Thermal insulation concrete for composite floor and preparation method thereof

Abstract

The application relates to the technical field of building materials, and particularly discloses a kind of thermal insulation concrete for composite floor slab and a preparation method thereof.A kind of thermal insulation concrete for composite floor slab, raw materials include sulphoaluminate cement, metakaolin, silica fume, double modified lightweight aggregate, nano aerogel powder, organic emulsion, montmorillonite / vermiculite nanosheet layer material, admixture and water;Double modified lightweight aggregate is lightweight aggregate treated by inorganic sol coating and organosilicon two steps;Montmorillonite / vermiculite nanosheet layer material is prepared by ion exchange reaction of organoamine modified vermiculite and montmorillonite;Organic emulsion includes acrylate emulsion and silicone-acrylate emulsion.The thermal insulation concrete of the application has the advantages of strong stability of thermal insulation performance, and can meet the long-term requirements of thermal insulation performance of composite floor slab in complex environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, more particularly, it relates to a kind of thermal insulation concrete for composite floor and a preparation method thereof. BACKGROUND

[0002] Composite floor, as a new type of floor system integrating structure bearing and function, is often applied to multi-story buildings, large-span workshops and other scenarios. It is usually composed of structural layer, insulation layer and surface layer, and thermal insulation concrete, as the core material of the insulation layer of composite floor, directly determines the energy-saving performance and comfort level of the floor. By combining thermal insulation concrete with reinforced concrete structural layer, composite floor can not only block heat transfer and reduce building heating and cooling energy consumption by using the low thermal conductivity of thermal insulation concrete, but also ensure the mechanical bearing capacity of the floor by the structural layer, realizing the integration of "structure-insulation". With the improvement of building energy-saving standards, the performance requirements of thermal insulation concrete for composite floor are becoming more and more strict. It not only needs to meet the basic insulation indicators, but also needs to work with the structural layer, adapt to the needs of construction technology and long-term use environment.

[0003] In the prior art, the components of thermal insulation concrete usually include cementitious materials, lightweight aggregates, admixtures and water. Cementitious materials are usually cement, supplemented by industrial waste such as fly ash and slag as admixtures to reduce hydration heat and improve workability; lightweight aggregate is the key to achieve thermal insulation function, common ones are expanded perlite, aerated concrete block, ceramsite, vitrified microbeads, polystyrene foam particles, etc. Their porous or lightweight characteristics can significantly reduce the apparent density of concrete; admixtures include water reducing agent, air entraining agent, water retaining agent, etc., which are used to adjust the fluidity, water retention and strength development of concrete; some formulations also add fibers (such as polypropylene fiber, glass fiber) to improve the crack resistance.

[0004] However, the existing thermal concrete has significant defects in practical application due to the water absorption characteristics of lightweight aggregates. Lightweight aggregates such as expanded perlite and aerated concrete blocks have a large number of open pores or through pores. The capillary action of the pore structure will actively adsorb moisture in the environment, including water vapor in the air and condensate water generated during the use of the composite floor, which directly leads to an increase in the water content of the aggregate with the increase in environmental humidity. When the water gradually fills the pores of the aggregate, it will replace the original air medium, forming a "shortcut" for heat transfer in the concrete, thereby significantly reducing its thermal insulation performance. More importantly, the composite floor made of such thermal concrete is at the interface between indoor and outdoor temperatures. When the temperature difference on both sides of the floor exceeds the dew point temperature, condensation is likely to occur in the thermal insulation layer, especially during winter heating or summer air conditioning operation. The condensate water generated cannot be discharged in time and will continue to be absorbed by the lightweight aggregate, forming a vicious cycle of "moisture absorption-thermal conductivity increase". Over time, the thermal insulation performance of the composite floor will be significantly degraded, seriously affecting the energy-saving effect and use comfort of the building. Therefore, the existing thermal concrete has the problems of strong sensitivity of thermal insulation performance to environmental humidity and poor long-term stability, which is difficult to meet the long-term requirements of the thermal insulation performance of the composite floor in complex environments. SUMMARY

[0005] In order to enhance the stability of the thermal insulation performance of the thermal concrete and meet the long-term requirements of the thermal insulation performance of the composite floor in complex environments, the present application provides a thermal concrete for composite floor and a preparation method thereof.

[0006] The thermal concrete for composite floor provided by the present application adopts the following technical scheme:

[0007] A thermal concrete for composite floor is prepared from the following raw materials by weight:

[0008] 200-300 parts of sulphoaluminate cement, 60-120 parts of metakaolin, 30-60 parts of silica fume, 220-380 parts of double-modified lightweight aggregate, 5-15 parts of nano-aerogel powder, 15-30 parts of organic emulsion, 5-10 parts of montmorillonite / vermiculite nanosheet layer material, 10-25 parts of admixture, and 150-200 parts of water;

[0009] The double-modified lightweight aggregate is a lightweight aggregate treated by two steps of inorganic sol coating and organic silane;

[0010] The montmorillonite / vermiculite nanosheet layer material is prepared by ion exchange reaction of organoamine-modified vermiculite and montmorillonite;

[0011] The organic emulsion includes acrylate emulsion and silicone-acrylate emulsion.

[0012] By adopting the technical scheme, the light aggregate coated by the inorganic sol and grafted by the fluorine-containing silane fills the through pores inside the aggregate with the silicon sol and the aluminum sol to form a dense SiO2-Al2O3 layer to block the capillary water absorption channel; after the grafting of the fluorine-containing silane, the water contact angle of the surface of the light aggregate is increased, and the ability of the surface to absorb water is reduced. After the double modification, the water absorption rate of the aggregate is greatly reduced, and the moisture intake is reduced from the source. The layered structure of the montmorillonite / vermiculite nanosheet layer material is staggered to form a "labyrinth" barrier, and the water migration path is extended by 3-5 times, thereby effectively enhancing the impermeability of the concrete and reducing the amount of water reaching the aggregate; the long-chain alkyl groups grafted on the surface of the montmorillonite / vermiculite nanosheet layer material form a hydrophobic layer, reduce the water adsorption and capillary permeation driving force, and avoid the rapid rise of the thermal conductivity caused by water replacing air; the montmorillonite / vermiculite nanosheet layer material and the organic emulsion form an interpenetrating network through "electrostatic attraction + chemical crosslinking", the nanosheet fills the defects of the emulsion film, the emulsion covers the gap between the nanosheets, improves the durability of the water-blocking system, and at the same time inhibits microcracks and avoids secondary water absorption channels. The nano-aerogel powder can strengthen the thermal insulation performance due to its nano-porous structure, and the hydrophobic property avoids the increase of the thermal conductivity caused by water absorption. In cooperation with the closed pores of the modified aggregate, the thermal conductivity of the concrete in a dry state is effectively reduced, and the thermal conductivity can be kept stable in a high-humidity environment, solving the vicious cycle of "moisture absorption-thermal conductivity increase". Therefore, through the cooperation of various raw materials described above, the stability of the thermal conductivity of the thermal insulation concrete in a high-humidity environment can be ensured, and the stability of the thermal insulation performance of the concrete is significantly improved.

[0013] Optionally, the double-modified light aggregate is prepared by the following method:

[0014] A1, immersing the light aggregate in a mixed solution of silicon sol and aluminum sol, taking out after 30-60 min of immersion, and drying at 120-150 DEG C to obtain a coated light aggregate;

[0015] A2, mixing the coated light aggregate with an ethanol solution of fluorine-containing silane, stirring at 50-70 DEG C for 60-90 min, and drying after taking out to obtain a double-modified light aggregate.

[0016] By adopting the technical scheme, the lightweight aggregate is immersed in the mixed solution of silica sol and alumina sol, and the sol is fully penetrated into the surface and shallow micropores of the aggregate for 30-60 min, and a SiO2-Al2O3 composite coating layer is formed after drying. The coating layer has inorganic rigid structure and high chemical stability, can physically seal the through pores of the lightweight aggregate, and avoids the problem that the simple organic modification is easily damaged by the alkaline environment of cement. After the coated aggregate is reacted with the fluorine-containing silane ethanol solution, the silane molecules are combined with the hydroxyl groups on the surface of the coating layer through Si-O bonds, and the low surface energy groups such as -CF3 are introduced after grafting, so that the water contact angle of the aggregate surface is effectively improved, and the surface adsorbed water is reduced. Through the two-step treatment, the lightweight aggregate is both "non-water absorbing" and "non-water sticking". This lays a foundation for reducing the humidity sensitivity and improving the thermal stability of concrete.

[0017] Optionally, in A1, the mass ratio of the silica sol to the alumina sol is (3-3.5):1.

[0018] By adopting the technical scheme, the inorganic sol of the above-mentioned ratio has better coating layer integrity for the lightweight aggregate than the silica sol alone or the alumina sol in a high proportion, can effectively block the water absorption channels in the aggregate, and ensure the low water absorption of the modified aggregate during long-term use.

[0019] Optionally, in A2, the mass concentration of the fluorine-containing silane in the ethanol solution containing the fluorine-containing silane is 3%-5%, and the solid-liquid ratio of the coated lightweight aggregate to the ethanol solution containing the fluorine-containing silane is 1:(5-7).

[0020] By adopting the technical scheme, the above-mentioned parameters cooperate to stabilize the hydrophobic performance of the modified aggregate, and after long-term use in a high-humidity environment, the surface hydrophobic layer can still maintain good integrity, avoiding water absorption rebound caused by defects in the hydrophobic layer.

[0021] Optionally, the lightweight aggregate is any one of expanded perlite and vitrified microbeads.

[0022] Optionally, the montmorillonite / vermiculite nanosheet layer material is prepared by the following method:

[0023] B1, dispersing vermiculite nanosheets in deionized water to obtain a vermiculite suspension, adding an organic amine solution to the vermiculite suspension, stirring and reacting at a temperature of 50-60℃ for 3-4h, and then filtering, washing and drying to obtain an organic amine modified vermiculite;

[0024] B2, the organic amine modified vermiculite is dispersed in deionized water, ultrasonic dispersion is carried out for 20-30 min, then hydrochloric acid is added to adjust the pH to 3.0-3.5, then the montmorillonite is added, stirring is carried out at 50-55℃ for 2-3 h, then cetyltrimethylammonium bromide is added, and stirring is continued at 50-55℃ for 3-5 h, and then centrifugal separation, washing and drying are carried out to obtain the montmorillonite / vermiculite nanosheet layer material.

[0025] Optionally, in B1, the mass ratio of the vermiculite nanosheet to deionized water is 1:(20-30); and the organic amine solution is a dodecylamine ethanol solution with a mass concentration of 3%-8%.

[0026] By using the above technical solution, the dodecylamine ethanol solution reacts with the vermiculite nanosheet, the long-chain alkyl of dodecylamine is grafted on the surface of the vermiculite, the hydrophobicity is preliminarily improved, and active sites are provided for subsequent compounding with the montmorillonite. The protonation (pH 3.0-3.5) makes the amine group on the surface of the vermiculite positively charged, enhances the electrostatic attraction with the montmorillonite, and promotes the combination of the layers; after the addition of cetyltrimethylammonium bromide, the quaternary ammonium salt is inserted between the layers of the montmorillonite and the vermiculite, the interlayer distance is expanded, the dispersion of the layers is improved, the quaternary ammonium salt is fully inserted, and the agglomeration of the layers is avoided.

[0027] The composite layers prepared in this step are uniformly dispersed in the concrete, have good compatibility with the organic emulsion, the staggered intercalation structure can effectively prolong the water migration path and effectively enhance the stability of the water-blocking network, thereby being conducive to improving the thermal insulation stability of the thermal insulation concrete in a high-humidity environment.

[0028] Optionally, in B2, the mass ratio of the organic amine modified vermiculite to deionized water is 1:(15-20); the addition amount of the montmorillonite is 30%-50% of the mass of the organic amine modified vermiculite; and the addition amount of the cetyltrimethylammonium bromide is 10%-15% of the mass of the organic amine modified vermiculite.

[0029] Optionally, the organic emulsion comprises 60%-70% of an acrylate emulsion and 30%-40% of a silicone-acrylate emulsion.

[0030] By using the above technical solution, the emulsion film layer has high flexibility and high hydrophobicity under the above-mentioned ratio, the organic silicon segment of the silicone-acrylate emulsion can react with the hydroxyl group of the concrete matrix, the adhesion strength of the film layer and the matrix is effectively improved, and the film layer is prevented from peeling off. The compatibility of the above-mentioned compound emulsion and the montmorillonite / vermiculite layer is good, the water-blocking network constructed by the compound emulsion and the montmorillonite / vermiculite layer has good stability, and the thermal insulation performance of the concrete is effectively maintained.

[0031] The application also provides a preparation method of the thermal insulation concrete for the composite floor slab, and the following technical solution is adopted:

[0032] The application discloses a preparation method of thermal insulation concrete for composite floor slabs, and comprises the following steps:

[0033] S1, uniformly mixing sulphoaluminate cement, metakaolin, silica fume, montmorillonite / vermiculite nanosheet layer material and nano aerogel powder to obtain dry materials;

[0034] S2, adding double modified lightweight aggregates, organic emulsion, admixtures and water into the dry materials, and stirring for 2-4 minutes to obtain the thermal insulation concrete.

[0035] By adopting the technical scheme, the preparation method avoids the problems of aggregate agglomeration and uneven emulsion distribution caused by traditional one-time feeding, makes the performance of the concrete uniform in each region, stabilizes the thermal conductivity, ensures the synergistic effect of the water-blocking network and the thermal insulation system, and meets the long-term thermal insulation requirement of the composite floor slabs.

[0036] In summary, the application has the following beneficial effects:

[0037] 1. The thermal insulation concrete breaks the traditional water absorption characteristics of the double modified lightweight aggregates, the inorganic sol is used to coat and seal the through pores in the aggregates, and the water is prevented from penetrating into the aggregates through capillary action; the organic silane is used to graft and improve the hydrophobicity of the aggregate surface, and the water adsorption is reduced. Meanwhile, the interpenetrating network formed by the montmorillonite / vermiculite nanosheet layer and the organic emulsion prolongs the water migration path through the layered structure, and reduces the penetration power by using the hydrophobic property. The double modification and the water-blocking network synergistically act on the water absorption and hinder the water transmission from the source, break the vicious cycle of the traditional thermal insulation concrete that the thermal conductivity increases rapidly after absorbing moisture, and make the thermal insulation performance of the concrete stable in a high-humidity environment.

[0038] 2. In the application, the montmorillonite / vermiculite nanosheet layer and the organic emulsion are preferably combined by chemical crosslinking and electrostatic attraction, the nanosheet layer fills the defects of the emulsion film, the emulsion covers the gap between the nanosheet layers, and a water-blocking barrier without dead angle is formed, so that the single material failure problem is avoided. The system can resist the stress caused by the drying shrinkage and temperature change of the concrete, reduce the crack generation, and prevent secondary water absorption. Meanwhile, the nano aerogel has the hydrophobic property and porous structure, and can strengthen the thermal insulation effect without water absorption deterioration with humidity change. The multiple protections make the thermal insulation concrete maintain stable low thermal conductivity even in the environment with large indoor and outdoor temperature difference and easy condensation during long-term use, and further ensure the stability of the thermal insulation performance of the concrete.

[0039] 3、The application can ensure low thermal conductivity through the synergistic effect of cementitious materials and modified aggregates, and can improve the strength of concrete through fast-hardening cement and mineral admixtures to meet the structural bearing requirements of composite floors. The addition of montmorillonite / vermiculite nanosheets not only enhances the water resistance, but also inhibits microcracks and improves the crack resistance of concrete. The flexibility of organic emulsion makes the system adapt to deformation during construction and use, avoiding membrane shedding. The overall formulation not only has excellent thermal stability, but also meets the construction operability and structural safety, and can be directly applied to composite floors in multi-story buildings, large-span workshops and other scenes to realize the integration of "thermal insulation-structure". DETAILED DESCRIPTION

[0040] The application will be further described in detail below in conjunction with examples.

[0041] Preparation example of double-modified lightweight aggregate

[0042] Preparation example 1

[0043] The double-modified lightweight aggregate is prepared by the following method:

[0044] A1, immerse 100 kg of expanded perlite particles with an average particle size of 5 mm in a mixed solution of silica sol and aluminum sol, the mixed solution includes 300 kg of silica sol with a solid content of 45% and 100 kg of aluminum sol with a solid content of 25%, take out after 30 min of immersion, and dry at 120°C to obtain coated lightweight aggregate;

[0045] A2, mix 100 kg of coated lightweight aggregate with 500 kg of ethanol solution of fluorine-containing silane with a mass concentration of 3%, stir and react at 50°C for 60 min, take out and dry to obtain double-modified lightweight aggregate.

[0046] Preparation example 2

[0047] The double-modified lightweight aggregate is prepared by the following method:

[0048] A1, immerse 100 kg of expanded perlite particles with an average particle size of 5 mm in a mixed solution of silica sol and aluminum sol, the mixed solution includes 320 kg of silica sol with a solid content of 43% and 100 kg of aluminum sol with a solid content of 22%, take out after 45 min of immersion, and dry at 135°C to obtain coated lightweight aggregate;

[0049] A2, mix 100 kg of coated lightweight aggregate with 600 kg of ethanol solution of fluorine-containing silane with a mass concentration of 4%, stir and react at 60°C for 70 min, take out and dry to obtain double-modified lightweight aggregate.

[0050] Preparation example 3

[0051] A double modified lightweight aggregate is prepared by the following method:

[0052] A1, 100 kg of vitrified microbeads with an average particle size of 5 mm are immersed in a mixed solution of silica sol and alumina sol, the mixed solution includes 350 kg of silica sol with a solid content of 40% and 100 kg of alumina sol with a solid content of 20%, after 60 min of immersion, the coated lightweight aggregate is taken out and dried at 150°C to obtain the coated lightweight aggregate;

[0053] A2, 100 kg of the coated lightweight aggregate is mixed with 700 kg of an ethanol solution of fluorine-containing silane with a mass concentration of 5%, stirred and reacted at 70°C for 90 min, and then dried to obtain the double modified lightweight aggregate.

[0054] Preparation Example 4

[0055] A modified lightweight aggregate is prepared by the following method:

[0056] 100 kg of expanded perlite particles with an average particle size of 5 mm are mixed with 5 kg of KH-131 type silane coupling agent, stirred at 0°C for 60 min, and then dried to obtain the modified lightweight aggregate.

[0057] Preparation Example of Montmorillonite / Vermiculite Nanosheet Layer Material

[0058] Preparation Example 5

[0059] A montmorillonite / vermiculite nanosheet layer material is prepared by the following method:

[0060] B1, 10 kg of vermiculite nanosheets are dispersed in 200 kg of deionized water to obtain a vermiculite suspension, 55 kg of a dodecylamine ethanol solution with a mass concentration of 3% is added to the vermiculite suspension, stirred and reacted at 50°C for 3 h, and then filtered, washed and dried to obtain an organic amine modified vermiculite;

[0061] B2, 10 kg of the organic amine modified vermiculite is dispersed in 150 kg of deionized water, ultrasonically dispersed for 20 min, then hydrochloric acid is added to adjust the pH to 3.0, then 3 kg of montmorillonite is added, stirred and reacted at 50°C for 2 h, then 1 kg of cetyltrimethylammonium bromide is added, and the stirring and reaction at 50°C is continued for 3 h, after the reaction is completed, centrifugal separation, washing and drying are carried out to obtain the montmorillonite / vermiculite nanosheet layer material.

[0062] Preparation Example 6

[0063] A montmorillonite / vermiculite nanosheet layer material is prepared by the following method:

[0064] B1, 10 kg of vermiculite nanosheets were dispersed in 250 kg of deionized water to obtain a vermiculite suspension, 53 kg of a dodecylamine ethanol solution with a mass concentration of 5% was added to the vermiculite suspension, stirring reaction was carried out at 55°C for 3.5 h, and then filtration, washing and drying were carried out to obtain organic amine modified vermiculite;

[0065] B2, 10 kg of organic amine modified vermiculite was dispersed in 180 kg of deionized water, ultrasonic dispersion was carried out for 25 min, then hydrochloric acid was added to adjust the pH to 3.5, then 4 kg of montmorillonite was added, stirring reaction was carried out at 52°C for 2.5 h, then 1.2 kg of cetyltrimethylammonium bromide was added, and stirring reaction was continued at 52°C for 4 h, and then centrifugal separation, washing and drying were carried out to obtain a montmorillonite / vermiculite nanosheet layer material.

[0066] Preparation Example 7

[0067] The montmorillonite / vermiculite nanosheet layer material was prepared by the following method:

[0068] B1, 10 kg of vermiculite nanosheets were dispersed in 300 kg of deionized water to obtain a vermiculite suspension, 50 kg of a dodecylamine ethanol solution with a mass concentration of 8% was added to the vermiculite suspension, stirring reaction was carried out at 60°C for 4 h, and then filtration, washing and drying were carried out to obtain organic amine modified vermiculite;

[0069] B2, 10 kg of organic amine modified vermiculite was dispersed in 200 kg of deionized water, ultrasonic dispersion was carried out for 30 min, then hydrochloric acid was added to adjust the pH to 3.5, then 5 kg of montmorillonite was added, stirring reaction was carried out at 55°C for 3 h, then 1.5 kg of cetyltrimethylammonium bromide was added, and stirring reaction was continued at 55°C for 5 h, and then centrifugal separation, washing and drying were carried out to obtain a montmorillonite / vermiculite nanosheet layer material.

[0070] Preparation Example 8

[0071] The montmorillonite / vermiculite nanosheet layer material was prepared by the following method:

[0072] B1, 10 kg of vermiculite nanosheets were dispersed in 200 kg of deionized water to obtain a vermiculite suspension, 55 kg of a dodecylamine ethanol solution with a mass concentration of 3% was added to the vermiculite suspension, stirring reaction was carried out at 50°C for 3 h, and then filtration, washing and drying were carried out to obtain organic amine modified vermiculite;

[0073] B2, 10 kg of organic amine modified vermiculite was dispersed in 150 kg of deionized water, ultrasonic dispersion was carried out for 20 min, then hydrochloric acid was added to adjust the pH to 3.0, then 3 kg of montmorillonite was added, stirring reaction was carried out at 50°C for 2 h, and then centrifugal separation, washing and drying were carried out to obtain a montmorillonite / vermiculite nanosheet layer material.

[0074] Embodiment

[0075] Embodiment 1

[0076] A thermal insulation concrete for composite floor slab, raw material components and amounts are shown in Table 1, wherein the double modified lightweight aggregate is selected from the double modified lightweight aggregate of Preparation Example 1; the nano aerogel powder is a silicon dioxide nano aerogel powder; the organic emulsion is a ratio of 60% of acrylate emulsion and 40% of silicone-acrylate emulsion; the montmorillonite / vermiculite nanosheet layer material is the montmorillonite / vermiculite nanosheet layer material of Preparation Example 5, and the admixture is a 1:1 ratio of polycarboxylic acid water reducer and sodium methyl silicate.

[0077] A thermal insulation concrete for composite floor slab is prepared by the following method:

[0078] S1, uniformly mix the sulphoaluminate cement, metakaolin, silica fume, montmorillonite / vermiculite nanosheet layer material and nano aerogel powder to obtain dry materials;

[0079] S2, add double modified lightweight aggregate, organic emulsion, admixture and water to the dry materials, and stir for 2 min to obtain the thermal insulation concrete.

[0080] Embodiment 2

[0081] A thermal insulation concrete for composite floor slab, raw material components and amounts are shown in Table 1, wherein the double modified lightweight aggregate is selected from the double modified lightweight aggregate of Preparation Example 1; the nano aerogel powder is a silicon dioxide nano aerogel powder; the organic emulsion is a ratio of 60% of acrylate emulsion and 40% of silicone-acrylate emulsion; the montmorillonite / vermiculite nanosheet layer material is the montmorillonite / vermiculite nanosheet layer material of Preparation Example 5, and the admixture is a 1:1 ratio of polycarboxylic acid water reducer and sodium methyl silicate.

[0082] A thermal insulation concrete for composite floor slab is prepared by the following method:

[0083] S1, uniformly mix the sulphoaluminate cement, metakaolin, silica fume, montmorillonite / vermiculite nanosheet layer material and nano aerogel powder to obtain dry materials;

[0084] S2, add double modified lightweight aggregate, organic emulsion, admixture and water to the dry materials, and stir for 2 min to obtain the thermal insulation concrete.

[0085] Embodiment 3

[0086] A thermal insulation concrete for composite floor slab, raw material components and amounts are shown in Table 1, wherein the double modified lightweight aggregate is selected from the double modified lightweight aggregate of Preparation Example 1; the nano aerogel powder is a silicon dioxide nano aerogel powder; the organic emulsion is a mixture of 70% of acrylate emulsion and 30% of silicone-acrylate emulsion; the montmorillonite / vermiculite nanosheet layer material is the montmorillonite / vermiculite nanosheet layer material of Preparation Example 7, and the admixture is a mixture of polycarboxylic acid water reducer and sodium methyl silicate at a ratio of 1:1.

[0087] A thermal insulation concrete for composite floor slab is prepared by the following method:

[0088] S1, uniformly mix the sulphoaluminate cement, metakaolin, silica fume, montmorillonite / vermiculite nanosheet layer material and nano aerogel powder to obtain dry materials;

[0089] S2, add double modified lightweight aggregate, organic emulsion, admixture and water to the dry materials, and stir for 4 minutes to obtain the thermal insulation concrete.

[0090] Table 1 Raw material components and amounts (kg) of the thermal insulation concrete in Examples 1-3

[0091]

[0092] Example 4

[0093] A thermal insulation concrete for composite floor slab, which is different from Example 1 in that the double modified lightweight aggregate in the raw materials of the present example is selected from the double modified lightweight aggregate of Preparation Example 2.

[0094] Example 5

[0095] A thermal insulation concrete for composite floor slab, which is different from Example 1 in that the double modified lightweight aggregate in the raw materials of the present example is selected from the double modified lightweight aggregate of Preparation Example 3.

[0096] Example 6

[0097] A thermal insulation concrete for composite floor slab, which is different from Example 1 in that the montmorillonite / vermiculite nanosheet layer material in the raw materials of the present example is selected from the montmorillonite / vermiculite nanosheet layer material of Preparation Example 8.

[0098] Comparative Example

[0099] Comparative Example 1

[0100] A thermal insulation concrete for composite floor slab, which is different from Example 1 in that an equal amount of expanded perlite particles is used in the present comparative example instead of the double modified lightweight aggregate in Example 1.

[0101] Comparative Example 2

[0102] A kind of thermal insulation concrete for composite floor slab, the difference with example 1 is that, in the raw materials of this comparative example, equal amount of modified lightweight aggregate of preparation example 4 is selected instead of double modified lightweight aggregate.

[0103] Comparative example 3

[0104] A kind of thermal insulation concrete for composite floor slab, the difference with example 1 is that, in the raw materials of this comparative example, no montmorillonite / vermiculite nanosheet layer material is added, and the difference is made up by sulphoaluminate cement.

[0105] Comparative example 4

[0106] A kind of thermal insulation concrete for composite floor slab, the difference with example 1 is that, in the raw materials of this comparative example, no organic emulsion is added, and the difference is made up by water.

[0107] Performance detection test

[0108] The thermal insulation concrete slurries of example 1-6 and comparative example 1-4 are poured into 300mm×300mm×50mm cuboid test blocks, all test blocks are demolded after curing for 24h under the condition of temperature 20±2℃, relative humidity ≥90%, and continue to be standard cured to 28d age, to obtain test blocks to be tested.

[0109] Then take 28d age test blocks, place them in an environment of (23±2)℃, relative humidity 50% for 7d, so that the test blocks reach a constant weight state, and the thermal conductivity of the test blocks is determined by referring to "GB / T10294-2008 Determination of Steady-state Thermal Resistance and Related Properties of Thermal Insulation Materials by Guarded Hot Plate Method"; then take another batch of 28d age test blocks, place them in a constant temperature and humidity box, set the temperature to (23±2)℃ and the relative humidity to 90%, and continuously place them for 3 months, then take out the test blocks, and determine the thermal conductivity, the results are shown in Table 2.

[0110] Table 2 detection results

[0111]

[0112] As shown in Table 2, the thermal conductivities of examples 1-6 are 0.032-0.038 W / (m·K) at a relative humidity of 50%, and increase to 0.035-0.042 W / (m·K) at a relative humidity of 90%, with an increase of only 8.33%-15.15%, which is significantly lower than that of the comparative examples, showing excellent thermal insulation stability. Among them, the thermal conductivity of example 6 increases by 15.15% compared with examples 1-5 in a high humidity environment, because the montmorillonite / vermiculite nanosheet layer material used in example 6 is not further treated with quaternary ammonium salt in the preparation process, which finally leads to the loss of the thermal insulation performance of the concrete in a high humidity environment to be enhanced.

[0113] The unmodified lightweight aggregate is used in Comparative Example 1, and the unmodified expanded perlite has a large number of through pores and strong capillary action, and a large amount of water is absorbed under high humidity, forming a "shortcut" for heat transfer, resulting in an increase in the thermal conductivity from 0.034 to 0.052 W / (m·K), an increase of 52.94%, directly reflecting the key influence of water absorption of lightweight aggregate on thermal insulation performance.

[0114] In Comparative Example 2, a single organosilane modified aggregate is used, which is only treated with organosilane, lacks a dense layer of SiO2-Al2O3, and the through pores in the aggregate are not closed, and the organosilane is easy to fail in the alkaline environment of cement, resulting in a large amount of water absorption under high humidity, an increase of 43.75%, which illustrates the necessity of two-step modification of lightweight aggregate.

[0115] In Comparative Example 3, no montmorillonite / vermiculite nanosheet material is added, and the water barrier is missing, the water migration path is shortened, and it is easier for water to reach the aggregate and be absorbed, resulting in an increase in thermal conductivity of 31.58%, which illustrates the key role of nanosheet material in extending the water migration path and reducing water absorption of the aggregate.

[0116] In Comparative Example 4, no organic emulsion is added, and the interpenetrating network of organic emulsion and nanosheet in the thermal insulation concrete is missing, the gap between the sheets and the emulsion film defects cannot be filled, and secondary water absorption channels are easy to form, and microcracks are difficult to inhibit, resulting in an increase in water absorption under high humidity, an increase of 37.84%, which illustrates the importance of organic emulsion to the durability of the water barrier system.

[0117] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An insulating concrete for composite floor, characterized by, The raw material is made of the following weight components: sulfoaluminate cement 200-300 parts, metakaolin 60-120 parts, silica fume 30-60 parts, double modified lightweight aggregate 220-380 parts, nano aerogel powder 5-15 parts, organic emulsion 15-30 parts, montmorillonite / vermiculite nanosheet material 5-10 parts, additive 10-25 parts and water 150-200 parts; the double modified lightweight aggregate is a lightweight aggregate treated by two steps of inorganic sol coating and organic silane; the montmorillonite / vermiculite nanosheet material is prepared by the following method: B1, disperse vermiculite nanosheets in deionized water to obtain a vermiculite suspension, add an organic amine solution to the vermiculite suspension, stir and react at a temperature of 50-60℃ for 3-4h, then filter, wash and dry to obtain organic amine modified vermiculite; B2, disperse the organic amine modified vermiculite in deionized water, ultrasonic dispersion for 20-30min, then add hydrochloric acid to adjust the pH to 3.0-3.5, then add montmorillonite, stir and react at 50-55℃ for 2-3h, then add cetyltrimethylammonium bromide, continue to stir and react at 50-55℃ for 3-5h, after the reaction is completed, centrifugal separation, washing and drying are carried out to obtain the montmorillonite / vermiculite nanosheet material; the organic emulsion includes an acrylate emulsion and a silicone-acrylate emulsion.

2. The insulating concrete for composite floor slab according to claim 1, characterized in that, the double modified lightweight aggregate is prepared by the following method: A1, immerse the lightweight aggregate in a mixed solution of silica sol and aluminum sol, take it out after 30-60min of immersion, and dry at 120-150℃ to obtain a coated lightweight aggregate; A2, mix the coated lightweight aggregate with a fluorine-containing silane ethanol solution, stir and react at 50-70℃ for 60-90min, take it out and dry to obtain the double modified lightweight aggregate.

3. The insulating concrete for composite floor slab according to claim 2, characterized in that, In A1, the mass ratio of the mixed silica sol and aluminum sol is (3-3.5):

1.

4. The insulating concrete according to claim 2, wherein In A2, the mass concentration of fluorine-containing silane in the fluorine-containing silane ethanol solution is 3%-5%, and the solid-liquid ratio of the coated lightweight aggregate to the fluorine-containing silane ethanol solution is 1:(5-7).

5. The insulating concrete according to claim 2, wherein The lightweight aggregate is any one of expanded perlite and vitrified microbeads.

6. The insulating concrete according to claim 1, wherein In B1, the mass ratio of the vermiculite nanosheet to deionized water is 1:(20-30); the organic amine solution is a dodecylamine ethanol solution with a mass concentration of 3%-8%.

7. The insulating concrete according to claim 1, wherein In B2, the mass ratio of the organic amine modified vermiculite to deionized water is 1:(15-20); the addition amount of the montmorillonite is 30%-50% of the mass of the organic amine modified vermiculite; the addition amount of the cetyltrimethylammonium bromide is 10%-15% of the mass of the organic amine modified vermiculite.

8. The insulating concrete according to claim 1, wherein The organic emulsion includes an acrylate emulsion 60%-70% and a silicone-acrylate emulsion 30%-40%.

9. A method of producing the thermal concrete for composite floor slabs according to any one of claims 1-8, characterized in that, The method includes the following steps: S1, mix sulfoaluminate cement, metakaolin, silica fume, montmorillonite / vermiculite nanosheet material and nano aerogel powder uniformly to obtain dry materials; S2, to dry material is added to the double modified lightweight aggregate, organic emulsion, admixture and water, stirring 2-4min get thermal insulation concrete.

Images