A preparation method of aerogel mortar

Abstract

The present invention discloses a preparation method of aerogel mortar, belonging to the field of building materials. Mix recycled fine aggregates of decoration waste, cementitious materials, admixtures and an aqueous solution of water reducer to obtain mortar; stir and modify hydrophobic SiO2 aerogel particles in an aqueous solution of γ-aminopropyltriethoxysilane to obtain hydrophilic SiO2 aerogel particles; disperse the dispersion solution of hydrophilic SiO2 aerogel particles and add it to the mortar and stir until the SiO2 aerogel particles are completely incorporated into the mortar to prepare aerogel mortar. The aerogel mortar of the present invention has excellent thermal insulation performance and is environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the field of building materials, and particularly relates to a preparation method of aerogel mortar. Background Art

[0002] In recent years, with the rapid development of urbanization in China, a large number of buildings and infrastructure have been constructed, which has also accelerated the renovation of urban buildings, resulting in a large amount of decoration waste. Generally, the lower the density of a material, the lower its thermal conductivity, indicating better heat insulation ability. Aerogel, as a material with extremely low density, precisely has this characteristic. By recycling decoration waste to obtain recycled fine aggregate and incorporating different amounts of aerogel into the decoration waste mortar to prepare aerogel mortar, a reasonable solution to reduce the waste of decoration waste is proposed to achieve multiple benefits such as economic energy conservation and environmental protection.

[0003] In existing research, there are mainly three types of mixing processes for preparing aerogel mortar. For example, Gao et al. mentioned in "Aerogel-incorporated concrete: an experimental study" the slurry wrapping method of preparing paste first and then adding aerogel and fine aggregate in sequence; Wang Fei et al. mentioned in "Optimization study on the performance of SiO2 aerogel mortar" the mortar method of preparing mortar first and then incorporating aerogel; and Kim et al. proposed in "Cliemical retreating for gel-typed aerogel and insulation performance of cement containing aerogel" a dispersant method using methanol as a dispersant to modify aerogel.

[0004] In the slurry wrapping method, a large number of aerogel particles are broken in the mortar; in the mortar method, the aerogel particles are not tightly combined with the cement matrix and float to the surface of the mortar; although the aerogel particles after methanol treatment can be tightly combined with the cement matrix and fewer aerogel particles are broken, methanol, as a toxic substance, not only affects the health of users but also causes environmental pollution. Summary of the Invention

[0005] The purpose of the present invention is to disclose a preparation method of aerogel mortar for the problems existing in the prior art. Specifically, the preparation method of the present invention can simultaneously replace the above-mentioned slurry wrapping method, mortar method, and dispersant method using methanol as a dispersant. For the aerogel mortar prepared according to the present invention, the aerogel can be evenly distributed in the mortar, is relatively tightly combined with the mortar, and has good mechanical properties, excellent thermal insulation properties, and durability. When applied to the external wall external insulation project, it can greatly improve the service life of the external wall external insulation material.

[0006] The technical solution of the present invention to achieve the above object is: a preparation method of aerogel mortar, specifically including the following steps:

[0007] S1: Preparation of mortar

[0008] Calculate the components required for the mortar, wet the mixing pan, and add the gelling material, recycled fine aggregate, admixture and polypropylene fiber into the mixing pan according to the required portions, and stir at a speed of 60 ± 5 r / min for 60 - 90 s. After stirring evenly, add the water reducing agent aqueous solution and stir at a speed of 60 - 65 r / min for 90 s to make the mortar.

[0009] The water-binder ratio of the mortar is 0.5 - 0.6.

[0010] Specifically, the gelling material is composed of cement, slag and silica fume.

[0011] Specifically, the admixture is composed of an air-entraining agent, redispersible latex powder and methyl cellulose.

[0012] The recycled fine aggregate is recycled fine aggregate from decoration waste, with an apparent density of 2270 kg / m 3 , a bulk density of 1337 kg / m 3 , and a fineness modulus of 2.80.

[0013] The cement is PO52.5 ordinary Portland cement, with a compressive strength of 48.1 MPa and a flexural strength of 6.9 MPa.

[0014] The slag is S95 granulated blast furnace slag powder, with an apparent density of 2680 kg / m 3 .

[0015] The silica fume is special grade silica fume, with an apparent density of 2200 kg / m 3 .

[0016] The air-entraining agent is a high-efficiency air-entraining agent.

[0017] The redispersible latex powder is redispersible latex powder.

[0018] The methyl cellulose is hydroxypropyl methyl cellulose HPMC.

[0019] The polypropylene fiber is PP-12 polypropylene fiber, and the material is 100% polypropylene.

[0020] The water reducing agent is a polycarboxylate superplasticizer, with a pH value of 6.7.

[0021] S2: Modification of SiO2 aerogel particles

[0022] Add γ-aminopropyltriethoxysilane to water and stir evenly to obtain an aqueous solution of γ-aminopropyltriethoxysilane; calculate the mass of SiO2 aerogel with a substitution amount of 80% of the aggregate volume, add the SiO2 aerogel particles to the aqueous solution of γ-aminopropyltriethoxysilane, and use a cantilever electric stirrer to stir at a speed of 60±5 r / min for 60 - 90 s to make the aerogel evenly distributed in the aqueous solution of γ-aminopropyltriethoxysilane, and carry out the modification of SiO2 aerogel particles. After the modification is completed, filter out the aerogel particles with a 0.075 mm square hole sieve, and obtain γ-aminopropyltriethoxysilane-modified aerogel particles after natural drying.

[0023] The SiO2 aerogel particles are hydrophobic nano-aerogels with a density of 100 kg / m 3 , a specific surface area of 800 - 1000 m 2 / g, and a thermal conductivity of 0.018 W / m·K.

[0024] The mass ratio of the γ-aminopropyltriethoxysilane to water is 1:100.

[0025] The mass ratio of the SiO2 aerogel particles to γ-aminopropyltriethoxysilane is 9 - 10:1.

[0026] S3: Preparation of aerogel mortar

[0027] Add the γ-aminopropyltriethoxysilane-modified aerogel particles to water and stir evenly, add them to the well-stirred mortar in multiple batches, and stir clockwise at a constant speed to make the aerogel completely blend into the mortar. After stirring for about 60 s, pour into the mold and wait for the aerogel mortar to take shape.

[0028] The volume of the γ-aminopropyltriethoxysilane-modified aerogel particles replacing the aggregate is 80%, which is calculated according to the apparent density of the aggregate and the aerogel.

[0029] The aerogel mortar prepared by the method of the present invention all meets the requirements of the standard GB / T 20473 - 2021 "Building Thermal Insulation Mortar", and the thermal conductivity ≤ 0.04 W / (m·K).

[0030] Compared with the prior art, the beneficial effects of the present invention:

[0031] Compared with the slurry wrapping method of preparing neat paste and then adding aerogel and fine aggregate in sequence, the SiO2 aerogel particles in the mortar of the present invention will not be broken in large quantities, and the strength of the prepared mortar is higher than that of the mortar prepared by the slurry wrapping method.

[0032] Compared with the mortar method of adding aerogel after preparing mortar, the SiO2 aerogel particles of the present invention are tightly combined with the cement matrix, and the dispersion uniformity is better than that of the mortar prepared by the mortar method.

[0033] Compared with the dispersant method using methanol as the dispersant to modify aerogel, the present invention uses γ-aminopropyltriethoxysilane as the dispersant, with stronger surface proton movement activity, closer binding to the mortar and more uniform distribution in the mortar. At the same time, compared with methanol, γ-aminopropyltriethoxysilane is non-toxic and will not harm human health and the environment. Detailed implementation mode

[0034] The present invention will be described in detail below. Example 1

[0035] Prepare modified silica aerogel mortar by the dispersant method:

[0036] The water-binder ratio of the mortar is 0.5; the volume fraction of aerogel is 80%;

[0037] Step 1: Take 272.4 parts of recycled fine aggregate from construction waste, 323.5 parts of P·O 52.5 cement, 86.3 parts of slag, 21.6 parts of silica fume, 2.16 parts of latex powder, 0.43 parts of air-entraining agent, 0.86 parts of methyl cellulose and 0.86 parts of polypropylene fiber and place them in a stirring pot. Stir dry at a speed of 62 r / min for 60 s, add an aqueous solution of water reducer prepared from 72.5 parts of water and 4.31 parts of water reducer, and stir at a speed of 62 r / min for 90 s to make mortar;

[0038] Step 2: Add 5 parts of γ-aminopropyltriethoxysilane and 48 parts of SiO2 aerogel to 500 parts of water for modified pretreatment. Stir with a cantilever electric stirrer at a speed of 62 r / min for 60 s. After the modification, use a 0.075 mm square hole sieve to screen out the aerogel particles; after natural drying, obtain SiO2 aerogel particles modified by γ-aminopropyltriethoxysilane for standby;

[0039] Step 3: Add all the aerogel particles to 100 parts of water, and add them to the mortar in Step 1 in multiple times. Stir clockwise at a constant speed by hand to make the SiO2 aerogel particles completely integrate into the mortar. After hand-stirring for about 60 s, mold the aerogel mortar.

[0040] Step 4: After curing for 28 d, test its performance, and the results are listed in Table 1. Example 2

[0041] Prepare modified silica aerogel mortar by the dispersant method:

[0042] The water-binder ratio of the mortar is 0.54, and the volume fraction of aerogel is 80%;

[0043] Step 1: Take 255 parts of recycled fine aggregate from decoration waste, 291.4 parts of P·O 52.5 cement, 78.1 parts of slag, 20.3 parts of silica fume, 1.91 parts of latex powder, 0.78 part of air-entraining agent, 0.76 part of methyl cellulose and 0.77 part of polypropylene fiber and place them in a mixing pan. Stir dry at a speed of 62 r / min for 60 s, then add the water-reducing agent aqueous solution prepared with 106.3 parts of water and 3.89 parts of water-reducing agent, and stir at a speed of 62 r / min for 90 s to make mortar;

[0044] Step 2: Add 5 parts of γ-aminopropyltriethoxysilane and 48 parts of SiO2 aerogel to 500 parts of water for modified pretreatment. Use a cantilever electric stirrer to stir at a speed of 62 r / min for 60 s. After the modification, use a 0.075 mm square-hole sieve to screen out the aerogel particles; after natural drying, obtain the SiO2 aerogel particles modified by γ-aminopropyltriethoxysilane for standby;

[0045] Step 3: Add all the aerogel particles to 100 parts of water, and add them to the mortar in Step 1 in multiple batches. Stir evenly in the clockwise direction by hand to make the SiO2 aerogel particles completely dissolve into the mortar. After hand-stirring for about 60 s, mold the aerogel mortar to make it take shape.

[0046] Step 4: After curing for 28 d, test its performance, and the results are listed in Table 1. Example 3

[0047] Prepare modified silica aerogel mortar by the dispersant method:

[0048] The water-binder ratio of the mortar is 0.59, and the volume admixture of aerogel is 80%;

[0049] Step 1: Take 256.4 parts of recycled fine aggregate from decoration waste, 272.2 parts of P·O 52.5 cement, 73.4 parts of slag, 17.6 parts of silica fume, 1.83 parts of latex powder, 1.07 parts of air-entraining agent, 0.75 part of methyl cellulose and 0.74 part of polypropylene fiber and place them in a mixing pan. Stir dry at a speed of 62 r / min for 60 s, then add the water-reducing agent aqueous solution prepared with 113.5 parts of water and 3.61 parts of water-reducing agent, and stir at a speed of 62 r / min for 90 s to make mortar;

[0050] Step 2: Add 5 parts of γ-aminopropyltriethoxysilane and 48 parts of SiO2 aerogel to 500 parts of water for modified pretreatment. Use a cantilever electric stirrer to stir at a speed of 62 r / min for 60 s. After the modification, use a 0.075 mm square-hole sieve to screen out the aerogel particles; after natural drying, obtain the SiO2 aerogel particles modified by γ-aminopropyltriethoxysilane for standby;

[0051] Step 3: Add all the aerogel particles into 100 parts of water, and add them into the mortar in Step 1 in several times. Stir clockwise at a constant speed by hand until the SiO2 aerogel particles are completely incorporated into the mortar. After stirring by hand for about 60 s, pour it into a mold to form aerogel mortar.

[0052] Step 4: After curing for 28 d, test its performance, and the results are listed in Table 1. Example 4

[0053] Prepare modified silica aerogel mortar by the mortar method:

[0054] The water-binder ratio of the mortar is 0.5; the volume admixture of aerogel is 80%;

[0055] Step 1: Take 272.4 parts of recycled fine aggregates from construction waste, 323.5 parts of P·O 52.5 cement, 86.3 parts of slag, 21.6 parts of silica fume, 2.16 parts of latex powder, 0.43 part of air-entraining agent, 0.86 part of methyl cellulose and 0.86 part of polypropylene fiber and place them in a mixing pan. Stir dry at a speed of 62 r / min for 60 s, add the water-reducing agent aqueous solution prepared from 172.5 parts of water and 4.31 parts of water-reducing agent, and stir at a speed of 62 r / min for 90 s to make mortar;

[0056] Step 2: Add 5 parts of γ-aminopropyltriethoxysilane and 48 parts of SiO2 aerogel into 500 parts of water for modification pretreatment. Stir with a cantilever electric stirrer at a speed of 62 r / min for 60 s. After the modification, use a 0.075 mm square-hole sieve to screen out the aerogel particles; after natural drying, obtain the SiO2 aerogel particles modified by γ-aminopropyltriethoxysilane for standby;

[0057] Step 3: Add all the modified SiO2 aerogel particles into the well-stirred mortar in several times. Stir clockwise at a constant speed by hand until the aerogel is completely incorporated into the mortar. After stirring by hand for about 60 s, pour it into a mold to form.

[0058] Step 4: After curing for 28 d, test its performance, and the results are listed in Table 1. Example 5

[0059] Prepare modified silica aerogel mortar by the slurry-wrapping method:

[0060] The water-binder ratio of the mortar is 0.5; the volume admixture of aerogel is 80%;

[0061] Step 1: Take 323.5 parts of P·O 52.5 cement, 86.3 parts of slag, 21.6 parts of silica fume, 2.16 parts of latex powder, 0.43 parts of air-entraining agent, 0.86 parts of methyl cellulose and 0.86 parts of polypropylene fiber and place them in a mixing pan. Stir dry at a speed of 62 r / min for 60 s, add the water-reducing agent aqueous solution prepared with 172.5 parts of water and 4.31 parts of water-reducing agent, and stir at a speed of 62 r / min for 90 s to make a neat paste.

[0062] Step 2: Add 5 parts of γ-aminopropyltriethoxysilane and 48 parts of SiO2 aerogel to 500 parts of water for modification pretreatment. Use a cantilever electric stirrer to stir at a speed of 62 r / min for 60 s. After the modification, use a 0.075 mm square-hole sieve to screen out the aerogel particles; after natural drying, obtain the SiO2 aerogel particles modified by γ-aminopropyltriethoxysilane for standby.

[0063] Step 3: Add all the modified SiO2 aerogel particles to the well-stirred neat paste in multiple batches, and stir evenly in the clockwise direction by hand to make the aerogel integrate into the neat paste, and stir by hand for about 60 s.

[0064] Step 4: Add 272.4 parts of recycled fine aggregate of construction waste to the neat paste, stir at a speed of 62 r / min for 30 s, and mold to make the aerogel mortar take shape.

[0065] Step 5: After curing for 28 d, test its performance, and the results are listed in Table 1. Comparative Example 1

[0066] Prepare unmodified silica aerogel by the dispersant method:

[0067] The water-binder ratio of the mortar is 0.5; the volume content of aerogel is 80%;

[0068] Step 1: Take 272.4 parts of recycled fine aggregate of construction waste, 323.5 parts of P·O 52.5 cement, 86.3 parts of slag, 21.6 parts of silica fume, 2.16 parts of latex powder, 0.43 parts of air-entraining agent, 0.86 parts of methyl cellulose and 0.86 parts of polypropylene fiber and place them in a mixing pan. Stir dry at a speed of 62 r / min for 60 s, add the water-reducing agent aqueous solution prepared with 72.5 parts of water and 4.31 parts of water-reducing agent, and stir at a speed of 62 r / min for 90 s to make a mortar.

[0069] Step 2: Add 48 parts of SiO2 aerogel to 100 parts of water, and add it to the mortar in multiple batches. Stir evenly in the clockwise direction by hand to make the SiO2 aerogel particles completely integrate into the mortar. After stirring by hand for about 60 s, mold to make the aerogel mortar take shape.

[0070] Step 3: After curing for 28 d, test its performance, and the results are listed in Table 1. Comparative Example 2

[0071] Unmodified silica aerogel was prepared by the mortar method:

[0072] The water-binder ratio of the mortar was 0.5; the volume content of the aerogel was 80%;

[0073] Step 1: Take 272.4 parts of recycled fine aggregate from construction waste, 323.5 parts of P·O 52.5 cement, 86.3 parts of slag, 21.6 parts of silica fume, 2.16 parts of latex powder, 0.43 part of air-entraining agent, 0.86 part of methyl cellulose and 0.86 part of polypropylene fiber and place them in a mixer. Stir dry at a speed of 62 r / min for 60 s, add an aqueous solution of water reducer prepared from 172.5 parts of water and 4.31 parts of water reducer, and stir at a speed of 62 r / min for 90 s to make mortar;

[0074] Step 2: Add 48 parts of SiO2 aerogel particles to the well-stirred mortar in several times, and stir evenly in the clockwise direction by hand to completely integrate the aerogel into the mortar. After stirring by hand for about 60 s, load it into a mold to form.

[0075] Step 3: After curing for 28 d, test its performance, and the results are listed in Table 1. Comparative Example 3

[0076] Unmodified silica aerogel was prepared by the slurry-wrapping method:

[0077] The water-binder ratio of the mortar was 0.5; the volume content of the aerogel was 80%;

[0078] Step 1: Take 323.5 parts of P·O 52.5 cement, 86.3 parts of slag, 21.6 parts of silica fume, 2.16 parts of latex powder, 0.43 part of air-entraining agent, 0.86 part of methyl cellulose and 0.86 part of polypropylene fiber and place them in a mixer. Stir dry at a speed of 62 r / min for 60 s, add an aqueous solution of water reducer prepared from 172.5 parts of water and 4.31 parts of water reducer, and stir at a speed of 62 r / min for 90 s to make neat paste;

[0079] Step 2: Add 48 parts of SiO2 aerogel particles to the well-stirred neat paste in several times, and stir evenly in the clockwise direction by hand to integrate the aerogel into the neat paste. Stir by hand for about 60 s;

[0080] Step 3: Add 272.4 parts of recycled fine aggregate from construction waste to the neat paste, stir at a speed of 62 r / min for 30 s, and load it into a mold to form aerogel mortar.

[0081] Step 4: After curing for 28 d, test its performance, and the results are listed in Table 1.

[0082] According to the requirements of the standard GB / T 20473-2021 "Building Thermal Insulation Mortar", the mechanical properties of the thermal insulation mortar are determined.

[0083] Table 1 Properties of different embodiments

[0084] Group Compressive strength (MPa) Flexural strength (MPa) Tensile bond strength (MPa) Thermal conductivity (W / (m·K)) Example 1 2.37 1.06 0.72 0.031 Example 2 1.82 0.81 0.60 0.033 Example 3 1.75 0.74 0.52 0.034 Example 4 2.12 0.97 0.70 0.038 Example 5 2.08 0.93 0.65 0.039 Comparative example 1 1.87 0.78 0.59 0.091 Comparative example 2 1.85 0.77 0.57 0.093 Comparative example 3 1.83 0.75 0.56 0.107

[0085] According to the requirements of the standard GB / T 20473-2021 "Building Thermal Insulation Mortar", the compressive strength of the mortar ≥ 1.0 MPa, the flexural strength ≥ 0.2 MPa, the tensile bond strength 0.15 MPa, and the thermal conductivity ≤ 0.085 W / (m·K).

[0086] By comparing Examples 1, 2, 3, Comparative Example 1 and the data in Table 1, it can be seen that with different water-cement ratios, the thermal conductivity of the mortar is greatly improved by using the aerogel particles modified with γ-aminopropyltriethoxysilane.

[0087] By comparing Examples 1, 4, 5, Comparative Examples 1, 2, 3 and the data in Table 1, it can be seen that with a certain water-cement ratio, the thermal conductivity of the aerogel mortar prepared by using the aerogel particles modified with γ-aminopropyltriethoxysilane is greatly improved.

[0088] By comparing Examples 1, 4, 5 and the data in Table 1, it can be seen that Example 1 has the best effect. The dispersant method used in Example 1, compared with the mortar method used in Example 4 and the slurry coating method used in Example 5, can make the modified aerogel particles more evenly distributed and have better integrity, so the use effect of the modified aerogel can be more significantly exerted.

[0089] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and improvements made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of aerogel mortar, characterized in that, It includes the following steps: S1: Prepare mortar. The water-binder ratio of the mortar is 0.

5. Wet the mixing pan, add the gelling material, recycled fine aggregate, admixture and polypropylene fiber into the mixing pan, stir evenly at a speed of 55 - 65 r / min, then add the water-reducing agent aqueous solution, and stir at a speed of 60 - 65 r / min to make the mortar. The gelling material is composed of cement, slag and silica fume. The admixture is composed of air-entraining agent, latex powder and methyl cellulose. The recycled fine aggregate is recycled fine aggregate from decoration waste, with an apparent density of 2270 kg / m 3 , a bulk density of 1337 kg / m 3 , and a fineness modulus of 2.80; S2: Prepare modified SiO2 aerogel particles. Add γ-aminopropyltriethoxysilane into water and stir evenly to obtain an aqueous solution of γ-aminopropyltriethoxysilane. Calculate the mass of SiO2 aerogel with a substitution amount of 80% of the aggregate volume. Add the SiO2 aerogel particles into the aqueous solution of γ-aminopropyltriethoxysilane, and stir at a speed of 55-65 r / min to make the distribution uniform for the modification of SiO2 aerogel particles. After the modification is completed, screen out the aerogel particles and naturally dry them to obtain SiO2 aerogel particles modified by γ-aminopropyltriethoxysilane. The mass ratio of γ-aminopropyltriethoxysilane to water is 1:

100. The mass ratio of the SiO2 aerogel particles to γ-aminopropyltriethoxysilane is 9-10:1; S3: Prepare aerogel mortar. Add all the modified SiO2 aerogel particles prepared in step S2 into water and stir evenly. Add them into the mortar prepared in step S1 in batches, and stir clockwise at a uniform speed to make the aerogel completely incorporated into the mortar, and then cast and form.

2. The preparation method of the aerogel mortar according to claim 1, wherein, The SiO2 aerogel particles described in step S2 are hydrophobic nano-aerogels with a density of 100 kg / m 3 , a specific surface area of 800 - 1000 m 2 / g, and a thermal conductivity of 0.018 W / (m·K).