A low thermal conductivity cement-based thermal insulation material and its preparation method

Abstract

The application relates to a low-thermal-conductivity cement-based thermal insulation material and a preparation method thereof, raw material components and mass percentage of the low-thermal-conductivity cement-based thermal insulation material are as follows: cement 40-50%, fly ash 15-25%, low-thermal-conductivity particles 10-20%, foaming agent 4.5-5%, foam stabilizer 0.2-0.5%, water reducing agent 0.3-0.5%, and the balance is water. The low-thermal-conductivity cement-based thermal insulation material is prepared by a pressurized foaming-pressure relief foaming process, pressurized foams and cement slurry are respectively prepared under the same pressurized environment (pressure 0.1-0.6 MPa), the foams and the slurry are uniformly mixed to obtain pressurized foaming slurry, the foaming slurry is freely expanded after pressure relief, and the low-thermal-conductivity cement-based thermal insulation material is obtained after hardening and standard curing for 28 days. The inorganic thermal insulation material provided by the application has the advantages of ultra-low thermal conductivity and low water absorption, and the preparation process is simple, and the building energy-saving demand can be met.

Description

Technical Field

[0001] This invention belongs to the technical field of mortar, concrete or similar building materials resistant to chemical, physical or biological erosion, and relates to a low thermal conductivity cement-based insulation material and its preparation method. Background Technology

[0002] In 2019, carbon emissions from the operation phase of buildings nationwide reached 2.13 billion tons, accounting for 21.6% of the country's total carbon emissions. Therefore, it is urgent to improve the energy efficiency of buildings in my country and reduce energy consumption and carbon emissions during the building operation phase.

[0003] Thermal insulation materials are a crucial material foundation for achieving building energy conservation. While new high-efficiency insulation materials such as aerogel boards and vacuum insulation boards have extremely low thermal conductivity, they suffer from high cost, complex construction, and easy performance degradation. Organic materials such as expanded polystyrene offer good insulation performance, are inexpensive, and easy to install, but they are flammable and struggle to meet Class A non-combustible standards, posing a fire hazard.

[0004] Cement-based insulation materials are building materials prepared by creating pores in cement slurry using physical or chemical foaming techniques. They offer advantages such as low cost and non-combustibility. However, existing cement-based insulation materials often suffer from insufficient gas generation or pore defects. If the foamed slurry sets too quickly during the hardening process, it hinders sufficient gas generation, while setting too slowly can cause air bubbles to burst, resulting in structural defects. Currently, the thermal conductivity of cement-based insulation materials is typically 0.08-0.22 W / m·K, significantly higher than that of organic insulation materials (0.025-0.042 W / m·K), failing to meet the insulation requirements of modern buildings. Therefore, developing new inorganic high-efficiency insulation materials that combine ultra-low thermal conductivity with Class A fire safety, thereby meeting building energy conservation needs while improving building fire safety, is of great significance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a low thermal conductivity cement-based insulation material and its preparation method. The low thermal conductivity cement-based insulation material is prepared by using P.O42.5 cement, fly ash and hollow glass microspheres as raw materials and by using a pressure foaming-decompression foaming process. It has low thermal conductivity and certain compressive strength, and has market application prospects.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0007] A low thermal conductivity cement-based thermal insulation material, the raw material composition and mass percentage of which are as follows: cement 40-50%, fly ash 15-25%, low thermal conductivity particles 10-20%, foaming agent 4.5-5%, foam stabilizer 0.2-0.5%, water-reducing agent 0.3-0.5%, and the balance being water.

[0008] According to the above scheme, the cement is PO 42.5 cement.

[0009] According to the above scheme, the low thermal conductivity particles are hollow glass microspheres with a density of 0.2-0.6 g / mL and a median particle size of 38-120 μm.

[0010] According to the above scheme, the foaming agent is an animal protein foaming agent with a solid content of 35-41% and a foaming ratio of 20-25 times.

[0011] According to the above scheme, the foam stabilizer is a mixture of hygroscopic rubber and sodium α-olefin sulfonate in a mass ratio of 1-4:6.

[0012] According to the above scheme, the water-reducing agent is a high-efficiency polycarboxylate water-reducing agent with a water reduction rate of 25-35%.

[0013] This invention also includes a method for preparing the above-mentioned low thermal conductivity cement-based insulation material, the specific steps of which are as follows:

[0014] 1) Weigh each raw material component according to the formula and set aside;

[0015] 2) Dilute the foaming agent with water to obtain a foaming agent solution, then mix it evenly with the foam stabilizer, put it into a pressure tank, and stir under pressure to obtain fine and uniform pre-made foam.

[0016] 3) Add cement, fly ash, and low thermal conductivity particles into the pressure tank, then add water-reducing agent and the remaining water, and apply the same pressure as in step 2) for pressure mixing and foaming, and mix thoroughly to obtain cement slurry.

[0017] 4) Under pressure, add the cement slurry obtained in step 3) to the pre-made foam obtained in step 2), mix evenly to obtain pressurized foamed slurry, then depressurize, allow the pressurized foamed slurry to expand and harden freely, and then cure naturally to obtain low thermal conductivity cement-based insulation material.

[0018] According to the above scheme, the concentration of the foaming agent solution in step 2) is 5.5-7.5 wt%.

[0019] According to the above scheme, the pressure applied during step 2) of pressurized stirring and foaming is 0.1-0.6MPa, the stirring speed is 500-800rpm, and the stirring time is 90-120s.

[0020] According to the above plan, the natural maintenance time for step 4) is 28-35 days.

[0021] This invention prepares low thermal conductivity cement-based insulation materials through a pressurized foaming-depressurization foaming process. Pre-formed foam and cement slurry are prepared separately under pressurized conditions. Then, uniform and stable pressurized air bubbles are mixed with cement slurry under pressurized conditions to obtain pressurized foamed slurry. During the depressurization process, the air bubbles inside the pressurized foamed slurry expand uniformly, achieving consistency between the solidification and hardening of the foamed slurry and the formation of the pore structure. This solves the problems of insufficient gas generation or pore structure defects in existing cement-based insulation materials during the foaming process.

[0022] The beneficial effects of this invention are as follows: 1. The low thermal conductivity cement-based insulation material provided by this invention has low thermal conductivity (thermal conductivity coefficient 0.029-0.11 W / (m·K)), uniform internal pore size, and low density (102-161 kg / m³). 3 1) High strength (compressive strength 0.9-2.1MPa), low water absorption (<0.21%), excellent comprehensive performance, realizing the ultra-lightweight design of cement-based thermal insulation materials; 2) The preparation process of the method described in this invention is simple, energy consumption is low, and it is easy to realize industrial production. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to embodiments.

[0024] The cement used in this embodiment of the invention is Yangchun brand PO 42.5 cement, with a 28-day compressive strength >

[0025] 42.5 MPa; the fly ash used was purchased from Henan Hengyuan New Material Technology Co., Ltd., and was grade II fly ash; the density of the hollow glass microspheres used was 0.2-0.6 g / mL, and the median particle size was 38-120 μm; the water-reducing agent used was a commercially available polycarboxylate-based water-reducing agent with a water reduction rate of 30%; the animal protein foaming agent used was animal protein foaming agent mother liquor produced by Henan Huatai Building Materials Development Co., Ltd., with a solid content of 35% and a foaming ratio of 25 times.

[0026] Examples 1-9

[0027] The specific steps for preparing low thermal conductivity cement-based insulation materials are as follows:

[0028] 1) Weigh the raw materials according to the raw material composition ratio in Table 1. First, dilute the animal protein foaming agent with water to obtain a foaming agent solution with a concentration of 6wt%. Then, mix it evenly with the foam stabilizer (obtained by compounding warm wheel glue and sodium α-alkenyl sulfonate). After adding it to the pressure tank, control the foaming pressure to 0.1-0.6MPa and stir at 700rpm for 120s to obtain pre-made foam.

[0029] 2) Add cement, fly ash, and hollow glass microspheres to another pressure tank, then add water-reducing agent and the remaining water, and apply the same pressure as in step 1) foaming process. Stir thoroughly to obtain cement slurry, then mix it with pre-made foam under pressure to obtain pressurized foamed slurry. Then open the pressure relief valve of the pressure tank, and the foamed slurry expands freely. After hardening, cure naturally (temperature 20±1℃, humidity>90%) for 28 days to obtain low thermal conductivity cement-based insulation material.

[0030] The raw material composition ratios and foaming pressures of Examples 1-9 are shown in Table 1.

[0031] Table 1

[0032]

[0033]

[0034] The parameters of some raw materials used in Examples 1-9 are shown in Table 2.

[0035] Table 2

[0036]

[0037] Examples 10-12

[0038] Low thermal conductivity cement-based insulation materials were prepared using a method similar to that used in Examples 1-9. The raw material composition ratio and foaming pressure are shown in Table 3 below. The density of the hollow glass microspheres used was 0.4 g / mL, and the median particle size was 50 μm. The mass ratio of the foam stabilizer medium-temperature sizing agent to sodium α-olefin sulfonate was 2:6.

[0039] Table 3

[0040]

[0041]

[0042] The water absorption rate, thermal conductivity, compressive strength and bulk density of the samples obtained in each embodiment were tested, and the test results are shown in Table 4.

[0043] Table 4

[0044]

[0045] As can be seen from the above embodiments, the thermal conductivity of the low thermal conductivity cement-based insulation material provided by the present invention is 0.029-0.11 W / (m·K), which is much lower than that of conventional cement-based insulation materials. This indicates that the cement-based insulation material prepared by the pressurized foaming-depressurization foaming process greatly improves the insulation performance of the material compared with the insulation material prepared by the traditional foaming process. Moreover, the preparation method is simple to operate and easy to implement, meeting the requirements of building energy conservation. In addition, as shown in Examples 10-12, under the same raw material ratio, as the pressure applied in the pressure tank increases, the density and thermal conductivity of the prepared cement-based insulation material decrease.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low thermal conductive cement-based thermal insulation material, characterized in that, The raw material components and mass percentage ratio are as follows: cement 40-50%, fly ash 15-25%, low thermal conductivity particles 10-20%, foaming agent 4.5-5%, foam stabilizer 0.2-0.5%, water reducing agent 0.3-0.5%, and the balance is water; The foam stabilizer is a mixture of warm rubber and sodium alpha-alkenyl sulfonate at a mass ratio of 1-4:6; The preparation method of the low thermal conductivity cement-based thermal insulation material comprises the following steps: 1) weighing each raw material component according to the proportion, and reserving; 2) diluting the foaming agent with water to obtain a foaming agent solution, mixing the foaming agent solution with the foam stabilizer uniformly, and then placing the mixture into a pressure barrel to perform pressure stirring and foaming to obtain fine and uniform prefabricated foam; 3) adding cement, fly ash, and low thermal conductivity particles into the pressure barrel, and then adding a water reducing agent and the remaining water, and applying the same pressure as that in the step 2) to perform stirring and foaming to obtain cement slurry; 4) under the condition of maintaining the pressure, adding the cement slurry obtained in the step 3) into the prefabricated foam obtained in the step 2) to mix uniformly, obtaining a pressure foaming slurry, then releasing the pressure, and then allowing the pressure foaming slurry to expand and harden freely, and then naturally curing to obtain the low thermal conductivity cement-based thermal insulation material.

2. The low thermal conductivity cement-based insulation material according to claim 1, characterized in that The cement is P.O 42.5 cement.

3. The low thermal conductivity cement-based insulation material according to claim 1, characterized in that, The low thermal conductivity particles are hollow glass microbeads, the density of which is 0.2-0.6 g / mL, and the median particle size of which is 38-120 μm.

4. The low thermal conductivity cement-based insulation material of claim 1, wherein The foaming agent is an animal protein foaming agent, the solid content of which is 35-41%, and the foaming multiple of which is 20-25 times.

5. The low thermal conductivity cement-based insulation material of claim 1, wherein The water reducing agent is a high-efficiency polycarboxylic acid water reducing agent, and the water reducing rate of which is 25-35%.

6. A method of producing the low thermal conductive cement-based thermal insulation material according to any one of claims 1 to 5, characterized in that, The specific steps are as follows: 1) weighing each raw material component according to the proportion, and reserving; 2) diluting the foaming agent with water to obtain a foaming agent solution, mixing the foaming agent solution with the foam stabilizer uniformly, and then placing the mixture into a pressure barrel to perform pressure stirring and foaming to obtain fine and uniform prefabricated foam; 3) adding cement, fly ash, and low thermal conductivity particles into the pressure barrel, and then adding a water reducing agent and the remaining water, and applying the same pressure as that in the step 2) to perform stirring and foaming to obtain cement slurry; 4) under the condition of maintaining the pressure, adding the cement slurry obtained in the step 3) into the prefabricated foam obtained in the step 2) to mix uniformly, obtaining a pressure foaming slurry, then releasing the pressure, and then allowing the pressure foaming slurry to expand and harden freely, and then naturally curing to obtain the low thermal conductivity cement-based thermal insulation material.

7. The method for preparing the low thermal conductivity cement-based insulation material according to claim 6, characterized in that, The concentration of the foaming agent solution in the step 2) is 5.5-7.5 wt%.

8. The method of claim 6, wherein the low thermal conductivity cement-based thermal insulation material is prepared by mixing the cement, the filler, the hollow microsphere, the first and second fibers, and the water, and then curing the mixture. The pressure applied in the step 2) is 0.1-0.6 MPa, the stirring speed is 500-800 rpm, and the stirring time is 90-120 s.

9. The method of claim 6, wherein the low thermal conductivity cement-based thermal insulation material is prepared by mixing the cement, the filler, the hollow microsphere, the first and second fibers, and the water, and then curing the mixture. The natural curing time in the step 4) is 28-35 days.

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