A thermal insulation wall repairing material and a preparation method thereof

Abstract

The application discloses a kind of thermal insulation wall repair materials and preparation method thereof.The thermal insulation wall repair material of the application includes the following components by weight parts: modified burnt magnesium oxide 125-166 parts, ammonium dihydrogen phosphate 120-165 parts, fly ash floating bead 72-105 parts, water glass 20-55 parts, steel slag powder 25-55 parts, aluminum powder 18-40 parts, alpha-hemihydrate gypsum 10-40 parts, xanthan gum 15-45 parts, water 185-286 parts.The application fuses surface modification technology, polymer enhancement technology and the like, so that the modified magnesium oxide particles have good fluidity, controllable setting time in the later hydration process, and can improve the bonding performance of the material in the later period.After fully mixing modified burnt magnesium oxide, ammonium dihydrogen phosphate, mixed mineral admixture, water glass and foaming agent, the prepared thermal insulation wall repair material has high permeability, high fluidity, high cohesiveness, operability, and prolongs the service life of the thermal insulation wall.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal insulation wall repair, and particularly relates to a thermal insulation wall repair material and a preparation method thereof. BACKGROUND

[0002] As an important building energy-saving technology, the external wall thermal insulation technology has developed rapidly in the past 20 years in China. However, due to the complexity of the external wall thermal insulation engineering technology, the materials are more prone to aging under the action of dry-wet alternating and freeze-thaw cycles, and a series of quality problems such as hollowing, peeling, cracking and water leakage occur, which affects the safety and comfort of living and living environment.

[0003] To solve this problem, China has successively formulated standards such as "Building External Wall External Insulation Repair Standard" (JGJ 376-2015) and "Existing External Wall External Insulation Reconstruction Technical Specification" (TCECS 574-2019), which provide protection for the standardized operation of related technologies. In general, when a small amount of hollowing and other phenomena occur in the early stage of the current external insulation wall, the main repair method is to inject adhesive materials into the cavity between the wall and the thermal insulation layer by grouting method. As a key link of this technology, the repair material has been studied to some extent, and the repair materials used are mainly divided into organic repair materials and inorganic repair materials. The organic repair materials include epoxy resin and polyurea, but the epoxy resin is not resistant to acid and alkali corrosion and has general solvent resistance. When the epoxy resin contacts the external insulation board of the thermal insulation wall, it will cause the wall to appear hollow due to similar solubility. The inorganic repair material mainly includes various cement mortar, which has good durability, but its bonding strength with the wall interface is low, the shrinkage is large, and the permeability is poor, which is difficult to meet the strength requirements of wall repair.

[0004] Phosphate cement has excellent freeze-thaw resistance, heat resistance, good biocompatibility and other characteristics, and has good interface bonding performance with old concrete. It is often used as an interface repair material to repair damaged thermal insulation walls, highway bridges and aircraft runways, etc. It is an economical and efficient new type of repair material. However, due to the large initial viscosity of phosphate cement and short reaction time, it is difficult to construct in actual engineering application, it is difficult to fill the cavity of the thermal insulation structure, and it cannot achieve effective bonding. To solve this problem, starting from the source of the viscosity of phosphate cement, current research has improved its workability through the slow-release effect, for example, some scholars have proposed that CaCO3 capsule wall material with a thickness of 30-80 microns is made into microcapsules together with magnesium oxide, which is gradually released when used, thereby effectively delaying the setting. However, in the preparation of microcapsules, it is difficult to control the thickness of the capsule wall, and the capsule wall material only plays a buffering role in later use without other functions.

[0005] Therefore, it is urgent to develop a thermal insulation wall repairing material with high permeability, high adhesion, high flow, micro-expansion, long service life and other functions. SUMMARY

[0006] Therefore, the present application aims to provide a thermal insulation wall repairing material to solve the problems of poor flowability, short workable time, poor adhesion, short service life and other problems of the existing thermal insulation wall repairing material, thereby causing the existing thermal insulation wall to be prone to cracking and aging and falling off.

[0007] To achieve the above-mentioned purposes, the technical scheme of the present application is as follows:

[0008] A thermal insulation wall repairing material, comprising the following components in parts by weight: modified overburned magnesium oxide 125-166 parts, ammonium dihydrogen phosphate 120-165 parts, fly ash floating bead 72-105 parts, water glass 20-55 parts, steel slag powder 25-55 parts, aluminum powder 18-40 parts, alpha-hemihydrate gypsum 10-40 parts, xanthan gum 15-45 parts, and water 185-286 parts.

[0009] Optionally, the modified overburned magnesium oxide is prepared by the following method:

[0010] The magnesium oxide is high-temperature calcined to obtain overburned magnesium oxide;

[0011] In parts by weight, 125-166 parts of the overburned magnesium oxide is ball milled and then added to 60-85 parts of anhydrous ethanol for sufficient stirring until completely mixed, and then a hydroxylation reaction is carried out at a certain temperature, and after the hydroxylation reaction is completed, the obtained hydroxylation-treated overburned magnesium oxide particles are filtered and dried.

[0012] The hydroxylation-treated overburned magnesium oxide particles are mixed and stirred uniformly with 10-35 parts of polyethylene glycol octylphenyl ether, and then filtered and dried to obtain modified overburned magnesium oxide.

[0013] Optionally, the calcination temperature of the high-temperature calcination is 1600-1750℃, and the calcination time is 2.5-4.0h; the particle size of the overburned magnesium oxide after ball milling is 20-30μm.

[0014] Optionally, the reaction temperature of the hydroxylation reaction is 45-60℃, and the reaction time is 5-8h.

[0015] Optionally, the mass ratio of the anhydrous ethanol to the polyethylene glycol octylphenyl ether is 2-6:1.

[0016] Optionally, the sphericity of the fly ash floating bead is 0.93-0.98, and the bulk density is 0.32-0.37g / m 3The moisture content is ≤0.5%; the particle size distribution of the fly ash cenospheres by mass percentage is: 10-40μm: 15%, 40-70μm: 40%, 70-100μm: 45%.

[0017] Optionally, the purity of NH4H2PO4 in the ammonium dihydrogen phosphate is ≥99%; the fineness of the steel slag powder is 100-150 mesh, the CaO content is 8.5%-10%, and the MgO content is 10%-12%.

[0018] Optionally, the water glass is one or more of sodium water glass and potassium water glass, and the SiO2 content is 26% to 30%, and the solid content is ≥40%.

[0019] Optionally, the effective content of the aluminum powder is ≥60%, and the particle size is ≤5μm; the final setting time of the α-hemihydrate gypsum is ≤30min, and the flexural strength at 2h is ≥3.0MPa; the bulk density of the xanthan gum is 0.4~0.6g / mL, and the pH of the 1% xanthan gum solution is 6-8.

[0020] A second objective of this invention is to provide a method for preparing the above-mentioned thermal insulation wall repair material, the method comprising the following steps:

[0021] 1) The fly ash cenospheres, the steel slag powder, the α-hemihydrate gypsum, and the modified overburned magnesium oxide are thoroughly mixed to obtain mixed powder A;

[0022] 2) Dissolve the water glass in a portion of the water, wherein the ratio of the water glass to the portion of the water is 0.5 to 0.8, to obtain solution B;

[0023] 3) Place the mixed powder A in a mixing pot, add the solution B, stir quickly for 30-55 seconds, then add the remaining water and the ammonium dihydrogen phosphate, stir slowly for 20-50 seconds to obtain magnesium ammonium phosphate cement mortar.

[0024] 4) Add the aluminum powder and xanthan gum to the magnesium ammonium phosphate cement mortar, and foam to obtain the thermal insulation wall repair material.

[0025] Compared with existing technologies, the thermal insulation wall repair material of the present invention has the following advantages:

[0026] 1. The thermal insulation wall repair material of this invention has high adhesion. Based on the existing magnesium ammonium phosphate cementitious materials which already possess certain bonding properties, this invention adds water glass, effectively improving the morphology and structure of the cement hydration products, thus giving magnesium ammonium phosphate cement superior adhesion. The main component of water glass is silicate, and the solution contains SiO3. 2-The main structure is a long-chain structure, which can helically arrange itself to form a cavity structure. This cavity structure is capable of absorbing surrounding solvents and cations. Increased water glass content means an increased concentration of SiO32- in the solution. More SiO32- long-chain structures participate in the helical arrangement process, resulting in an increase in the number and size of the cavity structures. Larger cavity structures can absorb more solvents and cations, which enhances the intermolecular interactions in the grout system. Simultaneously, the intermolecular forces between the molecules in the grout system and the old concrete surface also increase, resulting in strong adhesion. However, excessive water glass promotes the activation of fly ash, leading to a shortened grout setting time. Furthermore, the addition of water glass can increase the Mg content in the grout. 2+ Increasing the pH value of the solution accelerates the setting speed of the slurry. Therefore, this application modifies the surface of magnesium oxide with ethanol and polyethylene glycol octylphenyl ether, causing it to encapsulate some magnesium oxide particles during cement hydration, thereby delaying its reaction with ammonium dihydrogen phosphate and water, and thus prolonging its setting time. Simultaneously, by adding aluminum powder as a foaming agent and xanthan gum as a foam stabilizer, this invention enables the magnesium ammonium phosphate cement mortar to form a fine bubble structure. This structure provides an additional insulation layer, enhances the structural performance of the wall, improves the building's energy efficiency, and in the later stages of the reaction, the aluminum in the aluminum powder reacts with α-hemihydrate gypsum and calcium and magnesium substances in steel slag to generate expansive ettringite, which complements the gas expansion and enhances the bonding strength with the wall interface.

[0027] 2. The thermal insulation wall repair material of this invention has excellent workability. While maintaining the original bonding performance of magnesium ammonium phosphate cement, the setting time is significantly extended. In daily construction, traditional retarders such as borax, boric acid, and sodium tripolyphosphate are widely used. However, in magnesium ammonium phosphate cement systems, boron-containing retarders form a borophosphorus magnesium stone phase during hydration. This mineral phase encapsulates MgO, causing excess retarders in the system to lose their effectiveness. This invention introduces hydroxyl groups onto the surface of magnesium oxide particles using anhydrous ethanol, and simultaneously modifies the magnesium oxide particles using the surfactant polyethylene glycol octylphenyl ether. The modification principle is that polyethylene glycol octylphenyl ether reacts with the hydroxyl groups on the surface of magnesium oxide particles and adsorbs onto the particle surface. During cement hydration, it encapsulates the magnesium oxide particles, delaying their release time and thus retarding the setting process. This improves the problem of poor workability caused by excessively rapid setting time in magnesium ammonium phosphate cement. This invention achieves the goal of controlling the setting time of magnesium ammonium phosphate cement while using water glass. The polyethylene glycol octylphenyl ether used in this invention is a nonionic surfactant with stable chemical properties and good compatibility with anhydrous ethanol. Furthermore, it is not easily decomposed or deteriorated and maintains good stability under acidic and alkaline conditions.

[0028] 3. The thermal insulation wall repair material of this invention has high fluidity. This invention uses fly ash cenospheres as a mineral admixture to replace part of the magnesium oxide, improving the fluidity of the cement paste. The main hydration product of magnesium ammonium phosphate cement is NH4MgPO4·6H2O (i.e., struvite). Struvite crystals are generally relatively stable and can provide a high degree of bonding to the system, which is why magnesium ammonium phosphate cement itself has high adhesive properties. However, high viscosity is detrimental to construction, making it difficult for the cement paste to flow quickly. Therefore, adding fly ash cenospheres to magnesium ammonium phosphate cement reduces the total porosity of the magnesium ammonium phosphate cement, increases the density of the matrix, and hinders the penetration of water molecules into the matrix. On the other hand, the smooth surface of fly ash cenospheres reduces the frictional resistance in magnesium phosphate cement, making the cement paste flow more easily. Using nonionic surfactants to modify the surface of magnesium oxide particles at the molecular level, in the later stages of the reaction, polyethylene glycol octylphenyl ether can work together with fly ash cenospheres to enhance the fluidity of the paste and improve construction efficiency. Compared to general mineral admixtures, fly ash cenospheres can more effectively improve the fluidity of slurry, enabling rapid extrusion during actual construction and improving construction efficiency. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions and effects of the present invention, several embodiments will be provided below. Obviously, the following description is only an embodiment and does not limit the scope of protection of the present invention.

[0030] The performance indicators of the raw materials used in Examples 1-6 of this invention are as follows:

[0031] The sphericity of fly ash cenospheres is 0.96, and the bulk density is 0.35 g / m³. 3 The moisture content is 0.4%; the particle size distribution of the fly ash cenospheres by mass percentage is: 10-40μm: 15%, 40-70μm: 40%, 70-100μm: 45%.

[0032] The purity of NH4H2PO4 in ammonium dihydrogen phosphate is ≥99%;

[0033] The steel slag powder has a fineness of 150 mesh, a CaO content of 9.0%, and a MgO content of 11.5%.

[0034] The SiO2 content in sodium silicate and potassium silicate is 30%, and the solid content is ≥40%.

[0035] The effective content of aluminum powder is 70%, and the particle size is 3-5 μm;

[0036] The final setting time of α-hemihydrate gypsum was 28 min, and its flexural strength after 2 hours was 3.68 MPa.

[0037] The bulk density of xanthan gum is 0.5 g / mL, and the pH of a 1% xanthan gum solution is 8.

[0038] Example 1

[0039] A thermal insulation wall repair material, by weight, comprises the following components: 125 parts modified overburned magnesium oxide, 120 parts ammonium dihydrogen phosphate, 72 parts fly ash cenospheres, 20 parts sodium silicate, 25 parts steel slag powder, 18 parts aluminum powder, 10 parts α-hemihydrate gypsum, 15 parts xanthan gum, and 185 parts water.

[0040] The modified overburned magnesium oxide is prepared by the following method:

[0041] Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide. Under high temperature, the grain size and particle density of MgO are significantly increased, which can significantly reduce the activity of magnesium oxide.

[0042] Overburned magnesium oxide was mechanically ground in a ball mill and then sieved to obtain overburned magnesium oxide particles with a particle size of 20-30 μm.

[0043] By weight, 125 parts of overburned magnesium oxide particles were added to 60 parts of anhydrous ethanol and stirred thoroughly for 10 minutes until completely mixed. Then, a hydroxylation reaction was carried out at 50°C to introduce hydroxyl groups onto the surface of the overburned magnesium oxide particles. After the hydroxylation reaction was carried out for 5 hours, the mixture was filtered to obtain hydroxylated overburned magnesium oxide particles.

[0044] Hydroxylated overburned magnesium oxide particles were mixed with 10 parts of polyethylene glycol octylphenyl ether and stirred for 15 minutes until homogeneous. The mixture was then filtered and dried to obtain modified overburned magnesium oxide.

[0045] The aforementioned thermal insulation wall repair material is prepared using the following methods:

[0046] 1) 72 parts fly ash cenospheres, 25 parts steel slag powder, 10 parts α-hemihydrate gypsum, and 125 parts modified overburned magnesium oxide were thoroughly mixed to obtain mixed powder A;

[0047] 2) Weigh 20 parts of sodium silicate and 33 parts of water (the ratio of silicate to water is 0.6). Add the silicate to the water and stir thoroughly until completely dissolved to obtain solution B.

[0048] 3) Place the mixed powder A in a mixing pot, add solution B, stir quickly for 30 seconds, then add 152 parts water and 120 parts ammonium dihydrogen phosphate, stir slowly for 20 seconds to obtain magnesium ammonium phosphate cement mortar.

[0049] 4) Add 18 parts aluminum powder and 15 parts xanthan gum to magnesium ammonium phosphate cement mortar, foam, and obtain thermal insulation wall repair material.

[0050] Example 2

[0051] A thermal insulation wall repair material, by weight, comprises the following components: 137 parts modified overburned magnesium oxide, 131 parts ammonium dihydrogen phosphate, 80 parts fly ash cenospheres, 28 parts sodium silicate, 32 parts steel slag powder, 24 parts aluminum powder, 20 parts α-hemihydrate gypsum, 23 parts xanthan gum, and 212 parts water.

[0052] The modified overburned magnesium oxide is prepared by the following method:

[0053] Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide. Under high temperature, the grain size and particle density of MgO are significantly increased, which can significantly reduce the activity of magnesium oxide.

[0054] Overburned magnesium oxide was mechanically ground in a ball mill and then sieved to obtain overburned magnesium oxide particles with a particle size of 20-30 μm.

[0055] By weight, 137 parts of overburned magnesium oxide particles were added to 67 parts of anhydrous ethanol and stirred thoroughly for 10 minutes until completely mixed. Then, a hydroxylation reaction was carried out at 50°C to introduce hydroxyl groups onto the surface of the overburned magnesium oxide particles. After the hydroxylation reaction was carried out for 5 hours, the mixture was filtered to obtain hydroxylated overburned magnesium oxide particles.

[0056] Hydroxylated overburned magnesium oxide particles were mixed with 18 parts of polyethylene glycol octylphenyl ether and stirred for 15 minutes until homogeneous. The mixture was then filtered and dried to obtain modified overburned magnesium oxide.

[0057] The aforementioned thermal insulation wall repair material is prepared using the following methods:

[0058] 1) Mix 80 parts fly ash cenospheres, 32 parts steel slag powder, 20 parts α-hemihydrate gypsum, and 137 parts modified overburned magnesium oxide thoroughly to obtain mixed powder A;

[0059] 2) Weigh 28 parts of sodium silicate and 47 parts of water (the ratio of silicate to water is 0.6). Add the silicate to the water and stir thoroughly until completely dissolved to obtain solution B.

[0060] 3) Place the mixed powder A in a mixing pot, add solution B, stir quickly for 30 seconds, then add 165 parts water and 131 parts ammonium dihydrogen phosphate, stir slowly for 20 seconds to obtain magnesium ammonium phosphate cement mortar.

[0061] 4) Add 24 parts aluminum powder and 23 parts xanthan gum to magnesium ammonium phosphate cement mortar, foam, and obtain thermal insulation wall repair material.

[0062] Example 3

[0063] A thermal insulation wall repair material, by weight, comprises the following components: 145 parts modified overburned magnesium oxide, 143 parts ammonium dihydrogen phosphate, 89 parts fly ash cenospheres, 36 parts sodium silicate, 39 parts steel slag powder, 30 parts aluminum powder, 25 parts α-hemihydrate gypsum, 30 parts xanthan gum, and 236 parts water.

[0064] The modified overburned magnesium oxide is prepared by the following method:

[0065] Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide. Under high temperature, the grain size and particle density of MgO are significantly increased, which can significantly reduce the activity of magnesium oxide.

[0066] Overburned magnesium oxide was mechanically ground in a ball mill and then sieved to obtain overburned magnesium oxide particles with a particle size of 20-30 μm.

[0067] By weight, 145 parts of overburned magnesium oxide particles were added to 76 parts of anhydrous ethanol and stirred thoroughly for 10 minutes until completely mixed. Then, a hydroxylation reaction was carried out at 50°C to introduce hydroxyl groups onto the surface of the overburned magnesium oxide particles. After the hydroxylation reaction was carried out for 5 hours, the mixture was filtered to obtain hydroxylated overburned magnesium oxide particles.

[0068] Hydroxylated overburned magnesium oxide particles were mixed with 25 parts of polyethylene glycol octylphenyl ether and stirred for 15 minutes until homogeneous. The mixture was then filtered and dried to obtain modified overburned magnesium oxide.

[0069] The aforementioned thermal insulation wall repair material is prepared using the following methods:

[0070] 1) 89 parts fly ash cenospheres, 39 parts steel slag powder, 25 parts α-hemihydrate gypsum, and 145 parts modified overburned magnesium oxide were thoroughly mixed to obtain mixed powder A;

[0071] 2) Weigh 36 parts of sodium silicate and 60 parts of water (the ratio of silicate to water is 0.6). Add the silicate to the water and stir thoroughly until completely dissolved to obtain solution B.

[0072] 3) Place the mixed powder A in a mixing pot, add solution B, stir quickly for 30 seconds, then add 176 parts water and 143 parts ammonium dihydrogen phosphate, stir slowly for 20 seconds to obtain magnesium ammonium phosphate cement mortar.

[0073] 4) Add 30 parts aluminum powder and 30 parts xanthan gum to magnesium ammonium phosphate cement mortar, foam, and obtain thermal insulation wall repair material.

[0074] Example 4

[0075] A thermal insulation wall repair material, by weight, comprises the following components: 155 parts modified overburned magnesium oxide, 152 parts ammonium dihydrogen phosphate, 90 parts fly ash cenospheres, 45 parts sodium silicate, 44 parts steel slag powder, 35 parts aluminum powder, 36 parts α-hemihydrate gypsum, 36 parts xanthan gum, and 255 parts water.

[0076] The modified overburned magnesium oxide is prepared by the following method:

[0077] Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide. Under high temperature, the grain size and particle density of MgO are significantly increased, which can significantly reduce the activity of magnesium oxide.

[0078] Overburned magnesium oxide was mechanically ground in a ball mill and then sieved to obtain overburned magnesium oxide particles with a particle size of 20-30 μm.

[0079] By weight, 155 parts of overburned magnesium oxide particles were added to 80 parts of anhydrous ethanol and stirred thoroughly for 10 minutes until completely mixed. Then, a hydroxylation reaction was carried out at 50°C to introduce hydroxyl groups onto the surface of the overburned magnesium oxide particles. After the hydroxylation reaction was carried out for 5 hours, the mixture was filtered to obtain hydroxylated overburned magnesium oxide particles.

[0080] Hydroxylated overburned magnesium oxide particles were mixed with 30 parts of polyethylene glycol octylphenyl ether and stirred for 15 minutes until uniformly mixed. The mixture was then filtered and dried to obtain modified overburned magnesium oxide.

[0081] The aforementioned thermal insulation wall repair material is prepared using the following methods:

[0082] 1) Mix 90 parts fly ash cenospheres, 44 parts steel slag powder, 36 parts α-hemihydrate gypsum, and 155 parts modified overburned magnesium oxide thoroughly to obtain mixed powder A;

[0083] 2) Weigh 45 parts sodium silicate and 75 parts water (the ratio of water glass to water is 0.6). Add the water glass to the water and stir thoroughly until completely dissolved to obtain solution B.

[0084] 3) Place the mixed powder A in a mixing pot, add solution B, stir quickly for 30 seconds, then add 180 parts water and 152 parts ammonium dihydrogen phosphate, stir slowly for 20 seconds to obtain magnesium ammonium phosphate cement mortar.

[0085] 4) Add 35 parts aluminum powder and 36 parts xanthan gum to magnesium ammonium phosphate cement mortar, foam, and obtain thermal insulation wall repair material.

[0086] Example 5

[0087] A thermal insulation wall repair material, by weight, comprises the following components: 166 parts modified overburned magnesium oxide, 165 parts ammonium dihydrogen phosphate, 105 parts fly ash floats, 55 parts sodium silicate, 55 parts steel slag powder, 40 parts aluminum powder, 40 parts α-hemihydrate gypsum, 45 parts xanthan gum, and 286 parts water.

[0088] The modified overburned magnesium oxide is prepared by the following method:

[0089] Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide. Under high temperature, the grain size and particle density of MgO are significantly increased, which can significantly reduce the activity of magnesium oxide.

[0090] Overburned magnesium oxide was mechanically ground in a ball mill and then sieved to obtain overburned magnesium oxide particles with a particle size of 20-30 μm.

[0091] By weight, 166 parts of overburned magnesium oxide particles were added to 85 parts of anhydrous ethanol and stirred thoroughly for 10 minutes until completely mixed. Then, a hydroxylation reaction was carried out at 50°C to introduce hydroxyl groups onto the surface of the overburned magnesium oxide particles. After the hydroxylation reaction was carried out for 5 hours, the mixture was filtered to obtain hydroxylated overburned magnesium oxide particles.

[0092] Hydroxylated overburned magnesium oxide particles were mixed with 35 parts of polyethylene glycol octylphenyl ether and stirred for 15 minutes until homogeneous. The mixture was then filtered and dried to obtain modified overburned magnesium oxide.

[0093] The aforementioned thermal insulation wall repair material is prepared using the following methods:

[0094] 1) Mix 105 parts fly ash cenospheres, 55 parts steel slag powder, 40 parts α-hemihydrate gypsum, and 166 parts modified overburned magnesium oxide thoroughly to obtain mixed powder A;

[0095] 2) Weigh 55 parts of sodium silicate and 92 parts of water (the ratio of water glass to water is 0.6). Add the water glass to the water and stir thoroughly until completely dissolved to obtain solution B.

[0096] 3) Place the mixed powder A in a mixing pot, add solution B, stir quickly for 30 seconds, then add 194 parts water and 165 parts ammonium dihydrogen phosphate, stir slowly for 20 seconds to obtain magnesium ammonium phosphate cement mortar.

[0097] 4) Add 40 parts aluminum powder and 45 parts xanthan gum to magnesium ammonium phosphate cement mortar, foam, and obtain thermal insulation wall repair material.

[0098] Example 6

[0099] The difference between this embodiment and Embodiment 1 is that the water glass is made by mixing sodium water glass and potassium water glass in a mass ratio of 1:1, while the rest is the same as in Embodiment 1.

[0100] Comparative Example 1

[0101] The difference between this comparative example and Example 1 is that this comparative example does not use anhydrous ethanol and polyethylene glycol octylphenyl ether to perform surface modification treatment on magnesium oxide particles.

[0102] That is, the modified overburned magnesium oxide in this comparative example was prepared by the following method:

[0103] Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide. Under high temperature, the grain size and particle density of MgO are significantly increased, which can significantly reduce the activity of magnesium oxide.

[0104] Overburned magnesium oxide was mechanically ground in a ball mill and then sieved to obtain overburned magnesium oxide particles with a particle size of 20-30 μm.

[0105] Comparative Example 2

[0106] The difference between this comparative example and Example 1 is that water glass is not used in the preparation of magnesium ammonium phosphate cement mortar in this comparative example.

[0107] Comparative Example 3

[0108] The difference between this comparative example and Example 1 is that this comparative example does not use α-hemihydrate gypsum. In order to ensure that the proportions of other components remain unchanged, 10 parts of α-hemihydrate gypsum are replaced with 10 parts of steel slag powder.

[0109] The test methods for the tensile bond strength, shear strength, flowability, and setting time of the thermal insulation wall repair materials of Examples 1-6 and Comparative Examples 1-3 prepared according to the above technical solution are as follows:

[0110] The tensile bond strength was tested in accordance with JGJ144-2019 "Technical Standard for External Wall Insulation Engineering"; the shear strength was tested in accordance with GB / T 7124-2008 "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)"; the fluidity was tested in accordance with GB / T 2419-2005 "Standard for Test of Flowability of Cement Mortar"; and the setting time was tested in accordance with GB / T1346-2011 "Test Method for Standard Consistency Water Requirement, Setting Time and Soundness of Cement".

[0111] Tensile bond strength: The prepared thermal insulation wall repair material slurry was applied to a 45mm thick thermal insulation board or concrete wall surface with a thickness of 8mm. The sample was then installed on a tensile testing machine with a tensile speed of 0.1mm / min, and the tensile force at failure was recorded.

[0112] Shear strength: The prepared thermal insulation wall repair material slurry is placed into the connecting hole formed by the upper and lower pull rods of the shearing device. The thickness and width of the shear-loaded portion in the middle of the sample are measured. The motor is started, the sample is sheared, and its maximum shear force value is recorded. The shearing device consists of two steel pull rods (upper and lower). The working part of the upper pull rod is 30mm wide, and the working parts on both sides of the lower pull rod are 25mm wide.

[0113] Flowability: Place the truncated cone mold in the center of the work surface, then slowly pour the prepared thermal insulation wall repair material slurry into the mold. Tamp it down with a tamping rod, then quickly lift it out. After 1 minute, measure the diameter of the slurry's bottom surface in two mutually perpendicular directions using calipers, calculate the average value, and round it to the nearest integer in mm. This average value is the flowability of the cement slurry. The dimensions of the truncated cone mold are: height 60mm, upper inner diameter 70mm, and lower inner diameter 100mm.

[0114] Setting time: Slowly pour the prepared thermal insulation wall repair material slurry into the mold, place the mold under the test needle, tighten the screw and then suddenly loosen it, observing the pointer reading when the test needle stops sinking. Measure every 3 minutes, and express the setting time of the cement slurry in minutes. The mold specifications are a truncated cone with a depth of 40mm ± 0.2mm, a bottom inner diameter of Φ65mm ± 0.5mm, and a bottom inner diameter of Φ75mm ± 0.5mm. Each mold should be equipped with a flat glass plate with a side length or diameter of approximately 100mm and a thickness of 4-5mm.

[0115] The main performance indicators of the thermal insulation wall repair materials prepared in Examples 1-6 and Comparative Examples 1-3 were tested according to the above performance testing methods, as shown in Table 1.

[0116] As shown in Table 1, the experimental results of Example 1 and Comparative Example 1 indicate that the lack of surface molecular-level modification of magnesium oxide particles accelerates the setting time of cement paste. However, surface hydroxylation treatment of magnesium oxide particles with anhydrous ethanol and molecular-level modification of their surface with polyethylene glycol octylphenyl ether delays the setting time of cement. This is because the magnesium oxide particles are coated with polyethylene glycol octylphenyl ether, which inhibits the release of magnesium oxide particles in the early stages of magnesium ammonium phosphate cement hydration, thereby slowing down the cement hydration process and achieving the effect of delaying cement setting time, thus facilitating the actual construction process.

[0117] As shown in Table 1, the experimental results of Example 1 and Comparative Example 2 indicate that the setting time of the cement paste is longer when water glass is not added, but its fluidity is somewhat reduced compared to Example 2. This is because the main component of water glass is sodium silicate, and the SiO3 in the solution... 2-The grout primarily consists of long-chain structures that can helically arrange themselves to form cavities. These cavities are capable of absorbing surrounding solvents and cations. As the amount of water glass increases, these cavities become larger, allowing them to absorb more solvents and cations. This enhances the intermolecular interactions within the grout system and also increases the intermolecular forces between the molecules in the grout system and the old concrete surface, thereby increasing the initial viscosity of the grout.

[0118] As shown in Table 1, the experimental results of Examples 1 and 6 indicate that the cement slurry exhibits greater bonding strength when both types of water glass are added simultaneously. This is because the addition of potassium water glass reacts with ammonium dihydrogen phosphate to precipitate colloidal potassium silicate. This colloidal potassium silicate provides greater bonding performance to the slurry, increasing the adhesion between the wall and the repair material.

[0119] As shown in Table 1, the experimental results of Example 1 and Comparative Example 3 indicate that the bonding strength of the cement paste decreases when α-hemihydrate gypsum is not added. This is because, in the later stage of the reaction, the aluminum in the foaming agent aluminum powder reacts with the calcium and magnesium substances in the α-hemihydrate gypsum and steel slag to generate expansive ettringite, which complements the gas expansion and enhances the bonding strength with the wall interface.

[0120] Table 1

[0121]

[0122] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal insulation wall repair material, characterized in that, By weight, it includes the following components: 125-166 parts of modified overburned magnesium oxide, 120-165 parts of ammonium dihydrogen phosphate, 72-105 parts of fly ash cenospheres, 20-55 parts of water glass, 25-55 parts of steel slag powder, 18-40 parts of aluminum powder, 10-40 parts of α-hemihydrate gypsum, 15-45 parts of xanthan gum, and 185-286 parts of water. The modified overburned magnesium oxide was prepared by the following method: Magnesium oxide is calcined at high temperature to obtain over-calcined magnesium oxide; By weight, 125-166 parts of the overburned magnesium oxide were ball-milled and added to 60-85 parts of anhydrous ethanol. After stirring thoroughly until completely mixed, a hydroxylation reaction was carried out at a certain temperature. After the hydroxylation reaction was completed, the mixture was filtered to obtain hydroxylated overburned magnesium oxide particles. The hydroxylated overburned magnesium oxide particles were mixed with 10-35 parts of polyethylene glycol octylphenyl ether, stirred evenly, filtered and dried to obtain modified overburned magnesium oxide.

2. The thermal insulation wall repair material according to claim 1, characterized in that, The calcination temperature of the high-temperature calcination is 1600~1750 ℃, and the calcination time is 2.5~4.0 h; the particle size of the over-calcined magnesium oxide after ball milling is 20~30 μm.

3. The thermal insulation wall repair material according to claim 1, characterized in that, The hydroxylation reaction is carried out at a temperature of 45-60 °C for 5-8 h.

4. The thermal insulation wall repair material according to claim 1, characterized in that, The mass ratio of anhydrous ethanol to polyethylene glycol octylphenyl ether is 2~6:

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5. The thermal insulation wall repair material according to claim 1, characterized in that, The sphericity of the fly ash cenospheres is 0.93~0.98, and the bulk density is 0.32~0.37 g / m³. 3 The moisture content is ≤0.5%; the particle size composition of the fly ash cenospheres by mass percentage is: 10~40μm: 15%, 40~70μm: 40%, 70~100μm: 45%.

6. The thermal insulation wall repair material according to claim 1, characterized in that, The purity of NH4H2PO4 in the ammonium dihydrogen phosphate is ≥99%; the fineness of the steel slag powder is 100~150 mesh, the CaO content is 8.5%~10%, and the MgO content is 10%~12%.

7. The thermal insulation wall repair material according to claim 1, characterized in that, The water glass is one or more of sodium water glass and potassium water glass, and the SiO2 content is 26%~30%, and the solid content is ≥40%.

8. The thermal insulation wall repair material according to claim 1, characterized in that, The effective content of the aluminum powder is ≥60%, and the particle size is ≤5μm; the final setting time of the α-hemihydrate gypsum is ≤30 min, and the flexural strength at 2 h is ≥3.0 MPa; the bulk density of the xanthan gum is 0.4~0.6 g / mL, and the pH of the 1% xanthan gum solution is 6-8.

9. A method for preparing the thermal insulation wall repair material according to any one of claims 1 to 8, characterized in that, Includes the following steps: 1) The fly ash cenospheres, the steel slag powder, the α-hemihydrate gypsum, and the modified overburned magnesium oxide are thoroughly mixed to obtain mixed powder A; 2) Dissolve the water glass in a portion of the water, wherein the ratio of the water glass to the portion of the water is 0.5 to 0.8, to obtain solution B; 3) Place the mixed powder A in a mixing pot, add the solution B, stir quickly for 30-55 seconds, then add the remaining water and the ammonium dihydrogen phosphate, stir slowly for 20-50 seconds to obtain magnesium ammonium phosphate cement mortar. 4) Add the aluminum powder and xanthan gum to the magnesium ammonium phosphate cement mortar, and foam to obtain the thermal insulation wall repair material.

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