waterproof mortar of the embodiment is composed of the following raw materials by weight: ordinary Portland cement 33 kg, machine-made sand 75 kg, modified nanomaterial 0.5 kg, redispersible latex powder 3.6 kg, organic silicon hydrophobic agent 0.5 kg, water-retention thickening material 0.25 kg, and polycarboxylic acid water reducer 0.12 kg.

[0034] The cement is ordinary Portland cement with a strength grade of 42.5. The machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4, and a stone powder content of ≤10%. The redispersible latex powder is type 5010N. The hydrophobic agent is type 6034H. The water-retention thickening material is hydroxypropyl methyl cellulose. The polycarboxylic acid water reducer is type SC-11.

[0035] The preparation method of the modified nanomaterial of the embodiment is as follows: 5 g of polyvinyl alcohol is dissolved in a water (100 mL) bath at 80°C for 30 min, and naturally cooled to room temperature. 1 g of modified nanosilica is added, and ultrasonic treatment is performed for 10 min. 10 g of N-isopropyl acrylamide monomer is added, and stirred until the N-isopropyl acrylamide is completely dissolved to form a uniform mixture. Ammonium persulfate and tetramethyl ethylenediamine are added as a redox initiation system, and reacted at room temperature for 2 h to form N-isopropyl acrylamide polymer chains and physically entangle / mix with the polyvinyl alcohol molecular chains to obtain a poly N-isopropyl acrylamide / polyvinyl alcohol blend system containing nanoparticles. The mixture is frozen at -25°C for 24 h, and thawed at room temperature for 20 min. The above process is referred to as one freezing-thawing process (N=1), and the process is repeated for 7 cycles (N=7) to obtain a hydrogel. The obtained hydrogel is soaked in distilled water for 48 h, and the distilled water is replaced constantly to remove uncrosslinked polymer chains and impurities. The purified hydrogel is freeze-dried to remove water to obtain a dry state poly N-isopropyl acrylamide / polyvinyl alcohol hydrogel containing nanoparticles, which is stored for use.

[0036] The preparation method of the modified nanosilica of the embodiment is as follows: 1.5 g of dry modified β-cyclodextrin is dissolved in 200 mL of anhydrous DMF under stirring, and 0.4 mL of triethoxy (3-isocyanate propyl) silicon is slowly added dropwise at room temperature, and then the temperature is increased to 70°C for reaction for 6 h. Then, 10 g of nanosilica (average particle size 50±5 nm) is added to the above solution, and the temperature is increased to 110°C for continuous reaction for 24 h. After cooling to room temperature, the crude product is filtered, and repeatedly washed with DMF, methanol and acetone until the filtrate is clear. Finally, the solid is vacuum dried at 85°C for 6 h to obtain the modified β-cyclodextrin modified nanosilica material.

[0037] The preparation method of the modified β-cyclodextrin of the embodiment includes the following steps:

[0038] S1. 10 g of β-cyclodextrin was dissolved in 100 mL of aqueous NaOH solution (1 wt%) and stirred in an ice-water bath until completely dissolved. 1.68 g of p-toluenesulfonyl chloride was dissolved in 5 mL of acetonitrile and slowly added to the reaction system using a constant pressure dropping funnel. White precipitates gradually separated out. After stirring the reaction for 2 h, NH4Cl was added to adjust the pH of the solution to 8, and a large amount of white material precipitated out. The solution was washed twice with deionized water and ethanol, respectively, and filtered under suction. The filter cake was dried under vacuum to obtain mono-6-p-toluenesulfonyl-β-cyclodextrin.

[0039] S2. 10 g of n-hexadecanol was dissolved in dichloromethane solution. A solution containing 7.9 g of p-toluenesulfonyl chloride in dichloromethane was slowly added to the solution in an ice-water bath, and the dropwise addition was completed in 30 min. After stirring the reaction in an ice-water bath for 1 h and then at 30°C for 5 h, a light yellow solid was obtained by distillation under reduced pressure. The solid was washed twice with water, filtered under suction, and dried under vacuum to obtain hexadecyl tosylate.

[0040] S3. In a three-necked flask equipped with a reflux condenser, 5 g of mono-6-p-toluenesulfonyl-β-cyclodextrin was added, and excess ethylenediamine was added under nitrogen protection. After being warmed to 70°C, the reaction was stirred for 4 h. The excess ethylenediamine was removed by distillation under reduced pressure at this temperature to obtain a light yellow solid. The solid was dissolved in a small amount of water, precipitated with anhydrous ethanol, filtered under suction, and dried under vacuum to obtain white powder, which was vacuum dried to obtain mono-[6-(2-aminoethyl)-amino-6-deoxy]-cyclodextrin.

[0041] S4. In a three-necked flask equipped with a reflux condenser and a dropping funnel, mono-[6-(2-aminoethyl)-amino-6-deoxy]-β-cyclodextrin and hexadecyl tosylate were added in a mass ratio of 1.5:1, and 50 mL of N-methyl pyrrolidone (NMP) was added. The reaction mixture was stirred for 30 min to ensure uniform mixing. The temperature was raised to 70°C, and the reaction was stirred for 6 h. The unreacted starting materials were removed by washing the light yellow solid obtained by filtration under suction with NMP, and the light yellow solid was dried under vacuum to obtain the modified cyclodextrin.

[0042] The preparation method of the nanomaterial-based composite type dry-mixed waterproof mortar of the present embodiment is as follows: ordinary Portland cement, machine-made sand, and modified nanomaterials were weighed and pre-mixed in a mixer for 5 min at a rotation speed of ≤30 r / min; 5010N redispersible latex powder, 6034H water repellent, and hydroxypropyl methylcellulose were mixed for 10 min (the rotation speed was increased to 45 r / min); and polycarboxylic acid water reducer SC11 was added and stirred at a low speed for 5 min to prepare a dry-mixed waterproof mortar in the form of dry powder.

[0043] Example 2

[0044] The nanomaterial-based composite dry-mixed waterproof mortar of the embodiment is composed of the following raw materials by weight: ordinary Portland cement 32 kg, machine-made sand 78 kg, modified nanomaterial 0.6 kg, redispersible latex powder 4.2 kg, hydrophobic agent 0.55 kg, water-retention thickening material 0.28 kg, and polycarboxylic acid water reducer 0.15 kg.

[0045] The cement is ordinary Portland cement with a strength grade of 42.5. The machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4, and a stone powder content of ≤10%. The redispersible latex powder is type 5010N. The hydrophobic agent is type 6034H. The water-retention thickening material is hydroxypropyl methyl cellulose. The polycarboxylic acid water reducer is type SC-11.

[0046] The preparation method of the modified nanomaterial of the embodiment is as follows: 5 g of polyvinyl alcohol is dissolved in a water (100 mL) bath at 80°C for 30 min, and naturally cooled to room temperature. 1.5 g of modified nanosilica is added, and ultrasonic treatment is performed for 10 min. 10 g of N-isopropyl acrylamide monomer is added, and stirred until the N-isopropyl acrylamide is completely dissolved to form a uniform mixture. Ammonium persulfate and tetramethyl ethylenediamine are added as a redox initiation system, and reaction is performed at room temperature for 2 h to form N-isopropyl acrylamide polymer chains and physically entangle / mix with polyvinyl alcohol molecular chains to obtain a poly N-isopropyl acrylamide / polyvinyl alcohol blend system containing nanoparticles. The mixture is frozen at -25°C for 24 h, and thawed at room temperature for 20 min. The above process is referred to as one freezing-thawing process (N=1), and the process is repeated for 7 cycles (N=7) to obtain a hydrogel. The obtained hydrogel is soaked in distilled water for 48 h, and distilled water is replaced continuously to remove uncrosslinked polymer chains and impurities. The purified hydrogel is freeze-dried to remove water to obtain a dry poly N-isopropyl acrylamide / polyvinyl alcohol hydrogel containing nanoparticles, which is stored for use.

[0047] The preparation method of the modified nanosilica of the embodiment is as follows: 1.5 g of dry modified β-cyclodextrin is dissolved in 200 mL of anhydrous DMF under stirring, and 0.4 mL of triethoxy (3-isocyanate propyl) silicon is slowly added dropwise at room temperature. After the dropwise addition is completed, the temperature is increased to 70°C, and reaction is performed for 6 h. Then, 12 g of nanosilica (average particle size 50±5 nm) is added to the above solution, the temperature is increased to 110°C, and reaction is continued for 24 h. After cooling to room temperature, the crude product is filtered, and repeatedly washed with DMF, methanol, and acetone until the filtrate is clear. Finally, the solid is vacuum dried at 85°C for 6 h to obtain a modified β-cyclodextrin modified nanosilica material.

[0048] The preparation method of the modified β-cyclodextrin of the embodiment includes the following steps:

[0049] S1. 10 g of β-cyclodextrin was dissolved in 100 mL of aqueous NaOH solution (1 wt%) and stirred in an ice-water bath until completely dissolved. 1.68 g of p-toluenesulfonyl chloride was dissolved in 5 mL of acetonitrile and slowly added to the reaction system using a constant pressure dropping funnel. White precipitates gradually separated out. After stirring the reaction for 2 h, NH4Cl was added to adjust the pH of the solution to 8, and a large amount of white material precipitated out. The solution was washed twice with deionized water and ethanol, respectively, and filtered under suction. The filter cake was dried under vacuum to obtain mono-6-p-toluenesulfonyl-β-cyclodextrin.

[0050] S2. 10 g of n-hexadecanol was dissolved in dichloromethane solution. A solution containing 7.9 g of p-toluenesulfonyl chloride in dichloromethane was slowly added to the solution in an ice-water bath, and the dropwise addition was completed in 30 min. After stirring the reaction in an ice-water bath for 1 h and then at 30°C for 5 h, a light yellow solid was obtained by distillation under reduced pressure. The solid was washed twice with water, filtered under suction, and dried under vacuum to obtain hexadecyl tosylate.

[0051] S3. In a three-necked flask equipped with a reflux condenser, 5 g of mono-6-p-toluenesulfonyl-β-cyclodextrin was added, and excess ethylenediamine was added under nitrogen protection. After being warmed to 70°C, the reaction was stirred for 4 h. The excess ethylenediamine was removed by distillation under reduced pressure at this temperature to obtain a light yellow solid. The solid was dissolved in a small amount of water, precipitated with anhydrous ethanol, filtered under suction, and dried under vacuum to obtain white powder, which was vacuum dried to obtain mono-[6-(2-aminoethyl)-amino-6-deoxy]-cyclodextrin.

[0052] S4. In a three-necked flask equipped with a reflux condenser and a dropping funnel, mono-[6-(2-aminoethyl)-amino-6-deoxy]-β-cyclodextrin and hexadecyl tosylate were added in a mass ratio of 1.5:1, and 50 mL of N-methyl pyrrolidone (NMP) was added. The reaction mixture was stirred for 30 min to ensure uniform mixing. The temperature was raised to 70°C, and the reaction was stirred for 6 h. The unreacted starting materials were removed by washing the light yellow solid obtained by filtration under suction with NMP, and the light yellow solid was dried under vacuum to obtain the modified cyclodextrin.

[0053] The preparation method of the nanomaterial-based composite type dry-mixed waterproof mortar of the present embodiment is as follows: ordinary Portland cement, machine-made sand, and modified nanomaterials were weighed and pre-mixed in a mixer for 5 min at a rotation speed of ≤30 r / min; 5010N redispersible latex powder, 6034H water repellent, and hydroxypropyl methylcellulose were mixed for 10 min (the rotation speed was increased to 45 r / min); and polycarboxylic acid water reducer SC11 was added and stirred at a low speed for 5 min to prepare dry powder type dry-mixed waterproof mortar.

[0054] Example 3

[0055] The nanomaterial-based composite dry-mixed waterproof mortar of the embodiment is composed of the following raw materials by weight: ordinary Portland cement 34 kg, machine-made sand 80 kg, modified nanomaterial 0.8 kg, redispersible latex powder 4.5 kg, hydrophobic agent 0.6 kg, water-retention thickening material 0.3 kg, and polycarboxylic acid water reducer 0.17 kg.

[0056] The cement is ordinary Portland cement with a strength grade of 42.5. The machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4, and a stone powder content of ≤10%. The redispersible latex powder is type 5010N. The hydrophobic agent is type 6034H. The water-retention thickening material is hydroxypropyl methyl cellulose. The polycarboxylic acid water reducer is type SC-11.

[0057] The preparation method of the modified nanomaterial of the embodiment is as follows: 5 g of polyvinyl alcohol is dissolved in a 100 mL water bath at 80°C for 30 min, and naturally cooled to room temperature. 1 g of modified nanosilica is added, and ultrasonic treatment is performed for 10 min. 10 g of N-isopropyl acrylamide monomer is added, and stirred until the N-isopropyl acrylamide is completely dissolved to form a uniform mixture. Ammonium persulfate and tetramethyl ethylenediamine are added as a redox initiation system, and reacted at room temperature for 2 h to form N-isopropyl acrylamide polymer chains and physically entangle / mix with the polyvinyl alcohol molecular chains to obtain a poly N-isopropyl acrylamide / polyvinyl alcohol blend system containing nanoparticles. The mixture is frozen at -25°C for 24 h, and thawed at room temperature for 20 min. The above process is referred to as one freezing-thawing process (N=1), and the process is repeated for 7 cycles (N=7) to obtain a hydrogel. The obtained hydrogel is soaked in distilled water for 48 h, and the distilled water is replaced constantly to remove uncrosslinked polymer chains and impurities. The purified hydrogel is freeze-dried to remove water to obtain a dry poly N-isopropyl acrylamide / polyvinyl alcohol hydrogel containing nanoparticles, which is stored for use.

[0058] The preparation method of the modified nanosilica of the embodiment is as follows: 1.5 g of dry modified β-cyclodextrin is dissolved in 200 mL of anhydrous DMF under stirring, and 0.4 mL of triethoxy (3-isocyanate propyl) silicon is slowly added dropwise at room temperature. After the dropwise addition is completed, the temperature is increased to 70°C, and the reaction is continued for 6 h. Then, 10 g of nanosilica (average particle size 50±5 nm) is added to the above solution, the temperature is increased to 110°C, and the reaction is continued for 24 h. After cooling to room temperature, the crude product is filtered, and repeatedly washed with DMF, methanol, and acetone until the filtrate is clear. Finally, the solid is vacuum dried at 85°C for 6 h to obtain the modified β-cyclodextrin modified nanosilica material.

[0059] The preparation method of the modified β-cyclodextrin of the embodiment includes the following steps:

[0060] S1. 10 g of β-cyclodextrin was dissolved in 100 mL of aqueous NaOH solution (1 wt%) and stirred in an ice-water bath until completely dissolved. 1.68 g of p-toluenesulfonyl chloride was dissolved in 5 mL of acetonitrile and slowly added to the reaction system using a constant pressure dropping funnel. White precipitates gradually separated out. After stirring the reaction for 2 h, NH4Cl was added to adjust the pH of the solution to 8, and a large amount of white material precipitated out. The solution was washed twice with deionized water and ethanol, respectively, and filtered under suction. The filter cake was dried under vacuum to obtain mono-6-p-toluenesulfonyl-β-cyclodextrin.

[0061] S2. 10 g of n-hexadecanol was dissolved in dichloromethane solution. A solution containing 7.9 g of p-toluenesulfonyl chloride in dichloromethane was slowly added to the solution in an ice-water bath, and the dropwise addition was completed in 30 min. After stirring the reaction in an ice-water bath for 1 h and then at 30°C for 5 h, a light yellow solid was obtained by distillation under reduced pressure. The solid was washed twice with water, filtered under suction, and dried under vacuum to obtain hexadecyl tosylate.

[0062] S3. In a three-necked flask equipped with a reflux condenser, 5 g of mono-6-p-toluenesulfonyl-β-cyclodextrin was added, and excess ethylenediamine was added under nitrogen protection. After being warmed to 70°C, the reaction was stirred for 4 h. The excess ethylenediamine was removed by distillation under reduced pressure at this temperature to obtain a light yellow solid. The solid was dissolved in a small amount of water, precipitated with anhydrous ethanol, filtered under suction, and dried under vacuum to obtain white powder, which was vacuum dried to obtain mono-[6-(2-aminoethyl)-amino-6-deoxy]-cyclodextrin.

[0063] S4. In a three-necked flask equipped with a reflux condenser and a dropping funnel, mono-[6-(2-aminoethyl)-amino-6-deoxy]-β-cyclodextrin and hexadecyl tosylate were added in a mass ratio of 1.5:1, and 50 mL of N-methyl pyrrolidone (NMP) was added. The reaction mixture was stirred for 30 min to ensure uniform mixing. The temperature was raised to 70°C, and the reaction was stirred for 6 h. The unreacted starting materials were removed by washing the light yellow solid obtained by filtration under suction with NMP, and the light yellow solid was dried under vacuum to obtain the modified cyclodextrin.

[0064] The preparation method of the nanomaterial-based composite type dry-mixed waterproof mortar of the embodiment is as follows: ordinary Portland cement, machine-made sand, and modified nanomaterials were weighed and pre-mixed in a mixer for 5 min at a rotation speed of ≤30 r / min; 5010N redispersible latex powder, 6034H water repellent, and hydroxypropyl methylcellulose were mixed for 10 min (the rotation speed was increased to 45 r / min); and polycarboxylic acid water reducer SC11 was added and stirred at a low speed for 5 min to prepare a dry-mixed waterproof mortar in the form of dry powder.

[0065] Comparative Example 1

[0066] The nanomaterial-based composite dry-mixed waterproof mortar of the present comparative example is composed of the following raw materials by weight: ordinary portland cement 33 kg, machine-made sand 75 kg, nanometer silicon dioxide (average particle size 50±5 nm) 0.4 kg, redispersible latex powder 3.6 kg, hydrophobic agent 0.5 kg, water-retention thickening material 0.25 kg, and polycarboxylic acid water reducer 0.12 kg.

[0067] The cement is ordinary portland cement with a strength grade of 42.5. The machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4, and a stone powder content of ≤10%. The redispersible latex powder is of type 5010N. The hydrophobic agent is of type 6034H. The water-retention thickening material is hydroxypropyl methyl cellulose. The polycarboxylic acid water reducer is of type SC-11.

[0068] The preparation method of the nanomaterial-based composite dry-mixed waterproof mortar of the present comparative example is as follows: the ordinary portland cement, machine-made sand, and nanometer silicon dioxide are weighed and added into a mixer for pre-mixing for 5 minutes at a speed of ≤30 r / min; the 5010N redispersible latex powder, 6034H hydrophobic agent, and hydroxypropyl methyl cellulose are mixed for 10 minutes (the speed is increased to 45 r / min); and the polycarboxylic acid water reducer SC11 is added and stirred at a low speed for 5 minutes to obtain dry-mixed waterproof mortar in the form of dry powder.

[0069] Comparative Example 2

[0070] The nanomaterial-based composite dry-mixed waterproof mortar of the present comparative example is composed of the following raw materials by weight: ordinary portland cement 33 kg, machine-made sand 75 kg, β-cyclodextrin modified nanometer silicon dioxide 0.4 kg, redispersible latex powder 3.6 kg, hydrophobic agent 0.5 kg, water-retention thickening material 0.25 kg, and polycarboxylic acid water reducer 0.12 kg.

[0071] The cement is ordinary portland cement with a strength grade of 42.5. The machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4, and a stone powder content of ≤10%. The redispersible latex powder is of type 5010N. The hydrophobic agent is of type 6034H. The water-retention thickening material is hydroxypropyl methyl cellulose. The polycarboxylic acid water reducer is of type SC-11.

[0072] The preparation method of the modified nanometer silicon dioxide of the present comparative example is as follows: 1.3 g of dry β-cyclodextrin is dissolved in 200 mL of anhydrous DMF under stirring, 0.4 mL of triethoxy (3-isocyanate propyl) silicon is slowly dropped at room temperature, and the temperature is raised to 70°C for 6 h of reaction, then 10 g of nanometer silicon dioxide (average particle size 50±5 nm) is added to the above solution, the temperature is raised to 110°C for 24 h of continuous reaction, and after cooling to room temperature, the crude product is obtained after filtration, and then repeatedly washed with DMF, methanol and acetone until the filtrate is clear, and finally the solid is vacuum dried at 85°C for 6 h to obtain the β-cyclodextrin modified nanometer silicon dioxide material.

[0073] The preparation method of the nanometer material based composite type dry-mixed waterproof mortar of the present comparative example is as follows: the ordinary portland cement, machine-made sand and β-cyclodextrin modified nanometer silicon dioxide are weighed by weight and pre-mixed in a blender for 5 minutes at a speed of ≤30 r / min; 5010N redispersible latex powder, 6034H water repellent and hydroxypropyl methyl cellulose are added and mixed for 10 minutes (the speed is raised to 45 r / min); and polycarboxylic acid water reducing agent SC11 is added and stirred at low speed for 5 minutes to prepare dry powder type dry-mixed waterproof mortar.

[0074] Comparative Example 3

[0075] The nanometer material based composite type dry-mixed waterproof mortar of the present comparative example is composed of the following raw materials by weight: ordinary portland cement 32 kg, machine-made sand 78 kg, modified β-cyclodextrin modified nanometer silicon dioxide 0.6 kg, redispersible latex powder 4.2 kg, water repellent 0.55 kg, water-retaining thickening material 0.28 kg, and polycarboxylic acid water reducing agent 0.15 kg.

[0076] Among them, the cement is ordinary portland cement with a strength grade of 42.5. The machine-made sand has a fineness modulus of 2.3-3.0, an MB value of ≤1.4 and a stone powder content of ≤10%. The redispersible latex powder is type 5010N. The water repellent is type 6034H. The water-retaining thickening material is hydroxypropyl methyl cellulose. The polycarboxylic acid water reducing agent is type SC-11.

[0077] The preparation method of the modified β-cyclodextrin modified nanometer silicon dioxide of the present comparative example is as follows: 1.5 g of dry modified β-cyclodextrin is dissolved in 200 mL of anhydrous DMF under stirring, 0.4 mL of triethoxy (3-isocyanate propyl) silicon is slowly dropped at room temperature, and the temperature is raised to 70°C for 6 h of reaction, then 10 g of nanometer silicon dioxide (average particle size 50±5 nm) is added to the above solution, the temperature is raised to 110°C for 24 h of continuous reaction, and after cooling to room temperature, the crude product is obtained after filtration, and then repeatedly washed with DMF, methanol and acetone until the filtrate is clear, and finally the solid is vacuum dried at 85°C for 6 h to obtain the modified β-cyclodextrin modified nanometer silicon dioxide material.

[0078] The preparation method of the modified β-cyclodextrin of the present comparative example comprises the following steps:

[0079] S1. 10 g of β-cyclodextrin was added into 100 mL of an aqueous NaOH solution (1 wt%), and stirred in an ice water bath until completely dissolved. 1.68 g of p-toluenesulfonyl chloride was dissolved in 5 mL of acetonitrile, and slowly added into the reaction system through a constant pressure dropping funnel, and white precipitate gradually separated out. After stirring the reaction for 2 h, ammonium chloride was added to adjust the pH value of the solution to 8, and a large amount of white substance separated out. The product was washed with deionized water and ethanol for 2 times respectively, and filtered under suction, and the filter cake was dried under vacuum to obtain mono-6-p-toluenesulfonyl-β-cyclodextrin.

[0080] S2. 10 g of n-hexadecanol was dissolved in dichloromethane solution, and a dichloromethane solution containing 7.9 g of p-toluenesulfonyl chloride was slowly added into the solution system in an ice water bath, and the dropping was completed in 30 min. After reaction in the ice water bath for 1 h, reaction was continued at 30°C for 5 h, and light yellow solid was obtained by distillation under reduced pressure. The product was washed with water for 2 times, filtered under suction, and dried under vacuum to obtain hexadecyl tosylate.

[0081] S3. In a three-necked flask equipped with a reflux condenser, 5 g of mono-6-p-toluenesulfonyl-β-cyclodextrin was added, and excess ethylenediamine was added under nitrogen protection. After being warmed to 70°C, the reaction was stirred for 4 h. The excess ethylenediamine was removed by distillation under reduced pressure at the temperature, and light yellow solid was obtained. The product was dissolved in a small amount of water, and precipitated with anhydrous ethanol. The white powder was obtained by filtering under suction, and dried under vacuum to obtain mono-[6-(2-aminoethyl)-amino-6-deoxy]-cyclodextrin.

[0082] S4. In a three-necked flask equipped with a reflux condenser and a dropping funnel, mono-[6-(2-aminoethyl)-amino-6-deoxy]-β-cyclodextrin and hexadecyl tosylate were added according to a mass ratio of 1.5:1, and 50 mL of N-methyl pyrrolidone (NMP) was added. The reactants were stirred for 30 min to be fully mixed and uniform. The temperature was raised to 70°C, and the reaction was stirred for 6 h. Light yellow solid was obtained by filtering under suction. The unreacted raw materials were removed by washing with NMP, and the light yellow solid obtained by filtering under suction was dried under vacuum to obtain the modified cyclodextrin.

[0083] The preparation method of the composite type dry-mixed waterproof mortar based on nanomaterials of the present comparative example is as follows: ordinary Portland cement, machine-made sand, and modified β-cyclodextrin modified nanosilica were weighed according to the weight, and pre-mixed in a stirrer for 5 min at a rotation speed of ≤30 r / min; 5010N redispersible latex powder, 6034H hydrophobic agent, and hydroxypropyl methyl cellulose were mixed for 10 min (the rotation speed was raised to 45 r / min); and polycarboxylic acid water reducer SC11 was low-speed stirred for 5 min to prepare dry-mixed waterproof mortar in the form of dry powder.

[0084] Performance detection

[0085] 1. According to JGJ / T 70-2009 "Standard for Testing Methods of Basic Properties of Building Mortar", the permeability of the mortar was determined by using a mortar permeability instrument. The sample was a truncated cone with a size of 70 mm x 80 mm x 30 mm. The mortar test piece was standard cured for 28 days, then sealed around the annular part of the test piece with heated paraffin, pressurized to 0.2 MPa, and then pressurized to 0.3 MPa after 2 hours of constant pressure. Thereafter, the pressure was increased by 0.1 MPa every 1 hour. When water seeped out of the surface of 3 of the 6 test pieces, the test was immediately stopped, and the data was recorded. The test results are shown in Table 1.

[0086] 2. According to "Cement Mortar Strength Test Method (ISO Method)", the compressive and flexural strength of the mortar was tested by using a cement mortar compressive and flexural strength integrated machine. The prepared mortar was filled into a 40 mm x 40 mm x 160 mm test mold in two times, and three test blocks were prepared for each test group to test the compressive and flexural strength. The mortar test blocks were standard cured for 28 days, and then the strength test was performed. The flexural strength test was performed first, and then the compressive strength test was performed on the fractured mortar test blocks. The strength value was calculated as the average value of the three test blocks. The test results are shown in Table 1.

[0087] Table 1: Test data of the permeability and mechanical properties of the mortar of Examples 1-3 and Comparative Examples 1-3

[0088]

[0089] Analysis of Examples 1-3 and Comparative Examples 1-3 and Table 1 shows that the waterproof mortar with modified nano-silica wrapped with poly N-isopropyl acrylamide / polyvinyl alcohol gel has good impermeable pressure and mechanical properties. In Comparative Example 1, the added nano-silica was not modified, and the dispersion was not uniform, the compressive strength and flexural strength were lower than those of Examples 1-3. In Comparative Example 2, the added β-cyclodextrin modified nano-silica had limited improvement in hydrophobicity and slightly improved impermeable pressure compared to Comparative Example 1. In Comparative Example 3, the added modified β-cyclodextrin modified nano-silica further improved the hydrophobicity compared to Comparative Examples 1-2.

[0090] 3. The impermeability and dispersion performance of the mortar of Example 3 and Comparative Example 1 was determined using a mortar permeameter, according to the following specific scheme: first, the mortar was prepared according to the preparation method of Example 3 into a test piece with a size of 210 mm x 140 mm x 30 mm, and the water-cement ratio was 0.40. The test piece was divided into six parts with a size of 70 mm x 70 mm x 30 mm, and was marked as A1, A2, A3, A4, A5 and A6. The mortar test piece was standard cured for 28 days, and then was sealed around the test piece with heated paraffin. The test piece was pressurized to 0.2 MPa, and was kept for 2 hours. Then the pressure was increased to 0.3 MPa, and was increased by 0.1 MPa every 1 hour. When water appeared on the surface of the test piece, the test was stopped immediately, and the data was recorded. The test was repeated for three times, and the average value was taken. The results are shown in Table 2. The impermeability and dispersion performance of the mortar of Comparative Example 1 was determined according to the same scheme. The test piece of Comparative Example 1 was divided into six parts, and was marked as B1, B2, B3, B4, B5 and B6.

[0091] Table 2. The impermeability and dispersion performance data of the mortar of Example 3 and Comparative Example 1

[0092]

[0093] It can be seen from the analysis of the impermeability and dispersion performance data of the mortar of Example 3 and Comparative Example 1 and Table 2 that the impermeability pressure of the test pieces A1-A6 fluctuates in a small range, and the data is stable, which indicates that the modified nanometer material is uniformly dispersed in the waterproof mortar. The impermeability pressure of the test pieces B1-B6 fluctuates in a large range, which indicates that the dispersion of the nanometer silicon dioxide added in Comparative Example 1 is poor.

[0094] 4. The functional groups of the modified β-cyclodextrin prepared in Example 3 were characterized using a TENSOR 27 Fourier infrared spectrometer of BRUKER company. The specific steps are as follows: 200 mg of KBr and 1 mg of the test substance were put into an agate mortar and were finely ground. The thin slice was pressed and tested. The scanning wavelength range was 4000-400 cm -1 , and the results are shown in Figure 1 .

[0095] The analysis results show that the modified β-cyclodextrin has a new N-H bending vibration peak at 1650-1550 cm -1 , which is the structure of the connected ethylenediamine; and the peak intensity at 2920 cm -1 is significantly enhanced, which is the asymmetric methylene stretching vibration peak in the connected n-hexanol.

[0096] 5. The nanometer silicon dioxide of Comparative Example 1 and the modified nanometer silicon dioxide prepared in Example 3 were observed using a scanning electron microscope, and the obtained images are shown in Figure 2 and Figure 3 .

[0097] Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified by those skilled in the art, or some of the technical features can be replaced by equivalents, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A composite type dry-mixed waterproofing mortar based on nanomaterials, characterized in that it comprises: The application relates to a dry-mixed waterproof mortar, which comprises the following raw materials: ordinary portland cement, machine-made sand, modified nanomaterial, redispersible latex powder, water-repellent agent, water-retention thickening agent and water-reducing agent; the preparation method of the modified nanomaterial comprises the following steps: dissolving polyvinyl alcohol in deionized water, then adding modified nanosilica and N-isopropyl acrylamide, uniformly mixing, adding ammonium persulfate and tetramethylethylenediamine for polymerization, and freeze-drying to obtain the modified nanomaterial; the modified nanosilica is prepared by grafting modified cyclodextrin onto the surface of nanosilica; the preparation method of the modified cyclodextrin comprises the following steps: S1, reacting cyclodextrin with p-toluenesulfonyl chloride to generate p-toluenesulfonylated cyclodextrin; S2, reacting linear alkyl alcohol with p-toluenesulfonyl chloride to generate p-toluenesulfonic acid alkyl ester; S3, reacting p-toluenesulfonylated cyclodextrin with a diamine compound to generate a cyclodextrin derivative; and S4, reacting the cyclodextrin derivative with the p-toluenesulfonic acid alkyl ester, filtering and drying to obtain the modified cyclodextrin.

2. The nanomaterial-based composite dry-mixed waterproof mortar according to claim 1, characterized in that: The mass ratio of the modified cyclodextrin to nanosilica is 1:(7-9).

3. The nanomaterial-based composite dry-mixed waterproof mortar according to claim 1, characterized in that: In the step S2, the linear alkyl alcohol is one of n-dodecanol, n-tetradecanol and n-hexadecanol. In the step S3, the diamine compound is one of ethylenediamine, 1,3-propanediamine and 1,4-butanediamine.

4. The nanomaterial-based composite dry-mixed waterproof mortar according to claim 1, characterized in that: In the step S4, the mass ratio of the cyclodextrin derivative to the p-toluenesulfonic acid alkyl ester is (1.5-2):

1.

5. The nanomaterial-based composite dry-mixed waterproof mortar according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol, N-isopropyl acrylamide and modified nanosilica is 5:10:(1-1.5).

6. A method for preparing the nanomaterial-based composite dry-mixed waterproof mortar according to any one of claims 1-5, characterized in that, The application further discloses a preparation method of the dry-mixed waterproof mortar.

7. Use of a nanomaterial-based composite dry-mixed waterproofing mortar, characterized in that: The mortar prepared by the preparation method is used for building waterproofing, water conservancy projects and industrial facilities.

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