An ultra-high ductility interface treatment mortar suitable for fabricated steel structure and a preparation method thereof

Abstract

The application discloses an interface treatment mortar suitable for assembled steel structure and a preparation method thereof, and belongs to the technical field of building materials. The interface treatment mortar comprises, in terms of weight parts, 350-450 parts of Portland cement, 410-510 parts of graded sand, 0.4-0.6 parts of water reducing agent, 80-120 parts of redispersible latex powder, 0.5-1.5 parts of defoaming agent, 1-3 parts of cellulose ether and 21-62 parts of modified rubber powder / polyvinyl alcohol fiber composite material. The modified rubber powder / polyvinyl alcohol fiber composite material is prepared by surface modification of rubber powder through a silane coupling agent, then polyvinyl alcohol fiber is added into the modified rubber powder in batches, and EVA hot melt adhesive powder is added and heat treated. The mortar prepared by the application has high tensile bonding strength, low compression bending ratio and large transverse deformation capacity, can effectively relieve the interface stress concentration problem between the base layer and the mortar layer of the assembled steel structure caused by temperature change, stress deformation and difference in linear expansion coefficient, and reduces the risk of debonding, hollowing and cracking.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures and its preparation method. Background Technology

[0002] Prefabricated steel structure buildings are increasingly widely used in construction projects due to their high construction efficiency, light structural weight, and excellent seismic performance. However, steel structures have smooth surfaces and low surface energy, resulting in poor adhesion with traditional interface mortars. Furthermore, the linear expansion coefficients of steel and mortar differ significantly (the linear expansion coefficient of steel is approximately 12 × 10⁻⁶). -6 ℃ -1 Ordinary mortar, approximately 8×10 -6 ℃ -1 Under temperature cycling, structural stress deformation, and seismic action, stress concentration is easily generated at the interface, leading to defects such as debonding, hollowing, and cracking, which seriously affect the durability of the steel structure and the stability of the decorative layer.

[0003] In existing technologies, interface treatment mortars often improve bonding strength by adding latex powder, but they lack ductility and have poor deformation coordination, making it difficult to adapt to the dynamic deformation requirements of steel structures. Although some flexible mortars improve ductility, they sacrifice bonding strength significantly, failing to meet the core requirements of high bonding and high ductility.

[0004] Therefore, developing an interface treatment mortar that combines ultra-high bonding strength, excellent ductility, outstanding crack resistance, and is suitable for the construction characteristics of prefabricated steel structures has become the key to solving the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures and its preparation method, so as to overcome the defects of existing interface mortars, such as difficulty in achieving both bonding strength and ductility, poor coordination with steel structure deformation, and easy cracking.

[0006] To better solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] Firstly, an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures, comprising the following components by weight:

[0008] 350-450 parts silicate cement, 410-510 parts graded sand, 0.4-0.6 parts water-reducing agent, 80-120 parts redispersible latex powder, 0.5-1.5 parts defoamer, 1-3 parts cellulose ether, and 21-62 parts modified rubber powder / polyvinyl alcohol fiber composite material.

[0009] The preparation of the modified rubber powder / polyvinyl alcohol fiber composite material includes: modifying the rubber powder with a silane coupling agent; adding polyvinyl alcohol fiber to the modified rubber powder in batches; and adding EVA hot melt adhesive powder for post-treatment.

[0010] Preferably, the silicate cement is P.O42.5 grade cement; or the graded sand is a mixture of 40-80 mesh and 80-120 mesh quartz sand, with a mass ratio of 40-80 mesh quartz sand to 80-120 mesh quartz sand of 1:(1.0-1.5); or the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent; or the redispersible latex powder includes one or more of ethylene-vinyl acetate copolymer and acrylic copolymer; or the defoamer is an organosilicon defoamer; or the cellulose ether is one of hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose.

[0011] In this invention, the molecular weight of the cellulose ether is 100,000 to 200,000.

[0012] Preferably, the preparation method of the modified rubber powder / polyvinyl alcohol fiber composite material includes the following steps:

[0013] S1. First, use a silane coupling agent to modify the rubber powder to obtain modified rubber powder;

[0014] S2. Under low-speed stirring, add polyvinyl alcohol fiber to the modified rubber powder in batches. After adding the polyvinyl alcohol fiber, continue stirring.

[0015] S3. Add EVA hot melt adhesive powder to the mixture of modified rubber powder and polyvinyl alcohol fiber from step S2. After the addition is complete, stir again to obtain a mixture.

[0016] S4. Spread the mixture evenly in an oven for processing, and finally let it cool naturally to room temperature. Then break it up and sieve it to obtain the modified rubber powder / polyvinyl alcohol fiber composite material.

[0017] Preferably, the rubber powder has a particle size of 0.075-0.12 mm and a density of 0.9 g / cm³; the polyvinyl alcohol fiber has a length of 5-6 mm and a diameter of 20-30 μm; and the mass ratio of the rubber powder to the polyvinyl alcohol fiber is (20-60):(1-2).

[0018] Preferably, in step S2, the stirring speed of the low-speed stirring is 80-120 r / min, and the stirring time is 1-2 min.

[0019] Preferably, in step S3, the amount of EVA hot melt adhesive powder added is 4-6 wt% of the rubber powder mass, the stirring time is 2-3 min, and the stirring speed is 100-150 r / min.

[0020] Preferably, in step S4, the heat treatment temperature is 140-145℃ and the time is 30-40 min.

[0021] Preferably, the process of modifying rubber powder using a silane coupling agent includes:

[0022] First, mix ethanol and water evenly, and then slowly add silane coupling agent KH-550 while stirring. After the addition is complete, stir at room temperature to obtain silane hydrolysate.

[0023] Add rubber powder to the above silane hydrolysate, stir at room temperature, remove, drain excess liquid, and air dry in a ventilated place to obtain modified rubber powder.

[0024] Preferably, the mass ratio of the silane coupling agent KH-550, ethanol, water, and rubber powder is 1:(4-5):1:(60-80); or the stirring time after the addition of the silane coupling agent KH-550 is 5-10 min, and the stirring speed is 200-300 r / min; or the stirring speed after the rubber powder is added is 150-250 r / min, and the stirring time is 5-10 min.

[0025] Secondly, a method for preparing an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures, characterized by comprising the following steps:

[0026] (1) Weigh out cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether, modified rubber powder / polyvinyl alcohol fiber composite material according to the proportion;

[0027] (2) Add the weighed cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether and modified rubber powder / polyvinyl alcohol fiber composite material to the mixer and mix thoroughly to obtain ultra-high ductility interface treatment mortar powder.

[0028] (3) Mix the ultra-high ductility interface treatment mortar powder with water at a water-to-material ratio of 20-24%, the mixing speed is 200±5r / min, the mixing time is 5±1min, and the mixture is left to stand for 1-2min to obtain the freshly mixed interface treatment mortar.

[0029] Compared with the prior art, the present invention has at least the following advantages:

[0030] This invention provides an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures and its preparation method. The mortar, through the synergistic compounding of silicate cement, graded sand, redispersible latex powder, water-reducing agent, defoamer, cellulose ether, and modified rubber powder / polyvinyl alcohol fiber composite material, constructs an interface mortar system that combines bonding strength, flexibility, and construction adaptability. In the interface mortar system, the redispersible latex powder improves the interfacial bonding ability between the mortar and the steel structure substrate; the water-reducing agent helps improve the fluidity and density of the mortar; the cellulose ether enhances water retention and workability; and the defoamer reduces harmful air bubbles within the system. Thus, the mortar achieves high interfacial bonding stability while maintaining good construction performance.

[0031] In preparing the modified rubber powder / polyvinyl alcohol fiber composite material, this invention employs a silane coupling agent to modify the surface of the rubber powder, thereby addressing the issues of high surface inertness and poor compatibility with cement-based materials. The modified material can be better dispersed in the mortar system and acts as a flexible buffer when the mortar is subjected to tension, bending, or temperature deformation, absorbing and releasing localized stress, reducing stress concentration between the steel structure base layer and the mortar layer, thus improving the crack resistance and deformation coordination of the interface layer.

[0032] This invention involves adding polyvinyl alcohol (PVA) fibers in batches to modified rubber powder and then heat-treating them with EVA hot melt adhesive powder to form a modified rubber powder / PVA fiber composite material. This treatment method reduces the agglomeration, floating, and uneven dispersion of PVA fibers in dry powder systems and mixed slurries, resulting in a more uniform fiber distribution within the mortar matrix. When microcracks form within the mortar, the PVA fibers act as bridges, tensioners, and crack inhibitors, delaying crack propagation; the rubber powder absorbs energy through flexible deformation, and the two work synergistically to enhance the toughness and ductility of the mortar.

[0033] The interface treatment mortar obtained by this invention has a low compressive-flexural ratio and high lateral deformation capacity, exhibiting good workability and adaptability to various application methods such as roller coating, brush coating, and scraping. It is suitable for applications in prefabricated steel structure buildings where the steel surface is smooth, the coefficient of linear expansion differs from that of the mortar, and structural nodes are prone to deformation. It effectively improves the interface layer's adaptability to temperature cycling, structural vibration, load deformation, and seismic forces. The preparation method of this invention is simple, uses readily available raw materials, requires no complex equipment, and is suitable for industrial production. Detailed Implementation

[0034] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with preferred embodiments, is provided below.

[0035] The raw material parameters for some embodiments of the present invention are as follows:

[0036] The silicate cement used is P.O42.5 grade cement produced by Anhui Conch Cement Co., Ltd.

[0037] Cellulose ether: Hydroxypropyl methylcellulose (molecular weight 100,000);

[0038] Rubber powder: particle size 0.075-0.12mm, density 0.9g / cm³ 3 ;

[0039] Polyvinyl alcohol fiber: 5mm in length, 20μm in diameter;

[0040] Unless otherwise specified, all other raw materials are commercially available materials or conventional technologies in this field.

[0041] Example 1

[0042] A method for preparing an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures includes the following steps:

[0043] (1) Weigh out 400 parts of silicate cement, 460 parts of graded sand (40-80 mesh: 80-120 mesh = 1:1.25), 0.5 parts of polycarboxylate superplasticizer, 100 parts of redispersible latex powder (WACKER 5044N), 1 part of organosilicon defoamer, 2 parts of cellulose ether, 40 parts of rubber powder, and 2 parts of polyvinyl alcohol fiber by weight.

[0044] (2) Silane coupling agent KH-550, ethanol, water and rubber powder are weighed in a mass ratio of 1:4:1:60; ethanol and water are mixed evenly, and silane coupling agent KH-550 is added at a stirring speed of 200 r / min. After the addition is completed, the mixture is stirred at room temperature for 5 min to obtain silane hydrolysate; rubber powder is added to silane hydrolysate and stirred at 150 r / min for another 5 min; the mixture is drained and then dried in a ventilated place for 24 h to obtain modified rubber powder;

[0045] (3) Add polyvinyl alcohol fiber slowly in batches to the modified rubber powder at a stirring speed of 80 r / min (add in 2 batches). After the addition is completed, stir for 2 min. Then add 2 parts of EVA hot melt adhesive powder (Arkema 33-45) and stir at a speed of 100 r / min for 3 min. Spread the resulting mixture evenly in the oven, heat it to 145℃, and keep it at a constant temperature for 35 min to melt the EVA hot melt adhesive powder and bond the fiber and rubber particles together. Take it out, let it cool naturally to room temperature, gently break it up and sieve it to obtain the modified rubber powder / polyvinyl alcohol fiber composite material.

[0046] (4) Add cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether, modified rubber powder / polyvinyl alcohol fiber composite material to a mixer and mix well to obtain dry material; add water at a water-material ratio of 20%, stir at 200 r / min for 5 min, let stand for 2 min to obtain ultra-high ductility interface treatment mortar.

[0047] Example 2

[0048] A method for preparing an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures includes the following steps:

[0049] (1) Weigh the following by weight: 370 parts silicate cement, 490 parts graded sand (40-80 mesh: 80-120 mesh = 1:1.1), 0.4 parts polycarboxylate superplasticizer, 100 parts redispersible latex powder (WACKER 5044N), 1.5 parts organosilicon defoamer, 1 part cellulose ether, 40 parts redispersible rubber powder, and 1 part polyvinyl alcohol fiber.

[0050] (2) Weigh silane coupling agent KH-550, ethanol, water and rubber powder in a mass ratio of 1:5:1:70; first mix ethanol and water evenly, add silane coupling agent KH-550 at a stirring speed of 200 r / min, and stir at room temperature for 5 min after the addition is completed to obtain silane hydrolysate; add rubber powder to silane hydrolysate and stir at 150 r / min for another 5 min; drain and finally air dry in a ventilated place for 24 h to obtain modified rubber powder;

[0051] (3) Add polyvinyl alcohol fiber slowly in batches to the modified rubber powder at a stirring speed of 80 r / min (add in 2 batches). After the addition is completed, stir for 2 min. Then add 2 parts of EVA hot melt adhesive powder (Arkema 33-45) and stir at a speed of 100 r / min for 3 min. Spread the resulting mixture evenly in the oven, heat it to 145℃, and keep it at a constant temperature for 35 min to melt the EVA hot melt adhesive powder and bond the fiber and rubber particles together. Take it out, let it cool naturally to room temperature, gently break it up and sieve it to obtain the modified rubber powder / polyvinyl alcohol fiber composite material.

[0052] (4) Add cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether, modified rubber powder / polyvinyl alcohol fiber composite material to a mixer and mix well to obtain dry material; add water at a water-material ratio of 20%, stir at 200 r / min for 5 min, let stand for 2 min to obtain ultra-high ductility interface treatment mortar.

[0053] Example 3

[0054] A method for preparing an ultra-high ductility interface treatment mortar suitable for prefabricated steel structures includes the following steps:

[0055] (1) Weigh the following by weight: 440 parts silicate cement, 410 parts graded sand (40-80 mesh: 80-120 mesh = 1:1.4), 0.6 parts polycarboxylate superplasticizer, 90 parts redispersible latex powder (WACKER 5044N), 0.8 parts organosilicon defoamer, 2 parts cellulose ether, 60 parts rubber powder, and 1.5 parts polyvinyl alcohol fiber;

[0056] (2) Weigh silane coupling agent KH-550, ethanol, water and rubber powder in a mass ratio of 1:5:1:80; first mix ethanol and water evenly, add silane coupling agent KH-550 at a stirring speed of 200 r / min, and stir at room temperature for 5 min after the addition is completed to obtain silane hydrolysate; add rubber powder to silane hydrolysate and stir at 150 r / min for another 5 min; drain and finally air dry in a ventilated place for 24 h to obtain modified rubber powder;

[0057] (3) Add polyvinyl alcohol fiber slowly in batches to the modified rubber powder at a stirring speed of 80 r / min (add in 2 batches). After the addition is completed, stir for 2 min. Then add 3 parts of EVA hot melt adhesive powder (Arkema 33-45) and stir at a speed of 100 r / min for 3 min. Spread the resulting mixture evenly in the oven, heat it to 145℃, and keep it at a constant temperature for 35 min to melt the EVA hot melt adhesive powder and bond the fiber and rubber particles together. Take it out, let it cool naturally to room temperature, gently break it up and sieve it to obtain the modified rubber powder / polyvinyl alcohol fiber composite material.

[0058] (4) Add cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether, modified rubber powder / polyvinyl alcohol fiber composite material to a mixer and mix well to obtain dry material; add water at a water-material ratio of 20%, stir at 200 r / min for 5 min, let stand for 2 min to obtain ultra-high ductility interface treatment mortar.

[0059] To verify the effects of modified rubber powder and modified polyvinyl alcohol fiber on the performance of ultra-high ductility interface treatment mortar, the following comparison examples 1-3 further illustrate this point.

[0060] Comparative Example 1

[0061] Compared with Example 1, this comparative example directly adds rubber powder and polyvinyl alcohol fiber without modification, and other conditions are the same as in Example 1.

[0062] Comparative Example 2

[0063] Compared with Example 1, this comparative example uses an equal amount of polyvinyl alcohol fiber to replace the modified rubber powder / polyvinyl alcohol fiber composite material, and other conditions are the same as in Example 1.

[0064] Comparative Example 3

[0065] Compared with Example 1, this comparative example does not add modified rubber powder / polyvinyl alcohol fiber composite material, and other conditions are the same as in Example 1.

[0066] The above-mentioned interface treatment mortar was tested. The test methods and results are as follows:

[0067] 1. Tensile bond strength: Conducted according to JC / T 907-2018, with specific tests as follows:

[0068] Test substrate: Q235 steel was used as the test substrate, with a size of 400mm×400mm×7mm and a rust removal grade of not less than St3;

[0069] Molded frame: The thickness is 5mm, as specified in 12.2.3 of GB / T 29756-2013;

[0070] Preparation of specimens: Place the molding frame on the molding surface of the substrate, then fill the molding frame with the mixed interface agent, press and smooth it with a trowel, and demold after 48 hours. Ten specimens are used as a group.

[0071] Original strength: The prepared specimens were cured under standard test conditions for 13 days. The pull-out joints were then bonded to the 50mm×50mm×5mm interface agent specimens using a suitable high-strength adhesive (epoxy adhesive). The test was conducted 24 hours later. The test procedure was carried out according to the provisions of 7.6.3.2 in JC / T 907-2018.

[0072] Immersion: As specified in section 7.6.4 of JC / T 907-2018.

[0073] Tensile bond strength after heat treatment: as specified in 7.6.5 of JC / T 907-2018.

[0074] Tensile bond strength after freeze-thaw cycle treatment: as specified in section 7.6.6 of JC / T 907-2018.

[0075] Tensile bond strength after alkali-resistant treatment: as specified in 7.6.7 of JC / T 907-2018.

[0076] 2. Consistency: Tested in accordance with JGJ / T 70-2009 "Test Methods for Basic Performance of Building Mortar".

[0077] 3. Lateral deformation: Tested according to Appendix A of JC / T 1004-2017 "Ceramic Tile Grout".

[0078] 4. Compression-to-flexural ratio: The compressive strength and flexural strength were tested according to JC / T 1004-2017 "Ceramic Tile Grout", and the compression-to-flexural ratio was calculated.

[0079] The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As can be seen from Table 1, compared with the comparative example, the present invention adds a composite system of rubber powder and polyvinyl alcohol fiber to the mortar matrix, and adds graded sand, polycarboxylate superplasticizer, organosilicon defoamer, etc. The resulting mortar has good bonding performance, ultra-high ductility and excellent deformation coordination ability. It can specifically resist the deformation of prefabricated steel structures under temperature changes and stress, and significantly reduce the risk of crack initiation and cracking.

[0083] From the tensile bond strength perspective, the original strength of the examples was higher than that of Comparative Example 3, indicating that the introduction of modified rubber powder / polyvinyl alcohol fiber composite material into the mortar system can effectively improve the bonding performance between the mortar and the substrate. Compared with Comparative Example 1, Example 1 showed improvements in original strength, alkali resistance, water immersion, and bond strength after freeze-thaw cycles, indicating that simply adding untreated rubber powder and polyvinyl alcohol fiber is insufficient to fully utilize their reinforcing and toughening effects; however, after silane modification and EVA heat treatment, the dispersibility and interfacial bonding state of the rubber powder and fiber were improved, thereby enhancing the overall stability of the mortar system.

[0084] In terms of durable bonding performance, the mortar in the embodiment maintained a good level of tensile bond strength after heat resistance, alkali resistance, water immersion, and freeze-thaw cycles, which was better than that of Comparative Example 3. The above test results show that the interface-treated mortar prepared by the present invention not only has high initial bond strength, but also maintains relatively stable interfacial bonding ability under adverse conditions such as heat, alkaline environment, water immersion, and freeze-thaw cycles, and has good environmental adaptability and durability.

[0085] In terms of consistency, the mortar in this embodiment exhibits good workability and can meet the requirements of roller, brush, or trowel application of interface treatment materials. Compared to the 126mm consistency of Comparative Example 3, the consistency of this embodiment is slightly lower, but it still maintains good fluidity and workability, indicating that the addition of the modified rubber powder / polyvinyl alcohol fiber composite material did not lead to a significant deterioration in the mortar's workability. On the contrary, due to the relatively uniform fiber dispersion, the overall system stability is good, which helps to reduce problems such as fiber agglomeration, local accumulation, or mortar segregation during construction.

[0086] From the perspective of the compression-to-flexure ratio, the compression-to-flexure ratios of Examples 1-3 are significantly lower than those of Comparative Examples 1, 2, and 3. A lower compression-to-flexure ratio indicates lower brittleness and better toughness of the material. These results demonstrate that the present invention, by incorporating modified rubber powder / polyvinyl alcohol fiber composite material, effectively reduces the brittleness of the mortar, making it less prone to sudden cracking and failure when subjected to external forces or substrate deformation. In particular, Example 2 exhibits the lowest compression-to-flexure ratio at 2.76, indicating its outstanding flexibility.

[0087] In terms of lateral deformation performance, the lateral deformations of Examples 1-3 reached 5.13 mm, 5.29 mm, and 5.07 mm, respectively, significantly higher than 2.88 mm of Comparative Example 1, 2.31 mm of Comparative Example 2, and 1.05 mm of Comparative Example 3. These results demonstrate that the mortar of the present invention possesses excellent ductility and deformation coordination capabilities. Compared to Comparative Example 1, the lateral deformation of Example 1 increased from 2.88 mm to 5.13 mm, indicating that the modification with rubber powder and polyvinyl alcohol fiber can more effectively exert flexible buffering and fiber bridging effects. Compared to Comparative Example 2, the lateral deformation of Example 1 significantly improved, indicating that rubber powder plays an important role in enhancing the deformation capacity of the mortar. Compared to Comparative Example 3, the improvement in lateral deformation of Example 1 was even more pronounced, indicating a synergistic toughening effect between rubber powder and polyvinyl alcohol fiber, rather than a simple superposition of single components.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-ductility interface treatment mortar suitable for prefabricated steel structures, characterized in that, Based on parts by weight, it includes the following components: 350-450 parts silicate cement, 410-510 parts graded sand, 0.4-0.6 parts water-reducing agent, 80-120 parts redispersible latex powder, 0.5-1.5 parts defoamer, 1-3 parts cellulose ether, and 21-62 parts modified rubber powder / polyvinyl alcohol fiber composite material. The preparation of the modified rubber powder / polyvinyl alcohol fiber composite material includes: modifying the rubber powder with a silane coupling agent; adding polyvinyl alcohol fiber to the modified rubber powder in batches; and adding EVA hot melt adhesive powder for post-treatment.

2. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 1, characterized in that, The silicate cement is P.O42.5 grade cement; or the graded sand is a mixture of 40-80 mesh and 80-120 mesh quartz sand, with a mass ratio of 40-80 mesh quartz sand to 80-120 mesh quartz sand of 1:(1.0-1.5); or the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent; or the redispersible latex powder includes one or more of ethylene-vinyl acetate copolymer and acrylic copolymer; or the defoamer is an organosilicon defoamer; or the cellulose ether is one of hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose.

3. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 1, characterized in that, The preparation method of the modified rubber powder / polyvinyl alcohol fiber composite material includes the following steps: S1. First, use a silane coupling agent to modify the rubber powder to obtain modified rubber powder; S2. Under low-speed stirring, add polyvinyl alcohol fiber to the modified rubber powder in batches. After adding the polyvinyl alcohol fiber, continue stirring. S3. Add EVA hot melt adhesive powder to the mixture of modified rubber powder and polyvinyl alcohol fiber from step S2. After the addition is complete, stir again to obtain a mixture. S4. Spread the mixture evenly in an oven for processing, and finally let it cool naturally to room temperature. Then break it up and sieve it to obtain the modified rubber powder / polyvinyl alcohol fiber composite material.

4. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 3, characterized in that, The rubber powder has a particle size of 0.075-0.12 mm and a density of 0.9 g / cm³. 3 The polyvinyl alcohol fiber has a length of 5-6 mm and a diameter of 20-30 μm; the mass ratio of the rubber powder to the polyvinyl alcohol fiber is (20-60):(1-2).

5. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 3, characterized in that, In step S2, the stirring speed of the low-speed stirring is 80-120 r / min, and the stirring time is 1-2 min.

6. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 3, characterized in that, In step S3, the amount of EVA hot melt adhesive powder added is 4-6 wt% of the rubber powder mass, the stirring time is 2-3 min, and the stirring speed is 100-150 r / min.

7. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 3, characterized in that, In step S4, the heat treatment temperature is 140-145℃ and the time is 30-40 min.

8. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 3, characterized in that, The process of modifying rubber powder using silane coupling agents includes: First, mix ethanol and water evenly, and then slowly add silane coupling agent KH-550 while stirring. After the addition is complete, stir at room temperature to obtain silane hydrolysate. Add rubber powder to the above silane hydrolysate, stir at room temperature, remove, drain excess liquid, and air dry in a ventilated place to obtain modified rubber powder.

9. The ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to claim 8, characterized in that, The mass ratio of the silane coupling agent KH-550, ethanol, water, and rubber powder is 1:(4-5):1:(60-80); or the stirring time after the addition of the silane coupling agent KH-550 is 5-10 min, and the stirring speed is 200-300 r / min; or the stirring speed after the rubber powder is added is 150-250 r / min, and the stirring time is 5-10 min.

10. A method for preparing an ultra-high ductility interface treatment mortar adapted to prefabricated steel structures according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Weigh out cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether, modified rubber powder / polyvinyl alcohol fiber composite material according to the proportion; (2) Add the weighed cement, graded sand, water-reducing agent, redispersible latex powder, defoamer, cellulose ether and modified rubber powder / polyvinyl alcohol fiber composite material to the mixer and mix thoroughly to obtain ultra-high ductility interface treatment mortar powder. (3) Mix the ultra-high ductility interface treatment mortar powder with water at a water-to-material ratio of 20-24%, the mixing speed is 200±5r / min, the mixing time is 5±1min, and the mixture is left to stand for 1-2min to obtain the freshly mixed interface treatment mortar.

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