A water-resistant and mildew-resistant β-type building gypsum plaster mortar and its preparation method

Abstract

This invention relates to a water-resistant and mildew-resistant β-type building gypsum plastering mortar and its preparation method, belonging to the technical field of comprehensive utilization of industrial solid waste resources. By weight, the mortar consists of 40-85 parts β-type building gypsum, 10-45 parts composite aggregate, 5-10 parts inorganic composite activator, 3-5 parts composite waterproof and antibacterial component, 0.10-0.5 parts retarder, 0.2-0.6 parts toughening agent, 0.05-0.20 parts water, and 25-50 parts water. The composite waterproof and antibacterial component is composed of waterproof component, anti-mildew component, and surfactant in a weight ratio of (1-6):(3-8):(0.05-0.20). The mortar achieves adjustable density through aggregate gradation, improving construction efficiency, and exhibits excellent waterproof and mildew-resistant properties, strong durability, and good mechanical properties, thus accelerating the utilization of industrial by-product gypsum solid waste resources.

Description

Technical Field

[0001] This invention relates to a water-resistant and mildew-resistant β-type building gypsum plastering mortar and its preparation method, belonging to the technical field of comprehensive utilization of industrial solid waste resources. Background Technology

[0002] Industrial by-product gypsum is currently a major source of solid waste in China, with annual emissions exceeding 200 million tons. In particular, industrial by-product phosphogypsum accounts for nearly 100 million tons annually, with an actual utilization rate of less than 30%, resulting in significant environmental pollution. As a byproduct of the phosphate chemical industry, the large-scale accumulation of phosphogypsum causes enormous environmental damage. Besides occupying vast areas of land, it also leads to dust pollution, groundwater and soil contamination, and landslides caused by phosphogypsum accumulation. Currently, incorporating it into specific products used in bulk building materials is an effective way to achieve comprehensive and large-scale utilization of phosphogypsum.

[0003] The calcination of raw industrial by-product gypsum yields building gypsum primarily composed of β-hemihydrate gypsum and type II anhydrous gypsum. This gypsum is then mixed with fine aggregates and various additives to prepare building gypsum plastering mortar. This plastering mortar possesses numerous advantages, including high air permeability, fire resistance, readily available raw materials, strong plasticity, and low cost, making it one of the main methods for disposing of large quantities of gypsum solid waste. However, due to the high solubility of gypsum itself, the large number of hydrophilic groups on its surface, and the porous structure of its hardened form, gypsum materials also exhibit defects such as high water absorption, susceptibility to dampness and mold, and poor water resistance, significantly limiting the application range of building gypsum plastering mortar.

[0004] Currently, the mainstream methods of gypsum waterproofing include external waterproofing, inorganic internal waterproofing, and organic internal waterproofing. External waterproofing refers to applying hydrophobic substances (such as asphalt and pure acrylic polymers) to the surface of gypsum products to form a hydrophobic film that isolates water erosion. However, it is greatly affected by the external environment and cannot maintain its waterproofing performance for a long time. Inorganic internal waterproofing involves adding inorganic active powders, including silicates and pozzolanic materials, to improve mechanical properties and softening coefficient by changing the hydration products that fill the pores inside the hardened material. However, the improvement in waterproofing is limited, and the incorporation of some colored inorganic powders affects the appearance of gypsum products. Organic internal waterproofing involves adding organic hydrophobic substances that can cover the surface of gypsum crystals or form a waterproof film inside the gypsum during the hydration and hardening process. This can change the hydrophilicity of the gypsum surface, regulate the growth rate of gypsum crystals, and prevent water erosion, effectively improving waterproofing performance. However, it will affect its mechanical properties to some extent.

[0005] In summary, existing gypsum plastering mortars have defects such as poor waterproofing and susceptibility to moisture and mold. Waterproof gypsum mortars obtained using external waterproofing technology have poor waterproofing durability, while waterproof mortars obtained using internal waterproofing technology have affected mechanical properties. Furthermore, the addition of components increases the density of gypsum plastering mortars, making them difficult to apply and affecting construction efficiency. Summary of the Invention

[0006] In view of the shortcomings of existing gypsum plastering mortar, such as poor waterproofing and durability, susceptibility to dampness and mold, and high density which makes it difficult to construct efficiently, one of the objectives of this invention is to provide a water-resistant and mold-resistant β-type building gypsum plastering mortar. The mortar has good waterproofing and durability, low density which makes it easy to apply by spraying, and has the dual functions of water resistance and mold resistance.

[0007] The second objective of this invention is to provide a method for preparing water-resistant and mildew-resistant β-type building gypsum plaster mortar.

[0008] The objective of this invention is achieved through the following technical solutions.

[0009] A water-resistant and mildew-resistant β-type building gypsum plaster mortar, composed of the following components in parts by weight:

[0010]

[0011] The β-type building gypsum is desulfurized gypsum, phosphogypsum, or titanium gypsum; preferably, the β-type building gypsum is phosphogypsum.

[0012] The composite waterproof and antibacterial component is composed of a waterproof component, an antifungal component, and a surfactant in a weight ratio of (1-6):(3-8):(0.05-0.20); wherein the waterproof component includes at least one of methylsiloxane, paraffin emulsion, and silicone-acrylic emulsion; the antifungal component includes an organic antibacterial component and an inorganic antibacterial component; the organic antibacterial component is a cyclodextrin-essential oil encapsulation compound, and the inorganic antibacterial component is at least one of nano-nitrogen-doped titanium dioxide and nano-zinc oxide; the surfactant is triethylhexylphosphoric acid;

[0013] Preferably, the waterproofing component is composed of methylsiloxane, paraffin emulsion, and silicone-acrylic emulsion in a weight ratio of (0.2-1):(0-4):(0.5-1); the methylsiloxane is sodium methylsiloxane or potassium methylsiloxane; the paraffin emulsion is prepared by compounding and emulsifying a biionic surfactant, with a hydrophilic-lipophilic balance (HLB) value of 8-18; the antifungal component is a nano-titanium dioxide and cyclodextrin-essential oil encapsulation complex, and the surfactant is triethylhexylphosphonic acid.

[0014] The composite aggregate is obtained by continuous gradation of lightweight aggregate and sand; wherein, the lightweight aggregate is composed of lightweight fine aggregate with a particle size of 2.5 mm to 75 μm and micro / nano-scale lightweight aggregate with a particle size < 75 μm; the lightweight fine aggregate is at least one of vitrified microspheres, perlite, polystyrene particles and rock wool particles; the micro / nano-scale lightweight aggregate is at least one of nano-silica aerogel powder and ultrafine microspheres, with a bulk density of 40 to 60 kg / m³. 3 The sand is at least one of limestone manufactured sand, granite manufactured sand, quartz sand, iron tailings sand, phosphorus tailings sand and stone powder tailings sand, and the sand has a methylene blue value (MB) ≤ 1.4, a fineness modulus (Mx) of 0.8 to 1.5 and a sphericity coefficient ≥ 0.9.

[0015] Preferably, the composite aggregate is obtained by combining vitrified microspheres, nano-silica aerogel powder and phosphate tailings sand in a weight ratio of (50-110):(3-8):(100-40).

[0016] The inorganic composite activator is composed of two or more of the following: granulated blast furnace slag powder, silicate cement, calcium oxide, sodium silicate, and sodium sulfate.

[0017] Preferably, the inorganic composite activator is composed of granulated blast furnace slag powder, silicate cement, and calcium oxide in a weight ratio of (2.5–5):(5–10):(0–3), and the total mass fraction of SiO2, Al2O3, and CaO in the inorganic composite activator is ≥80%, and the specific surface area of ​​the inorganic composite activator is 450–500 m². 2 / kg.

[0018] The retarder is a composite powder of an organic retarder and an inorganic inert powder; the organic retarder includes protein retarders, citric acid, or sodium tripolyphosphate; the inorganic inert powder is zeolite powder.

[0019] Preferably, the retarder is a composite powder composed of an organic retarder and an inorganic inert powder in a weight ratio of (1-5):(95-99);

[0020] More preferably, the retarder is a composite powder composed of a protein-based retarder and zeolite powder in a weight ratio of (1-3):(97-99). The zeolite powder has a rough surface and porous structure, which has a strong carrying capacity, allowing the organic retarder to be evenly dispersed in gypsum and improving the fluidity of gypsum to a certain extent. In addition, the zeolite powder has a strong adsorption capacity and can adsorb harmful impurities such as phosphorus, fluorine, and organic matter in gypsum, thereby improving the performance of gypsum products. The zeolite powder contains a certain amount of active silica and alumina, which have good compatibility with gypsum and can react with inorganic composite activators to form gel substances, which is beneficial to the performance of gypsum.

[0021] The toughening agent is silicon carbide whiskers, calcium carbonate whiskers, or calcium sulfate whiskers.

[0022] Preferably, the toughening agent is calcium sulfate whiskers with a length of 0.05–0.20 mm and a diameter of 0.5–0.8 μm; the calcium sulfate whiskers have excellent toughening properties, chemical corrosion resistance, and high strength. Calcium sulfate whiskers have good compatibility with gypsum, can exist stably in gypsum without changing their morphology and crystal form, and are tightly bonded to the gypsum matrix to form a spatial network structure, thereby significantly improving the strength and toughness of the gypsum.

[0023] The water-retaining agent is at least one of adhesive powder and cellulose ether; the adhesive powder is a styrene-butadiene copolymer, a tert-carbonate copolymer, or an ethylene-vinyl acetate copolymer; the cellulose ether is one or two of methylcellulose, hydroxypropyl methylcellulose, and hydroxyethyl methylcellulose, and the viscosity of the cellulose ether is 5W to 20W; the addition of the water-retaining agent can significantly improve the water retention and viscosity of gypsum mortar, facilitate the hydration and hardening reaction of inorganic components in the mortar, strengthen the bonding between components, and improve the mechanical properties of gypsum mortar.

[0024] Preferably, the water-retaining agent is composed of a styrene-butadiene copolymer and hydroxypropyl methylcellulose with a viscosity of 5W to 10W in a weight ratio of (0 to 0.1):(0 to 0.2), and the weight parts of the styrene-butadiene copolymer and the hydroxypropyl methylcellulose are not both 0.

[0025] The working principle of the composite waterproof and antibacterial component is as follows: Paraffin emulsion and silicone-acrylic emulsion in the waterproof component are added to β-type building gypsum. During the gypsum hardening process, the hydrophilic groups of the silicone-acrylic emulsion combine with the hydrophilic groups on the gypsum surface, encapsulating the gypsum crystal surface. The hydrophobic groups are arranged sequentially on the outside, playing a certain hydrophobic role. With thorough mixing of the gypsum powder, the methylsiloxane in the waterproof component is evenly distributed inside the gypsum. The silanol groups inside its molecules undergo a dehydration cross-linking reaction with the hydrophilic groups on the gypsum surface, generating a highly hydrophobic polymer compound. As the hydration reaction proceeds and water is consumed, the methylsiloxane gradually forms a closed hydrophobic resin film, i.e., a hydrophobic film, on the gypsum crystal surface, further hindering water penetration. Simultaneously, it reacts with the hydroxyl groups in the silicate material to form silane chains with Si-R groups at the ends (R is generally CH3), blocking the pores inside the gypsum, thereby significantly improving the water resistance of the gypsum mortar. In addition, the addition of the emulsion can play a certain lubricating role, which is beneficial to the formation of the methylsiloxane hydrophobic film.

[0026] The organic antibacterial component in the antifungal component kills mold by binding to the active sites of mold, while the inorganic antibacterial component prevents the formation of mold cell membranes through physical adsorption, thereby reducing the survival ability of mold, reducing the reproduction process, and achieving the purpose of antibacterial action.

[0027] The surfactant is a surfactant with both lipophilic and hydrophilic properties within its molecule, which allows the waterproof and anti-mildew components to form a well-adapted mixture that is evenly dispersed in the gypsum, further enhancing the anti-mildew and waterproof effect of the gypsum.

[0028] Preferably, a water-resistant and mildew-resistant β-type building gypsum plaster mortar is composed of the following components in parts by weight:

[0029] 70-85 parts of β-type building gypsum, 3-4 parts of composite waterproof and antibacterial component, 15-30.1 parts of composite aggregate, 6.1-9.9 parts of inorganic composite activator, 0.5 parts of retarder, 0.3 parts of toughening agent, 0.1-0.20 parts of water-retaining agent, and 50 parts of water.

[0030] A method for preparing the water-resistant and mildew-resistant β-type building gypsum plaster mortar of the present invention includes the following steps:

[0031] Step 1: Dissolve the composite waterproof and antibacterial components and retarder in water, stir for 30-40 minutes, and homogenize for 60-80 minutes to obtain solution A;

[0032] Step 2: Dry mix β-type building gypsum, composite aggregate, inorganic composite activator, toughening agent and water-retaining agent for 1.5 to 3.0 minutes to obtain powder B;

[0033] Step 3: Slowly add solution A to powder B and stir for 2-4 minutes to obtain a uniform water-resistant and mildew-resistant β-type building gypsum plaster mortar.

[0034] Preferably, the preparation method of the composite waterproof and antibacterial component in step one is as follows:

[0035] (1) Add methylsiloxane and acetic acid to deionized water at the same time, and stir at 20-25°C for 15-30 minutes to allow them to react fully and obtain an organosilicon solution; wherein acetic acid is a catalyst, and the mass ratio of methylsiloxane to acetic acid is methylsiloxane:acetic acid = 2:(0.5-0.8);

[0036] (2) Add the paraffin emulsion and silicone-acrylic emulsion to the organosilicon solution obtained in step (1), stir evenly, and obtain a waterproof component solution;

[0037] (3) Add the organic antibacterial component and the inorganic antibacterial component to the waterproof component solution obtained in step (2) to obtain a mixed solution;

[0038] (4) Add surfactant to the mixed solution obtained in step (3) while stirring, and stir for 30 to 45 minutes to make the components evenly dispersed to obtain a well-adapted mixed solution, namely a composite waterproof and antibacterial component.

[0039] Preferably, when the β-type building gypsum selected in step two is phosphogypsum, the modification step of phosphogypsum is also included: drying phosphogypsum at 100-120℃ for 2-3 hours, neutralizing it with alkali with a mass concentration of 4-9%, aging it for 48-72 hours, and grinding it to a fineness of 40-80 μm to prepare β-type hemihydrate phosphogypsum; the hemihydrate gypsum content in the β-type hemihydrate phosphogypsum is ≥85%, and the dihydrate gypsum content is ≤4%. The drying, neutralization, and aging processes in the modification process can reduce the content of harmful impurities such as soluble phosphorus, soluble fluorine, and organic matter in phosphogypsum, and ensure the quality of the prepared gypsum products.

[0040] An application of the water-resistant and mildew-resistant β-type building gypsum plastering mortar of the present invention, wherein the mortar is used for plastering the interior and exterior walls and kitchen and bathroom areas of building and decoration projects;

[0041] Specifically, the application is carried out by manual application or mechanical spraying, and the effective application time is 1 to 2 hours.

[0042] Beneficial effects

[0043] (1) This invention provides a water-resistant and mildew-resistant β-type building gypsum plastering mortar. The mortar uses industrial by-product gypsum solid waste β-type building gypsum as the main raw material, which broadens the application range of building gypsum plastering mortar and accelerates the disposal speed of gypsum solid waste. Composite aggregate, composite waterproof and antibacterial components, inorganic composite activators, retarders, toughening agents and water-retaining agents are added. The waterproof components and mildew-resistant components are compounded to form a closed mesh hydrophobic film, which covers the surface of gypsum crystals and changes the hydrophilicity and mildew susceptibility of the gypsum crystal surface. At the same time, the composite waterproof and antibacterial components work synergistically with the inorganic composite activators and retarders to change the composition of gypsum hydration products and hydration process, so as to achieve a balance between mechanical properties and water resistance and mildew resistance. The prepared gypsum mortar has a water absorption rate of less than 6% and a softening coefficient of 0.60 to 0.90. Through the gradation combination technology of lightweight aggregate and sand in the composite aggregate, a lightweight waterproof and antibacterial plastering mortar with good workability is prepared, which is easy to spray and apply.

[0044] (2) This invention provides a water-resistant and mildew-resistant β-type building gypsum plastering mortar. In this gypsum plastering mortar, the composite aggregate is prepared using a combination of lightweight aggregate and sand gradation. The lightweight aggregate consists of fine lightweight aggregate with a particle size of 2.5 mm to 75 μm and micro / nano-grade lightweight aggregate with a particle size less than 75 μm. The use of micro / nano-grade lightweight aggregate can further reduce the thermal conductivity and density of the gypsum plastering mortar, increase its thermal insulation performance, and form a close packing with ordinary lightweight aggregate and sand, increasing the workability of the mortar and the mechanical properties of the hardened body. Based on the principle of close packing, by optimizing the combination of different types, particle sizes, and gradations of aggregates, and by adjusting the ratio of lightweight aggregate and sand in the composite aggregate, the optimal range of composite aggregate dosage and the optimal combination ratio range of ordinary lightweight aggregate, micro / nano-grade lightweight aggregate, and sand in the composite aggregate can be obtained. This allows for the preparation of ordinary plastering mortar and lightweight plastering mortar with good workability, and their density grades can range from 500 to 1400 kg / m³. 3 Adjustable internally.

[0045] (3) This invention provides a water-resistant and mildew-resistant β-type building gypsum plastering mortar. The components in the gypsum plastering mortar work synergistically to obtain a gypsum plastering mortar with good waterproof and antibacterial properties, strong waterproof durability, and good mechanical properties: the methyl silanol salt in the waterproof component reacts with the hydroxyl groups of the silicate material in the inorganic composite activator to form silane chains with Si-R groups at the ends, which block the pores inside the gypsum, thereby significantly improving the water resistance of the gypsum mortar; while the alkaline environment created by the inorganic composite activator is also conducive to the hydrolysis and polymerization reaction of the waterproof component in the composite waterproof and antibacterial component, which promotes the formation of the hydrophobic film. The addition of waterproofing components enhances the water resistance of gypsum. It maintains low humidity within the gypsum specimen, positively contributing to its anti-mildew properties. Furthermore, the paraffin emulsion and silicone-acrylic emulsion in the waterproofing components fill the pores of the gypsum matrix, increasing the density of the hardened body and improving the mechanical properties of the gypsum plaster mortar. The organic retarder improves the fluidity of the gypsum plaster mortar, while the inorganic retarder adsorbs harmful impurities such as phosphorus, fluorine, and organic matter in β-type building gypsum. It also reacts chemically with the inorganic composite activator to form a gel, improving the waterproof durability of the plaster mortar. In addition, the surfactant prevents flocculation of the gypsum, retarder, and inorganic composite activator, enhancing the overall effectiveness of each component.

[0046] (4) This invention provides a water-resistant and mildew-resistant β-type building gypsum plastering mortar. The inorganic composite activator in the gypsum plastering mortar can react with water and minerals in gypsum to produce an alkaline activation effect and a sulfate activation effect. Granulated blast furnace slag releases active silica and alumina in the alkaline environment formed by the dissolution of silicate cement and calcium oxide. It reacts with the sulfate provided by gypsum to generate a large amount of ettringite and hydrated calcium silicate (calcium aluminate) gel. Cement reacts with water to generate ettringite and hydrated calcium silicate. The hydration products generated by the inorganic composite activator cover the surface of gypsum crystals or fill the gaps in gypsum crystals to form an inorganic waterproof layer and increase the density of the hardened body. While improving water resistance, it ensures the mechanical properties of gypsum mortar.

[0047] (5) This invention provides a method for preparing water-resistant and mildew-resistant β-type building gypsum plastering mortar. Industrial by-product phosphogypsum has poor bonding strength and mechanical properties due to its high impurity content, making it more difficult to dispose of than other β-type building gypsum solid wastes. The method modifies industrial by-product phosphogypsum. The drying, neutralization, and aging processes in the modification process can reduce the content of harmful impurities such as soluble phosphorus, soluble fluorine, and organic matter in phosphogypsum. At the same time, through the synergistic effect of the components in the gypsum plastering mortar, the defects of low bonding strength and poor mechanical properties of β-type building gypsum as plastering mortar are overcome, realizing the utilization of solid waste of industrial by-product phosphogypsum and ensuring the quality of water-resistant and mildew-resistant β-type building gypsum plastering mortar.

[0048] (6) This invention provides an application of water-resistant and mildew-resistant β-type building gypsum plastering mortar. The mortar is water-resistant and mildew-resistant, waterproof and durable, low in density and light in weight. It can be applied by manual application or mechanical spraying. It can be used not only for indoor plastering, but also for kitchens, bathrooms, building exterior walls and other areas that are prone to dampness. This invention broadens the application range of building gypsum plastering mortar and accelerates the disposal of industrial by-product gypsum solid waste resources. Attached Figure Description

[0049] Figure 1 The mold growth status of the sample in Comparative Example 1-1;

[0050] Figure 2 The mold growth of the sample in Example 2 is shown. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention. Unless otherwise specified, the methods described are conventional methods, and the raw materials are all available from publicly available commercial sources.

[0052] Example 1

[0053] A water-resistant and mildew-resistant β-type building gypsum plaster mortar, composed of the following components in parts by weight:

[0054] 85 parts of industrial by-product phosphogypsum, 15 parts of composite aggregate, 3 parts of composite waterproof and antibacterial component, 6.1 parts of inorganic composite activator, 0.5 parts of retarder, 0.3 parts of toughening agent, 0.1 parts of water-retaining agent, and 50 parts of water.

[0055] The composite waterproof and antibacterial component, by weight, consists of 0.99 parts waterproof component, 1.98 parts antifungal component, and 0.03 parts surfactant; wherein, the waterproof component comprises 0.17 parts sodium methylsiloxane, 0.65 parts paraffin emulsion, and 0.17 parts silicone-acrylic emulsion; the paraffin emulsion is a biionic surfactant composed of paraffin, stearic acid, borax, and carboxymethyl cellulose, with an HLB value of 8-18; the antifungal component comprises 1.10 parts nano-nitrogen-doped titanium dioxide, 0.55 parts nano-zinc oxide, and 0.33 parts cyclodextrin-essential oil encapsulation; the surfactant is triethylhexylphosphonic acid;

[0056] The composite aggregate, by weight, consists of 5.2 parts of lightweight aggregate and 9.8 parts of continuously graded limestone manufactured sand with an MB value ≤1.4 and an Mx value between 0.8 and 1.5; wherein the lightweight aggregate consists of 4.9 parts of vitrified microspheres with a particle size between 75 μm and 2.5 mm and 0.3 parts of nano-silica aerogel powder with a particle size less than 75 μm.

[0057] The inorganic composite activator, by weight, consists of 1.8 parts granulated blast furnace slag powder, 3.6 parts silicate cement, and 0.7 parts calcium oxide;

[0058] The retarder, by weight, consists of 0.01 parts of secondary amide protein retarder and 0.49 parts of zeolite powder;

[0059] The toughening agent is calcium sulfate whiskers with a length of 0.05–0.20 mm and a diameter of 0.5–0.8 μm;

[0060] The water-retaining agent, by weight, consists of 0.03 parts styrene-butadiene copolymer and 0.06 parts hydroxypropyl methylcellulose.

[0061] A method for preparing the water-resistant and mildew-resistant β-type building gypsum plaster mortar described in this embodiment includes the following steps:

[0062] Step 1: Dissolve the composite waterproof and antibacterial components and retarder in the mixing water, stir for 35 minutes, and homogenize for 70 minutes to obtain solution A;

[0063] In step one, the preparation method of the composite waterproof and antibacterial component is as follows:

[0064] (1) Add 0.17 parts by weight of methylsilyl alkoxide and 0.05 parts by weight of acetic acid to deionized water at the same time, and stir at 20°C for 20 minutes to allow the two to react fully and obtain an organosilicon solution.

[0065] (2) Add the paraffin emulsion and silicone-acrylic emulsion to the organosilicon solution obtained in step (1), stir evenly, and obtain a waterproof component solution;

[0066] (3) Add nano-nitrogen-doped titanium dioxide, nano-zinc oxide and cyclodextrin-essential oil embedding material to the waterproof component solution obtained in step (2) to obtain a mixed solution;

[0067] (4) Add triethylhexylphosphoric acid to the mixed solution obtained in step (3) while stirring, and stir for 35 minutes to make the components evenly dispersed to obtain a well-adapted mixed solution, namely a composite waterproof and antibacterial component;

[0068] Step 2: Dry mix industrial by-product phosphogypsum, composite aggregate, inorganic composite activator, toughening agent, and water-retaining agent for 2.5 minutes to obtain powder B;

[0069] Step 3: Slowly add solution A to powder B and stir for 3 minutes to obtain a uniform water-resistant and mildew-resistant β-type building gypsum plaster mortar.

[0070] Comparative Example 1-1

[0071] A gypsum plastering mortar, comprising the following components in parts by weight:

[0072] The mixture contains 85 parts of industrial by-product phosphogypsum, 15 parts of composite aggregate, 0.01 parts of retarder, 0.1 parts of water-retaining agent, and 50 parts of water.

[0073] The composite aggregate, by weight, is composed of 8 parts vitrified microspheres with a particle size of 75μm to 2.5mm and 7 parts limestone manufactured sand with an MB value ≤1.4 and an Mx value of 0.8 to 1.5, which are continuously graded and composited.

[0074] The water-retaining agent is hydroxypropyl methylcellulose;

[0075] The retarder is a secondary amide protein retarder.

[0076] A method for preparing the gypsum plaster mortar described in this comparative example comprises the following steps:

[0077] (1) Dissolve the protein retarder in the mixing water and stir for 35 minutes, then homogenize for 70 minutes to obtain solution A;

[0078] (2) Dry mix industrial by-product phosphogypsum, vitrified microspheres, limestone manufactured sand, and hydroxypropyl methylcellulose for 2.5 min to obtain powder B;

[0079] (3) Slowly add solution A to powder B and stir for 3 minutes to obtain uniform gypsum plaster mortar.

[0080] Comparative Examples 1-2

[0081] Comparative Examples 1-2 were obtained by removing the composite waterproof and antibacterial component from Example 1, while keeping all other conditions unchanged, to obtain gypsum plastering mortar.

[0082] Example 2

[0083] A water-resistant and mildew-resistant β-type building gypsum plaster mortar, composed of the following components by weight:

[0084] 70 parts of industrial by-product phosphogypsum, 30.1 parts of composite aggregate, 4 parts of composite waterproof and antibacterial component, 9.9 parts of inorganic composite activator, 0.5 parts of retarder, 0.3 parts of toughening agent, 0.2 parts of water-retaining agent, and 50 parts of water.

[0085] The composite aggregate, by weight, consists of 20.3 parts of lightweight aggregate and 9.8 parts of continuously graded phosphorus tailings sand with an MB value ≤1.4 and an Mx value between 0.8 and 1.5; wherein the lightweight aggregate consists of 16 parts of vitrified microspheres with a particle size of 75 μm to 2.5 mm, 3 parts of polystyrene particles with a particle size of 75 μm to 2.5 mm, and 1.3 parts of nano-silica aerogel powder with a particle size less than 75 μm;

[0086] The composite waterproof and antibacterial component, by weight, consists of 1.52 parts waterproof component, 2.42 parts antifungal component, and 0.06 parts surfactant. The waterproof component is composed of a paraffin emulsion with an HLB value of 8-18, prepared by emulsification of 0.3 parts potassium methylsilanolate and 0.92 parts biionic surfactant, and 0.3 parts silicone-acrylic emulsion. The antifungal component consists of 1.22 parts nano-nitrogen-doped titanium dioxide, 0.61 parts nano-zinc oxide, and 0.59 parts cyclodextrin-essential oil encapsulation. The surfactant is triethylhexylphosphonic acid.

[0087] The inorganic composite activator, by weight, consists of 2.6 parts granulated blast furnace slag powder, 5.3 parts silicate cement, and 2 parts sodium silicate;

[0088] The retarder, by weight, consists of 0.01 parts of secondary amide protein retarder and 0.49 parts of zeolite powder;

[0089] The toughening agent is calcium sulfate whiskers with a length of 0.05–0.20 mm and a diameter of 0.5–0.8 μm;

[0090] The water-retaining agent, by weight, consists of 0.08 parts of styrene-butadiene copolymer and 0.12 parts of hydroxypropyl methylcellulose.

[0091] A method for preparing the water-resistant and mildew-resistant β-type building gypsum plaster mortar described in this embodiment includes the following steps:

[0092] Step 1: Dissolve the composite waterproof and antibacterial components and retarder in the mixing water, stir for 35 minutes, and homogenize for 70 minutes to obtain solution A;

[0093] In step one, the preparation method of the waterproof and antibacterial component is as follows:

[0094] (1) Add 0.30 parts of potassium methylsilanolate and 0.09 parts of acetic acid to deionized water at the same time, and stir at 22°C for 20 minutes to allow the two to react fully and obtain an organosilicon solution;

[0095] (2) Add the paraffin emulsion and silicone-acrylic emulsion to the organosilicon solution obtained in step (1), stir evenly, and obtain a waterproof component solution;

[0096] (3) Add nano-nitrogen-doped titanium dioxide, nano-zinc oxide and cyclodextrin-essential oil embedding material to the waterproof component solution obtained in step (2) to obtain a mixed solution;

[0097] (4) While stirring, add triethylhexylphosphoric acid to the mixed solution obtained in step (3) and stir for 35 minutes to make the components evenly dispersed to obtain a well-adapted mixed solution, namely the waterproof and antibacterial component;

[0098] Step 2: Dry mix phosphogypsum, composite aggregate, inorganic composite activator, toughening agent, and water-retaining agent for 2.5 minutes to obtain powder B;

[0099] Step 3: Slowly add solution A to powder B and stir for 3 minutes to obtain a uniform water-resistant and mildew-resistant β-type building gypsum plaster mortar.

[0100] Comparative Example 2-1

[0101] A gypsum plastering mortar, comprising the following components in parts by weight:

[0102] 70 parts of industrial by-product phosphogypsum, 30 parts of composite aggregate, 0.01 parts of retarder, 0.2 parts of water-retaining agent, and 50 parts of water;

[0103] The composite aggregate, by weight, is composed of 16 parts vitrified microspheres and 14 parts limestone manufactured sand in a continuous gradation process.

[0104] The water-retaining agent is hydroxypropyl methylcellulose;

[0105] The retarder is a secondary amide protein retarder.

[0106] A method for preparing the gypsum plaster mortar described in this comparative example comprises the following steps:

[0107] (1) Dissolve the protein retarder in the mixing water and stir for 35 minutes, then homogenize for 70 minutes to obtain solution A;

[0108] (2) Dry mix industrial by-product phosphogypsum, vitrified microspheres, manufactured sand, and hydroxypropyl methylcellulose for 2.5 min to obtain powder B;

[0109] (3) Slowly add solution A to powder B and stir for 3 minutes to obtain uniform gypsum plaster mortar.

[0110] Comparative Example 2-2

[0111] A gypsum plastering mortar, comprising the following components in parts by weight:

[0112] The mixture contains 70 parts of industrial by-product phosphogypsum, 30.1 parts of composite aggregate, 9.9 parts of inorganic composite activator, 0.5 parts of retarder, 0.3 parts of toughening agent, 0.2 parts of water-retaining agent, and 50 parts of water.

[0113] The composite aggregate, by weight, consists of 19 parts vitrified microspheres, 1.3 parts perlite powder, and 9.8 parts phosphate tailings sand gradation.

[0114] The inorganic composite activator, by weight, consists of 2.6 parts granulated blast furnace slag powder, 5.3 parts silicate cement, and 2 parts calcium oxide;

[0115] The retarder, by weight, consists of 0.01 parts protein retarder and 0.49 parts zeolite powder;

[0116] The toughening agent is calcium sulfate whiskers with a length of 0.05–0.20 mm and a diameter of 0.5–0.8 μm;

[0117] The water-retaining agent, by weight, consists of 0.08 parts ethylene-vinyl acetate copolymer and 0.12 parts hydroxyethyl methyl cellulose.

[0118] A method for preparing the gypsum plaster mortar described in this comparative example comprises the following steps:

[0119] (1) Dissolve the retarder in the mixing water and stir for 35 minutes, then homogenize for 70 minutes to obtain liquid A;

[0120] (2) Dry mix industrial by-product phosphogypsum, vitrified microspheres, perlite powder, natural sand, granulated blast furnace slag powder, silicate cement, calcium oxide, calcium sulfate whiskers, ethylene-vinyl acetate copolymer, and hydroxyethyl methyl cellulose for 2.5 min to obtain powder B.

[0121] (3) Slowly add solution A to powder B and stir for 3 minutes to obtain uniform gypsum plaster mortar.

[0122] The test reference standards were GB / T 28627-2012 Plastering Gypsum, JC / T 2474-2018 Mechanically Sprayed Plastering Gypsum, GB / T 1741-2007 Test Method for Mildew Resistance of Paint Films, and GB / T 9776-2008 Building Gypsum. Performance tests were conducted on the gypsum plastering mortars prepared in Examples 1-2 and Comparative Examples 1-1, 1-2, 2-1, and 2-2, respectively. During the mildew resistance test, mildew growth was recorded every 7 days. Observation and comparison were used to verify whether the tested samples had mildew resistance. The mildew resistance level was evaluated according to the reference standard ASTM G21-2013. The results are shown in Table 1.

[0123] Table 1. Test results of water-resistant and mildew-resistant gypsum plaster mortar performance.

[0124]

[0125]

[0126] Figure 1 and Figure 2 The tests conducted on the mildew resistance of the gypsum plaster mortar samples described in Comparative Examples 1-1 and Example 2, respectively, demonstrate that the water-resistant and mildew-resistant β-type building gypsum plaster mortar of this invention possesses excellent water resistance, mildew resistance, waterproof durability, and mechanical properties. Furthermore, the mortar density ranges from 500 to 1400 kg / m³ achieved through composite aggregate gradation. 3 The internal adjustment is suitable for gypsum plaster mortar spraying construction; the water resistance and mildew prevention performance of Comparative Example 2-2 is higher than that of Comparative Example 2-1, but lower than that of Example 2, indicating that the composite waterproof and antibacterial component in the mortar has a significant waterproof and antibacterial effect. At the same time, in addition to the composite waterproof and antibacterial component, the synergistic effect of other components in the mortar also has a certain waterproof effect, thereby keeping the interior of the gypsum specimen at a low humidity, which has a positive effect on its mildew resistance.

[0127] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water-resistant and mildew-resistant β-type building gypsum plaster mortar, characterized in that: It is composed of the following components in parts by weight: 40-85 parts of β-type building gypsum, 3-5 parts of composite waterproof and antibacterial component, 10-45 parts of composite aggregate, 5-10 parts of inorganic composite activator, 0.10-0.50 parts of retarder, 0.20-0.60 parts of toughening agent, 0.05-0.20 parts of water-retaining agent, and 25-50 parts of water; The composite waterproof and antibacterial component is composed of a waterproof component, an antifungal component, and a surfactant in a weight ratio of (1-6):(3-8):(0.05-0.20); the waterproof component is composed of methylsiloxane, paraffin emulsion, and silicone-acrylic emulsion in a weight ratio of (0.2-1):(0-4):(0.5-1); wherein, the methylsiloxane is sodium methylsiloxane or potassium methylsiloxane, the paraffin emulsion is prepared by compounding and emulsifying a biionic surfactant, and the HLB value is 8-18; the antifungal component is a nano-nitrogen-doped titanium dioxide and cyclodextrin-essential oil encapsulation complex; the surfactant is triethylhexylphosphonic acid; The composite aggregate is obtained by combining vitrified microspheres, nano-silica aerogel powder, and phosphate tailings sand in a weight ratio of (50-110):(3-8):(100-40); the particle size of the vitrified microspheres is 2.5 mm to 75 μm; the particle size of the nano-silica aerogel powder is <75 μm, and the bulk density is 40-60 kg / m³. 3 The phosphate tailings sand has an MB value ≤ 1.4, an Mx value of 0.8 to 1.5, and a sphericity coefficient ≥ 0.

9. The β-type building gypsum is phosphogypsum; The inorganic composite activator is composed of granulated blast furnace slag powder, silicate cement, and calcium oxide in a weight ratio of (2.5–5):(5–10):(0–3), and the sum of the mass fractions of SiO2, Al2O3, and CaO in the inorganic composite activator is ≥80%, and the specific surface area of ​​the inorganic composite activator is 450–500 m². 2 / kg; The retarder is a composite powder composed of an organic retarder and an inorganic inert powder in a weight ratio of (1-5):(95-99); wherein the organic retarder includes protein retarder, citric acid or sodium tripolyphosphate; and the inorganic inert powder is zeolite powder. The toughening agent is calcium sulfate whiskers with a length of 0.05–0.20 mm and a diameter of 0.5–0.8 μm; The water-retaining agent is composed of a styrene-butadiene copolymer and hydroxypropyl methylcellulose with a viscosity of 5W to 10W in a weight ratio of (0 to 0.1):(0 to 0.2), wherein the weight parts of the styrene-butadiene copolymer and the hydroxypropyl methylcellulose are not both 0.

2. The water-resistant and mildew-resistant β-type building gypsum plastering mortar according to claim 1, characterized in that: The retarder is a composite powder composed of a protein retarder and zeolite powder in a weight ratio of (1-3):(97-99).

3. The water-resistant and mildew-resistant β-type building gypsum plastering mortar according to claim 1 or 2, characterized in that: It includes the following components by weight: 70-85 parts of β-type building gypsum, 3-4 parts of composite waterproof and antibacterial component, 15-30.1 parts of composite aggregate, 6.1-9.9 parts of inorganic composite activator, 0.5 parts of retarder, 0.3 parts of toughening agent, 0.1-0.20 parts of water-retaining agent, and 50 parts of water.

4. A method for preparing water-resistant and mildew-resistant β-type building gypsum plastering mortar as described in any one of claims 1 to 3, characterized in that: Includes the following steps: Step 1: Dissolve the composite waterproof and antibacterial components and retarder in water, stir for 30-40 minutes, and homogenize for 60-80 minutes to obtain solution A; Step 2: Dry mix β-type building gypsum, composite aggregate, inorganic composite activator, toughening agent and water-retaining agent for 1.5 to 3.0 minutes to obtain powder B; Step 3: Add solution A to powder B and stir for 2-4 minutes to obtain a uniform water-resistant and mildew-resistant β-type building gypsum plaster mortar.

5. The method for preparing a water-resistant and mildew-resistant β-type building gypsum plastering mortar according to claim 4, characterized in that: The preparation method of the waterproof and antibacterial component is as follows: (1) Add methylsiloxane and acetic acid to deionized water at the same time, and stir at 20-25°C for 15-30 minutes to obtain an organosilicon solution; wherein acetic acid is a catalyst, and the mass ratio of methylsiloxane to acetic acid is 2:(0.5-0.8); (2) Add paraffin emulsion and silicone-acrylic emulsion to the organosilicon solution and stir evenly to obtain a waterproof component solution; (3) Add the organic antibacterial component and the inorganic antibacterial component to the waterproof component solution to obtain a mixed solution; (4) Add surfactant to the mixed solution while stirring for 30-45 minutes to obtain a composite waterproof and antibacterial component.

6. The method for preparing a water-resistant and mildew-resistant β-type building gypsum plastering mortar according to claim 4, characterized in that: When the selected β-type building gypsum is phosphogypsum, the modification step of phosphogypsum is also included: The phosphogypsum was dried at 100–120°C for 2–3 hours, neutralized with alkali at a mass concentration of 4–9%, aged for 48–72 hours, and ground to a fineness of 40–80 μm to prepare β-type hemihydrate phosphogypsum, thus completing the modification.

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