Multifunctional microcrystalline mortar and preparation method thereof

Abstract

The invention discloses multifunctional microcrystalline mortar and a preparation method thereof, and belongs to the technical field of building energy-saving materials. The mortar comprises Portland cement, volcanic ash, microcrystalline particles, a specially-made thermal insulation reinforcing additive and the like. The thermal insulation reinforcing additive is prepared by copolymerizing polyethylene glycol monomethyl ether methacrylate and maleic anhydride and grafting polyether amine and gamma-aminopropyltriethoxysilane, a flexible thermal insulation layer is formed on an inorganic material interface through a comb-shaped molecular structure, and meanwhile, a micropore structure in the mortar is stabilized; the mortar is prepared by premixing dry powder and mixing the dry powder with water on site. The additive designed by the invention significantly improves the thermal insulation performance, greatly reduces the heat conductivity coefficient, enhances the waterproof and sound insulation performance, maintains good mechanical strength and constructability, effectively solves the technical problems that the traditional inorganic thermal insulation material interface thermal bridge is prominent, the function is single, and the strength is difficult to consider, and is suitable for various building energy-saving projects.

Description

Technical Field

[0001] This invention relates to the field of building energy-saving materials technology, and in particular to a multifunctional microcrystalline mortar and its preparation method. Background Technology

[0002] Inorganic thermal insulation mortar, especially that using microcrystalline particles and vitrified microspheres as lightweight aggregates, plays an important role in building energy-saving projects due to its advantages such as fire safety (Class A), good durability, and lifespan comparable to the main building structure. Its basic principle is to utilize lightweight porous aggregates combined with cementitious materials to form numerous closed pores within the mortar, thereby hindering heat transfer. However, this technology system has long faced several inherent defects, restricting its further performance improvement and widespread application.

[0003] First, the interfacial thermal bridging effect is significant. In traditional processes, the inorganic insulating aggregate and the cement matrix are mainly bonded by physical-mechanical interlocking and van der Waals forces. This interface contains numerous microscopic defects and rigid contact points, forming highly efficient "phonon" heat transfer channels, which become weak points for heat escape. Although optimizing aggregate gradation and reducing cement content can reduce the overall thermal conductivity to some extent, the heat transfer problem in the interfacial region has not been fundamentally solved.

[0004] Secondly, the pore structure is large and unstable. Existing technologies typically rely on physical air-entraining agents or the pores of the aggregate itself for insulation. This method introduces air bubbles of uneven size and poor stability, which are prone to coalescing, breaking, or escaping during mixing, pumping, and hardening, leading to a decrease in effective insulation porosity. Simultaneously, the density difference between the aggregate and the slurry easily causes stratification, further deteriorating the uniformity of pore distribution.

[0005] Furthermore, the trade-off between performance improvement and cost / strength is prominent. To improve workability, enhance adhesion, and crack resistance, polymer additives such as redispersible latex powder and cellulose ethers are often added. However, these general-purpose additives mainly function through physical film formation or adsorption, with limited bonding strength to inorganic substrates and no specific targeting for improving interfacial thermal resistance. Some solutions on the market involve physical blending of multiple functional additives (such as air-entraining agents, water-repellent agents, and coupling agents), but each component has a single function and poor synergy, failing to achieve molecular-level functional integration and precise interfacial modification.

[0006] Therefore, it is extremely difficult to further reduce the thermal conductivity of inorganic insulating mortars using existing technologies (they typically hover above 0.065-0.070 W / (m·K)), and they generally suffer from the dilemma of "high strength equals poor insulation, and good insulation equals high cost." Developing a new type of additive and matching mortar system that can reconstruct the internal interface structure of mortar at the molecular level, achieve multiple functional synergies with extremely low dosage, and thus significantly improve insulation efficiency while ensuring mechanical properties, has become crucial for breaking through industry technical bottlenecks and meeting higher energy-saving standards. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a multifunctional microcrystalline mortar and its preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention first proposes a multifunctional microcrystalline mortar, comprising the following components in parts by weight:

[0010] Silicate cement: 350 parts

[0011] Volcanic ash: 80-100 parts

[0012] Microcrystalline particles: 400-450 parts

[0013] Redispersible latex powder: 10-15 parts

[0014] Thermal insulation enhancement additive: 5-8 parts

[0015] Hydroxypropyl methylcellulose ether: 1.5-2.5 parts,

[0016] Water-reducing agent: 1-1.5 parts

[0017] The mixing ratio of the slurry during construction is 1:0.15-0.17;

[0018] The thermal insulation and reinforcing additive has a main chain obtained by copolymerizing polyethylene glycol monomethyl ether methacrylate and maleic anhydride, and a polyether amine and γ-aminopropyltriethoxysilane grafted thereon.

[0019] The redispersible latex powder is ethylene-vinyl acetate latex powder; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0020] The microcrystalline particles are prepared by mixing vitrified microspheres and fine sand at a mass ratio of 1:0.3-0.6; wherein the particle size of the vitrified microspheres is 0.5-1 mm; and the particle size of the fine sand is 70-140 mesh.

[0021] The vitrified microspheres are hollow glass microspheres obtained by sintering SiO2, CaO, Al2O3, MgO, P2O5, K2O, Fe2O3, and SiC in a mass ratio of 50-55:15-18:11-13:10-12:2-4:3-5:7-10:0.3-0.5.

[0022] Preferably, the preparation process of the thermal insulation and enhancing additive includes the following steps:

[0023] S1. Preparation of intermediate polymer solution:

[0024] At 75-80℃, polyethylene glycol monomethyl ether methacrylate was added to the reactor and dissolved in a mixed solvent of propylene glycol methyl ether / ethanol / ethyl acetate; maleic anhydride and azobisisobutyronitrile were added, and the reaction was stirred for 2 hours. The reaction mixture was then cooled to below 40℃ to obtain an intermediate polymer solution.

[0025] Polyethylene glycol monomethyl ether methacrylate (MPEGMA) and maleic anhydride (MAH) are dissolved in deionized water to form a homogeneous solution. After adding the initiator azobisisobutyronitrile (AIBN) and heating to 75°C, the monomers are gradually converted into high molecular weight copolymers, eventually forming a stable aqueous solution (intermediate) of poly(MPEGMA-co-MAH) copolymer. After cooling, the solution remains homogeneous (without precipitation).

[0026]

[0027] S2, amidation grafting and silanization modification:

[0028] Under stirring, polyetheramine and γ-aminopropyltriethoxysilane were diluted with ethyl acetate and added to the intermediate polymer solution; the temperature was raised to 85-90℃ and the reaction was maintained for 3-3.5h to obtain a silanized polyether-maleic anhydride copolymer solution.

[0029] The anhydride ring of the intermediate copolymer backbone undergoes an amidation reaction with the amino group (-NH2) of polyetheramine and γ-aminopropyltriethoxysilane (KH550), forming maleamide after drying, and finally yielding silanized polyether-maleic anhydride copolymer (grafted modified product).

[0030]

[0031] Instead of existing as free small molecules, silane groups are grafted onto the main polymer chain of polyethylene glycol-maleic anhydride copolymer. This main polymer chain, especially its hydrophilic polyethylene glycol segments, dissolves or expands in the aqueous phase during the initial stirring stage, encapsulating the terminal silane groups in a hydrophilic polymer environment. This slows down their direct and rapid contact with the strongly alkaline pore liquid (pH 12.5-13.5) after cement hydration, and prevents uncontrolled hydrolysis.

[0032] During stirring and settling, the molecular chains gradually migrate and accumulate towards the solid-liquid interface (cement particles, vitrified microspheres) and the gas-liquid interface (microbubble surface) through hydrophobic interactions. When the molecules anchor near the interface, the silane groups undergo hydrolysis in a relatively localized and controlled environment and immediately react with the hydroxyl groups on the interface.

[0033] Due to the anchoring effect of the molecular chains, the silanol groups are fixed at the interface, which greatly reduces the probability of them colliding and self-polymerizing with other silanol molecules in the solution, thus making them more inclined to undergo heterogeneous condensation with inorganic surfaces.

[0034] S3, Post-processing:

[0035] The silanized polyether-maleic anhydride copolymer solution was spray-dried to obtain a white or pale yellow fine powder. After cooling to room temperature, it was sealed and packaged to obtain a heat-insulating and reinforcing additive.

[0036] Preferably, in step S1, the Mn of polyethylene glycol monomethyl ether methacrylate is 950; the solid content of the intermediate polymer solution is 30-35%; during the addition of maleic anhydride to polyethylene glycol monomethyl ether methacrylate, the reaction temperature is controlled below 82°C; in the propylene glycol methyl ether / ethanol / ethyl acetate mixed solvent, the mass ratio of propylene glycol methyl ether, ethanol and ethyl acetate is 5:3:2; and the amount of azobisisobutyronitrile is 0.8-1.2% of the total mass of polyethylene glycol monomethyl ether methacrylate and maleic anhydride.

[0037] Preferably, in S2, the Mn of the polyether amine is 230; when the polyether amine and γ-aminopropyltriethoxysilane are mixed evenly and then added to the intermediate polymer solution, the temperature is controlled to not exceed 50°C; the solid content of the silanized polyether-maleic anhydride copolymer solution is 30-35%.

[0038] Preferably, in step S3, the thermal insulation enhancement additive needs to be sealed in an aluminum-plastic composite moisture-proof bag.

[0039] Preferably, the mass ratio of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, polyetheramine and γ-aminopropyltriethoxysilane is 30:5-8:10-12:3-5.

[0040] This invention also proposes a method for preparing the aforementioned multifunctional microcrystalline mortar, comprising the following steps:

[0041] (1) Preparation of premixed dry material: Silicate cement, volcanic ash, hydroxypropyl methylcellulose ether, water-reducing agent and redispersible latex powder are put into a dry powder mixer in sequence and mixed at high speed until all powders are uniform in color; heat-insulating and reinforcing additives are added and high-speed mixing is continued for 6-8 minutes; microcrystalline particles are added and low-speed gentle mixing is carried out for 3-4 minutes; the machine is stopped and the material is discharged to obtain the premixed material.

[0042] (2) Construction preparation: Add water to the premix and stir until the slurry is uniform and free of dry powder particles. Apply the slurry by layering. After the construction is completed, keep it moist and maintain it.

[0043] During the mortar mixing process, the thermal insulation and reinforcing additive is rapidly adsorbed on the air-water interface introduced by the mixing. The hydrophilic part is anchored in the aqueous phase (cement slurry), and the hydrophobic part extends to the air, thereby significantly reducing the interfacial tension and making it easier for the air to be sheared and dispersed into fine bubbles, without the need to add an additional air-entraining agent.

[0044] When latex powder is redispersed with water, the resulting polymer emulsion particles will gradually deposit and accumulate on cement hydration products, aggregate surfaces, and bubble walls as water migrates and cement hydration occurs.

[0045] As the mortar begins to dry and harden, these polymer particles fuse together to form a continuous polymer film that wraps around the air bubbles stabilized by the insulation enhancer. This tightly binds with the cement matrix, forming a composite structure of "cement stone-polymer film-air bubble". This provides additional mechanical strength and flexibility, better resisting shrinkage stress, drying stress, and potential damage from external loads during the cement hydration process, ensuring that the air bubbles do not easily collapse or connect during the mortar's service life.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] This invention designs and synthesizes a comb-shaped polymer additive, in which the terminal silane groups form covalent bonds with the inorganic phase for anchoring. At the same time, the grafted flexible long chains construct an elastic interface layer, transforming the traditional rigid high thermal conductivity interface into an efficient phonon scattering system and weakening the thermal bridging effect. Meanwhile, chemical bonding greatly enhances the interfacial adhesion strength, while the flexible chains play a toughening and crack-resistant role. Thus, while significantly reducing the thermal conductivity, it simultaneously ensures excellent mechanical strength and crack resistance, reconciling the contradiction between thermal insulation, load-bearing capacity, and crack prevention.

[0048] This invention utilizes a multi-scale insulating porous network formed by the self-assembly of polymers at the gas-liquid interface and the stable encapsulation of numerous closed microbubbles by latex powder film formation, along with the inherent pores of lightweight aggregates. This dense and closed-cell structure not only effectively impedes heat flow but also synergistically blocks the permeation paths of liquid water and water vapor, endowing the material with excellent impermeability and waterproofing properties. Furthermore, this multiphase, porous, heterogeneous structure exhibits significant scattering and absorption of sound waves, thus providing a comprehensive physical barrier integrating thermal insulation, waterproofing, and sound insulation for building envelopes.

[0049] During the construction phase, the steric hindrance and lubrication effect of the polymer in this invention greatly improves the rheological properties and water retention of the slurry, ensuring easy application, preventing blistering and hollow areas. During the hardening and service phases, the dense interface and closed pores formed by the chemical bonds of this invention effectively resist the intrusion of harmful media such as moisture and chloride ions, significantly improving the material's freeze-thaw resistance, carbonation resistance, and volume stability. Therefore, this material provides an excellent construction experience while possessing the durability potential to last as long as traditional building structures.

[0050] In summary, this invention utilizes a self-synthesized comb-like polymer to construct a "chemical anchoring-flexible buffer" layer at the interface of inorganic materials, weakening the thermal bridging effect and simultaneously improving thermal insulation, compressive strength, and crack resistance. This polymer also stabilizes the internal closed-cell structure, integrating thermal insulation, waterproofing, and auxiliary sound insulation functions. The mortar obtained by this invention possesses both excellent construction rheology and long-term durability, and has the potential for internal curing and microcrack bridging, making it an advanced building energy-saving material integrating multiple high-performance features. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0052] Example 1: A multifunctional microcrystalline mortar, comprising the following components by weight:

[0053] Silicate cement: 350kg

[0054] Volcanic ash: 80kg

[0055] Microcrystalline particles: 450kg

[0056] Redispersible latex powder: 10kg

[0057] Thermal insulation enhancement additive: 8kg

[0058] Hydroxypropyl methylcellulose ether: 1.5 kg

[0059] Water-reducing agent: 1.5kg

[0060] The thermal insulation and reinforcing additive has a main chain obtained by copolymerizing polyethylene glycol monomethyl ether methacrylate and maleic anhydride, and a polyether amine and γ-aminopropyltriethoxysilane grafted thereon.

[0061] The redispersible latex powder is ethylene-vinyl acetate latex powder; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0062] The microcrystalline particles are prepared by mixing vitrified microspheres and fine sand at a mass ratio of 1:0.3; wherein the particle size of the vitrified microspheres is 0.5-1 mm; and the particle size of the fine sand is 70-140 mesh.

[0063] Vitrified microspheres are obtained by firing volcanic ash, slag, waste glass, P2O5, K2O, Fe2O3, and SiC in a mass ratio of 40:30:20:3:4:8:0.5.

[0064] The preparation process of the thermal insulation and enhancement additive includes the following steps:

[0065] S1. Preparation of intermediate polymer solution:

[0066] At 75-80℃, polyethylene glycol monomethyl ether methacrylate was added to the reactor and dissolved in a mixed solvent of propylene glycol methyl ether / ethanol / ethyl acetate; maleic anhydride and azobisisobutyronitrile were added, and the reaction was stirred for 2 hours. The reaction mixture was then cooled to below 40℃ to obtain an intermediate polymer solution.

[0067] S2, amidation grafting and silanization modification:

[0068] Under stirring, polyetheramine and γ-aminopropyltriethoxysilane were diluted with ethyl acetate and added to the intermediate polymer solution; the temperature was raised to 85°C and the reaction was maintained for 3 hours to obtain a silanized polyether-maleic anhydride copolymer solution.

[0069] S3, Post-processing:

[0070] The silanized polyether-maleic anhydride copolymer solution was spray-dried to obtain a white or pale yellow fine powder. After cooling to room temperature, it was sealed and packaged to obtain a heat-insulating and reinforcing additive.

[0071] In S1, the Mn of polyethylene glycol monomethyl ether methacrylate is 950; the solid content of the intermediate polymer solution is 30%; during the addition of maleic anhydride to polyethylene glycol monomethyl ether methacrylate, the reaction temperature is controlled below 82°C; in the propylene glycol methyl ether / ethanol / ethyl acetate mixed solvent, the mass ratio of propylene glycol methyl ether, ethanol and ethyl acetate is 5:3:2; the amount of azobisisobutyronitrile used is 1% of the total mass of polyethylene glycol monomethyl ether methacrylate and maleic anhydride.

[0072] In S2, the Mn of the polyether amine is 230; when the polyether amine and γ-aminopropyltriethoxysilane are mixed evenly and added to the intermediate polymer solution, the temperature is controlled not to exceed 50°C; the solid content of the silanized polyether-maleic anhydride copolymer solution is 35%.

[0073] In step S3, the thermal insulation enhancement additive needs to be sealed in an aluminum-plastic composite moisture-proof bag.

[0074] The mass ratio of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, polyetheramine and γ-aminopropyltriethoxysilane is 30:5:12:3.

[0075] The preparation method of multifunctional microcrystalline mortar includes the following steps:

[0076] (1) Preparation of premixed dry material: Silicate cement, volcanic ash, hydroxypropyl methylcellulose ether, water-reducing agent, and redispersible latex powder are sequentially added to a dry powder mixer and mixed at high speed until all powders are uniform in color; thermal insulation and reinforcing additives are added, and high-speed mixing is continued for 7 minutes, followed by the addition of microcrystalline particles. The mixture is then gently mixed at low speed for 4 minutes, and the machine is stopped to discharge the material, thus obtaining the premixed material;

[0077] (2) Construction preparation: Add water to the premix and stir until the slurry is uniform and free of dry powder particles. Apply the slurry by layering. After the construction is completed, keep it moist and maintain it.

[0078] The mixing ratio of the slurry during construction is 1:0.17.

[0079] Example 2: A multifunctional microcrystalline mortar, comprising the following components by weight:

[0080] Silicate cement: 350kg

[0081] Volcanic ash: 90kg

[0082] Microcrystalline particles: 425kg

[0083] Redispersible latex powder: 12.5 kg

[0084] Thermal insulation enhancement additive: 6.5kg

[0085] Hydroxypropyl methylcellulose ether: 2kg

[0086] Water-reducing agent: 1.25 kg

[0087] The thermal insulation and reinforcing additive has a main chain obtained by copolymerizing polyethylene glycol monomethyl ether methacrylate and maleic anhydride, and a polyether amine and γ-aminopropyltriethoxysilane grafted thereon.

[0088] The redispersible latex powder is ethylene-vinyl acetate latex powder; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0089] The microcrystalline particles are prepared by mixing vitrified microspheres and fine sand at a mass ratio of 1:0.45; wherein the particle size of the vitrified microspheres is 0.5-1 mm; and the particle size of the fine sand is 70-140 mesh.

[0090] Vitrified microspheres are obtained by firing volcanic ash, slag, waste glass, P2O5, K2O, Fe2O3, and SiC in a mass ratio of 40:30:20:3:4:8:0.5.

[0091] The preparation process of the thermal insulation and enhancement additive includes the following steps:

[0092] S1. Preparation of intermediate polymer solution:

[0093] At 75-80℃, polyethylene glycol monomethyl ether methacrylate was added to the reactor and dissolved in a mixed solvent of propylene glycol methyl ether / ethanol / ethyl acetate; maleic anhydride and azobisisobutyronitrile were added, and the reaction was stirred for 2 hours. The reaction mixture was then cooled to below 40℃ to obtain an intermediate polymer solution.

[0094] S2, amidation grafting and silanization modification:

[0095] Under stirring, polyetheramine and γ-aminopropyltriethoxysilane were diluted with ethyl acetate and added to the intermediate polymer solution; the temperature was raised to 85°C and the reaction was maintained for 3 hours to obtain a silanized polyether-maleic anhydride copolymer solution.

[0096] S3, Post-processing:

[0097] The silanized polyether-maleic anhydride copolymer solution was spray-dried to obtain a white or pale yellow fine powder. After cooling to room temperature, it was sealed and packaged to obtain a heat-insulating and reinforcing additive.

[0098] In S1, the Mn of polyethylene glycol monomethyl ether methacrylate is 950; the solid content of the intermediate polymer solution is 32%; during the addition of maleic anhydride to polyethylene glycol monomethyl ether methacrylate, the reaction temperature is controlled below 82°C; in the propylene glycol methyl ether / ethanol / ethyl acetate mixed solvent, the mass ratio of propylene glycol methyl ether, ethanol and ethyl acetate is 5:3:2; the amount of azobisisobutyronitrile used is 1% of the total mass of polyethylene glycol monomethyl ether methacrylate and maleic anhydride.

[0099] In S2, the Mn of the polyether amine is 230; when the polyether amine and γ-aminopropyltriethoxysilane are mixed evenly and added to the intermediate polymer solution, the temperature is controlled not to exceed 50°C; the solid content of the silanized polyether-maleic anhydride copolymer solution is 32%.

[0100] In step S3, the thermal insulation enhancement additive needs to be sealed in an aluminum-plastic composite moisture-proof bag.

[0101] The mass ratio of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, polyetheramine and γ-aminopropyltriethoxysilane is 30:6:11:4.

[0102] The preparation method of multifunctional microcrystalline mortar includes the following steps:

[0103] (1) Preparation of premixed dry material: Silicate cement, volcanic ash, hydroxypropyl methylcellulose ether, water-reducing agent and redispersible latex powder are put into a dry powder mixer in sequence and mixed at high speed until all powders are uniform in color; heat-insulating and reinforcing additives are added and high-speed mixing is continued for 7 minutes; microcrystalline particles are added and low-speed gentle mixing is carried out for 4 minutes; the machine is stopped and the material is discharged to obtain the premixed material.

[0104] (2) Construction preparation: Add water to the premix and stir until the slurry is uniform and free of dry powder particles. Apply the slurry by layering. After the construction is completed, keep it moist and maintain it.

[0105] The mixing ratio of the slurry during construction is 1:0.16.

[0106] Example 3: A multifunctional microcrystalline mortar, comprising the following components by weight:

[0107] Silicate cement: 350kg

[0108] Volcanic ash: 100kg

[0109] Microcrystalline particles: 400kg

[0110] Redispersible latex powder: 15kg

[0111] Thermal insulation enhancement additive: 5kg

[0112] Hydroxypropyl methylcellulose ether: 2.5 kg

[0113] Water-reducing agent: 1kg

[0114] The thermal insulation and reinforcing additive has a main chain obtained by copolymerizing polyethylene glycol monomethyl ether methacrylate and maleic anhydride, and a polyether amine and γ-aminopropyltriethoxysilane grafted thereon.

[0115] The redispersible latex powder is ethylene-vinyl acetate latex powder; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0116] The microcrystalline particles are prepared by mixing vitrified microspheres and fine sand at a mass ratio of 1:0.6; wherein the particle size of the vitrified microspheres is 0.5-1 mm; and the particle size of the fine sand is 70-140 mesh.

[0117] Vitrified microspheres are obtained by firing volcanic ash, slag, waste glass, P2O5, K2O, Fe2O3, and SiC in a mass ratio of 40:30:20:3:4:8:0.5.

[0118] The preparation process of the thermal insulation and enhancement additive includes the following steps:

[0119] S1. Preparation of intermediate polymer solution:

[0120] At 75-80℃, polyethylene glycol monomethyl ether methacrylate was added to the reactor and dissolved in a mixed solvent of propylene glycol methyl ether / ethanol / ethyl acetate; maleic anhydride and azobisisobutyronitrile were added, and the reaction was stirred for 2 hours. The reaction mixture was then cooled to below 40℃ to obtain an intermediate polymer solution.

[0121] S2, amidation grafting and silanization modification:

[0122] Under stirring, polyetheramine and γ-aminopropyltriethoxysilane were diluted with ethyl acetate and added to the intermediate polymer solution; the temperature was raised to 85°C and the reaction was maintained for 3 hours to obtain a silanized polyether-maleic anhydride copolymer solution.

[0123] S3, Post-processing:

[0124] The silanized polyether-maleic anhydride copolymer solution was spray-dried to obtain a white or pale yellow fine powder. After cooling to room temperature, it was sealed and packaged to obtain a heat-insulating and reinforcing additive.

[0125] In S1, the Mn of polyethylene glycol monomethyl ether methacrylate is 950; the solid content of the intermediate polymer solution is 35%; during the addition of maleic anhydride to polyethylene glycol monomethyl ether methacrylate, the reaction temperature is controlled below 82°C; in the propylene glycol methyl ether / ethanol / ethyl acetate mixed solvent, the mass ratio of propylene glycol methyl ether, ethanol and ethyl acetate is 5:3:2; the amount of azobisisobutyronitrile used is 1% of the total mass of polyethylene glycol monomethyl ether methacrylate and maleic anhydride.

[0126] In S2, the Mn of the polyetheramine is 230; when the polyetheramine and γ-aminopropyltriethoxysilane are mixed evenly and added to the intermediate polymer solution, the temperature is controlled not to exceed 50°C; the solid content of the silanized polyether-maleic anhydride copolymer solution is 22%.

[0127] In step S3, the thermal insulation enhancement additive needs to be sealed in an aluminum-plastic composite moisture-proof bag.

[0128] The mass ratio of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, polyetheramine and γ-aminopropyltriethoxysilane is 30:8:10:5.

[0129] The preparation method of multifunctional microcrystalline mortar includes the following steps:

[0130] (1) Preparation of premixed dry material: Silicate cement, volcanic ash, hydroxypropyl methylcellulose ether, water-reducing agent and redispersible latex powder are put into a dry powder mixer in sequence and mixed at high speed until all powders are uniform in color; heat-insulating and reinforcing additives are added and high-speed mixing is continued for 7 minutes; microcrystalline particles are added and low-speed gentle mixing is carried out for 4 minutes; the machine is stopped and the material is discharged to obtain the premixed material.

[0131] (2) Construction preparation: Add water to the premix and stir until the slurry is uniform and free of dry powder particles. Apply the slurry by layering. After the construction is completed, keep it moist and maintain it.

[0132] The mixing ratio of the slurry during construction is 1:0.15.

[0133] Based on this, the following design was also created:

[0134] Comparative Example 1: No thermal insulation enhancement additives were added.

[0135] Comparative Example 2: Based on Example 2, the difference is that a copolymer without γ-aminopropyltriethoxysilane was used. That is, only a copolymer of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, and polyetheramine was synthesized, and the rest was the same as in Example 2.

[0136] Comparative Example 3: Based on Example 2, the difference is that the raw material components of the additive of the present invention are simply physically mixed instead of chemically grafted copolymerized, and the rest is the same as Example 2.

[0137] Comparative Example 4: Based on Example 2, the difference is that a copolymer without polyetheramine is used. That is, only a copolymer of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, and a small amount of silane is synthesized, and the rest is the same as in Example 2.

[0138] Comparative Example 5: The core material of the currently mainstream thin-plastered external wall insulation system is expanded polystyrene board adhesive mortar.

[0139] Performance testing: Using a 100*100*100mm square cast specimen as the standard, the fluidity, vertical expansion rate, setting time, compressive strength, and flexural strength of the standard specimen were tested according to GB / T 50448; the thermal conductivity of the standard specimen was tested according to GB / T 10294-2008; the heat storage coefficient of the standard specimen was tested according to GB / T 20473-2021; and the thermal resistance of the standard specimen was tested according to GB / T 10295-2008. The test results are shown in Table 1.

[0140] Table 1. Performance Tests of Grouting Material

[0141]

[0142] Data Analysis:

[0143] The molecular chain dispersion-lubrication effect of the thermal insulation and reinforcing additives in the examples:

[0144] Steric hindrance dispersion of PEGMA long chains: The polyethylene glycol (PEG) segments of the PEGMA main chain are hydrophilic and flexible long chains that can be adsorbed on the surface of cement particles / microcrystalline particles, hindering particle agglomeration through steric hindrance effect and improving initial flowability.

[0145] Synergistic lubrication of polyetheramine (D-230): The grafted D-230 flexible segments can fill the gaps between particles, reduce interparticle frictional resistance, and further optimize flowability;

[0146] Interface anchoring and water retention of KH-550: The silaneoxy groups of KH-550 are initially weakly polar groups and do not interfere with the initial dispersion; at the same time, the PEG segments and hydroxypropyl methylcellulose ether (HPMC) work together to lock in water, delay the cement hydration rate, and maintain the fluidity retention value after 1 hour.

[0147] Comparative Example 1 (without additives): lack of steric dispersion, severe particle agglomeration, poor flowability and slump retention;

[0148] Comparative Example 3 (physically mixed additives): The molecular chains did not form a grafted structure, the PEG segment, polyetheramine, and KH-550 were unevenly dispersed, the steric hindrance / lubrication effect was weak, and the slump retention was significantly reduced.

[0149] The interfacial reinforcement effect of "chemical bonding-flexible toughening" dominates mechanical properties:

[0150] KH-550 interfacial chemical bonding: The silanoxy groups of KH-550 hydrolyze into silanol groups (-Si(OH)3), which form Si-O-Si covalent bonds with the hydroxyl groups (-OH) on the surface of cement hydration products (CSH gel), anchoring the thermal insulation and reinforcing additive to the cement matrix / microcrystalline particle interface, eliminating interfacial voids, and improving interfacial bonding strength (source of compressive strength).

[0151] Flexible toughening of polyetheramine (D-230): The grafted D-230 flexible segments can form an "elastic buffer layer" in the interface area. When the mortar is subjected to external forces (especially tensile stress in flexural strength), the flexible segments can slip, absorb energy, and hinder crack propagation, thereby improving flexural strength and reducing the compression-flexural ratio (balancing strength and toughness).

[0152] Comparative Example 2 (without KH-550): The interface is only physically adsorbed, the bonding strength is weak, cracks are easy to propagate along the interface, and the compressive / flexural strength is lower than that of the Example.

[0153] Comparative Example 4 (without D-230): Lacking a flexible buffer layer, crack propagation is unimpeded, resulting in low flexural strength and high compression-flexural ratio;

[0154] Comparative Example 3 (physical mixing): KH-550 / polyetheramine was not grafted to the main chain, and the interface could not be uniformly anchored, resulting in the failure of the interface reinforcement / toughening effect.

[0155] Phonon transport blocking effect at the "molecular structure-microscopic interface":

[0156] Phonon scattering of "hard-soft hybrid" molecular chains: The molecular chains of thermal insulation and reinforcing additives are hybrid structures of "hard segments (MA copolymer segments) - soft segments (PEG / polyetheramine segments)". The modulus / sound velocity of different segments are very different, and phonons will be scattered multiple times at the hard-soft segment interface, which will disrupt the continuity of phonon transmission.

[0157] Multiphase interface scattering of KH-550 crosslinking network: The Si-O-Si bonding interface formed by KH-550 and cement matrix, and the interface between additives and microcrystalline particles together constitute the multiphase microstructure of "cement matrix-additives-microcrystalline particles". Phonons will be reflected / scattered at each interface, which greatly extends the heat conduction path.

[0158] Chemically grafted continuous thermal resistance network: The grafting structure allows additive molecules to be evenly dispersed in the mortar, forming a continuous "flexible chain-siloxane" thermal resistance network, which completely blocks the long-range conduction of phonons.

[0159] Comparative Example 1 (without additives): It relies solely on the physical pores of microcrystalline particles for thermal insulation, lacks molecular-level phonon scattering, and has high thermal conductivity and low thermal resistance.

[0160] Comparative Example 2 / 4 (lacking KH-550 / polyetheramine): unable to form a complete "soft-hard hybrid-crosslinked network" structure, insufficient phonon scattering points, and higher thermal conductivity than the Example;

[0161] Comparative Example 5 (Traditional Adhesive Mortar): Without microcrystalline particles and without molecular-level thermal resistance network, phonons can be rapidly conducted through the continuous cement matrix, and the thermal conductivity is extremely high at 0.85 W / (m・K).

[0162] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multifunctional microcrystalline mortar, characterized in that, The components include the following parts by weight: Silicate cement: 350 parts Volcanic ash: 80-100 parts Microcrystalline particles: 400-450 parts Redispersible latex powder: 10-15 parts Thermal insulation enhancement additive: 15-18 parts Hydroxypropyl methylcellulose ether: 1.5-2.5 parts, Water-reducing agent: 1-1.5 parts The mixing ratio of the slurry during construction is 1:0.15-0.17; The thermal insulation and reinforcing additive has a main chain obtained by copolymerizing polyethylene glycol monomethyl ether methacrylate and maleic anhydride, and a polyether amine and γ-aminopropyltriethoxysilane grafted thereon. The redispersible latex powder is ethylene-vinyl acetate latex powder; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent. The microcrystalline particles are prepared by mixing vitrified microspheres and fine sand at a mass ratio of 1:0.3-0.6; wherein the particle size of the vitrified microspheres is 0.5-1 mm; and the particle size of the fine sand is 70-140 mesh. The vitrified microspheres are hollow glass microspheres obtained by sintering SiO2, CaO, Al2O3, MgO, P2O5, K2O, Fe2O3, and SiC in a mass ratio of 50-55:15-18:11-13:10-12:2-4:3-5:7-10:0.3-0.

5.

2. The multifunctional microcrystalline mortar according to claim 1, characterized in that, The preparation process of the thermal insulation and enhancement additive includes the following steps: S1. Preparation of intermediate polymer solution: At 75-80℃, polyethylene glycol monomethyl ether methacrylate was added to the reactor and dissolved in a mixed solvent of propylene glycol methyl ether / ethanol / ethyl acetate; maleic anhydride and azobisisobutyronitrile were added, and the reaction was stirred for 2 hours. The reaction mixture was then cooled to below 40℃ to obtain an intermediate polymer solution. S2, amidation grafting and silanization modification: Under stirring, polyetheramine and γ-aminopropyltriethoxysilane were diluted with ethyl acetate and added to the intermediate polymer solution; the temperature was raised to 85-90℃ and the reaction was maintained for 3-3.5h to obtain a silanized polyether-maleic anhydride copolymer solution. S3, Post-processing: The silanized polyether-maleic anhydride copolymer solution was spray-dried to obtain a white or pale yellow fine powder. After cooling to room temperature, it was sealed and packaged to obtain a heat-insulating and reinforcing additive.

3. The multifunctional microcrystalline mortar according to claim 2, characterized in that, In S1, the Mn of polyethylene glycol monomethyl ether methacrylate is 950; the solid content of the intermediate polymer solution is 30-35%; during the addition of maleic anhydride to polyethylene glycol monomethyl ether methacrylate, the reaction temperature is controlled below 82°C; in the propylene glycol methyl ether / ethanol / ethyl acetate mixed solvent, the mass ratio of propylene glycol methyl ether, ethanol and ethyl acetate is 5:3:2; the amount of azobisisobutyronitrile used is 0.8-1.2% of the total mass of polyethylene glycol monomethyl ether methacrylate and maleic anhydride.

4. The multifunctional microcrystalline mortar according to claim 2, characterized in that, In S2, the Mn of the polyether amine is 230; when the polyether amine and γ-aminopropyltriethoxysilane are mixed evenly and added to the intermediate polymer solution, the temperature is controlled not to exceed 50°C; the solid content of the silanized polyether-maleic anhydride copolymer solution is 30-35%.

5. The multifunctional microcrystalline mortar according to claim 2, characterized in that, In step S3, the thermal insulation enhancement additive needs to be sealed in an aluminum-plastic composite moisture-proof bag.

6. The multifunctional microcrystalline mortar according to claim 2, characterized in that, The mass ratio of polyethylene glycol monomethyl ether methacrylate, maleic anhydride, polyetheramine and γ-aminopropyltriethoxysilane is 30:5-8:10-12:3-5.

7. A method for preparing a multifunctional microcrystalline mortar as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of premixed dry materials: Silicate cement, volcanic ash, hydroxypropyl methylcellulose ether, water-reducing agent and redispersible latex powder are sequentially added into a dry powder mixer and mixed at high speed until all powders are uniform in color; Add the heat-insulating and reinforcing additives, continue mixing at high speed for 6-8 minutes, add microcrystalline particles, mix gently at low speed for 3-4 minutes, stop the machine and discharge the material to obtain the premix; (2) Construction preparation: Add water to the premix and stir until the slurry is uniform and free of dry powder particles. Apply the slurry by layering. After the construction is completed, keep it moist and maintain it.

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