Lightweight waterproof gypsum plastering mortar and preparation method thereof

Abstract

The invention discloses lightweight water-resistant gypsum plastering mortar and a preparation method thereof, the mortar takes beta-semi-hydrated phosphogypsum as a main raw material, and the main raw material is compounded with slag, silica fume and cement to form a composite gel system; and modified vitrified microbeads, sodium citrate, hydroxymethyl cellulose ether, attapulgite, dispersible latex powder, an air entraining agent, a waterproof agent and other functional additives are combined to prepare the coating. The mortar has good compressive strength, flexural strength and bonding strength, solves the problems of low strength, poor water resistance, unstable construction performance and the like of traditional gypsum mortar, realizes high-dosage resource utilization of phosphogypsum, and has the advantages of good water resistance, light volume weight, high strength, no cracking or hollowing and the like.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a lightweight water-resistant gypsum plaster mortar and a preparation method thereof. Background Art

[0002] As an eco-friendly plastering material for interior walls and ceilings of buildings, gypsum plaster mortar has attracted widespread attention since the country implemented the energy conservation and emission reduction plan. Compared with traditional cement mortar, lightweight gypsum plaster mortar has the following advantages: flexible construction methods, both manual and mechanical spraying are possible, high construction efficiency, and disguised cost reduction; gypsum plaster mortar has a short setting time, simple maintenance, and reduced project costs; low thermal conductivity, which can reduce the energy consumption of buildings; low volume density, which can effectively reduce the load on the substrate itself.

[0003] Phosphogypsum is a byproduct of the wet phosphoric acid production process. It has the advantages of stable chemical properties, stable volume and low price. Its application in plaster mortar can realize the recycling of phosphogypsum, reduce environmental pollution and reduce the cost of mortar production. However, phosphogypsum contains impurities such as free phosphoric acid, sodium salt, potassium salt and organic matter, which will hinder the hydration of mortar and affect the performance of phosphogypsum products. At present, the utilization of phosphogypsum in the field of building materials accounts for more than 75% of the total utilization of phosphogypsum, and it is mostly used in the manufacture of gypsum boards. Due to the low strength and poor water resistance of phosphogypsum itself, its application in humid environments is limited. In addition, in order to improve the defects of gypsum matrix, cement, mineral powder and other cementitious materials or latex powder, cellulose ether and other modifiers are often added to improve the performance, but the adjustment of a single component is easy to cause system imbalance. For example, although excessive cement can improve water resistance, it will increase the density of mortar, and the introduction of lightweight aggregate can reduce the bulk density, but it is easy to cause slurry stratification and decreased bonding strength.

[0004] Chinese patent CN111072361A discloses a novel phosphogypsum plaster mortar, which is composed of the following raw materials in the following weight ratio: 250-300 parts of phosphogypsum, 180-250 parts of white cement, 150-250 parts of heavy calcium powder, 150-300 parts of vitrified microspheres, 80-150 parts of silica sand, 0.5-3 parts of retarder, 2-15 parts of cellulose, 3-15 parts of redispersible latex powder, 30-50 parts of wood fiber, 1-5 parts of slip agent, 0.5-3 parts of air entraining agent, and 0.5-5 parts of starch ether. However, the patent uses too much cement, resulting in a high bulk density, and the comprehensive performance of the plaster mortar is not examined.

[0005] Most of the current plastering gypsum mortars have a single composition, and the comprehensive properties of the prepared gypsum mortars, such as water retention rate, flexural strength, compressive strength, bonding strength, and water resistance, are lacking, thus affecting the construction quality of buildings. Therefore, it is necessary to improve the existing formula so that the produced gypsum plaster mortar can not only reduce the production cost but also have good comprehensive properties to meet the market demand. Summary of the Invention

[0006] To solve the technical problems in the above-mentioned background technology, the main object of the present invention is to provide a lightweight water-resistant gypsum plaster mortar and its preparation method. The plaster mortar of the present invention has good strength, and has various advantages such as light weight and good water resistance, and is suitable for various environments.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: A lightweight water-resistant gypsum plaster mortar, comprising the following components in parts by mass: 75-85 parts of β-hemihydrate phosphogypsum, 5-15 parts of slag, 2-5 parts of silica fume, 4-9 parts of cement, 5-10 parts of modified expanded perlite, 0.15-0.25 parts of retarder, 0.15-0.25 parts of water retention agent, 0.05-0.15 parts of attapulgite, 0.15-0.25 parts of air-entraining agent, 0.3-0.5 parts of starch ether, 0.3-0.5 parts of redispersible latex powder, 0.5-1.5 parts of organosilicon waterproofing agent, 35-58 parts of water.

[0008] Preferably, the air-entraining agent includes at least one of sodium dodecyl sulfonate, α-olefin sulfonate, sodium rosinate, and cocamidopropyl betaine.

[0009] The retarder includes at least one of calcium hydroxycarboxylate, citric acid or its sodium salt.

[0010] The water retention agent is at least one of methyl cellulose and hydroxypropyl methyl cellulose.

[0011] Preferably, the redispersible latex powder includes at least one of vinyl acetate or vinyl acetate-based latex powder.

[0012] More preferably, the air-entraining agent is compounded from sodium dodecyl sulfonate and α-olefin sulfonate according to a mass ratio of 1:1.5-2.5.

[0013] Preferably, the modified expanded perlite is expanded perlite surface-coated with silane coupling agent and nano-silica sol.

[0014] More preferably, the modified expanded perlite is prepared as follows: Mix the silane coupling agent, nano-silica sol and ethanol evenly to form a mixed solution, atomize it through an atomizer, spray it onto the surface of the expanded perlite, and dry it to obtain the modified expanded perlite.

[0015] By modifying the vitrified microspheres, the present invention enhances their bonding force with inorganic cementitious materials such as cement and gypsum, reduces the water absorption rate, improves the density of the mortar structure. At the same time, the modified vitrified microspheres cooperate with the organic waterproof agent to further improve the water resistance of the mortar. The modified vitrified microspheres can also optimize the water retention performance of the mortar, thereby increasing the flexural strength, compressive strength and softening coefficient, ensuring the long-term stability of the plastering mortar in a humid environment.

[0016] Preferably, the dosage ratio of the silane coupling agent, nano-silica sol and ethanol is (0.5 - 1.5) g : (2 - 5) g : (45 - 55) ml.

[0017] Preferably, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane (KH-550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane.

[0018] Preferably, the mass ratio of the vitrified microspheres to the silane coupling agent is 30 - 40 : 1.

[0019] Preferably, the viscosity of the water retention agent is 10000 - 200000 mPa·s, and the specific surface area of the slag ≥ 600 m² / kg; the organosilicon waterproof agent is an alkoxysiloxane emulsion, including at least one of methyltrimethoxysilane emulsion, epoxy silane emulsion, aminopropyltriethoxysilane emulsion.

[0020] Preferably, the light water-resistant gypsum plastering mortar includes the following components in parts by mass: 80 parts of β-hemihydrate phosphogypsum, 10 parts of slag, 4 parts of silica fume, 7 parts of cement, 8 parts of modified vitrified microspheres, 0.2 part of sodium citrate, 0.2 part of hydroxyethyl cellulose ether, 0.1 part of attapulgite, 0.4 part of vinyl acetate-based redispersible latex powder, 0.065 part of sodium dodecyl sulfonate, 0.13 part of α-olefin sulfonate, 0.4 part of starch ether, 1 part of organosilicon waterproof agent, 45 parts of water.

[0021] On the other hand, the present invention provides a method for preparing a light water-resistant gypsum plastering mortar, comprising the following steps: (1) Sequentially adding β-hemihydrate phosphogypsum, slag, silica fume, cement, modified vitrified microspheres, retarder, water retention agent, attapulgite, air-entraining agent, redispersible latex powder and water into a mixing blender, and stirring and mixing evenly to obtain a mixed slurry; (2) Adding an organosilicon waterproof agent to the mixed slurry and stirring evenly to obtain the light water-resistant gypsum plastering mortar.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses β-hemihydrate phosphogypsum as the main raw material, combined with slag, silica fume and cement to form a multi-component cementitious system. Under the interfacial strengthening effect of redispersible latex powder, the compressive strength of the mortar is increased to 10.15 - 11.56 MPa, the flexural strength reaches 3.39 - 3.98 MPa, and the bonding strength is 0.95 - 1.07 MPa, avoiding cracking and hollowing; through the compounding of organosilicon waterproofing agent and attapulgite, the water absorption and water resistance of the mortar are improved, the water absorption rate is as low as 3.39 - 4.90%, and the softening coefficient is as high as 90 - 95%; at the same time, modified expanded perlite is used to control the bulk density at 795 - 823 kg / m³, achieving the balanced optimization of light weight and mechanical properties.

[0023] 2. The present invention uses the compounding of hydroxyethyl methyl cellulose ether and attapulgite to improve the water retention rate of the mortar, increasing the water retention rate to 83.33 - 85.67% to ensure sufficient hydration; the dual surfactant system of sodium dodecyl sulfonate and α-olefin sulfonate significantly improves the dispersion of the slurry. The mortar of the present invention has low density, high fluidity and construction adhesiveness, and is suitable for thin-layer plastering of walls in high-humidity environments such as basements and bathrooms.

[0024] 3. The lightweight and water-resistant gypsum plastering mortar of the present invention uses industrial by-product phosphogypsum as the main raw material, which not only solves the problems of environmental pollution and solid waste recycling, but also reduces the production cost, and has important economic and social benefits. Detailed implementation mode

[0025] In the following examples and comparative examples, some raw materials were prepared by the following methods: The β-hemihydrate phosphogypsum was obtained by calcining phosphogypsum at 200 °C for 2.5 h and then ball-milling to 150 mesh.

[0026] The modified expanded perlite was prepared as follows: 2 g of silane coupling agent KH550 and 8 g of nano-silica sol were dissolved in 100 ml of ethanol and water with a volume ratio of 1:1, stirred and mixed evenly to form a mixed solution, which was then atomized by an atomizer and sprayed onto the surface of 70 g of expanded perlite, and dried at 70 °C for 2 h to obtain the modified expanded perlite.

[0027] Example 1: The lightweight and water-resistant gypsum plastering mortar of this example includes the following components in parts by mass: 75 parts of β-hemihydrate phosphogypsum, 5 parts of slag, 2 parts of silica fume, 4 parts of cement, 5 parts of modified expanded perlite, 0.15 parts of sodium citrate, 0.15 parts of hydroxyethyl methyl cellulose ether, 0.05 parts of attapulgite, 0.3 parts of vinyl acetate-based redispersible latex powder, 0.05 parts of sodium dodecyl sulfonate, 0.1 parts of α-olefin sulfonate, 0.3 parts of starch ether, 0.5 parts of methyltrimethoxysilane emulsion, 35 parts of water, wherein the specific surface area of the slag is greater than 600 m 2 / kg; The viscosity grade of hydroxyethyl methyl cellulose ether is 100000 mPa•s.

[0028] The preparation method of the light-weight water-resistant gypsum plastering mortar in this example is as follows: (1) Add β-hemihydrate phosphogypsum, slag, silica fume, cement, modified expanded perlite, sodium citrate, hydroxyethyl methyl cellulose ether, attapulgite, vinyl acetate-based redispersible latex powder, sodium dodecyl sulfonate, α-olefin sulfonate, and water into a mixing blender in sequence, stir and mix evenly to obtain a mixed slurry; (2) Add methyltrimethoxysilane emulsion to the mixed slurry and stir evenly to obtain the light-weight water-resistant gypsum plastering mortar.

[0029] Example 2: The light-weight water-resistant gypsum plastering mortar in this example includes the following components in parts by mass: 80 parts of β-hemihydrate phosphogypsum, 10 parts of slag, 4 parts of silica fume, 7 parts of cement, 8 parts of modified expanded perlite, 0.2 part of sodium citrate, 0.2 part of hydroxyethyl methyl cellulose ether, 0.1 part of attapulgite, 0.4 part of vinyl acetate-based redispersible latex powder, 0.065 part of sodium dodecyl sulfonate, 0.13 part of α-olefin sulfonate, 0.4 part of starch ether, 1 part of methyltrimethoxysilane emulsion, 45 parts of water; among them, the specific surface area of the slag is greater than 600 m 2 / kg; The viscosity grade of hydroxyethyl methyl cellulose ether is 100000 mPa•s.

[0030] The preparation method of the light-weight water-resistant gypsum plastering mortar in this example is as follows: (1) Add β-hemihydrate phosphogypsum, slag, silica fume, cement, modified expanded perlite, sodium citrate, hydroxyethyl methyl cellulose ether, attapulgite, vinyl acetate-based redispersible latex powder, sodium dodecyl sulfonate, α-olefin sulfonate, and water into a mixing blender in sequence, stir and mix evenly to obtain a mixed slurry; (2) Add methyltrimethoxysilane emulsion to the mixed slurry and stir evenly to obtain the light-weight water-resistant gypsum plastering mortar.

[0031] Example 3: The light-weight water-resistant gypsum plastering mortar in this example includes the following components in parts by mass: 85 parts of β-hemihydrate phosphogypsum, 15 parts of slag, 5 parts of silica fume, 9 parts of cement, 10 parts of modified expanded perlite, 0.25 part of sodium citrate, 0.25 part of hydroxyethyl methyl cellulose ether, 0.15 part of attapulgite, 0.5 part of vinyl acetate-based redispersible latex powder, 0.08 part of sodium dodecyl sulfonate, 0.16 part of α-olefin sulfonate, 0.5 part of starch ether, 1.5 parts of methyltrimethoxysilane emulsion, 58 parts of water; among them, the specific surface area of the slag is greater than 600 m 2 / kg; The viscosity grade of hydroxyethyl methyl cellulose ether is 100000 mPa•s.

[0032] The preparation method of the lightweight water-resistant gypsum plastering mortar in this example is as follows: (1) Add β-hemihydrate phosphogypsum, slag, silica fume, cement, modified expanded perlite, sodium citrate, hydroxyethyl methyl cellulose ether, attapulgite, vinyl acetate-based redispersible latex powder, sodium dodecyl sulfonate, α-olefin sulfonate and water into a mixing blender in sequence, stir and mix evenly to obtain a mixed slurry; (2) Add methyltrimethoxysilane emulsion to the mixed slurry, stir evenly to obtain the lightweight water-resistant gypsum plastering mortar.

[0033] Example 4: The lightweight water-resistant gypsum plastering mortar in this example includes the following components in parts by mass: 80 parts of β-hemihydrate phosphogypsum, 10 parts of slag, 4 parts of silica fume, 5 parts of cement, 8 parts of modified expanded perlite, 0.15 part of sodium citrate, 0.15 part of hydroxyethyl methyl cellulose ether, 0.1 part of attapulgite, 0.4 part of vinyl acetate-based redispersible latex powder, 0.05 part of sodium dodecyl sulfonate, 0.1 part of α-olefin sulfonate, 0.5 part of starch ether, 0.6 part of methyltrimethoxysilane emulsion, 45 parts of water; among them, the specific surface area of the slag is greater than 600 m 2 / kg; the viscosity grade of the hydroxyethyl methyl cellulose ether is 100000 mPa•s.

[0034] The preparation method of the lightweight water-resistant gypsum plastering mortar in this example is as follows: (1) Add β-hemihydrate phosphogypsum, slag, silica fume, cement, modified expanded perlite, sodium citrate, hydroxyethyl methyl cellulose ether, attapulgite, vinyl acetate-based redispersible latex powder, sodium dodecyl sulfonate, α-olefin sulfonate and water into a mixing blender in sequence, stir and mix evenly to obtain a mixed slurry; (2) Add methyltrimethoxysilane emulsion to the mixed slurry, stir evenly to obtain the lightweight water-resistant gypsum plastering mortar.

[0035] Comparative Example 1: This comparative example is basically the same as Example 2, the difference is that: attapulgite is not used in the mortar.

[0036] Comparative Example 2: This comparative example is basically the same as Example 2, the difference is that: only sodium dodecyl sulfonate is used in the mortar.

[0037] Comparative Example 3: This comparative example is basically the same as Example 2, the difference is that: vinyl acetate-based redispersible latex powder is not used in the mortar.

[0038] Comparative Example 4: This comparative example is basically the same as Example 2, except that methyltrimethoxysilane emulsion is not used in the mortar.

[0039] The performance test results of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0040] Table 1

[0041] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A lightweight water-resistant gypsum plastering mortar, characterized in that, It comprises the following components in parts by mass: 75 - 85 parts of β - hemihydrate phosphogypsum, 5 - 15 parts of slag, 2 - 5 parts of silica fume, 4 - 9 parts of cement, 5 - 10 parts of modified expanded perlite, 0.15 - 0.25 parts of retarder, 0.15 - 0.25 parts of water - retaining agent, 0.05 - 0.15 parts of attapulgite, 0.15 - 0.25 parts of air - entraining agent, 0.3 - 0.5 parts of starch ether, 0.3 - 0.5 parts of redispersible latex powder, 0.5 - 1.5 parts of organosilicon waterproofing agent, and 35 - 58 parts of water.

2. The light water-resistant gypsum plastering mortar according to claim 1, characterized in that, The air - entraining agent includes at least one of sodium dodecyl sulfonate, α - olefin sulfonate, sodium rosinate, and coconut oil amide propyl betaine; The retarder includes at least one of calcium hydroxycarboxylate, citric acid or its sodium salt; The water - retaining agent is at least one of methyl cellulose and hydroxypropyl methyl cellulose; The redispersible latex powder includes at least one of vinyl acetate or vinyl acetate homopolymer.

3. The lightweight water-resistant gypsum plastering mortar according to claim 1, characterized in that, The modified expanded perlite is expanded perlite surface - coated with silane coupling agent and nano - silica sol.

4. The light water-resistant gypsum plastering mortar according to claim 3, wherein, The modified expanded perlite is prepared as follows: Mix the silane coupling agent, nano - silica sol, and ethanol evenly to form a mixed solution. After atomizing with an atomizer, spray it onto the surface of the expanded perlite and dry to obtain the modified expanded perlite.

5. The light water-resistant gypsum plastering mortar according to claim 4, characterized in that, The dosage ratio of the silane coupling agent, nano - silica sol, and ethanol is (0.5 - 1.5) g:(2 - 5) g:(45 - 55) ml.

6. The lightweight water-resistant gypsum plastering mortar according to claim 4, wherein The mass ratio of the expanded perlite to the silane coupling agent is 20 - 30:

1.

7. The light water-resistant gypsum plastering mortar according to claim 1, characterized in that, The specific surface area of the slag ≥ 600 m² / kg, and the organosilicon waterproofing agent is an alkylalkoxysiloxane emulsion.

8. The lightweight water-resistant gypsum plastering mortar according to claim 2, wherein The air - entraining agent is compounded from sodium dodecyl sulfonate and α - olefin sulfonate in a mass ratio of 1:1.5 - 2.

5.

9. The lightweight water-resistant gypsum plastering mortar according to claim 1, wherein The light - weight water - resistant gypsum plastering mortar comprises the following components in parts by mass: 80 parts of β - hemihydrate phosphogypsum, 10 parts of slag, 4 parts of silica fume, 7 parts of cement, 8 parts of modified expanded perlite, 0.2 part of slow - release agent, 0.2 part of water - retaining agent, 0.1 part of attapulgite, 0.4 part of redispersible latex powder, 0.195 part of air - entraining agent, 0.4 part of starch ether, 1 part of organosilicon waterproofing agent, and 45 parts of water.

10. A lightweight water-resistant gypsum plastering mortar according to any one of claims 1 to 8, characterized in that The preparation method is characterized by comprising the following steps: (1) Add β - hemihydrate phosphogypsum, slag, silica fume, cement, modified expanded perlite, retarder, water - retaining agent, attapulgite, air - entraining agent, redispersible latex powder, and water into a mixing blender in sequence, and stir and mix evenly to obtain a mixed slurry; (2) Add the organosilicon waterproofing agent to the mixed slurry and stir evenly to obtain the light - weight water - resistant gypsum plastering mortar.

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