A heat-insulating brick based on cement mixture and its preparation method

Abstract

The present invention discloses a heat-insulating brick based on cement mixture and a preparation method thereof, belonging to the technical field of building material processing. The present invention comprises the following components by weight: 60-70 parts of PEG-modified aggregate, 20-25 parts of modified silica, 8-12 parts of silicon-based fiber powder, 30-50 parts of cement, 6-7 parts of additive, and 30-40 parts of foaming liquid. A cement slurry is formed by mixing PEG-modified aggregate, modified silica, silicon-based fiber powder, and cement, and then mixed with foaming foam. After promoting the uniform dispersion of the foaming foam in the cement slurry and curing through molded bricks, it not only effectively improves the heat insulation performance and compressive strength of the heat-insulating brick, but also enables the heat-insulating brick to have good energy storage performance, further improving the heat insulation performance of the heat-insulating brick.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials processing, and particularly relates to a heat-insulating brick based on cement mixture and a preparation method thereof. Background Art

[0002] With the continuous improvement of the requirements for energy conservation, environmental protection and sustainable development, in the construction industry, traditional solid bricks are difficult to meet the needs of modern buildings due to their disadvantages such as large weight and poor heat insulation performance. Heat-insulating bricks are a new type of building material synthesized using polymer materials or other inorganic non-metallic materials, which have a low thermal conductivity and good heat insulation effect, can effectively reduce heat transfer, and improve the heat insulation performance of buildings.

[0003] Among the existing technologies, cement foamed bricks, as a new type of building material made with cement as the raw material, combined with an appropriate amount of foaming agent and auxiliary materials, have gradually occupied a place in the construction industry due to their multi-functional, environmental protection and high-strength characteristics. The heat insulation performance of heat-insulating bricks has a great relationship with the uniformity of the internal pore distribution and the porosity. The more uniform the pore distribution and the higher the porosity of the heat-insulating brick, the better its heat insulation performance, and vice versa. In the preparation process of traditional heat-insulating bricks, due to the poor wetting performance and dispersibility of the aggregate itself, inorganic particles are prone to agglomeration, and the bonding force between the particles and the cement matrix is poor, resulting in the need to further improve the mechanical compressive strength of the heat-insulating brick. Moreover, the low dispersibility of traditional concrete materials will reduce the stability of the foam in the cement mixture, making it difficult for the foam to be evenly dispersed and stably present in the foaming slurry. The heat insulation performance and compressive strength of the heat-insulating brick materials need to be further improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a heat-insulating brick based on cement mixture and a preparation method thereof, which are used to solve the technical problem that the heat insulation performance and compressive strength of the heat-insulating brick materials in the existing technology need to be further improved.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A heat-insulating brick based on cement mixture, comprising the following components by weight: 60-70 parts of PEG-modified aggregate, 20-25 parts of modified silica, 8-12 parts of silicon-based fiber powder, 30-50 parts of cement, 6-7 parts of additive, 30-40 parts of foaming liquid and 50-60 parts of drinking water;

[0006] The preparation method of the PEG-modified aggregate is: mixing and stirring the aggregate and drinking water, adding siloxane-modified PEG to the mixed system, raising the temperature of the reaction system to 60-70 °C, keeping warm and stirring for 4-6 h, and performing post-treatment to obtain the PEG-modified aggregate.

[0007] The synthesis reaction mechanism of the PEG-modified aggregate is:

[0008] During the reaction process, in an aqueous environment, the triethoxysilane molecules on the siloxane-modified PEG molecules hydrolyze to form silanols and bond with the surface of the aggregate particles, forming PEG modification on the aggregate particles to obtain PEG-modified aggregates.

[0009] Furthermore, the aggregates are composed of river sand, mullite powder, slag powder, and fly ash in a weight ratio of 15 - 17:6 - 7:5 - 7:8 - 10.

[0010] The additive is composed of a water reducer, a foam stabilizer, an air-entraining agent, and an early strength agent in a weight ratio of 5:3:2:2.

[0011] The foaming liquid is composed of 2-acrylamide-2-methylpropanesulfonic acid, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate, ammonium persulfate, and drinking water in a dosage ratio of 2g:1.2g:1g:0.2g:40mL.

[0012] Furthermore, the dosage ratio of the aggregates, drinking water, and siloxane-modified PEG is 5g:20mL:2g. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is reduced to room temperature, filtered by suction, the filter cake is washed twice with drinking water and then dried by suction, the filter cake is transferred to an oven at 60 - 70°C, and dried to a constant weight to obtain PEG-modified aggregates.

[0013] Furthermore, the preparation method of the siloxane-modified PEG is as follows: under the protection of an inert gas, PEG and tetrahydrofuran are mixed and stirred, the temperature of the reaction system is raised to 40 - 50°C, isocyanatopropyltriethoxysilane is added to the reaction system, and the reaction is carried out under insulation for 2 - 3h, and then post-treated to obtain siloxane-modified PEG.

[0014] The synthesis reaction mechanism of siloxane-modified PEG is as follows:

[0015] During the reaction process, the hydroxyl groups on the PEG molecules undergo a condensation reaction with the isocyanate groups on the isocyanatopropyltriethoxysilane molecules to form triethoxysilane modification on the PEG molecular chain, and siloxane-modified PEG is prepared.

[0016] Furthermore, the dosage ratio of the PEG, tetrahydrofuran, and isocyanatopropyltriethoxysilane is 7g:40mL:3g. The PEG is PEG-800. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 60°C, and the low-boiling substances are removed under reduced pressure to obtain siloxane-modified PEG.

[0017] Further, the preparation method of the modified silica is as follows: Mix lauric acid, dodecanol, and absolute ethanol and stir until the system dissolves. Add fumed silica to the reaction system, and under stirring at room temperature, disperse for 60 - 80 min. Then add the dispersion liquid to the reaction system, keep warm and stir for 30 - 50 min, and perform post-treatment to obtain the modified silica.

[0018] The synthesis reaction mechanism of the modified silica is as follows:

[0019] Ethanol is a good organic solvent, which helps dissolve lauric acid and dodecanol, enabling lauric acid and dodecanol to form a uniform dispersion liquid in absolute ethanol. When fumed silica is added to the reaction system, under the action of stirring, the fumed silica particles gradually disperse in the ethanol / lauric acid / dodecanol mixture to form a uniform dispersion system. Then, add the aqueous dispersion liquid to the reaction system. As a poor solvent, the aqueous dispersion liquid promotes the precipitation of lauric acid and dodecanol from ethanol and coats the outside of the fumed silica, and they precipitate from the solution in the form of coprecipitation to prepare the modified silica.

[0020] Further, the dosage ratio of lauric acid, dodecanol, absolute ethanol, fumed silica, and the dispersion liquid is 3 g: 2 g: 20 mL: 5 g: 40 mL. The dispersion liquid is composed of polyethylene glycol 400 and deionized water in a ratio of 2 - 3 g: 100 mL. The post-treatment includes: After the reaction is completed, lower the temperature of the reaction system to 10 - 15 °C, perform suction filtration, wash the filter cake with deionized water 3 times and then drain it, and let the filter cake dry naturally to obtain the modified silica.

[0021] Further, the silicon-based fiber powder is processed by the following steps:

[0022] A1. Mix chopped glass fibers and the activation liquid and stir. Raise the temperature of the reaction system to 60 - 80 °C, keep warm and react for 2 - 3 h, and perform post-treatment to obtain activated fibers.

[0023] A2. Stir and mix the activated fibers, methyltriethoxysilane, tetraethyl orthosilicate, 3-glycidoxypropyltriethoxysilane, and absolute ethanol. Lower the temperature of the reaction system to 10 - 15 °C, add hydrochloric acid solution to the reaction system, keep warm and react for 3 - 5 h, and perform post-treatment to obtain the silicon-based fiber powder.

[0024] The synthesis reaction mechanism of the silicon-based fiber powder is as follows:

[0025] As a strong base, sodium hydroxide can promote the decomposition of hydrogen peroxide to generate oxidizing free radicals. During the reaction, the silicate structure on the surface of the glass fiber is oxidized or etched by the free radicals in the activation solution, increasing the surface roughness and active sites of the chopped glass fiber. Methyltriethoxysilane, tetraethyl orthosilicate, and 3-glycidoxypropyltriethoxysilane contain ethoxysilane bonds in these silane molecules. Under the condition of an acid catalyst, the ethoxysilyl groups decompose to form silanol groups, and the silanol groups react with each other or with the active reaction sites on the surface of the activated fiber to form siloxane bonds, forming a polyorganosiloxane coating modified with epoxy groups outside the fiber, and obtaining silicon-based fiber powder.

[0026] Further, in step A1, the dosage ratio of the chopped glass fiber to the activation solution is 1 g: 5-6 mL. The activation solution is composed of a 3-5 wt% sodium hydroxide solution and 20 wt% hydrogen peroxide in a volume ratio of 5:1. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, suction filtration is carried out, the filter cake is washed with drinking water until neutral and then dried by suction, the filter cake is transferred to a drying oven at 60-70 °C, and vacuum dried to constant weight to obtain activated fiber.

[0027] Further, in step A2, the dosage ratio of the activated fiber, methyltriethoxysilane, tetraethyl orthosilicate, 3-glycidoxypropyltriethoxysilane, absolute ethanol, and hydrochloric acid solution is 30 g: 10-12 g: 8-10 g: 4-6 g: 60 mL: 10 mL. The concentration of the hydrochloric acid solution is 0.8-1.2 mol / L. The post-treatment includes: after the reaction is completed, ammonia water is added to the reaction system to adjust the pH of the system to 7, the temperature of the reaction system is raised to 60-70 °C, and low-boiling substances are removed by reduced pressure evaporation to obtain a wet gel. The wet gel is evenly spread in a drying oven at 110-120 °C and dried to constant weight and then crushed to obtain silicon-based fiber powder.

[0028] The present invention also provides a preparation method of a heat-insulating brick based on a cement mixture, including the following steps:

[0029] S1. Add the foaming liquid into a foaming machine for foaming to obtain foamed foam.

[0030] S2. Add PEG-modified aggregate, cement, silicon-based fiber powder, modified silica, and additive into a mixer and stir for 3-5 min, add drinking water into the mixer, stir and mix for 8-10 min, and then add the foamed foam into the mixer and stir and disperse for 1-2 min to obtain a foamed slurry.

[0031] S3. Pour the foamed slurry into several molds respectively, then scrape the slurry on the upper surface of the mold flat and seal the mold, let it stand for 4-6 h, and demold to obtain a heat-insulating brick blank.

[0032] S4. Place the heat-insulating brick blank in a curing chamber and cure for 7 days to obtain the heat-insulating brick.

[0033] The present invention has the following beneficial effects:

[0034] 1. In the present invention, an aggregate is composed of river sand, mullite powder, slag powder and fly ash. Under the action of cement, the inorganic particles of the aggregate are connected to each other through physical and chemical bonding to form a certain strength basis. In this application, siloxane-modified PEG is used to modify the aggregate, and PEG is grafted onto the surface of the aggregate through triethoxysilane. As a non-ionic surfactant, PEG has good wettability and dispersibility. During the material preparation process, PEG can effectively reduce the surface tension of the aggregate particles, promote uniform dispersion between the particles, reduce the agglomeration between the particles, enhance the interfacial bonding force between the aggregate and the cement matrix, reduce the propagation of microcracks, and enhance the mechanical strength of the heat-insulating brick. Moreover, by promoting the uniform dispersion of the aggregate by PEG, a more uniform and fine pore structure can be formed in the material, increasing the porosity of the heat-insulating brick and improving its heat insulation performance.

[0035] 2. The present invention uses chopped glass fibers as raw materials and coats and modifies them with polysiloxane to increase the interfacial bonding force between the glass fibers and the matrix, and at the same time improve the strength of the fibers themselves, thereby indirectly enhancing the compressive strength of the foamed heat-insulating brick. The fumed silica is modified with two organic substances with longer molecular chains, lauric acid and dodecanol, endowing the modified silica particles with flexibility and mechanical strength, enabling the silica particles to better absorb and disperse stress when subjected to external forces, while the mechanical strength ensures that the particles themselves are not easily broken, thus effectively improving the overall performance of the material. Moreover, lauric acid, dodecanol and PEG-800 can absorb and release heat within a certain temperature range, reducing the impact of external temperature fluctuations on the indoor temperature, making the indoor temperature more stable and reducing carbon emissions.

[0036] 3. The present invention uses 2-acrylamide-2-methylpropanesulfonic acid, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate, ammonium persulfate, and drinking water to form a foaming solution. 2-Acrylamide-2-methylpropanesulfonic acid in the foaming solution acts as a surfactant, which can reduce the surface tension of water and help form stable and fine foam. N,N'-methylenebisacrylamide acts as a crosslinking agent, which can enhance the stability of the foam. Sodium dodecylbenzenesulfonate acts as an anionic surfactant and can also play a role in stabilizing the foam. Ammonium persulfate acts as an initiator, which can initiate the polymerization of 2-acrylamide-2-methylpropanesulfonic acid and N,N'-methylenebisacrylamide to form a polymer network with a certain viscosity, ensuring the formation of a uniform and delicate foam structure in the foaming slurry. The long-chain fatty acid structure modified on the modified silica particles helps form a more compact foam structure, reducing the mutual connection between bubbles, thereby improving the compressive strength and stability of the foam. By modifying the aggregate with PEG, the surface tension of the aggregate can be reduced, its surface wettability can be improved, and the aggregate and the foaming foam can be uniformly mixed during stirring, thereby improving the dispersibility of the foam in the foaming slurry and enhancing the heat insulation and mechanical compressive strength of the insulation brick. Detailed implementation manners

[0037] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0038] In this application, the mesh number of river sand is 8 - 16 meshes;

[0039] In this application, the cement is Portland cement;

[0040] In this application, the foam stabilizer is selected from Jining Fangyu Chemical Co., Ltd., the product name is cement foaming foam stabilizer, the model is DX560, and it is a light yellow transparent liquid with a density of 1.00 g / cm 3 ;

[0041] In this application, the air-entraining agent is selected from Nanjing Chuhai New Material Technology Co., Ltd., the model is CHUPOL AE-503, the solid content is 31.4 - 34.6%, and the density is 1.03 - 1.07 g / cm 3 ;

[0042] In this application, the early strength agent is selected from Qidong Rongsheng Chemical Co., Ltd., the product name is calcium formate, the effective ingredient content is 98%, and the density is 200 g / cm 3 . Example 1

[0043] This embodiment provides a preparation method of heat-insulating bricks based on cement mixture, comprising the following steps:

[0044] S1. Prepare PEG-modified aggregate

[0045] Weigh: 700 g of PEG-800 and 4000 mL of tetrahydrofuran are added to a reaction kettle protected by nitrogen and stirred. The temperature of the reaction kettle is raised to 40°C. 300 g of isocyanatopropyltriethoxysilane is added to the reaction kettle, and the reaction is carried out under insulation for 2 h. The temperature of the reaction system is raised to 60°C, and low-boiling substances are removed under reduced pressure to obtain siloxane-modified PEG;

[0046] Mix river sand, mullite powder, slag powder, and fly ash evenly according to a weight ratio of 15:6:5:8 to obtain aggregate for standby;

[0047] Weigh: 500 g of aggregate and 2000 mL of drinking water are added to a stirring kettle and stirred for 30 min. 200 g of siloxane-modified PEG is added to the stirring kettle. The temperature of the stirring kettle is raised to 60°C, and the mixture is stirred under insulation for 4 h. After post-treatment, the temperature of the stirring kettle is lowered to room temperature, and suction filtration is carried out. The filter cake is washed twice with drinking water and then dried by suction. The filter cake is transferred to a drying oven at 60°C and dried to a constant weight to obtain PEG-modified aggregate.

[0048] S2. Prepare modified silica

[0049] Mix polyethylene glycol 400 and deionized water evenly according to 2 g:100 mL to obtain a dispersion for standby;

[0050] Weigh: 300 g of lauric acid, 200 g of dodecanol, and 2000 mL of absolute ethanol are added to a reaction kettle and stirred until the system is dissolved. 500 g of fumed silica is added to the reaction kettle. At room temperature, the mixture is stirred and dispersed for 60 min. 4000 mL of the dispersion is added to the reaction kettle, and the mixture is stirred under insulation for 30 min. The temperature of the reaction system is lowered to 10°C, and suction filtration is carried out. The filter cake is washed three times with deionized water and then dried by suction. The filter cake is air-dried naturally to obtain modified silica.

[0051] S3. Prepare silicon-based fiber powder

[0052] Mix 3 wt% sodium hydroxide solution and 20 wt% hydrogen peroxide evenly according to a volume ratio of 5:1 to obtain an activation solution for standby;

[0053] Weigh: 100 g of chopped glass fiber and 500 mL of the activation solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 60°C, and the reaction is carried out under insulation for 2 h. The temperature of the reaction kettle is lowered to room temperature, and suction filtration is carried out. The filter cake is washed with drinking water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 60°C and vacuum-dried to a constant weight to obtain activated fiber;

[0054] Weigh: 90 g of activated fiber, 30 g of methyltriethoxysilane, 24 g of tetraethyl orthosilicate, 12 g of 3-glycidoxypropyltriethoxysilane, and 180 mL of absolute ethanol, add them to a reaction kettle and stir. Lower the temperature of the reaction kettle to 10 °C, add 30 mL of 0.8 mol / L hydrochloric acid solution to the reaction kettle, keep the temperature for reaction for 3 h, add ammonia water to the reaction kettle, adjust the pH of the system to 7, raise the temperature of the reaction kettle to 60 °C, and distill off the low-boiling substances under reduced pressure to obtain a wet gel. Spread the wet gel evenly in an oven at 110 °C and dry it to a constant weight, then crush it to obtain silicon-based fiber powder.

[0055] S4. Prepare the foaming liquid

[0056] Add 2-acrylamido-2-methylpropanesulfonic acid, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate, ammonium persulfate, and drinking water to the reaction kettle according to the dosage ratio of 2 g:1.2 g:1 g:0.2 g:40 mL, mix and stir. Raise the temperature of the reaction kettle to 70 °C, keep the temperature for reaction for 3 h, and naturally cool to room temperature to obtain the foaming liquid.

[0057] S5. Prepare the thermal insulation bricks

[0058] Mix polycarboxylate water reducer, foam stabilizer, air-entraining agent, and early strength agent evenly according to the weight ratio of 5:3:2:2 to obtain an additive for standby;

[0059] Weigh by weight parts: 60 parts of PEG-modified aggregate, 20 parts of modified silica, 8 parts of silicon-based fiber powder, 30 parts of cement, 6 parts of additive, 30 parts of foaming liquid, and 50 parts of drinking water for standby;

[0060] Place the foaming liquid into a foaming machine, use carbon dioxide as the gas source for foaming to obtain foamed foam with a density of 60 kg / m 3 for standby;

[0061] Add PEG-modified aggregate, cement, silicon-based fiber powder, modified silica, and additive to a mixer and stir for 3 min, add drinking water to the mixer, stir and mix for 8 min, then add the foamed foam to the mixer and stir and disperse for 1 min to obtain a foamed slurry;

[0062] Pour the foamed slurry into several molds respectively, then scrape the slurry on the upper surface of the mold flat and seal the mold, let it stand for 4 h, and demold to obtain the blank of thermal insulation bricks;

[0063] Place the blank of thermal insulation bricks in a curing chamber at 20 °C and 80% humidity for curing for 7 days to obtain thermal insulation bricks. Example 2

[0064] This example provides a preparation method of thermal insulation bricks based on cement mixture, including the following steps:

[0065] S1. Preparation of PEG-modified aggregate

[0066] Weigh: 700 g of PEG-800 and 4000 mL of tetrahydrofuran are added to a reaction kettle protected by nitrogen and stirred. The temperature of the reaction kettle is raised to 45 °C, and 300 g of isocyanatopropyltriethoxysilane is added to the reaction kettle. After holding the reaction for 2.5 h, the temperature of the reaction system is raised to 60 °C, and low-boiling substances are removed under reduced pressure to obtain siloxane-modified PEG;

[0067] Mix river sand, mullite powder, slag powder, and fly ash evenly according to a weight ratio of 16:6.5:6:9 to obtain aggregate for standby;

[0068] Weigh: 500 g of aggregate and 2000 mL of drinking water are added to a stirring kettle and stirred for 40 min. 200 g of siloxane-modified PEG is added to the stirring kettle. The temperature of the stirring kettle is raised to 65 °C, and stirring is continued for 5 h under insulation. After post-treatment, the temperature of the stirring kettle is lowered to room temperature, and filtration is carried out. The filter cake is washed twice with drinking water and then dried by suction. The filter cake is transferred to a drying oven at 65 °C and dried to a constant weight to obtain PEG-modified aggregate.

[0069] S2. Preparation of modified silica

[0070] Mix polyethylene glycol 400 and deionized water evenly according to 2.5 g:100 mL to obtain a dispersion for standby;

[0071] Weigh: 300 g of lauric acid, 200 g of dodecanol, and 2000 mL of absolute ethanol are added to a reaction kettle and stirred until the system is dissolved. 500 g of fumed silica is added to the reaction kettle. At room temperature, stirring and dispersion are carried out for 70 min. 4000 mL of the dispersion is added to the reaction kettle, and stirring is continued for 40 min under insulation. The temperature of the reaction system is lowered to 13 °C, and filtration is carried out. The filter cake is washed three times with deionized water and then dried by suction. The filter cake is air-dried naturally to obtain modified silica.

[0072] S3. Preparation of silicon-based fiber powder

[0073] Mix a 4 wt% sodium hydroxide solution and 20 wt% hydrogen peroxide evenly according to a volume ratio of 5:1 to obtain an activation solution for standby;

[0074] Weigh: 100 g of chopped glass fiber and 550 mL of the activation solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 70 °C, and the reaction is carried out for 2.5 h under insulation. The temperature of the reaction kettle is lowered to room temperature, and filtration is carried out. The filter cake is washed with drinking water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 65 °C and dried under vacuum to a constant weight to obtain activated fiber;

[0075] Weigh: 90 g of activated fiber, 33 g of methyltriethoxysilane, 27 g of tetraethyl orthosilicate, 16 g of 3-glycidoxypropyltriethoxysilane, and 180 mL of absolute ethanol were added to a reaction kettle and stirred. The temperature of the reaction kettle was lowered to 13 °C, and 30 mL of 1.0 mol / L hydrochloric acid solution was added to the reaction kettle. The reaction was carried out under insulation for 4 h. Ammonia water was added to the reaction kettle to adjust the pH of the system to 7. The temperature of the reaction kettle was raised to 65 °C, and the low-boiling substances were removed by vacuum distillation to obtain a wet gel. The wet gel was evenly spread in an oven at 115 °C and dried to a constant weight, then pulverized to obtain silicon-based fiber powder.

[0076] S4. Preparation of foaming liquid

[0077] 2-Acrylamide-2-methylpropanesulfonic acid, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate, ammonium persulfate, and drinking water were added to a reaction kettle in a dosage ratio of 2 g:1.2 g:1 g:0.2 g:40 mL and mixed and stirred. The temperature of the reaction kettle was raised to 75 °C, and the reaction was carried out under insulation for 2.5 h, and then naturally cooled to room temperature to obtain a foaming liquid.

[0078] S5. Preparation of thermal insulation bricks

[0079] The polycarboxylate water reducer, foam stabilizer, air-entraining agent, and early strength agent were mixed evenly according to a weight ratio of 5:3:2:2 to obtain an additive for standby;

[0080] Weigh by weight: 65 parts of PEG-modified aggregate, 23 parts of modified silica, 10 parts of silicon-based fiber powder, 40 parts of cement, 6.5 parts of additive, 35 parts of foaming liquid, and 55 parts of drinking water for standby;

[0081] The foaming liquid was placed in a foaming machine and foamed with carbon dioxide as the gas source to obtain foamed foam with a density of 65 kg / m 3 for standby;

[0082] The PEG-modified aggregate, cement, silicon-based fiber powder, modified silica, and additive were added to a mixer and stirred for 4 min. Drinking water was added to the mixer and stirred and mixed for 9 min. Then the foamed foam was added to the mixer and stirred and dispersed for 1.5 min to obtain a foamed slurry;

[0083] The foamed slurry was poured into several molds respectively. Then the slurry on the upper surface of the mold was scraped flat and the mold was sealed. After standing for 5 h, the mold was removed to obtain a blank of thermal insulation bricks;

[0084] The blank of thermal insulation bricks was placed in a curing chamber at a temperature of 23 °C and a humidity of 85% and cured for 7 days to obtain thermal insulation bricks. Example 3

[0085] This example provides a preparation method of a thermal insulation brick based on a cement mixture, including the following steps:

[0086] S1. Preparation of PEG-modified aggregate

[0087] Weigh: 700 g of PEG-800 and 4000 mL of tetrahydrofuran, add them to a reaction kettle protected by nitrogen and stir. Raise the temperature of the reaction kettle to 50 °C, add 300 g of isocyanatopropyltriethoxysilane to the reaction kettle, keep the temperature for reaction for 3 h, raise the temperature of the reaction system to 60 °C, and reduce the pressure to remove low-boiling substances to obtain siloxane-modified PEG;

[0088] Mix river sand, mullite powder, slag powder, and fly ash evenly according to the weight ratio of 17:7:7:10 to obtain aggregate for standby;

[0089] Weigh: 500 g of aggregate and 2000 mL of drinking water, add them to a stirring kettle and stir for 50 min. Add 200 g of siloxane-modified PEG to the stirring kettle, raise the temperature of the stirring kettle to 70 °C, keep the temperature and stir for 6 h, conduct post-treatment, reduce the temperature of the stirring kettle to room temperature, filter by suction, wash the filter cake with drinking water twice and then drain it by suction. Transfer the filter cake to a drying oven at 70 °C and dry it to constant weight to obtain PEG-modified aggregate.

[0090] S2. Preparation of modified silica

[0091] Mix polyethylene glycol 400 and deionized water evenly according to 3 g:100 mL to obtain a dispersion for standby;

[0092] Weigh: 300 g of lauric acid, 200 g of dodecanol, and 2000 mL of absolute ethanol, add them to a reaction kettle and stir until the system is dissolved. Add 500 g of fumed silica to the reaction kettle, stir and disperse at room temperature for 80 min. Add 4000 mL of the dispersion to the reaction kettle, keep the temperature and stir for 50 min. Reduce the temperature of the reaction system to 15 °C, filter by suction, wash the filter cake with deionized water three times and then drain it by suction. Let the filter cake dry naturally to obtain modified silica.

[0093] S3. Preparation of silicon-based fiber powder

[0094] Mix a 5 wt% sodium hydroxide solution and 20 wt% hydrogen peroxide evenly according to the volume ratio of 5:1 to obtain an activation solution for standby;

[0095] Weigh: 100 g of chopped glass fiber and 600 mL of the activation solution, add them to a reaction kettle and stir. Raise the temperature of the reaction kettle to 80 °C, keep the temperature for reaction for 3 h, reduce the temperature of the reaction kettle to room temperature, filter by suction, wash the filter cake with drinking water until it is neutral and then drain it by suction. Transfer the filter cake to a drying oven at 70 °C and dry it under vacuum to constant weight to obtain activated fiber;

[0096] Weigh: 90 g of activated fiber, 36 g of methyltriethoxysilane, 30 g of tetraethyl orthosilicate, 18 g of 3-glycidoxypropyltriethoxysilane, and 180 mL of absolute ethanol were added to a reaction kettle and stirred. The temperature of the reaction kettle was lowered to 15 °C, 30 mL of 1.2 mol / L hydrochloric acid solution was added to the reaction kettle, and the reaction was carried out under insulation for 5 h. Ammonia water was added to the reaction kettle to adjust the pH of the system to 7. The temperature of the reaction kettle was raised to 70 °C, and the low-boiling substances were removed by reduced pressure distillation to obtain a wet gel. The wet gel was evenly spread in an oven at 120 °C and dried to a constant weight, and then crushed to obtain silicon-based fiber powder.

[0097] S4. Preparation of foaming liquid

[0098] 2-Acrylamido-2-methylpropanesulfonic acid, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate, ammonium persulfate, and drinking water were added to a reaction kettle in a dosage ratio of 2 g:1.2 g:1 g:0.2 g:40 mL and mixed and stirred. The temperature of the reaction kettle was raised to 80 °C, and the reaction was carried out under insulation for 2 h. It was naturally cooled to room temperature to obtain a foaming liquid.

[0099] S5. Preparation of thermal insulation bricks

[0100] The polycarboxylate water reducer, foam stabilizer, air-entraining agent, and early strength agent were mixed evenly according to a weight ratio of 5:3:2:2 to obtain an additive for standby;

[0101] Weigh by weight: 70 parts of PEG-modified aggregate, 25 parts of modified silica, 12 parts of silicon-based fiber powder, 50 parts of cement, 7 parts of additive, 40 parts of foaming liquid, and 60 parts of drinking water for standby;

[0102] The foaming liquid was placed in a foaming machine, and carbon dioxide was used as the gas source for foaming to obtain foamed foam with a density of 70 kg / m 3 for standby;

[0103] The PEG-modified aggregate, cement, silicon-based fiber powder, modified silica, and additive were added to a mixer and stirred for 5 min. Drinking water was added to the mixer, and it was stirred and mixed for 10 min. Then the foamed foam was added to the mixer and stirred and dispersed for 2 min to obtain a foamed slurry;

[0104] The foamed slurry was poured into several molds respectively. Then the slurry on the upper surface of the mold was scraped flat and sealed, and it was left standing for 6 h and then demolded to obtain thermal insulation brick blanks;

[0105] The thermal insulation brick blanks were placed in a curing chamber at a temperature of 26 °C and a humidity of 90% and cured for 7 days to obtain thermal insulation bricks.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 3 is that the aggregate in Step S1 is used to replace the PEG-modified aggregate in Step S5.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 3 is that lauric acid is not added in Step S2.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 3 is that the activated fiber in Step S3 is used to replace the silicon-based fiber powder in Step S5.

[0112] Comparative Example 4

[0113] The difference between this comparative example and Example 3 is that ammonium persulfate is not added in Step S4.

[0114] Performance test:

[0115] Select 5 pieces of insulation brick specimens prepared in Examples 1-3 and Comparative Examples 1-4 as test specimens, and refer to the standard GB / T 29060-2012 "Composite Insulation Bricks and Composite Insulation Blocks" to measure the compressive strength and thermal conductivity of the insulation brick test specimens prepared in Examples 1-3 and Comparative Examples 1-4, and calculate their averages;

[0116] Select 5 pieces of insulation brick specimens prepared in Examples 1-3 and Comparative Examples 1-4 as test specimens, and refer to the standard JC / T 2111-2012 "Test Method for Phase Change Temperature Regulation Performance of Building Materials" to measure the phase change latent heat of the insulation brick test specimens prepared in Examples 1-3 and Comparative Examples 1-4, and calculate their averages. The specific test results are shown in Table 1 below.

[0117] Table 1 - Performance Test Data Table of Specimens

[0118]

[0119] Data analysis:

[0120] By comparing and analyzing the data in Table 1 above, the compressive strength of the insulation brick prepared by the present invention reaches 18.41 MPa, the thermal conductivity is reduced to 0.1896 W / (m·k), and the phase change latent heat reaches 216.51 J / g. All the performance test data are better than those of the comparative examples. The present invention modifies the aggregate with PEG and then mixes it with modified silica, silicon-based fiber powder, and cement to form a cement slurry. Then, through foaming foam for mixing, it promotes the uniform dispersion of the foaming foam in the cement slurry to prepare a foaming slurry. After molding into bricks and curing, it not only effectively improves the heat insulation performance and compressive strength of the insulation brick, but also enables the insulation brick to have good energy storage performance, further improving the heat insulation performance of the insulation brick.

[0121] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific embodiments. Obviously, according to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A heat-insulating brick based on cement mixture, characterized in that, It comprises the following components by weight parts: 60 - 70 parts of PEG - modified aggregate, 20 - 25 parts of modified silica, 8 - 12 parts of silicon - based fiber powder, 30 - 50 parts of cement, 6 - 7 parts of additive, 30 - 40 parts of foaming liquid and 50 - 60 parts of drinking water. Among them, the foaming liquid is composed of 2 - acrylamide - 2 - methylpropanesulfonic acid, N,N’ - methylenebisacrylamide, sodium dodecylbenzenesulfonate, ammonium persulfate and drinking water in a dosage ratio of 2g:1.2g:1g:0.2g:40mL; The preparation method of PEG - modified aggregate is as follows: Mix and stir the aggregate and drinking water, add siloxane - modified PEG to the mixed system, raise the temperature of the reaction system to 60 - 70 °C, keep warm and stir for 4 - 6 h, and conduct post - treatment to obtain PEG - modified aggregate; The preparation method of modified silica is as follows: Mix and stir lauric acid, dodecanol and absolute ethanol until the system is dissolved, add fumed silica to the reaction system, stir and disperse at room temperature for 60 - 80 min, add the dispersion liquid to the reaction system, keep warm and stir for 30 - 50 min, and conduct post - treatment to obtain modified silica; The silicon - based fiber powder is processed through the following steps: A1. Mix and stir chopped glass fiber and activation liquid, raise the temperature of the reaction system to 60 - 80 °C, keep warm and react for 2 - 3 h, and conduct post - treatment to obtain activated fiber. Among them, the dosage ratio of chopped glass fiber to activation liquid is 1g:5 - 6mL, and the activation liquid is composed of 3 - 5wt% sodium hydroxide solution and 20wt% hydrogen peroxide in a volume ratio of 5:1; A2. Stir and mix the activated fiber, methyltriethoxysilane, tetraethyl orthosilicate, 3 - glycidoxypropyltriethoxysilane and absolute ethanol, lower the temperature of the reaction system to 10 - 15 °C, add hydrochloric acid solution to the reaction system, keep warm and react for 3 - 5 h, and conduct post - treatment to obtain silicon - based fiber powder. Among them, the dosage ratio of activated fiber, methyltriethoxysilane, tetraethyl orthosilicate, 3 - glycidoxypropyltriethoxysilane, absolute ethanol and hydrochloric acid solution is 30g:10 - 12g:8 - 10g:4 - 6g:60mL:10mL, and the concentration of the hydrochloric acid solution is 0.8 - 1.2mol / L.

2. The heat-insulating brick based on cement mixture according to claim 1, wherein The aggregate is composed of river sand, mullite powder, slag powder and fly ash in a weight ratio of 15 - 17:6 - 7:5 - 7:8 - 10; The additive is composed of water - reducing agent, foam stabilizer, air - entraining agent and early - strength agent in a weight ratio of 5:3:2:

2.

3. A heat-insulating brick based on cement mixture according to claim 1, characterized in that, The dosage ratio of the aggregate, drinking water and siloxane - modified PEG is 5g:20mL:2g. The post - treatment includes: After the reaction is completed, lower the temperature of the reaction system to room temperature, conduct suction filtration, wash the filter cake with drinking water twice and then drain it, transfer the filter cake to a drying oven at 60 - 70 °C, and dry it to constant weight to obtain PEG - modified aggregate.

4. A heat-insulating brick based on a cement mixture according to claim 1, characterized in that, The preparation method of siloxane - modified PEG is as follows: Under the protection of inert gas, mix and stir PEG and tetrahydrofuran, raise the temperature of the reaction system to 40 - 50 °C, add isocyanatopropyltriethoxysilane to the reaction system, keep warm and react for 2 - 3 h, and conduct post - treatment to obtain siloxane - modified PEG.

5. A heat-insulating brick based on cement mixture according to claim 1, characterized in that, The dosage ratio of the PEG, tetrahydrofuran, and isocyanatopropyltriethoxysilane is 7 g: 40 mL: 3 g. The PEG is PEG-800. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 60 °C, and the low-boiling substances are removed by reduced-pressure evaporation to obtain siloxane-modified PEG.

6. The heat-insulating brick based on cement mixture according to claim 1, wherein The dosage ratio of the lauric acid, dodecanol, absolute ethanol, fumed silica, and dispersion liquid is 3 g: 2 g: 20 mL: 5 g: 40 mL. The dispersion liquid is composed of polyethylene glycol 400 and deionized water in a ratio of 2-3 g: 100 mL. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to 10-15 °C, suction filtration is carried out, the filter cake is washed 3 times with deionized water and then dried by suction, and the filter cake is naturally air-dried to obtain modified silica.

7. The preparation method of a heat-insulating brick based on cement mixture according to any one of claims 1-6, characterized in that, It includes the following steps: S1. Add the foaming liquid into a foaming machine for foaming to prepare foamed foam. S2. Add the PEG-modified aggregate, cement, silicon-based fiber powder, modified silica, and additive into a mixer and stir for 3-5 min. Add drinking water into the mixer, stir and mix for 8-10 min, and then add the foamed foam into the mixer and stir and disperse for 1-2 min to obtain a foamed slurry. S3. Pour the foamed slurry into several molds respectively, then scrape the slurry on the upper surface of the mold flat and seal the mold, leave it standing for 4-6 h, and demold to obtain a blank of the thermal insulation brick. S4. Place the blank of the thermal insulation brick in a curing chamber and cure for 7 days to obtain the thermal insulation brick.

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