An impact-resistant epoxy resin modified mortar and a method for preparing the same

Abstract

The application discloses an impact-resistant and wear-resistant epoxy resin modified mortar and a preparation method thereof, and relates to the technical field of mortar.The application comprises the following raw materials in mass parts: deionized water 170-190 parts, modified boron nitride synergist 13.13-14.38 parts, water reducing agent 0.8-1.2 parts, tributyl phosphate 0.6-0.8 parts, composite modified porous polysiloxane microspheres 26.25-28.75 parts, water-based epoxy resin 21-23 parts, Portland cement 420-460 parts, sulphoaluminate cement 105-115 parts, concrete expansive agent 15.75-17.25 parts, river sand 1050-1150 parts, water-based epoxy curing agent 27.3-29.9 parts.The introduction of the modified boron nitride synergist and other raw materials in the application simultaneously improves the compressive strength, the bending strength, the impact strength, the wear resistance, the anti-cavitation ability, the aging resistance and the alkali corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an impact-resistant epoxy resin modified mortar and its preparation method. Background Technology

[0002] Epoxy resin modified mortar has been widely used in water conservancy projects for erosion and wear resistance repair of flood discharge structures, bridge deck paving, industrial floor wear-resistant layers, and concrete structure defect repair due to its advantages such as high bonding strength, chemical corrosion resistance, and convenient construction. It is a key engineering material for solving the problems of easy wear and cracking of concrete structures.

[0003] However, in practical applications, epoxy resin modified mortar still has the following performance shortcomings: First, it is difficult to improve strength and toughness in a coordinated manner. Pure epoxy resin mortar has excellent toughness but insufficient compressive strength. Although the strength of modified mortar with high cement content is improved, its brittleness is significantly increased, and it is prone to brittle fracture under load. Second, it has insufficient impact and abrasion resistance. Under the long-term abrasion and impact load of high-speed water flow carrying mud, sand and gravel, the surface is prone to peeling and wear, and the service life is greatly shortened. Third, it has weak cavitation resistance. In the high-speed water flow area of ​​water conservancy projects, the micro-jet and shock wave generated by the collapse of cavitation bubbles will cause rapid erosion of the mortar surface, forming honeycomb-like pores. Fourth, it has poor long-term durability. Epoxy resin is prone to aging and degradation under outdoor ultraviolet radiation, humid heat cycle and other environments. At the same time, the high alkalinity of the cement matrix will erode the epoxy-inorganic interface, resulting in a decrease in interfacial adhesion. Therefore, the compressive strength, flexural strength, impact strength, wear resistance, cavitation resistance, aging resistance and alkali corrosion resistance of existing epoxy resin modified mortars still need to be improved simultaneously. Summary of the Invention

[0004] The purpose of this invention is to provide an impact-resistant epoxy resin modified mortar and its preparation method, thereby solving the following technical problems: Existing epoxy resin modified mortars still suffer from poor compressive strength, flexural strength, impact strength, abrasion resistance, cavitation resistance, aging resistance, and alkali corrosion resistance.

[0005] The objective of this invention can be achieved through the following technical solutions: An impact-resistant epoxy resin modified mortar comprises the following raw materials in parts by weight: 170-190 parts deionized water, 13.13-14.38 parts modified boron nitride synergist, 0.8-1.2 parts water-reducing agent, 0.6-0.8 parts tributyl phosphate, 26.25-28.75 parts composite modified porous polysiloxane microspheres, 21-23 parts waterborne epoxy resin, 420-460 parts silicate cement, 105-115 parts sulfoaluminate cement, 15.75-17.25 parts concrete expansion agent, 1050-1150 parts river sand, and 27.3-29.9 parts waterborne epoxy curing agent; The composite modified porous polysiloxane microspheres are prepared by first amidizing the surface of porous polysiloxane microspheres made of methyltrimethoxysilane and dimethyldimethoxysilane with 3-aminopropyltriethoxysilane, then loading nano zinc oxide, and finally coating silica with tetraethyl orthosilicate hydrolysis. The modified boron nitride synergist is prepared by first modifying few-layer boron nitride nanosheets with polydopamine hydrochloride coating, then growing hydroxyapatite in situ, followed by hydrothermal treatment at 120°C, and finally by treating silica with tetraethyl orthosilicate hydrolysis.

[0006] Preferably, the method for preparing the composite modified porous polysiloxane microspheres is as follows: A1: After adjusting the pH of the mixture of anhydrous ethanol and deionized water to 9.0, stir at 30℃ for 10-15 min. Then, add dropwise the mixture of methyltrimethoxysilane and dimethyldimethoxysilane and stir for 6 h. Then, centrifuge, wash the precipitate, and dry to obtain porous polysiloxane microspheres. A2: Add porous polysiloxane microspheres to deionized water 1 and ultrasonically disperse for 10 min. Adjust the pH to 4.5-5.0, then add 3-aminopropyltriethoxysilane and stir at 40℃ for 2 h. After centrifugation and washing of the precipitate, add it to zinc acetate aqueous solution and stir at 25℃ for 4-5 h. Then add hexamethylenetetramine and sodium citrate and stir at 90℃ for 6 h. After centrifugation and washing, disperse it in a mixture of anhydrous ethanol and deionized water 2. Adjust the pH to 9.0-10.0, heat to 40℃, add tetraethyl orthosilicate dropwise and stir for 6 h. Then centrifuge, wash the precipitate, and dry to obtain composite modified porous polysiloxane microspheres.

[0007] Preferably, the mass ratio of anhydrous ethanol, deionized water, methyltrimethoxysilane, and dimethyldimethoxysilane in A1 is 300-320:100:60:40.

[0008] Preferably, the mass ratio of deionized water 1, porous polysiloxane microspheres, 3-aminopropyltriethoxysilane, zinc acetate aqueous solution, hexamethylenetetramine, sodium citrate, anhydrous ethanol, deionized water 2, and tetraethyl orthosilicate in A2 is 200-240:45:2:100:5.6:1:400:100:10; The zinc acetate aqueous solution described in A2 has a mass fraction of 11%.

[0009] Preferably, the modified boron nitride synergist is prepared as follows: B1: Tris(hydroxymethyl)aminomethane was added to deionized water 3 and stirred for 20 min. Then the pH was adjusted to 8.5 and boron nitride nanosheets were added. The mixture was ultrasonically dispersed in an ice-water bath for 1 h, and then dopamine hydrochloride was added and stirred in the dark for 24 h. After centrifugation and washing of the precipitate, it was redispersed in deionized water 4. Polyvinylpyrrolidone was added and stirred for 20-30 min. Then the pH was adjusted to 10.5-11, and the temperature was raised to 80℃. While stirring, calcium nitrate tetrahydrate aqueous solution and diammonium hydrogen phosphate aqueous solution were added dropwise. Finally, the mixture was aged at 80℃ for 2 h to obtain a polydopamine-modified boron nitride suspension. B2: The polydopamine-modified boron nitride suspension was first hydrothermally treated at 120℃ for 24h, then cooled and centrifuged to separate and wash the precipitate. The precipitate was then redispersed in a mixture of anhydrous ethanol and deionized water and the pH was adjusted to 9.0-10.0. The temperature was raised to 40℃ and tetraethyl orthosilicate was added dropwise and stirred for 4h. Subsequently, the precipitate was centrifuged, washed, dried and ground to obtain the modified boron nitride synergist.

[0010] Preferably, the mass ratio of deionized water 3, tris(hydroxymethyl)aminomethane, few-layer boron nitride nanosheets, dopamine hydrochloride, deionized water 4, polyvinylpyrrolidone, calcium nitrate tetrahydrate aqueous solution, and diammonium hydrogen phosphate aqueous solution in B1 is 800-820:1.2:10-11:2:400:1:200:100.

[0011] Preferably, the mass fraction of the calcium nitrate tetrahydrate aqueous solution in B1 is 11.8%; The mass fraction of the diammonium hydrogen phosphate aqueous solution described in B1 is 7.9%.

[0012] Preferably, the mass ratio of the polydopamine-modified boron nitride suspension, anhydrous ethanol, deionized water, and tetraethyl orthosilicate in B2 is 715:160:40:6-6.5.

[0013] A method for preparing impact-resistant epoxy resin modified mortar includes the following steps: S1: Add modified boron nitride synergist and water-reducing agent to deionized water and ultrasonically disperse for 20 min under ice-water bath conditions. Then add tributyl phosphate and stir for 20-30 min to obtain a nano suspension. S2: Place the composite modified porous polysiloxane microspheres and waterborne epoxy resin in a vacuum mixing tank and evacuate to -0.095MPa, then stir for 8-10 minutes to obtain the elastic microsphere composite. S3: Mix ordinary silicate cement, sulfoaluminate cement, concrete expansion agent, and river sand and stir for 90 seconds. Then add nano suspension and deionized water 2 and stir for 120 seconds. Then add elastic microsphere composite and water-based epoxy curing agent and stir for 60 seconds to obtain impact-resistant epoxy resin modified mortar.

[0014] Preferably, the mass ratio of deionized water 1 to deionized water 2 is 100-110:70-80.

[0015] The beneficial effects of this invention are: This invention provides an impact-resistant epoxy resin modified mortar and its preparation method. The invention simultaneously improves the compressive strength, flexural strength, impact strength, wear resistance, cavitation resistance, aging resistance and alkali corrosion resistance of the epoxy resin modified mortar through the following method.

[0016] (1) The composite modified porous polysiloxane microspheres of this invention use a porous polysiloxane core. First, amino active sites are introduced on the surface of the microspheres through 3-aminopropyltriethoxysilane. Then, the coordination and anchoring effect of amino groups on zinc ions is utilized to guide the in-situ nucleation and growth of nano-zinc oxide on the surface and in the pores of the microspheres. Finally, a dense silica protective layer is coated on the outer layer through a sol-gel method. During bending, the composite modified porous polysiloxane microspheres undergo elastic compression and deformation, absorbing a large amount of bending energy. At the same time, a plastic zone is formed in front of the crack tip to passivate the crack tip and reduce the driving force for crack propagation. The elastic core of the porous polysiloxane can absorb a large amount of impact energy through pore compression, polymer chain extension and slippage. The zinc oxide loading and silica coating improve the compressive strength and anti-fracture ability of the microspheres, ensuring that the microspheres undergo elastic deformation under impact load without being crushed, giving full play to the energy absorption effect and improving impact toughness. When subjected to abrasive impacts and scratches, the composite-modified porous polysiloxane microspheres undergo elastic deformation to buffer the abrasive impact force, reducing brittle material shedding. Simultaneously, the elastic recovery capability of the microspheres keeps the friction surface smooth, preventing pits and scratches, further improving wear resistance. When the shock wave generated by cavitation collapse encounters the composite-modified porous polysiloxane microspheres during propagation, it causes elastic vibration and deformation of the microspheres, thereby consuming a large amount of shock wave energy and reducing damage to the matrix. At the same time, the elastic recovery capability of the microspheres can offset part of the shock wave force. The porous polysiloxane maintains its elasticity and structural integrity during long-term aging; the silica coating prevents oxygen and moisture from penetrating into the microsphere interior, protecting the zinc oxide particles and the polysiloxane core. Furthermore, the porous structure of the microspheres can accommodate small molecules generated by epoxy resin degradation during aging, reducing volume changes and internal stress in the matrix, preventing cracking and peeling. The silica coating can significantly delay the penetration of alkaline solutions into the microspheres, protecting the core and the loaded zinc oxide from rapid corrosion; even with minor defects, the protective layer can significantly extend the time it takes for corrosive media to reach the sensitive interface.

[0017] (2) The modified boron nitride synergist of this invention uses few-layer boron nitride nanosheets as the core. First, its water dispersibility and interfacial activity are improved by coating with polydopamine. Then, highly crystalline hydroxyapatite nanocrystals are grown in situ on the polydopamine layer. The crystal structure is then optimized by hydrothermal treatment. Finally, silica is coated on the outer layer. After the few-layer boron nitride is uniformly dispersed, it can bear part of the external load and effectively inhibit the initiation and propagation of microcracks. The multilayer modification of polydopamine, hydroxyapatite and silica enables the formation of strong chemical bonds and mechanical interlocking between boron nitride and cement hydration products and epoxy resin, ensuring that stress can be effectively transferred from the matrix to the reinforcing phase and avoiding the decrease in strength caused by interfacial peeling. The hydrothermal treatment improves the crystallinity of hydroxyapatite and further strengthens the interfacial bonding force. Under bending loads, when cracks propagate along the matrix, they encounter boron nitride nanosheets and undergo deflection, bifurcation, and bridging, consuming a significant amount of fracture energy. Simultaneously, the layered structure of boron nitride allows for relative slippage between layers, further absorbing energy and delaying crack instability and propagation. Good interfacial bonding ensures that boron nitride can bear part of the load during crack propagation, playing a bridging role and preventing rapid crack penetration. Modified boron nitride synergists enhance the overall strength and toughness of the matrix, reducing cracking and breakage under impact loads, providing a favorable matrix environment for the microspheres to exert their energy absorption effect. Furthermore, the crack bridging and deflection effects of boron nitride also consume some impact energy. The layered structure of boron nitride can form a continuous anti-friction protective film on the friction surface, significantly reducing the coefficient of friction and decreasing abrasive and adhesive wear. The high hardness of boron nitride resists abrasive penetration and scraping, reducing material volume loss. Good interfacial bonding ensures that boron nitride will not be easily pulled out during friction, becoming new abrasive particles and exacerbating wear. When microcracks originating on the surface due to cavitation collapse propagate, they encounter boron nitride nanosheets, triggering crack deflection, bridging, and lamellar pull-out, consuming a large amount of fracture energy and thus delaying material spalling caused by cavitation erosion. The layered structure of boron nitride nanosheets can extend the penetration paths of water molecules and oxygen; at the same time, the excellent thermal stability of boron nitride helps maintain the bonding strength of the epoxy-inorganic interface at high temperatures; the silica coating layer can protect the internal polydopamine and hydroxyapatite, preventing them from being damaged during aging. The outer silica coating layer can prevent alkaline solutions from penetrating into the interior, protecting alkali-sensitive components such as polydopamine and hydroxyapatite; simultaneously, hydroxyapatite and silica can form a strong bond with the cement matrix, preventing alkaline solutions from penetrating along the interface and causing interfacial delamination.

[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention: The waterborne epoxy resin (a bisphenol A type waterborne epoxy resin emulsion with a solid content of 59%-61% and a pH of 7-8) was purchased from Shanghai Hanzhong Coatings Co., Ltd.; the waterborne epoxy curing agent (a modified polyamide waterborne epoxy curing agent with a solid content of 49%-51% and a pH of 8-9) was also purchased from Shanghai Hanzhong Coatings Co., Ltd.

[0021] Example 1: A method for preparing an impact-resistant epoxy resin modified mortar is as follows: S1: Using 25% ammonia water, the pH of a mixture of 300g anhydrous ethanol and 100g deionized water was adjusted to 9.0. The mixture was stirred at 30℃ for 10min. Then, a mixture of 60g methyltrimethoxysilane and 40g dimethyldimethoxysilane was added dropwise at 1mL / min and stirred for 6h. The mixture was then centrifuged and the precipitate was washed three times with anhydrous ethanol. The precipitate was then vacuum dried at 80℃ and -0.095MPa for 12h to obtain porous polysiloxane microspheres (average particle size 70μm, porosity 45%). S2: Add 45g of porous polysiloxane microspheres to 200g of deionized water and ultrasonically disperse for 10min. Adjust the pH to 4.5 with glacial acetic acid, then add 2g of 3-aminopropyltriethoxysilane and stir at 40℃ for 2h. After centrifugation, wash the precipitate three times with deionized water, then add it to 100g of 11% zinc acetate aqueous solution and stir at 25℃ for 4h. Then add 5.6g of hexamethylenetetramine and 1g of sodium citrate and stir at 90℃ for 6h. After centrifugation, wash twice with anhydrous ethanol and then disperse in a mixture of 400g anhydrous ethanol and 100g deionized water. Adjust the pH to 9.0 with 25% ammonia water, heat to 40℃, then add 10g of tetraethyl orthosilicate dropwise at 0.5mL / min and stir for 6h. After centrifugation, wash the precipitate three times with anhydrous ethanol and finally vacuum dry at 80℃ for 12h to obtain composite modified porous polysiloxane microspheres. S3: Add 1.2g of tris(hydroxymethyl)aminomethane to 800g of deionized water and stir for 20min. Then adjust the pH to 8.5 with hydrochloric acid and add 10g of few-layer boron nitride nanosheets (average thickness 1-2nm, lateral size 1-5μm). Disperse ultrasonically in an ice-water bath for 1h (power 1300W, 3 seconds on, 2 seconds off). Then add 2g of dopamine hydrochloride and stir at room temperature in the dark for 24h. Centrifuge, wash three times with deionized water, and redisperse in 400g of deionized water. Add 1g of polyvinylpyrrolidone and stir for 20min. Then adjust the pH to 10.5 with 25% ammonia. Heat to 80℃ and add 200g of 11.8% calcium nitrate tetrahydrate and 100g of 7.9% diammonium hydrogen phosphate at 0.5mL / min while stirring at 500r / min. Keep the pH between 10.8 and 11.2 during the addition. Finally, age at 80℃ for 2h to obtain polydopamine-modified boron nitride suspension. S4: 715g of polydopamine-modified boron nitride suspension was transferred to a 1L polytetrafluoroethylene hydrothermal reactor. It was then hydrothermally treated at 120℃ for 24h, cooled to room temperature, centrifuged, and the precipitate was washed three times with deionized water. It was then redispersed in a mixture of 160g anhydrous ethanol and 40g deionized water, and the pH was adjusted to 9.0 with 25% ammonia. The temperature was raised to 40℃, and 6g of tetraethyl orthosilicate was added dropwise at 0.5mL / min and stirred for 4h. It was then centrifuged and the precipitate was washed three times with anhydrous ethanol. Finally, it was vacuum dried at 80℃ for 12h and ground to obtain the modified boron nitride synergist. S5: Add 13.13g of modified boron nitride synergist and 0.8g of polycarboxylate high-performance water-reducing agent to 100g of deionized water and ultrasonically disperse for 20min under ice-water bath conditions (power of 200W). Then add 0.6g of tributyl phosphate and stir for 20min to obtain a nano suspension. S6: Place 26.25g of composite modified porous polysiloxane microspheres and 21g of waterborne epoxy resin in a vacuum mixing tank and evacuate to -0.095MPa. Then stir at 200r / min for 8min to obtain the elastic microsphere composite. S7: Mix 420g of ordinary Portland cement P·O 42.5, 105g of 42.5 grade sulfoaluminate cement, 15.75g of concrete expansion agent, and 1050g of natural river sand and stir for 90s. Then add 124.16g of nano suspension and 70g of deionized water and stir at 200r / min for 120s. Then add 47.25g of elastic microsphere composite and 27.3g of water-based epoxy curing agent and stir at 300r / min for 60s to obtain impact-resistant epoxy resin modified mortar. S8: Immediately after pouring the impact-resistant epoxy resin modified mortar into the mold, vibrate to compact it, cover the surface with a film to keep it moist, remove the mold after 24 hours, and finally cure it under standard conditions at 18℃ and relative humidity ≥95% for 28 days to obtain the impact-resistant epoxy resin modified mortar specimen.

[0022] Example 2: A method for preparing an impact-resistant epoxy resin modified mortar is as follows: S1: Using 27% ammonia water, the pH of a mixture of 310g anhydrous ethanol and 100g deionized water was adjusted to 9.0 and stirred at 30℃ for 13min. Then, a mixture of 60g methyltrimethoxysilane and 40g dimethyldimethoxysilane was added dropwise at 1mL / min and stirred for 6h. The mixture was then centrifuged and the precipitate was washed four times with anhydrous ethanol. The precipitate was then vacuum dried at 80℃ and -0.095MPa for 14h to obtain porous polysiloxane microspheres (average particle size 70μm, porosity 45%). S2: Add 45g of porous polysiloxane microspheres to 220g of deionized water and ultrasonically disperse for 10min. Adjust the pH to 4.8 with glacial acetic acid and then add 2g of... 3-Aminopropyltriethoxysilane was stirred at 40℃ for 2 h, then centrifuged and washed four times with deionized water. The precipitate was then added to 100 g of 11% zinc acetate aqueous solution and stirred at 25℃ for 4.5 h. Then, 5.6 g of hexamethylenetetramine and 1 g of sodium citrate were added and stirred at 90℃ for 6 h. After centrifugation and washing three times with anhydrous ethanol, the precipitate was dispersed in a mixture of 400 g of anhydrous ethanol and 100 g of deionized water. The pH was adjusted to 9.5 with 27% ammonia water. After heating to 40℃, 10 g of tetraethyl orthosilicate was added dropwise at 0.5 mL / min and stirred for 6 h. The precipitate was then centrifuged and washed four times with anhydrous ethanol. Finally, the precipitate was vacuum dried at 80℃ for 14 h to obtain composite modified porous polysiloxane microspheres. S3: Add 1.2g of tris(hydroxymethyl)aminomethane to 810g of deionized water and stir for 20min. Then adjust the pH to 8.5 with hydrochloric acid and add 10.5g of few-layer boron nitride nanosheets (average thickness 1-2nm, lateral size 1-5μm). Sonicate the mixture for 1h under ice-water bath conditions (power 1300W, 3 seconds on, 2 seconds off). Then add 2g of dopamine hydrochloride and stir at room temperature in the dark for 24h. Centrifuge and wash 4 times with deionized water, then redisperse in 400g of deionized water. Simultaneously, 1g of polyvinylpyrrolidone was added and stirred for 25min. Then, the pH was adjusted to 10.8 with 27% ammonia water. The temperature was then raised to 80℃ and 200g of 11.8% calcium nitrate tetrahydrate and 100g of 7.9% diammonium hydrogen phosphate aqueous solution were added dropwise at 0.5mL / min while stirring at 500r / min. The pH was maintained between 10.8 and 11.2 during the dropwise addition. Finally, the mixture was aged at 80℃ for 2h to obtain a polydopamine-modified boron nitride suspension. S4: 715g of polydopamine-modified boron nitride suspension was transferred to a 1L polytetrafluoroethylene hydrothermal reactor. It was then hydrothermally treated at 120℃ for 24h, cooled to room temperature, centrifuged, and the precipitate was washed four times with deionized water. It was then redispersed in a mixture of 160g anhydrous ethanol and 40g deionized water, and the pH was adjusted to 9.5 with 27% ammonia. The temperature was raised to 40℃, and 6.3g of tetraethyl orthosilicate was added dropwise at 0.5mL / min and stirred for 4h. It was then centrifuged and the precipitate was washed four times with anhydrous ethanol. Finally, it was vacuum dried at 80℃ for 14h and ground to obtain the modified boron nitride synergist. S5: Add 13.75g of modified boron nitride synergist and 1g of polycarboxylate high-performance water-reducing agent to 105g of deionized water and ultrasonically disperse for 20min under ice-water bath conditions (power of 200W). Then add 0.7g of tributyl phosphate and stir for 25min to obtain a nano suspension. S6: Place 27.5g of composite modified porous polysiloxane microspheres and 22g of waterborne epoxy resin in a vacuum mixing tank and evacuate to -0.095MPa. Then stir at 200r / min for 9min to obtain the elastic microsphere composite. S7: Combine 440g of ordinary Portland cement P·O 42.5, 110g of 42.5 grade sulfoaluminate cement, 16.5g of concrete expansion agent, and 1100g of natural river sand (apparent density 2720kg / m³). 3 Mix and stir for 90s with a fineness modulus of 2.8, then add 130.3g of nano suspension and 70g of deionized water and stir at 200r / min for 120s. Then add 49.5g of elastic microsphere composite and 28.6g of waterborne epoxy curing agent and stir at 300r / min for 60s to obtain impact-resistant epoxy resin modified mortar. S8: Immediately after pouring the impact-resistant epoxy resin modified mortar into the mold, vibrate to compact it, cover the surface with a film to keep it moist, remove the mold after 24 hours, and finally cure it under standard conditions at 20℃ and relative humidity ≥95% for 28 days to obtain the impact-resistant epoxy resin modified mortar specimen.

[0023] Example 3: A method for preparing an impact-resistant epoxy resin modified mortar is as follows: S1: Using 28% ammonia water, the pH of a mixture of 320g anhydrous ethanol and 100g deionized water was adjusted to 9.0 and stirred at 30℃ for 15min. Then, a mixture of 60g methyltrimethoxysilane and 40g dimethyldimethoxysilane was added dropwise at 1mL / min and stirred for 6h. The mixture was then centrifuged and the precipitate was washed 5 times with anhydrous ethanol. The precipitate was then vacuum dried at 80℃ and -0.095MPa for 16h to obtain porous polysiloxane microspheres (average particle size 70μm, porosity 45%). S2: Add 45g of porous polysiloxane microspheres to 240g of deionized water and ultrasonically disperse for 10min. Adjust the pH to 5.0 with glacial acetic acid and then add 2g of... 3-Aminopropyltriethoxysilane was stirred at 40℃ for 2 h, then centrifuged and washed 5 times with deionized water. The precipitate was then added to 100 g of 11% zinc acetate aqueous solution and stirred at 25℃ for 5 h. Then, 5.6 g of hexamethylenetetramine and 1 g of sodium citrate were added and stirred at 90℃ for 6 h. The mixture was centrifuged and washed 3 times with anhydrous ethanol, then dispersed in a mixture of 400 g of anhydrous ethanol and 100 g of deionized water. The pH was adjusted to 10.0 with 28% ammonia water. The temperature was raised to 40℃ and 10 g of tetraethyl orthosilicate was added dropwise at 0.5 mL / min and stirred for 6 h. The mixture was then centrifuged and washed 5 times with anhydrous ethanol. Finally, the mixture was vacuum dried at 80℃ for 16 h to obtain composite modified porous polysiloxane microspheres. S3: Add 1.2g of tris(hydroxymethyl)aminomethane to 820g of deionized water and stir for 20min. Then adjust the pH to 8.5 with hydrochloric acid and add 11g of few-layer boron nitride nanosheets (average thickness 1-2nm, lateral size 1-5μm). Sonicate the mixture for 1h under ice-water bath conditions (power 1300W, 3 seconds on, 2 seconds off). Then add 2g of dopamine hydrochloride and stir at room temperature in the dark for 24h. Centrifuge and wash 5 times with deionized water, then redisperse in 400g of deionized water. Simultaneously, 1g of polyvinylpyrrolidone was added and stirred for 30min. Then, the pH was adjusted to 11 with 28% ammonia water. The temperature was then raised to 80℃, and while stirring at 500r / min, 200g of 11.8% calcium nitrate tetrahydrate aqueous solution and 100g of 7.9% diammonium hydrogen phosphate aqueous solution were added dropwise at 0.5mL / min. During the dropwise addition, the pH was maintained at 10.8-11.2. Finally, the mixture was aged at 80℃ for 2h to obtain a polydopamine-modified boron nitride suspension. S4: 715g of polydopamine-modified boron nitride suspension was transferred to a 1L polytetrafluoroethylene hydrothermal reactor. It was then hydrothermally treated at 120℃ for 24h, cooled to room temperature, centrifuged, and the precipitate was washed 5 times with deionized water. It was then redispersed in a mixture of 160g anhydrous ethanol and 40g deionized water, and the pH was adjusted to 10.0 with 28% ammonia. The temperature was raised to 40℃, and 6.5g of tetraethyl orthosilicate was added dropwise at 0.5mL / min and stirred for 4h. It was then centrifuged and the precipitate was washed 5 times with anhydrous ethanol. Finally, it was vacuum dried at 80℃ for 16h and ground to obtain the modified boron nitride synergist. S5: Add 14.38g of modified boron nitride synergist and 1.2g of polycarboxylate high-performance water-reducing agent to 110g of deionized water and ultrasonically disperse for 20min under ice-water bath conditions (power of 200W). Then add 0.8g of tributyl phosphate and stir for 30min to obtain a nano suspension. S6: Place 28.75g of composite modified porous polysiloxane microspheres and 23g of waterborne epoxy resin in a vacuum mixing tank and evacuate to -0.095MPa. Then stir at 200r / min for 10min to obtain the elastic microsphere composite. S7: Combine 460g of ordinary Portland cement P·O 42.5, 115g of 42.5 grade sulfoaluminate cement, 17.25g of concrete expansion agent, and 1150g of natural river sand (apparent density 2720kg / m³). 3 Mix and stir for 90s (fineness modulus 2.8), then add 135.46g of nano suspension and 70g of deionized water and stir at 200r / min for 120s. Then add 51.75g ​​of elastic microsphere composite and 29.9g of waterborne epoxy curing agent and stir at 300r / min for 60s to obtain impact-resistant epoxy resin modified mortar. S8: Immediately after pouring the impact-resistant epoxy resin modified mortar into the mold, vibrate to compact it, cover the surface with a film to keep it moist, remove the mold after 24 hours, and finally cure it under standard conditions at 22℃ and relative humidity ≥95% for 28 days to obtain the impact-resistant epoxy resin modified mortar specimen.

[0024] Comparative Example 1: Compared with Example 1, this comparative example only omits the following steps in the preparation process of S2: "adding to 100g of 11% zinc acetate aqueous solution and stirring at 25°C for 4h, then adding 5.6g of hexamethylenetetramine and 1g of sodium citrate and stirring at 90°C for 6h, centrifuging and washing twice with anhydrous ethanol". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is impact-resistant epoxy resin modified mortar.

[0025] Comparative Example 2: Compared with Example 1, this comparative example only omits the following process in the preparation of S2: "redisperse in a mixture of 400g anhydrous ethanol and 100g deionized water, adjust the pH to 9.0 with 25% ammonia, heat to 40°C, add 10g tetraethyl orthosilicate dropwise at 0.5mL / min and stir for 6h, then centrifuge and wash the precipitate three times with anhydrous ethanol". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is an impact-resistant epoxy resin modified mortar.

[0026] Comparative Example 3: Compared with Example 1, this comparative example only replaces the "composite modified porous polysiloxane microspheres" added in the preparation process of S6 with the "porous polysiloxane microspheres" prepared in S1. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, the impact-resistant epoxy resin modified mortar is obtained.

[0027] Comparative Example 4: Compared with Example 1, this comparative example only omits the addition of "composite modified porous polysiloxane microspheres" in the preparation process of S6. All other steps and parameters are the same, and will not be repeated here. The final result is an impact-resistant epoxy resin modified mortar.

[0028] Comparative Example 5: Compared with Example 1, this comparative example only omits the following treatment in the preparation process of S3: "add 2g of dopamine hydrochloride and stir at room temperature in the dark for 24 hours, centrifuge and wash three times with deionized water, then redisperse in 400g of deionized water, and add 1g of polyvinylpyrrolidone and stir for 20 minutes." All other steps and parameters are the same, and this comparative example will not repeat them. The final result is an impact-resistant epoxy resin modified mortar.

[0029] Comparative Example 6: Compared with Example 1, this comparative example only omits the treatment of "transferring to a 1L polytetrafluoroethylene hydrothermal reactor, followed by hydrothermal treatment at 120°C for 24 hours, and then cooling to room temperature" in the preparation process of S4. All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is an impact-resistant epoxy resin modified mortar.

[0030] Comparative Example 7: Compared with Example 1, this comparative example only omits the following step in the preparation process of S4: "then redispersed in a mixture of 160g anhydrous ethanol and 40g deionized water, adjusted to pH 9.0 with 25% ammonia, heated to 40°C, then added 6g tetraethyl orthosilicate dropwise at 0.5mL / min and stirred for 4h, followed by centrifugation and washing the precipitate 35 times with anhydrous ethanol". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is an impact-resistant epoxy resin modified mortar.

[0031] Comparative Example 8: Compared with Example 1, this comparative example only replaces the "modified boron nitride synergist" added during the preparation of S6 with "few-layer boron nitride nanosheets (average thickness 1-2 nm, lateral size 1-5 μm)". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, the impact-resistant epoxy resin modified mortar is obtained.

[0032] Comparative Example 9: Compared with Example 1, this comparative example only did not add "modified boron nitride synergist" in the preparation process of S5. All other steps and parameters were the same, and will not be repeated here. The final result was an impact-resistant epoxy resin modified mortar.

[0033] Comparative Example 10: Compared with Example 1, this comparative example only omits the addition of "modified boron nitride synergist and composite modified porous polysiloxane microspheres" in the preparation processes of S5 and S6. All other steps and parameters are the same, and will not be repeated here. The final product is an impact-resistant epoxy resin modified mortar.

[0034] Performance testing: Determination of compressive strength: Referring to the DL / T 5193-2021 standard, the compressive strength (MPa) of the impact-resistant epoxy resin modified mortar specimens (cured for 28 days) prepared in Examples 1-3 and Comparative Examples 1-10 of this invention was determined, and the test results are shown in Table 1.

[0035] Determination of flexural strength: Referring to the DL / T 5193-2021 standard, the flexural strength (MPa) of the impact-resistant epoxy resin modified mortar specimens (cured for 28 days) prepared in Examples 1-3 and Comparative Examples 1-10 of this invention was determined, and the test results are shown in Table 1.

[0036] Impact strength determination: Referring to GB / T 1843-2008 standard, the impact strength (kJ / m²) of the impact-resistant epoxy resin modified mortar specimens prepared in Examples 1-3 and Comparative Examples 1-10 of this invention was determined. 2 The test results are shown in Table 1.

[0037] Abrasion resistance testing: Referring to DL / T 5193-2021 "Technical Specification for Epoxy Resin Mortar" standard, cylindrical specimens (Φ300mm×100mm, cured for 28 days) of impact-resistant epoxy resin modified mortar prepared in Examples 1-3 and Comparative Examples 1-10 of this invention were dried to constant weight at 105℃. The specimens were then fixed inside a concrete impact-resistant abrasion testing machine (underwater steel ball method). Ten 25mm diameter steel balls, 20 20mm diameter steel balls, and 40 15mm diameter steel balls, along with water to the specified level, were added. The testing machine was started and continuously impacted at an impeller speed of 1200r / min for 30 minutes. After impacting, the specimens were removed, rinsed clean, and dried to constant weight at 105℃. The mass loss (kg / m³) was measured. 2 The test results (·h) are shown in Table 1.

[0038] Determination of resistance to cavitation erosion: Referring to the DL / T 5207-2021 standard, the impact-resistant epoxy resin modified mortar Φ50mm×10mm disc specimens with a center hole of Φ10mm (cured for 28 days) prepared in Examples 1-3 and Comparative Examples 1-10 of this invention were dried to constant weight at 105℃. Then, the specimens were fixed to the edge of a rotating disc and immersed in clean water at 25℃ using a rotating disc cavitation tester. The tester was started and rotated at a linear speed of 40m / s for 24 hours. After the test, the specimens were taken out, the surface corrosion products were removed with a soft brush, rinsed clean, and dried to constant weight. The mass loss (mg) was measured, and the test results are shown in Table 2.

[0039] Determination of aging resistance: Referring to the DL / T 5193-2021 standard, the 40mm×40mm×40mm cubic specimens of impact-resistant epoxy resin modified mortar prepared in Examples 1-3 and Comparative Examples 1-10 of this invention (cured for 28 days) were dried at 105℃ to constant weight and weighed. Then, they were aged at 80℃ and 95% relative humidity for 1000h, dried at 105℃ to constant weight and weighed. The mass change rate (%) was then calculated as follows: mass change rate = (mass after aging - mass before aging) / mass before aging × 100%. The test results are shown in Table 2.

[0040] Determination of alkali corrosion resistance: Referring to the DL / T 5193-2021 standard, the 40mm×40mm×40mm cubic specimens of impact-resistant epoxy resin modified mortar prepared in Examples 1-3 and Comparative Examples 1-10 of this invention (cured for 28 days) were dried to constant weight at 105℃ and weighed. Then, they were immersed in a 10% sodium hydroxide aqueous solution at 25℃ for 28 days. After immersion, the specimens were removed, rinsed with clean water, dried to constant weight at 105℃, and weighed. The mass loss rate (%) was then calculated as follows: Mass loss rate = (initial mass - mass after immersion) / initial mass × 100%. The test results are shown in Table 2.

[0041] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-10

[0042] Table 2: Performance test results of Examples 1-3 and Comparative Examples 1-10

[0043] Data Analysis: As can be seen from Tables 1 and 2, the impact-resistant epoxy resin modified mortar prepared in the embodiments of the present invention has excellent compressive strength, flexural strength, impact strength, wear resistance, cavitation resistance, aging resistance and alkali corrosion resistance.

[0044] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. An impact-resistant epoxy resin modified mortar, characterized in that, The raw materials include the following parts by weight: 170-190 parts deionized water, 13.13-14.38 parts modified boron nitride synergist, 0.8-1.2 parts water-reducing agent, 0.6-0.8 parts tributyl phosphate, 26.25-28.75 parts composite modified porous polysiloxane microspheres, 21-23 parts waterborne epoxy resin, 420-460 parts silicate cement, 105-115 parts sulfoaluminate cement, 15.75-17.25 parts concrete expansion agent, 1050-1150 parts river sand, and 27.3-29.9 parts waterborne epoxy curing agent; The composite modified porous polysiloxane microspheres are prepared by first amidizing the surface of porous polysiloxane microspheres made of methyltrimethoxysilane and dimethyldimethoxysilane with 3-aminopropyltriethoxysilane, then loading nano zinc oxide, and finally coating silica with tetraethyl orthosilicate hydrolysis. The modified boron nitride synergist is prepared by first modifying few-layer boron nitride nanosheets with polydopamine hydrochloride coating, then growing hydroxyapatite in situ, followed by hydrothermal treatment at 120°C, and finally by treating silica with tetraethyl orthosilicate hydrolysis.

2. The impact-resistant epoxy resin modified mortar according to claim 1, characterized in that, The preparation method of the composite modified porous polysiloxane microspheres is as follows: A1: After adjusting the pH of the mixture of anhydrous ethanol and deionized water to 9.0, stir at 30℃ for 10-15 min. Then, add dropwise the mixture of methyltrimethoxysilane and dimethyldimethoxysilane and stir for 6 h. Then, centrifuge, wash the precipitate, and dry to obtain porous polysiloxane microspheres. A2: Add porous polysiloxane microspheres to deionized water 1 and ultrasonically disperse for 10 min. Adjust the pH to 4.5-5.0, then add 3-aminopropyltriethoxysilane and stir at 40℃ for 2 h. After centrifugation and washing of the precipitate, add it to zinc acetate aqueous solution and stir at 25℃ for 4-5 h. Then add hexamethylenetetramine and sodium citrate and stir at 90℃ for 6 h. After centrifugation and washing, disperse it in a mixture of anhydrous ethanol and deionized water 2. Adjust the pH to 9.0-10.0, heat to 40℃, add tetraethyl orthosilicate dropwise and stir for 6 h. Then centrifuge, wash the precipitate, and dry to obtain composite modified porous polysiloxane microspheres.

3. The impact-resistant epoxy resin modified mortar according to claim 2, characterized in that, The mass ratio of anhydrous ethanol, deionized water, methyltrimethoxysilane, and dimethyldimethoxysilane in A1 is 300-320:100:60:

40.

4. The impact-resistant epoxy resin modified mortar according to claim 2, characterized in that, The mass ratio of deionized water 1, porous polysiloxane microspheres, 3-aminopropyltriethoxysilane, zinc acetate aqueous solution, hexamethylenetetramine, sodium citrate, anhydrous ethanol, deionized water 2, and tetraethyl orthosilicate in A2 is 200-240:45:2:100:5.6:1:400:100:10; The zinc acetate aqueous solution described in A2 has a mass fraction of 11%.

5. The impact-resistant epoxy resin modified mortar according to claim 1, characterized in that, The preparation method of the modified boron nitride synergist is as follows: B1: Tris(hydroxymethyl)aminomethane was added to deionized water 3 and stirred for 20 min. Then the pH was adjusted to 8.5 and boron nitride nanosheets were added. The mixture was ultrasonically dispersed in an ice-water bath for 1 h, and then dopamine hydrochloride was added and stirred in the dark for 24 h. After centrifugation and washing of the precipitate, it was redispersed in deionized water 4. Polyvinylpyrrolidone was added and stirred for 20-30 min. Then the pH was adjusted to 10.5-11, and the temperature was raised to 80℃. While stirring, calcium nitrate tetrahydrate aqueous solution and diammonium hydrogen phosphate aqueous solution were added dropwise. Finally, the mixture was aged at 80℃ for 2 h to obtain a polydopamine-modified boron nitride suspension. B2: The polydopamine-modified boron nitride suspension was first hydrothermally treated at 120℃ for 24h, then cooled and centrifuged to separate and wash the precipitate. The precipitate was then redispersed in a mixture of anhydrous ethanol and deionized water and the pH was adjusted to 9.0-10.

0. The temperature was raised to 40℃ and tetraethyl orthosilicate was added dropwise and stirred for 4h. Subsequently, the precipitate was centrifuged, washed, dried and ground to obtain the modified boron nitride synergist.

6. The impact-resistant epoxy resin modified mortar according to claim 5, characterized in that, The mass ratio of deionized water 3, tris(hydroxymethyl)aminomethane, few-layer boron nitride nanosheets, dopamine hydrochloride, deionized water 4, polyvinylpyrrolidone, calcium nitrate tetrahydrate aqueous solution, and diammonium hydrogen phosphate aqueous solution in B1 is 800-820:1.2:10-11:2:400:1:200:

100.

7. The impact-resistant epoxy resin modified mortar according to claim 5, characterized in that, The mass fraction of the calcium nitrate tetrahydrate aqueous solution described in B1 is 11.8%; The mass fraction of the diammonium hydrogen phosphate aqueous solution described in B1 is 7.9%.

8. The impact-resistant epoxy resin modified mortar according to claim 5, characterized in that, The mass ratio of the polydopamine-modified boron nitride suspension, anhydrous ethanol, deionized water, and tetraethyl orthosilicate in B2 is 715:160:40:6-6.

5.

9. A method for preparing impact-resistant epoxy resin modified mortar according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Add modified boron nitride synergist and water-reducing agent to deionized water and ultrasonically disperse for 20 min under ice-water bath conditions. Then add tributyl phosphate and stir for 20-30 min to obtain a nano suspension. S2: Place the composite modified porous polysiloxane microspheres and waterborne epoxy resin in a vacuum mixing tank and evacuate to -0.095MPa, then stir for 8-10 minutes to obtain the elastic microsphere composite. S3: Mix ordinary silicate cement, sulfoaluminate cement, concrete expansion agent, and river sand and stir for 90 seconds. Then add nano suspension and deionized water 2 and stir for 120 seconds. Then add elastic microsphere composite and water-based epoxy curing agent and stir for 60 seconds to obtain impact-resistant epoxy resin modified mortar.

10. The method for preparing the impact-resistant epoxy resin modified mortar according to claim 9, characterized in that, The mass ratio of deionized water 1 to deionized water 2 is 100-110:70-80.

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