Additive capable of improving mortar stability and construction performance and preparation method

Abstract

The invention belongs to the technical field of building materials, and particularly relates to an additive capable of improving mortar stability and construction performance and a preparation method. The additive capable of improving the stability and the construction performance of the mortar is prepared from the following raw materials in parts by weight: 0.05 to 0.20 part of a water-retaining thickening agent, 0.05 to 0.20 part of modified rubber powder, 0.02 to 0.03 part of an anti-cracking agent and 0.05 to 0.10 part of an air entraining agent. Wherein the modified rubber powder is prepared by compounding resin rubber powder, polyvinyl alcohol, pregelatinized starch ether and a water reducing agent according to a specific proportion. The preparation method comprises the step of uniformly mixing all the raw materials. The additive is high in temperature adaptability and low in cost, can remarkably improve the water retention rate, mechanical strength and construction workability of mortar, and can be widely applied to various dry-mixed mortars.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an additive that can improve the stability and workability of mortar and its preparation method. Background Technology

[0002] Dry-mixed mortar, an indispensable green building material in construction engineering, has been widely used in various construction scenarios such as masonry, plastering, and floor leveling due to its advantages such as precise proportioning, high construction efficiency, and low environmental pollution. In the performance optimization of dry-mixed mortar, admixtures are the core functional components, which play a role in regulating the mortar's water retention capacity, setting time, mechanical strength, and workability, ensuring that the mortar can maintain stable performance even in complex construction environments.

[0003] Currently, the mainstream additive solutions in the industry mostly use hydroxypropyl methylcellulose ether as the core water-retaining and thickening ingredient. Some solutions will be combined with redispersible latex powder, starch ether or water-reducing agent for simple physical mixing. However, these traditional solutions have several technical challenges that urgently need to be addressed: First, they have poor temperature adaptability, especially in high-temperature summers or low-temperature winters, where the mortar's water retention fluctuates wildly. High temperatures can cause rapid evaporation of moisture, leading to wall cracking and sanding, while low temperatures can affect the cement hydration process and reduce mortar strength. Second, cost and performance are difficult to balance. To compensate for insufficient water retention at high temperatures, contractors often need to significantly increase the dosage of expensive cellulose ethers, which not only increases material costs but also leads to excessively high viscosity of fresh mortar, increased application resistance, reduced construction efficiency, and uneven plaster thickness. Third, they lack versatility. Existing admixture formulations are mostly designed for single-type mortars, requiring readjustment of the proportions when switching application scenarios, resulting in poor adaptability. Fourth, some formulations have weak synergy between components, with redundant or insufficient functional overlap, making it difficult to simultaneously meet the comprehensive requirements of water retention, crack resistance, strength, and workability. These problems severely restrict the application effect of dry-mixed mortar in actual engineering projects, and there is an urgent need for a new admixture solution that is stable in performance, cost-controllable, and widely adaptable.

[0004] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides an additive that can improve the stability and workability of mortar, comprising the following raw materials in parts by weight: 0.05-0.20 parts of water-retaining thickener, 0.05-0.20 parts of modified adhesive powder, 0.02-0.03 parts of crack-resistant agent, and 0.05-0.10 parts of air-entraining agent.

[0006] Preferably, the additive that can improve the stability and workability of mortar includes the following raw materials in parts by weight: 0.125 parts of water-retaining thickener, 0.125 parts of modified adhesive powder, 0.025 parts of crack-resistant agent and 0.05 parts of air-entraining agent.

[0007] Preferably, the water-retaining and thickening agent is hydroxypropyl methylcellulose ether; wherein: The viscosity of the hydroxypropyl methylcellulose ether is 200,000-250,000 mPa•s, and the ash content is 2-4%.

[0008] Preferably, the crack-resistant agent is one of polypropylene fiber, polyester fiber, and wood fiber.

[0009] Preferably, the air-entraining agent is one of rosin soap air-entraining agent, sodium dodecylbenzenesulfonate, or fatty alcohol polyoxyethylene ether.

[0010] Preferably, the modified adhesive powder includes resin adhesive powder, polyvinyl alcohol, pregelatinized starch ether, and water-reducing agent.

[0011] Preferably, the modified adhesive powder comprises resin adhesive powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent in a weight ratio of 15:1:6:4.

[0012] Preferably, the resin powder is vinyl acetate-ethylene copolymer resin powder or styrene-butadiene copolymer resin powder.

[0013] Preferably, the water-reducing agent is one of a polycarboxylate-based water-reducing agent, a naphthalene-based water-reducing agent, or an aliphatic water-reducing agent.

[0014] Based on the same technical concept, another aspect of the present invention is to provide a method for preparing an additive that can improve the stability and workability of mortar, wherein the preparation method is: mixing all raw materials.

[0015] The beneficial effects of this invention are as follows: The additive provided by this invention, through scientific formulation and synergistic design of components, effectively solves the problems of poor temperature adaptability, cost and performance imbalance, and insufficient versatility in the existing technology, and achieves a synergistic improvement in mortar performance, construction efficiency and economic benefits.

[0016] 1. Strong temperature adaptability and significantly improved performance stability: Through the synergistic effect of water-retaining thickener and modified adhesive powder, without the need to add additional high-priced components, it can effectively avoid problems such as high-temperature water loss cracking and low-temperature insufficient hydration, and ensure the mechanical strength and appearance quality of the mortar after hardening.

[0017] 2. Outstanding cost advantage and higher cost performance: The modified rubber powder is compounded with a specific ratio of resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent, which achieves a high-efficiency replacement of some high-priced cellulose ethers. While ensuring or even better than the performance of traditional formulas, it significantly reduces the total material cost and enhances the market competitiveness of the product.

[0018] 3. Improved ease of construction and wider adaptability: The mortar viscosity transition is uniform, and the troweling resistance is low, which can reduce the operation of frequently adjusting the amount of admixtures due to temperature changes on the construction site, simplify the water consumption control process, and improve construction efficiency; at the same time, the formula is highly versatile and can be directly applied to various dry-mixed mortar products such as masonry, plastering, and flooring without adjustment, reducing construction adaptation costs.

[0019] 4. Optimized overall performance and more reliable quality: The components work together to retain water, resist cracking and strengthen the mortar, which not only improves the water retention rate and mechanical strength of the mortar, but also improves the tensile bonding performance, effectively reducing quality defects such as wall cracking and sanding, and extending the service life of building finishes. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] Example 1 This embodiment provides a method for preparing an additive that can improve the stability and workability of mortar. The preparation method includes the following steps: This embodiment provides an additive that can improve the stability and workability of mortar. The raw materials are formulated in the following proportions by weight: 0.125 kg of water-retaining thickener, 0.125 kg of modified adhesive powder, 0.025 kg of crack-resistant agent, and 0.05 kg of air-entraining agent.

[0022] The water-retaining and thickening agent is hydroxypropyl methylcellulose ether with a viscosity of 220,000 mPa•s and an ash content of 3%; the crack-resistant agent is polypropylene fiber with a fiber length of 3 mm; the air-entraining agent is rosin soap air-entraining agent; the weight ratio of resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent in the modified rubber powder is 15:1:6:4, the resin powder is vinyl acetate-ethylene copolymer resin powder, and the water-reducing agent is a polycarboxylate water-reducing agent.

[0023] The preparation method of this additive includes the following steps: Weigh out the resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent according to the formula, put them in a high-speed mixer, and mix for 15 minutes at a speed of 800 r / min to obtain a uniform modified powder. Add the weighed water-retaining thickener, crack-resistant agent and air-entraining agent to the above modified adhesive powder, adjust the mixer speed to 600 r / min, and continue mixing for 20 minutes; After mixing, the mixture is sieved through a 200-mesh sieve to remove any clumps, thus obtaining the additive.

[0024] Tests showed that the mortar had a water retention rate of 92.5%, a 28-day compressive strength of 5.6 MPa, a tensile bond strength of 0.17 MPa, and showed no significant water loss or cracking after being placed in a 35°C high-temperature environment for 2 hours. It also exhibited low resistance during application and is suitable for exterior wall plastering.

[0025] Example 2 This embodiment provides a method for preparing an additive that can improve the stability and workability of mortar. The preparation method includes the following steps: This embodiment provides an additive that can improve the stability and workability of mortar. The raw materials are formulated in the following proportions by weight: 0.100 kg of water-retaining thickener, 0.150 kg of modified adhesive powder, 0.025 kg of crack-resistant agent, and 0.05 kg of air-entraining agent.

[0026] The water-retaining and thickening agent is hydroxypropyl methylcellulose ether with a viscosity of 220,000 mPa•s and an ash content of 4%; the crack-resistant agent is polypropylene fiber with a fiber length of 3 mm; the air-entraining agent is rosin soap air-entraining agent; the weight ratio of resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent in the modified rubber powder is 15:1:6:4, the resin powder is vinyl acetate-ethylene copolymer resin powder, and the water-reducing agent is a polycarboxylate water-reducing agent.

[0027] The preparation method of this additive includes the following steps: Weigh out the resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent according to the formula, put them in a high-speed mixer, and mix for 15 minutes at a speed of 700 r / min to obtain a uniform modified powder. Add the weighed water-retaining thickener, crack-resistant agent and air-entraining agent to the above modified adhesive powder, adjust the mixer speed to 500 r / min, and continue mixing for 20 minutes; After mixing, the mixture is sieved through a 200-mesh sieve to remove any clumps, thus obtaining the additive.

[0028] Tests showed that the mortar had a water retention rate of 91.6%, a 28-day compressive strength of 5.5 MPa, a tensile bond strength of 0.16 MPa, and showed no significant water loss or cracking after being placed in a 35°C high-temperature environment for 2 hours. It also exhibited low resistance during application and is suitable for exterior wall plastering.

[0029] Example 3 This embodiment provides a method for preparing an additive that can improve the stability and workability of mortar. The preparation method includes the following steps: This embodiment provides an additive that can improve the stability and workability of mortar. The raw materials are formulated in the following proportions by weight: 0.150 kg of water-retaining thickener, 0.100 kg of modified adhesive powder, 0.025 kg of crack-resistant agent, and 0.05 kg of air-entraining agent.

[0030] The water-retaining and thickening agent is hydroxypropyl methylcellulose ether with a viscosity of 200,000 mPa•s and an ash content of 2%; the crack-resistant agent is polypropylene fiber with a fiber length of 3 mm; the air-entraining agent is rosin soap air-entraining agent; the weight ratio of resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent in the modified rubber powder is 15:1:6:4, the resin powder is vinyl acetate-ethylene copolymer resin powder, and the water-reducing agent is a polycarboxylate water-reducing agent.

[0031] The preparation method of this additive includes the following steps: Weigh out the resin powder, polyvinyl alcohol, pregelatinized starch ether and water-reducing agent according to the formula, put them in a high-speed mixer, and mix for 20 minutes at a speed of 650 r / min to obtain a uniform modified powder. Add the weighed water-retaining thickener, crack-resistant agent and air-entraining agent to the above modified adhesive powder, adjust the mixer speed to 550 r / min, and continue mixing for 25 minutes; After mixing, the mixture is sieved through a 200-mesh sieve to remove any clumps, thus obtaining the additive.

[0032] Tests showed that the mortar had a water retention rate of 93.1%, a 28-day compressive strength of 5.5 MPa, a tensile bond strength of 0.17 MPa, and no significant water loss or cracking after being placed in a 35°C high-temperature environment for 2 hours. It also exhibited low resistance during application and is suitable for exterior wall plastering.

[0033] R&D example Through design, a four-factor, three-level orthogonal experimental study was conducted to analyze the effects of four components—resin powder, polyvinyl alcohol, pregelatinized starch ether, and water-reducing agent—on the water retention rate, compressive strength, and tensile bond strength of the basic plastering mortar formula. The modified powder formula was obtained through data analysis. The four-factor, three-level orthogonal experimental design is shown in Table 1.

[0034] Table 1 Orthogonal Experimental Design

[0035] Table 2 shows the formulas for different groups.

[0036] Table 2 Formulation Table

[0037] Table 3 shows the performance test results for each group.

[0038] Table 3 Performance Results

[0039] Analysis of Experimental Results: Tables 4-6 present the range analysis of water retention rate, strength, and tensile bond strength in the orthogonal experiment. Based on the data in the tables, the influencing factors on the water retention rate and tensile bond strength of the plastering mortar, from largest to smallest, are resin powder, polyvinyl alcohol, water-reducing agent, and pregelatinized starch ether. Resin powder is the main factor affecting both water retention rate and tensile bond strength, indicating that the amount of resin powder plays a dominant role in both. The results show that the water-reducing agent has the greatest impact on compressive strength. Considering water retention rate, the optimal mix ratio for plastering mortar is A3B3C3D3; considering compressive strength, the optimal formula is A2B2C3D3; and considering tensile bond strength, the optimal formula is A3B3C2D2. Range analysis shows that the optimal mix ratios for various performance tests are not consistent. Therefore, based on practical engineering considerations, water retention rate is the primary performance indicator, while compressive strength and tensile bond strength are secondary performance indicators. Combined with the range analysis, the resin powder dosage is a crucial factor affecting plastering mortar. A resin powder dosage of 0.15‰ results in the best water retention rate. Polyvinyl alcohol and pregelatinized starch ether do not have the largest ranges among the various performance indicators and have the least impact on water retention rate. Therefore, the dosage of polyvinyl alcohol and pregelatinized starch ether is taken as 0. The water-reducing agent has a small range in water retention performance indicators and has little effect on water retention rate, but it has the greatest impact on compressive strength. Considering the water-reducing agent dosage of 0.04‰, through comprehensive analysis of the influence of various factors on various indicators, the optimal test scheme for plastering mortar is A3B3C3D3. At the same time, based on cost considerations, it is sufficient to meet the indicator requirements. The resin powder dosage is 0.15‰, the polyvinyl alcohol dosage is 0.01‰, the pregelatinized starch ether dosage is 0.06‰, and the water-reducing agent dosage is 0.04‰.

[0040] Table 4. Analysis of water retention rate range

[0041] Table 5. Range analysis of 28-day compressive strength

[0042] Table 6. Range Analysis of Tensile Bond Strength

[0043] The formulation of the composite admixture was determined: By adjusting the dosage of cellulose ether and modified adhesive powder, a composite admixture with excellent construction performance, satisfactory mechanical properties, and high economic and social benefits was prepared. The basic formulation (preliminary study) is shown in Table 7.

[0044] Table 7 Basic Formulation of Composite Admixtures

[0045] The formulation design of the additives is shown in Table 8.

[0046] Table 8 Additive Formulation Design

[0047] After considering both performance and cost, the optimal formula is shown in Table 9.

[0048] Table 9 Optimal Formulation of Additives

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An additive capable of improving the stability and workability of mortar, characterized in that, The raw materials include the following components by weight: water-retention thickening agent 0.05-0.20 parts, modified glue powder 0.05-0.20 parts, anti-cracking agent 0.02-0.03 parts and air entraining agent 0.05-0.10 parts.

2. The additive capable of improving the stability and construction performance of mortar according to claim 1, characterized in that, The raw materials include the following components by weight: water-retention thickening agent 0.125 parts, modified glue powder 0.125 parts, anti-cracking agent 0.025 parts and air entraining agent 0.05 parts.

3. The additive capable of improving the stability and construction performance of mortar according to claim 1 or 2, characterized in that, The water-retention thickening agent is hydroxypropyl methyl cellulose ether; wherein: The viscosity of the hydroxypropyl methyl cellulose ether is 200000-250000 mPa•s, and the ash content is 2-4%.

4. The additive capable of improving the stability and construction performance of mortar according to claim 1 or 2, characterized in that, The anti-cracking agent is one of polypropylene fiber, polyester fiber and wood fiber.

5. The additive capable of improving the stability and workability of mortar according to claim 1 or 2, characterized by, The air entraining agent is one of rosin soap air entraining agent, sodium dodecyl benzene sulfonate or fatty alcohol polyoxyethylene ether.

6. The additive capable of improving the stability and workability of mortar according to claim 1 or 2, characterized by, The modified glue powder includes resin glue powder, polyvinyl alcohol, pre-gelatinized starch ether and water reducing agent.

7. The additive capable of improving the stability and workability of mortar according to claim 6, characterized by, The weight ratio of the modified glue powder, polyvinyl alcohol, pre-gelatinized starch ether and water reducing agent is 15:1:6:

4.

8. The additive capable of improving the stability and construction performance of mortar according to claim 6, characterized in that, The resin glue powder is vinyl acetate-ethylene copolymer resin glue powder or styrene-butadiene copolymer resin glue powder.

9. The additive capable of improving the stability and construction performance of mortar according to claim 6, characterized in that, The water reducing agent is one of polycarboxylic acid type water reducing agent, naphthalene type water reducing agent or aliphatic water reducing agent.

10. A process for the preparation of the additive capable of improving the stability and workability of mortar according to any one of claims 1 to 9, characterized in that, The preparation method is to mix all the raw materials.

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