Anti-cracking polymer cement waterproof slurry and preparation method thereof

Abstract

The invention provides anti-cracking polymer cement waterproof slurry and a preparation method thereof. The cement waterproof slurry comprises a liquid material and a powder material, and the liquid material comprises the following components in parts by weight: 40-50 parts of a polymer composite emulsion, 2-2.5 parts of compound fibers and 2.7-3.3 parts of a functional aid; the powder material comprises 90-100 parts of cement, 30 parts of heavy calcium carbonate, 70-80 parts of quartz sand and 10-11 parts of an auxiliary agent. According to the invention, the polymer composite emulsion, the compound fiber and the functional auxiliary agent form the liquid material of the cement waterproof slurry, so that the cement waterproof slurry is modified, and meanwhile, the use amount of the powder material is greatly higher than that of the liquid material, so that the whole polymer cement is used as rigid polymer cement. The compound fiber is combined with the synergistic effect of the polymer emulsion and the inorganic base material, so that the multi-stage anti-cracking effect of micro-pore filling, macro-crack bridging and interface bonding enhancing is realized, and the anti-cracking property and waterproof durability of the slurry are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of waterproof materials technology, specifically relating to a crack-resistant polymer cement waterproof slurry and its preparation method. Background Technology

[0002] Polymer cement waterproofing slurry (K11 for short) is a waterproofing slurry made by mixing cement and fine aggregate as the main components, and polymers and additives as modifying materials in appropriate proportions. The Type I specification in JC / T2090-2011 Polymer Cement Waterproofing Slurry stipulates a compressive strength of 12 MPa and a flexural strength of 4.0 MPa, making it one of the few rigid waterproofing materials in the polymer cement-based waterproofing material category. Compared to other flexible materials, the rigid K11 coating is hard after curing, resulting in a stronger bond to tiles and less detachment. It also has high compressive and impermeability, making it widely used for waterproofing and damp-proofing of walls in home decoration.

[0003] K11 coating also has shortcomings, including insufficient toughness and weak impact and crack resistance, often cracking during ground operations, thus limiting its application. Industry scholars have explored various approaches to improve the toughness of cement-based materials. JS coating, made from cement, stone powder, and a high proportion of polymer emulsion, significantly increases the elongation at break of the waterproof coating, achieving similar performance to polymer emulsion waterproof coatings, but thus deviating from the category of rigid coatings. Fiber-reinforced waterproof slurries, primarily using polymer fibers such as polyester fibers as reinforcement, effectively increase the dimensional stability of the dry film; however, their application to K11 is counterproductive due to weak interfaces. Some scholars have used cellulose for modification; cellulose has a small molecular weight and excellent thickening and wetting effects on coatings, but excessive use can lead to uneven surface after drying. Summary of the Invention

[0004] The purpose of this invention is to address at least one of the technical problems mentioned above by proposing a crack-resistant polymer cement waterproof slurry and its preparation method. By compounding fibers of different lengths, structures and modifications, and combining the synergistic effect of polymer emulsion and inorganic substrate, a multi-level crack-resistant effect of "filling micropores - bridging macro cracks - enhancing interfacial adhesion" is achieved, which significantly improves the crack resistance and waterproof durability of the slurry.

[0005] To achieve the above objectives, the present invention employs the following technical means: a crack-resistant polymer cement waterproof slurry, comprising liquid and powder, wherein, by weight, the liquid comprises 40-50 parts of polymer composite emulsion, 2-2.5 parts of compounded fiber, and 2.7-3.3 parts of functional additives; and the powder comprises 90-100 parts of cement, 30 parts of heavy calcium carbonate, 70-80 parts of quartz sand, and 10-11 parts of additives.

[0006] By modifying the cement waterproofing slurry by composing a liquid component of polymer composite emulsion, compounded fibers, and functional additives, the amount of powder component is significantly higher than that of the liquid component, allowing the entire polymer cement to be used as a rigid polymer cement. Through the synergistic effect of compounded fibers combined with the polymer emulsion and inorganic substrate, a multi-level crack-resistant effect of "filling micropores, bridging macroscopic cracks, and enhancing interfacial adhesion" is achieved, significantly improving the crack resistance and waterproof durability of the slurry.

[0007] More preferably, the above-mentioned polymer composite emulsion is compounded from vinyl acetate-ethylene copolymer emulsion and styrene-acrylic emulsion at a mass ratio of (2.3-3):1; the solid content of the vinyl acetate-ethylene copolymer emulsion is 52-55%, and the solid content of the styrene-acrylic emulsion is 45-48%.

[0008] More preferably, the above-mentioned composite fiber is composed of chopped modified polypropylene fiber, long-cut grooved polypropylene fiber and modified basalt fiber in a mass ratio of 2:1:1.

[0009] By compounding short-cut modified PP fibers, long-cut grooved PP fibers, and modified basalt fibers, and combining the synergistic effect of polymer emulsion and inorganic substrate, a multi-level crack-resistant effect of "filling micropores, bridging macro cracks, and enhancing interfacial adhesion" is achieved, effectively improving the crack resistance and waterproof durability of the slurry.

[0010] More preferably, the length of the above-mentioned chopped modified polypropylene fiber is 1-2 mm and the diameter is 20-30 μm; the length of the long-cut grooved polypropylene fiber is 3-5 mm and the diameter is 40-50 μm; and the length of the modified basalt fiber is 2-4 mm and the diameter is 15-25 μm.

[0011] More preferably, the above-mentioned chopped modified polypropylene fiber is a chopped polypropylene fiber whose surface is modified with a silane coupling agent; the above-mentioned long-cut grooved polypropylene fiber is a long-cut polypropylene fiber whose surface is formed with a groove structure by a melt scoring process; and the above-mentioned modified basalt fiber is a basalt fiber whose surface is modified with epoxy resin coating.

[0012] More preferably, the above-mentioned functional additives include, by weight, 0.3-0.8 parts thickener, 0.2-0.6 parts dispersant, 0.1-0.3 parts defoamer, 1-2 parts film-forming aid and 0.1-0.2 parts preservative.

[0013] More preferably, the silicate cement is PO42.5 cement, the heavy calcium carbonate is 400-600 mesh powder, and the quartz sand is 40-80 mesh particles.

[0014] More preferably, the above-mentioned additives include 0.5-1 parts by weight of wood fiber, 0.5-1.5 parts by weight of water-reducing agent, and 6-10 parts by weight of silica fume.

[0015] Based on the same technical concept, the present invention also provides a method for preparing a crack-resistant polymer cement waterproof slurry, comprising the following steps: Step 1: Add the thickener to the water at 700-800 rpm and stir for 10-15 minutes until completely dissolved. Then add the polymer composite emulsion and stir for 5-10 minutes. Step 2: Based on Step 1, add the dispersant, defoamer, film-forming aid, and preservative to the polymer composite emulsion in proportion and stir for 6-8 minutes; Step 3: Based on Step 2, slowly add the modified compound fiber, increase the rotation speed to 1000-1200 rpm, and stir for 15-20 minutes to obtain the liquid material; Step 4: Mix cement, heavy calcium carbonate, quartz sand and additives in the appropriate proportions to obtain powder. Step 5: Mix the liquid material obtained in Step 3 with the powder material obtained in Step 4 in the specified proportions and stir evenly to obtain the polymer cement waterproof slurry.

[0016] More preferably, in step five above, the powder is added to the liquid and stirred with an electric mixer at a speed of 800-1000 rpm for 3-5 minutes until a uniform paste is formed.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention modifies the cement waterproofing slurry by using a polymer composite emulsion, compounded fibers, and functional additives to form the liquid component. Simultaneously, it ensures that the amount of powder component is significantly higher than that of the liquid component, allowing the entire polymer cement to be used as a rigid polymer cement, thus significantly improving the crack resistance and waterproof durability of the slurry. Short-cut modified polypropylene fibers can fill microscopic pores, reducing cement hydration shrinkage cracks; long-cut grooved polypropylene fibers bridge macroscopic cracks through the groove structure, preventing crack propagation; modified basalt fibers, with high strength and high interfacial adhesion, resist tensile stress generated by the substrate; by compounding three modified fibers, multi-level crack resistance from "microscopic" to "macroscopic" is achieved, effectively preventing the formation and propagation of cracks, thereby significantly improving the crack resistance of the cement-based waterproofing slurry.

[0018] The cement waterproofing slurry of this invention exhibits excellent stability during construction and storage. Through compounding additives and stepwise mixing, the sedimentation rate of fibers in the liquid is significantly reduced; the liquid can be stored at room temperature for a longer period without stratification or flocculation. Detailed Implementation

[0019] To facilitate understanding of the present invention, it will be described more fully and in detail below, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0020] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0022] The raw materials used in the examples are described as follows: a crack-resistant polymer cement waterproof slurry, comprising liquid and powder; the liquid comprises polymer composite emulsion, compounded fibers and functional additives; the powder comprises ordinary silicate cement, quartz sand, heavy calcium carbonate and other additives.

[0023] The polymer composite emulsion is composed of VAE emulsion and styrene-acrylic emulsion in a mass ratio of (2.3-3):1, wherein the solid content of the VAE emulsion is 52-55% and the solid content of the styrene-acrylic emulsion is 45-48%; the composite fiber is composed of short-cut modified PP fiber, long-cut grooved PP fiber and modified basalt fiber in a 2:1:1 ratio; the short-cut modified PP fiber is 1-2 mm in length and 20-30 μm in diameter, and its surface is modified with a silane coupling agent; the long-cut grooved PP fiber is 3-5 mm in length and 40-50 μm in diameter, and its surface is formed with a groove structure by a melt scoring process; the modified basalt fiber is 2-4 mm in length and 15-25 μm in diameter, and its surface is modified with epoxy resin coating; the functional additives include thickeners, dispersants, and desiccant. The product comprises foaming agents, film-forming aids, and preservatives; the thickener is HEC4 cellulose ether; the dispersant is polycarboxylate dispersant P30 provided by Guangdong Longhu Technology Co., Ltd.; the defoamer is an organosilicon defoamer, specifically A203E defoamer provided by Guangdong Longhu Technology Co., Ltd.; the film-forming aid is alcohol ester-12; the preservative is isothiazolinone; the silicate cement is PO42.5 cement; the heavy calcium carbonate is selected as 400-600 mesh powder; the quartz sand is selected as 40-80 mesh particles; the wood fiber is ZZP540 wood fiber provided by Guangdong Longhu Technology Co., Ltd.; the water-reducing agent has a water reduction rate ≥20%, and is polycarboxylate water-reducing agent Hanrius P29 provided by Guangdong Longhu Technology Co., Ltd.; the silica fume has an average particle size of 0.1-0.3 μm and a specific surface area of ​​20-28 m². 2 / g, which is the commonly used SF90 silica ash on the market.

[0024] A method for preparing a crack-resistant polymer cementitious waterproof slurry, comprising the following steps: Step 1: Add the thickener to the water at 700-800 rpm and stir for 10-15 minutes until completely dissolved. Then add the polymer composite emulsion and stir for 5-10 minutes. Step 2: Based on Step 1, add the dispersant, defoamer, film-forming aid, and preservative to the polymer composite emulsion in proportion and stir for 6-8 minutes; Step 3: Based on Step 2, slowly add the modified compound fiber, increase the rotation speed to 1000-1200 rpm, and stir for 15-20 minutes to obtain the liquid material; Step 4: Mix cement, heavy calcium carbonate, quartz sand and additives in the appropriate proportions to obtain powder. Step 5: Mix the liquid material obtained in Step 3 with the powder material obtained in Step 4 at a mass ratio of liquid material: powder material = 1: (2-2.2), and stir evenly to obtain polymer cement waterproof slurry.

[0025] Example 1 Composition and detailed proportions: Liquid: 30 parts VAE emulsion, 10 parts styrene-acrylic emulsion, 2 parts compound fiber (1 part chopped modified PP fiber, 0.5 parts long-chopped grooved PP fiber, 0.5 parts modified basalt fiber), 0.5 parts thickener, 0.4 parts polycarboxylate dispersant, 0.2 parts silicone defoamer, 1.5 parts film-forming aid, 0.1 parts preservative, 55.3 parts deionized water; Powder: 90 parts ordinary Portland cement, 70 parts quartz sand, 30 parts heavy calcium carbonate, 8 parts silica fume, 1 part wood fiber, 1 part polycarboxylate superplasticizer.

[0026] Example 2 Composition and detailed proportions: Liquid component: 30 parts VAE emulsion, 12 parts styrene-acrylic emulsion, 2.5 parts compound fiber (1.25 parts chopped modified PP fiber, 0.625 parts long-chopped grooved PP fiber, 0.625 parts modified basalt fiber), 0.6 parts thickener, 0.5 parts polycarboxylate dispersant, 0.25 parts silicone defoamer, 1.8 parts film-forming aid, 0.15 parts preservative, 54.2 parts deionized water; Powder component: 100 parts ordinary Portland cement, 80 parts quartz sand, 30 parts heavy calcium carbonate, 9 parts silica fume, 0.8 parts wood fiber, 0.9 parts polycarboxylate superplasticizer.

[0027] Example 3 Composition and detailed proportions: Liquid component: 35 parts VAE emulsion, 15 parts styrene-acrylic emulsion, 2.2 parts compound fiber (1.1 parts chopped modified PP fiber, 0.55 parts long-chopped grooved PP fiber, 0.55 parts modified basalt fiber), 0.55 parts thickener, 0.45 parts polycarboxylate dispersant, 0.22 parts silicone defoamer, 1.6 parts film-forming aid, 0.12 parts preservative, 51.4 parts deionized water; Powder component: 95 parts ordinary Portland cement, 72 parts quartz sand, 30 parts heavy calcium carbonate, 8.5 parts silica fume, 0.9 parts wood fiber, 1.1 parts polycarboxylate superplasticizer.

[0028] Comparative Example 1 Components and detailed proportions: Liquid: Compared with Example 1, no compound fiber was added, and there were no other changes; Powder: Same as Example 1.

[0029] Comparative Example 2 Components and detailed proportions: Liquid: Compared with Example 1, the added compound fiber has not undergone any modification treatment, and there are no other changes; Powder: Same as Example 1.

[0030] Comparative Example 3 Composition and detailed proportions: Liquid material: Compared with Example 1, short-cut modified PP fiber and long-cut grooved fiber are compounded (1.0 part of short-cut modified PP fiber and 0.5 part of long-cut grooved PP fiber), and there are no other changes; Powder material: Same as Example 1.

[0031] Comparative Example 4 Components and detailed proportions: Liquid: Compared with Example 1, chopped modified PP fiber and modified basalt fiber are compounded (1.0 part of chopped modified PP fiber and 0.5 parts of modified basalt fiber), and there are no other changes; Powder: Same as Example 1.

[0032] Comparative Example 5 Composition and detailed proportions: Liquid material: Compared with Example 1, long-cut grooved fiber and modified basalt fiber are compounded (1.0 part of long-cut grooved fiber and 0.5 parts of modified basalt fiber), and there are no other changes; Powder material: Same as Example 1.

[0033] Comparative Example 6 Components and detailed proportions: Liquid material: Compared with Example 1, 2 parts of compound fiber (1.1 parts of chopped modified PP fiber, 0.4 parts of long-cut grooved PP fiber, and 0.5 parts of modified basalt fiber) were added, with no other changes; Powder material: Same as Example 1.

[0034] All examples and comparative examples were tested according to the national standard JC / T2090-2011 "Polymer Cement Waterproofing Grout". The test results are shown in the table below:

[0035] As shown in the table above, the addition of modified composite fibers in this invention primarily enhances the material's crack resistance, achieving no cracking or peeling after more than 10 hours of boiling water boiling. It also showed no cracking or peeling after more than 48 freeze-thaw cycles. This data indicates that the three modified fibers, blended in a 2:1:1 ratio, combined with the synergistic effect of the polymer emulsion and inorganic matrix, achieve a multi-level crack resistance effect of "filling micropores, bridging macroscopic cracks, and enhancing interfacial adhesion," significantly improving the material's crack resistance. Because the fibers contribute tensile strength from multiple angles, the dimensional stability of the material is greatly improved, resulting in an increase in compressive strength from the standard 12 MPa to 20 MPa and above, and flexural strength from 4.0 MPa to 7.8 MPa and above. The untreated bond strength of the material increased from 0.7 to 1.2 or higher. The main failure occurred within the material itself because the chopped modified PP fibers were uniformly dispersed in the slurry, reducing interfacial porosity. The grooved structure of the long-chopped grooved PP fibers could embed into the substrate, bridging macroscopic defects at the interface and dispersing locally concentrated shear stress over a wider interfacial area. Simultaneously, the modified basalt fibers effectively transferred tensile stress at the interface, preventing interface cracking caused by stress concentration. This triple reinforcement of interfacial bond strength by the three fibers eliminated weak areas at the interface. Therefore, this modified composite fiber does not directly enhance bond strength, but rather indirectly increases bond strength through a synergistic effect, leading to an increase in destructive strength.

[0036] Comparative experiments have yielded the following conclusions: After modifying the three types of fibers, the polymer waterproof slurry prepared by compounding them in a 2:1:1 ratio with emulsion and inorganic materials exhibits superior mechanical properties and crack resistance compared to conventional preparation methods.

[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, 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 should fall within the protection scope of the present invention.

Claims

1. A crack-resistant polymer cementitious waterproof slurry, characterized in that, It includes liquid and powder components. By weight, the liquid component includes 40-50 parts of polymer composite emulsion, 2-2.5 parts of compounded fiber, and 2.7-3.3 parts of functional additives. The powder comprises 90-100 parts cement, 30 parts heavy calcium carbonate, 70-80 parts quartz sand, and 10-11 parts additives.

2. The polymer cement waterproofing slurry according to claim 1, characterized in that, The polymer composite emulsion is composed of vinyl acetate-ethylene copolymer emulsion and styrene-acrylic emulsion in a mass ratio of (2.3-3):1; the solid content of the vinyl acetate-ethylene copolymer emulsion is 52-55%, and the solid content of the styrene-acrylic emulsion is 45-48%.

3. The polymer cement waterproofing slurry according to claim 2, characterized in that, The composite fiber is composed of chopped modified polypropylene fiber, long-cut grooved polypropylene fiber and modified basalt fiber in a mass ratio of 2:1:

1.

4. The polymer cement waterproofing slurry according to claim 3, characterized in that, The chopped modified polypropylene fibers are 1-2 mm long and 20-30 μm in diameter; the long-cut grooved polypropylene fibers are 3-5 mm long and 40-50 μm in diameter; and the modified basalt fibers are 2-4 mm long and 15-25 μm in diameter.

5. The polymer cement waterproofing slurry according to claim 4, characterized in that, The chopped modified polypropylene fiber is a chopped polypropylene fiber whose surface has been modified with a silane coupling agent; the long-cut grooved polypropylene fiber is a long-cut polypropylene fiber whose surface has been grooved by a melt scoring process; the modified basalt fiber is a basalt fiber whose surface has been modified with epoxy resin coating.

6. The polymer cement waterproofing slurry according to claim 5, characterized in that, The functional additives include, by weight, 0.3-0.8 parts thickener, 0.2-0.6 parts dispersant, 0.1-0.3 parts defoamer, 1-2 parts film-forming aid, and 0.1-0.2 parts preservative.

7. The polymer cementitious waterproofing slurry according to any one of claims 1-6, characterized in that, The silicate cement is PO42.5 cement, the heavy calcium carbonate is 400-600 mesh powder, and the quartz sand is 40-80 mesh particles.

8. The polymer cement waterproofing slurry according to claim 7, characterized in that, The additives include, by weight, 0.5-1 parts wood fiber, 0.5-1.5 parts water-reducing agent, and 6-10 parts silica fume.

9. A method for preparing a crack-resistant polymer cementitious waterproof slurry, characterized in that, Includes the following steps: Step 1: Add the thickener to the water at 700-800 rpm and stir for 10-15 minutes until completely dissolved. Then add the polymer composite emulsion and stir for 5-10 minutes. Step 2: Based on Step 1, add the dispersant, defoamer, film-forming aid, and preservative to the polymer composite emulsion in proportion and stir for 6-8 minutes; Step 3: Based on Step 2, slowly add the modified compound fiber, increase the rotation speed to 1000-1200 rpm, and stir for 15-20 minutes to obtain the liquid material; Step 4: Mix cement, heavy calcium carbonate, quartz sand and additives in the appropriate proportions to obtain powder. Step 5: Mix the liquid material obtained in Step 3 with the powder material obtained in Step 4 in the specified proportions and stir evenly to obtain the polymer cement waterproof slurry.

10. The preparation method according to claim 9, characterized in that, In step five, the powder is added to the liquid and stirred with an electric mixer at a speed of 800-1000 rpm for 3-5 minutes until a uniform paste is formed.

Images