Preparation method of gypsum-based lightweight plastering mortar

Abstract

The invention relates to the technical field of building construction, and discloses a gypsum-based lightweight plastering mortar preparation method, which comprises: 1, preparing basic components by weight: 85-90 parts of phosphorus building gypsum powder, 5-10 parts of glass beads, and 5-10 parts of heavy calcium carbonate, and the total weight of the basic components is 100 parts; according to the preparation method of the gypsum-based light plastering mortar, during construction, the gypsum-based light plastering mortar is moderate in fluidity and easy to operate, the dosage of the retarder and other components is accurately regulated and controlled, the initial setting time of the mortar is controlled to be 1-2 hours, the final setting time is controlled to be 2-3 hours, sufficient operation time is provided for constructors, meanwhile, it can be guaranteed that hardening is conducted within reasonable time, the project progress requirement is met, and the construction period is shortened. And the situation that construction cannot be carried out due to too fast condensation or follow-up procedure development is affected due to too slow condensation is avoided.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a method for preparing gypsum-based lightweight plastering mortar. Background Technology

[0002] With the rapid development of the construction industry, building energy conservation and green environmental protection have become core trends in the industry, placing higher demands on the performance of wall plastering materials. As a key material for leveling, protecting, and decorating building wall surfaces, plastering mortar's lightweight, thermal insulation, mechanical properties, and workability directly affect the quality of building projects, energy consumption, and living comfort.

[0003] Traditional cement-based plastering mortar suffers from problems such as high density, poor thermal insulation, and high drying shrinkage, making it difficult to meet the energy-saving and emission-reducing requirements of modern buildings. Gypsum-based plastering mortar, with its advantages of rapid setting and hardening, good volume stability, low thermal conductivity, and recyclability, is gradually becoming an ideal alternative to traditional cement-based mortar. However, the lightweight improvement of existing gypsum-based plastering mortars often faces the technical challenge of balancing strength and lightweighting: increasing the amount of lightweight aggregate to reduce weight can lead to a loose mortar structure, significantly reducing compressive and flexural strength, affecting the load-bearing and protective performance of the wall; simply optimizing the gypsum-based material ratio to increase strength is insufficient to achieve the desired lightweighting effect, and the improvement in thermal insulation performance is limited.

[0004] In addition, existing lightweight plastering mortars also suffer from poor workability, such as insufficient water retention leading to bleeding and segregation during construction, or unreasonable setting time affecting construction efficiency. Furthermore, some formulas contain chemical additives or industrial waste with poor compatibility, potentially causing later-stage strength reduction and decreased durability, thus limiting their widespread application in high-rise buildings and energy-efficient buildings.

[0005] To address the aforementioned technical challenges, developing a gypsum-based lightweight plastering mortar that combines low density, high strength, excellent thermal insulation properties, and good workability has become an urgent technical problem to be solved in this field, and is of great significance for promoting the greening and functional upgrading of building materials. Summary of the Invention

[0006] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing gypsum-based lightweight plastering mortar.

[0007] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a method for preparing gypsum-based lightweight plastering mortar, comprising the following steps: Step 1: Prepare the basic components by weight: 85-90 parts of phosphorus building gypsum powder, 5-10 parts of vitrified microspheres, and 5-10 parts of heavy calcium carbonate. The total weight of the basic components is 100 parts. Step 2: Prepare the following additives according to the following proportions relative to the total weight of the base components: 0.1-0.4% lime calcium, 0.5-2.0‰ water-retaining agent, 0.5-1.5‰ retarder, 1.5-5.0‰ thixotropic agent, 0.0-2.0‰ water-reducing agent, and 0.5-1.5% crack-resistant water-retaining agent. Step 3: Mix the basic components from Step 1 with the additives from Step 2 until homogeneous to obtain a dry powder mixture; Step 4: According to the weight ratio of dry powder mixture to water of 10:4~7, first add water to the container, then slowly pour in the dry powder mixture, and stir with an electric mixer for 2~3 minutes until the slurry is uniform and free of lumps. Let it stand for 2~3 minutes, then stir again for 1 minute to obtain gypsum-based lightweight plastering mortar. The plastering mortar should be used within 30 minutes after stirring.

[0008] Preferably, the water-retaining agent is one or more of hydroxypropyl methylcellulose ether, methylcellulose ether, starch ether, and polyvinyl alcohol.

[0009] Preferably, the retarder is one or more of polycitric acid, tartaric acid, amino acids, sodium hexametaphosphate, sodium pyrophosphate, zinc sulfate, aluminum sulfate, borax, and boric acid.

[0010] Preferably, the water-reducing agent is one or more of the following: acrylic polymer, naphthalene sulfonic acid formaldehyde condensate, lignin derivative, modified melamine, or polyether.

[0011] Preferably, the thixotropic agent is one or more of polyamide waxes, attapulgite, polyurethane associative thickeners, and modified guar gum.

[0012] Preferably, the crack-resistant and water-retaining agent is one or more of polyacrylates, polyvinyl alcohol, polyacrylamide, guar gum and their derivatives.

[0013] Preferably, the CaSO4・0.5H2O content of the phosphorus building gypsum powder in step 1 is ≥90.0%, and the whiteness is ≥81.

[0014] Preferably, the weight ratio of the dry powder mixture to water in step 4 is 10:5~6.

[0015] (III) Beneficial Effects Compared with the prior art, the present invention provides a method for preparing gypsum-based lightweight plastering mortar, which has the following beneficial effects: 1. The preparation method of this gypsum-based lightweight plastering mortar, wherein the present invention uses phosphorus-based building gypsum powder (CaSO4・0.5H2O≥90.0%) as the plastering mortar base material, with a dry density of 0.6~0.8 t / m³. 3 Compared to cement-based (1.2~1.8t / m³) 3 It is approximately 50% to 55% lighter and suitable for leveling, protecting, and decorating building wall surfaces. By adding compound admixtures, the gypsum plastering mortar of this invention has excellent workability. It can be quickly and evenly dispersed during mixing to form a fine and smooth paste. During construction, its fluidity is moderate, making it easy to handle. The dosage of retarder and other components can be precisely controlled to keep the initial setting time of the mortar within 1 to 2 hours and the final setting time within 2 to 3 hours. This provides sufficient working time for construction workers while ensuring that it hardens within a reasonable time to meet the project schedule requirements. It avoids the inability to construct due to excessively rapid setting or the impact of excessively slow setting on subsequent processes.

[0016] 2. The preparation method of this gypsum-based lightweight plastering mortar introduces a material with expansion compensation function into the mortar system, which effectively counteracts the shrinkage stress during the hardening process of gypsum, enhances the toughness and deformation resistance of the material, inhibits crack formation from the source, ensures a smooth and even plastering layer surface, and improves the appearance quality of the building. Its compressive strength is ≥2.6MPa, flexural strength is ≥1.2MPa, and tensile bond strength is ≥0.4MPa, which meets the standards for gypsum plastering mortar. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments 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.

[0018] A method for preparing gypsum-based lightweight plastering mortar includes the following steps: Step 1: Prepare the basic components by weight: 85-90 parts of phosphorus building gypsum powder, 5-10 parts of vitrified microspheres, and 5-10 parts of heavy calcium carbonate. The total weight of the basic components is 100 parts. Step 2: Prepare the following additives according to the following proportions relative to the total weight of the base components: 0.1-0.4% lime calcium, 0.5-2.0‰ water-retaining agent, 0.5-1.5‰ retarder, 1.5-5.0‰ thixotropic agent, 0.0-2.0‰ water-reducing agent, and 0.5-1.5% crack-resistant water-retaining agent. Step 3: Mix the basic components from Step 1 with the additives from Step 2 until homogeneous to obtain a dry powder mixture; Step 4: According to the weight ratio of dry powder mixture to water of 10:4~7, first add water to the container, then slowly pour in the dry powder mixture, and stir with an electric mixer for 2~3 minutes until the slurry is uniform and free of lumps. Let it stand for 2~3 minutes, then stir again for 1 minute to obtain gypsum-based lightweight plastering mortar. The plastering mortar should be used within 30 minutes after stirring. Preparation process: First, mix the basic components and additives evenly, then add water at a powder-to-water ratio of 10:(4~7) and stir twice (2~3 minutes for the first time and 1 minute after standing) to ensure the uniformity of the slurry and limit its use within 30 minutes to avoid coagulation failure. Performance regulation: The initial setting time is controlled at 1-2 hours and the final setting time at 2-3 hours by using a retarder (0.5-1.5‰), balancing the construction operation time and project progress; the crack-resistant and water-retaining agent (0.5-1.5%) and the expansion compensation mechanism are used to offset the hardening shrinkage stress of gypsum and inhibit the generation of cracks. Example 1: Prepare the basic components (parts by weight): 85 parts of phosphorus building gypsum powder (CaSO4・0.5H2O=92%, whiteness=82), 10 parts of vitrified microspheres, and 5 parts of heavy calcium carbonate; Prepare the admixtures (admixture ratio, relative to the total weight of the base components): 0.4% lime, 2.0‰ hydroxypropyl methylcellulose ether (water-retaining agent), 1.5‰ polycitric acid (retarder), 5.0‰ polyamide wax (thixotropic agent), 2.0‰ acrylic polymer (water-reducing agent), and 1.5% polyacrylate (crack-resistant water-retaining agent). Mix the base components and additives evenly, add water at a powder-to-water ratio of 10:7, stir with an electric mixer for 3 minutes until there are no lumps, let stand for 3 minutes, then stir again for 1 minute to obtain plastering mortar. Performance testing: Dry density 0.8 t / m³ 3 The initial setting time is 2 hours, the final setting time is 3 hours, the compressive strength is 2.6 MPa, the flexural strength is 1.2 MPa, the tensile bond strength is 0.4 MPa, there is no bleeding or stratification during construction, and there are no cracks after hardening.

[0019] Example 2: Prepare the basic components (parts by weight): 90 parts of phosphorus building gypsum powder (CaSO4・0.5H2O=95%, whiteness=83), 5 parts of vitrified microspheres, and 5 parts of heavy calcium carbonate; Prepare the admixtures (admixture ratio, relative to the total weight of the base components): 0.1% lime, 0.5‰ methyl cellulose ether (water-retaining agent), 0.5‰ tartaric acid (retarder), 1.5‰ attapulgite (thixotropic agent), 1.0‰ naphthalenesulfonic acid formaldehyde condensate (water-reducing agent), and 0.5% polyvinyl alcohol (crack-resistant water-retaining agent). Mix the base components and additives evenly, add water at a powder-to-water ratio of 10:4, stir with an electric mixer for 2 minutes until there are no lumps, let stand for 2 minutes, then stir again for 1 minute to obtain plastering mortar. Performance testing: Dry density 0.6 t / m³ 3 It has an initial setting time of 1 hour, a final setting time of 2 hours, a compressive strength of 3.0 MPa, a flexural strength of 1.5 MPa, a tensile bond strength of 0.5 MPa, moderate fluidity during construction, and a smooth surface after hardening.

[0020] Example 3: Prepare the basic components (parts by weight): 87 parts of phosphorus building gypsum powder (CaSO4・0.5H2O=93%, whiteness=82), 7 parts of vitrified microspheres, and 6 parts of heavy calcium carbonate; Prepare the admixtures (admixture ratio, relative to the total weight of the base components): 0.2% lime, 1.2‰ starch ether (water-retaining agent), 1.0‰ sodium hexametaphosphate (retarder), 3.0‰ polyurethane associative thickener (thixotropic agent), 0.5‰ lignin derivative (water-reducing agent), and 1.0% polyacrylamide (crack-resistant water-retaining agent). Mix the base components and additives evenly, add water at a powder-to-water ratio of 10:5, stir with an electric mixer for 2.5 minutes until there are no lumps, let stand for 2.5 minutes, then stir again for 1 minute to obtain plastering mortar. Performance testing: Dry density 0.7 t / m³ 3 It has an initial setting time of 1.5 hours, a final setting time of 2.5 hours, a compressive strength of 2.8 MPa, a flexural strength of 1.3 MPa, and a tensile bond strength of 0.45 MPa, exhibiting the best overall performance.

[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing gypsum-based lightweight plastering mortar, characterized in that, Includes the following steps: Step 1: Prepare the basic components by weight: 85-90 parts of phosphorus building gypsum powder, 5-10 parts of vitrified microspheres, and 5-10 parts of heavy calcium carbonate. The total weight of the basic components is 100 parts. Step 2: Prepare the following additives according to the following proportions relative to the total weight of the base components: 0.1-0.4% lime calcium, 0.5-2.0‰ water-retaining agent, 0.5-1.5‰ retarder, 1.5-5.0‰ thixotropic agent, 0.0-2.0‰ water-reducing agent, and 0.5-1.5% crack-resistant water-retaining agent. Step 3: Mix the basic components from Step 1 with the additives from Step 2 until homogeneous to obtain a dry powder mixture; Step 4: According to the weight ratio of dry powder mixture to water of 10:4~7, first add water to the container, then slowly pour in the dry powder mixture, and stir with an electric mixer for 2~3 minutes until the slurry is uniform and free of lumps. Let it stand for 2~3 minutes, then stir again for 1 minute to obtain gypsum-based lightweight plastering mortar. The plastering mortar should be used within 30 minutes after stirring.

2. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The water-retaining agent is one or more of hydroxypropyl methylcellulose ether, methylcellulose ether, starch ether, and polyvinyl alcohol.

3. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The retarder is one or more of the following: polycitric acid, tartaric acid, amino acids, sodium hexametaphosphate, sodium pyrophosphate, zinc sulfate, aluminum sulfate, borax, and boric acid.

4. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The water-reducing agent is one or more of the following: acrylic polymer, naphthalene sulfonic acid formaldehyde condensate, lignin derivative, modified melamine, or polyether.

5. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The thixotropic agent is one or more of polyamide waxes, attapulgite, polyurethane associative thickeners, and modified guar gum.

6. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The crack-resistant and water-retaining agent is one or more of polyacrylates, polyvinyl alcohol, polyacrylamide, guar gum and their derivatives.

7. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The phosphorus-containing building gypsum powder mentioned in step 1 has a CaSO4・0.5H2O content ≥90.0% and a whiteness ≥81.

8. The method for preparing a gypsum-based lightweight plastering mortar according to claim 1, characterized in that: The weight ratio of the dry powder mixture to water in step 4 is 10:5~6.