Facing layer for fabricated building, prefabricated outer wall and preparation method of facing layer and prefabricated outer wall

Abstract

The invention relates to a facing layer for a fabricated building, a prefabricated outer wall and a preparation method of the facing layer and the prefabricated outer wall. The first composition is prepared from the following components in parts by weight: 20 to 30 parts of recycled fine aggregate, 20 to 30 parts of tailings, 10 to 15 parts of modified silica powder, 20 to 30 parts of white cement, 0.5 to 1.5 parts of a water reducing agent, 0.4 to 0.6 part of PTB emulsion, 2 to 4 parts of organic silicon modified styrene-acrylic emulsion, 0.6 to 0.8 part of an internally doped waterproof agent, 1 to 2 parts of PVA fiber and 4 to 8 parts of water. The method has the beneficial effects that the strength and weather resistance of the finish coat of the fabricated building are remarkably improved, and the building cost is reduced by taking the solid waste as the raw material.

Description

Technical Field

[0001] This invention relates to the field of prefabricated buildings, and more particularly to a prefabricated exterior wall for prefabricated buildings and its preparation method. Background Technology

[0002] In prefabricated buildings, the exterior walls are usually prefabricated in the factory, transported to the site for installation, and then finished with finishing work, such as wet installation or dry hanging (using adhesives). This requires setting up formwork or scaffolding on site for finishing work, which not only prolongs the overall construction period, but also poses certain safety hazards for working at heights.

[0003] In addition, existing finishing layers have disadvantages such as low strength, easy aging, and easy degradation of the interface between the finishing layer and the wall: increasing the risk of the finishing layer falling off and the risk of falling objects from heights; the aging of the finishing layer leads to the deterioration of the building's appearance and the degradation of its functions; the finishing layer needs to be regularly inspected, partially repaired or even replaced due to aging or falling off, which not only increases the later operation and maintenance costs, but also affects the normal use of the building. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a prefabricated exterior wall for prefabricated buildings and a method for preparing the same, which solves the technical problems that the finishing layer of the existing prefabricated exterior wall cannot be prefabricated to the wall surface in advance, and that the building performance of the existing finishing layer needs to be improved.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, embodiments of the present invention provide a finishing layer for prefabricated buildings, obtained by molding a first slurry prepared from a first composition:

[0009] The first composition comprises, by weight: 20-30 parts recycled fine aggregate, 20-30 parts tailings, 10-15 parts modified silica powder, 20-30 parts white cement, 0.5-1.5 parts water-reducing agent, 0.4-0.6 parts PTB emulsion, 2-4 parts organosilicon-modified styrene-acrylic emulsion, 0.6-0.8 parts internally added waterproofing agent, 1-2 parts PVA fiber, and 4-8 parts water.

[0010] In the finishing layer, the recycled fine aggregate is made from crushed construction waste concrete, with a particle size of 10-30 mesh; the tailings are one or more of copper tailings, iron tailings, lithium tailings, and molybdenum tailings; the modified silica powder is modified from one or more of epoxy groups, silazanes, alkyl groups, and vinyl groups, with a particle size of 3-12µm; the white cement is white silicate 52.5 cement; the water-reducing agent is a high-performance polycarboxylate water-reducing agent with a water reduction rate greater than 25%; the PTB emulsion is a PTB emulsion produced by Polytechnisch Bedrijf in Belgium, with a solid content of 52±1% and a density of 1.1g / cm³. 3 The organosilicon-modified styrene-acrylic emulsion is obtained by modifying styrene-acrylic emulsion with one of vinylcyclotetrasiloxane or octamethylcyclotetrasiloxane; the internal waterproofing agent is composed of one or more of potassium methylsilicate, sodium methylsilicate, and nano-silane waterproofing agent; the PVA fiber length is 12mm.

[0011] Secondly, embodiments of the present invention provide a prefabricated exterior wall for prefabricated buildings, comprising a concrete base layer, an insulation layer, and a finishing layer as described in claim 1, which are sequentially poured and connected from the inside to the outside.

[0012] The insulation layer is formed by casting a second slurry prepared from the second composition onto the inner side of the finishing layer:

[0013] The second composition comprises, by weight: 10-20 parts slag, 5-10 parts fly ash, 10-15 parts steel slag, 5-10 parts desulfurized gypsum, 40-50 parts vitrified microspheres, 1-2 parts first auxiliary activator, 0.4-0.8 parts redispersible latex powder, 1-2 parts acrylate copolymer emulsion, 0.2-0.5 parts water-retaining agent, 0.1-0.3 parts PP fiber, and 12-20 parts water.

[0014] In the insulation layer, the slag is grade S95; the fly ash is grade I fly ash; the steel slag is high-alkalinity steel slag, with CaO / (SiO2+P2O5) > 2.4; the desulfurized gypsum is dihydrate desulfurized gypsum, with CaSO4·2H2O content > 90%; and the vitrified microspheres have a bulk density of 80-120 kg / m³. 3 The first auxiliary activator is sodium silicate; the redispersible latex powder is DA6200 produced by Dalian Chemical Industry Co., Ltd. in Taiwan, China; the solid content of the acrylate copolymer emulsion is 30%; the water-retaining agent is hydroxypropyl methylcellulose; and the length of the PP fiber is 6mm.

[0015] As a preferred embodiment of the present invention, the prefabricated exterior wall for prefabricated buildings further includes anchors;

[0016] The anchors are inserted into the concrete base layer, the insulation layer, and the finishing layer, and connect the finishing layer, the insulation layer, and the concrete base layer.

[0017] In a preferred embodiment of the present invention, the prefabricated exterior wall for prefabricated buildings has 4-8 anchors per square meter.

[0018] Thirdly, embodiments of the present invention provide a method for preparing the prefabricated exterior wall for prefabricated buildings, comprising the following steps:

[0019] S1. Preparation of decorative layer board: The first slurry prepared from the first composition is molded, vacuum pressed, cured and processed to obtain the decorative layer board;

[0020] S2. Prepare the second slurry using the second composition for later use;

[0021] S3. Lay the decorative layer sub-boards on the bottom of the exterior wall mold according to the preset pattern to form the decorative layer, and then pour the second slurry onto the decorative layer and cure it to form the insulation layer.

[0022] S4. Prepare a third grout for pouring the concrete base layer, then pour the third grout onto the insulation layer and cure it to form the concrete base layer. At this time, the concrete base layer, insulation layer and finishing layer are poured into an integrated structure.

[0023] S5. Demolding to obtain the prefabricated exterior wall used in prefabricated buildings.

[0024] In a preferred embodiment of the present invention, in the preparation method S1, the preparation process of the first slurry includes:

[0025] S11. First, the recycled fine aggregate, tailings, modified silica powder, white cement and PVA fiber in the first composition are mixed to obtain a dry material; S12. The water-reducing agent, PTB emulsion, organosilicon-modified styrene-acrylic emulsion, internal waterproofing agent and water are mixed to obtain a mixed solution; the mixed solution is mixed with the dry material to obtain the first slurry.

[0026] In a preferred embodiment of the present invention, in the preparation method S1,

[0027] The vacuum-pressed strips have the following characteristics: vacuum degree of -0.09 to -0.12 MPa, and holding time of 160-200 s;

[0028] The curing process is as follows: First stage: curing in mold: ambient temperature 20-40℃, humidity 65-80%, curing for 20-24 hours; Second stage: demolding curing: closed spraying, ambient temperature 25-40℃, humidity above 90%, curing for 14-28 days.

[0029] In a preferred embodiment of the present invention, in the preparation method S2, the preparation process of the second slurry includes:

[0030] S21. The slag, fly ash, steel slag, desulfurized gypsum, vitrified microspheres, and PP fiber in the second composition are mixed to obtain a dry material; S22. The first auxiliary activator, redispersible latex powder, acrylate copolymer emulsion, water-retaining agent, and water are stirred in a container for 30-60 seconds to obtain a mixed solution; then the mixed solution is poured into a mixer and stirred for 120-180 seconds to obtain the second slurry.

[0031] In a preferred embodiment of the present invention, in the preparation method S1,

[0032] It also includes anchors, which include a fixed base and an anchor hook; before vacuum pressing, the fixed base is pre-embedded in the first slurry, so that the side of the fixed base that contacts the first slurry in the mold sinks into the first slurry, while the other side is flush with the inner surface of the first slurry in the mold.

[0033] Furthermore, in S3, before the second slurry is poured onto the finishing layer, the anchor hook is connected to the fixing base;

[0034] The anchoring hook can extend into the concrete base layer in S4.

[0035] The anchoring components include a fixed base and an anchor hook. The fixed base consists of an anchor plate and a nut welded to one side. The anchor plate is a small steel plate, 4-6cm square, with a thickness of 2-4mm. The nut is an M6-M8 hexagonal nut with a thickness of approximately 5-6.5mm. The anchor hook is an L-shaped screw with a thread diameter of 6-8mm, a thread length of 40mm, a straight section length of 60mm, and a hook length of 25-35mm.

[0036] In a preferred embodiment of the present invention, in the preparation method S4, the third slurry is prepared from the third composition;

[0037] The third composition comprises, by weight: 30-40 parts recycled aggregate, 35-45 parts sand, 8-10 parts slag, 4-6 parts steel slag, 1-3 parts fly ash, 1-3 parts desulfurized gypsum, 0.2-0.4 parts water-reducing agent, 0.4-0.6 parts second auxiliary activator, and 6-8 parts water.

[0038] The third grout corresponding to the concrete base layer uses industrial solid waste to replace cement, reducing raw material costs. In the concrete base layer, the recycled aggregate is obtained by crushing construction waste concrete with a particle size of 5-25mm; the sand is manufactured sand with a fineness of medium sand; the slag is S95 grade; the steel slag is high-alkalinity steel slag with CaO / (SiO2+P2O5) > 2.4; the fly ash is grade I fly ash; the desulfurized gypsum is dihydrate desulfurized gypsum with a CaSO4·2H2O content > 90%; the water-reducing agent is a naphthalene-based water-reducing agent; and the second auxiliary activator is sodium sulfate.

[0039] (III) Beneficial Effects

[0040] The beneficial effects of the present invention are as follows: The finishing layer, prefabricated exterior wall and its preparation method for prefabricated buildings of the present invention, wherein the PTB emulsion in the finishing layer has excellent waterproof and flexible properties, and the combination of PTB emulsion and organosilicon-modified styrene-acrylic emulsion can greatly improve the weather resistance and waterproof performance of the finishing layer, prevent the finishing layer from aging, yellowing, efflorescence and easy pollution during use, and further enhance the strength of the inorganic finishing layer.

[0041] Meanwhile, the modified silica powder in the finishing layer has surface functional groups that chemically bond with the organic polymers in the emulsion, greatly improving interfacial adhesion and further enhancing the strength of the finishing layer. The finishing layer is prepared using recycled fine aggregates from construction solid waste and industrial solid waste tailings instead of calcium sand / silica sand, promoting the resource utilization of solid waste and significantly reducing building material costs.

[0042] Compared to existing technologies, it significantly improves the strength and weather resistance of the finishing layer of prefabricated buildings, and reduces construction costs by using solid waste as raw material.

[0043] In prefabricated exterior walls used in prefabricated buildings, dispersible latex powder emulsion particles and acrylic copolymer emulsion particles coexist in the insulation mortar. During the hydration and drying process of the mortar, they aggregate together to form an interpenetrating network polymer film. This network polymer film binds cement hydration products, aggregates, and other materials more tightly together. Furthermore, the acrylic copolymer emulsion can form an effective polymer film in the early stages of mortar curing, providing early flexibility and adhesion. The dispersible latex powder continues to play a role in the later stages. The combination of both ensures the long-term stable and reliable performance of the insulation layer, thereby improving the adhesion and flexibility of the insulation mortar.

[0044] Improving the adhesion of the insulation mortar helps it bond with the finishing layer during the pouring process, thus enhancing the adhesion between the finishing layer and the insulation layer.

[0045] Adding sodium silicate as an auxiliary activator to the insulation mortar greatly improves its early strength, which helps to shorten the pouring time between the insulation mortar and the concrete base layer, thus reducing the construction period. The use of industrial solid waste such as steel slag to replace cement in the insulation layer reduces raw material costs.

[0046] Precast exterior walls (including the finishing layer) can be prepared in the factory using a casting process, eliminating the need for secondary decoration on the construction site. This improves the integration of the precast exterior walls and shortens the on-site construction period. Furthermore, the application of the finishing layer helps to enhance the overall quality of prefabricated buildings.

[0047] While pouring the precast exterior wall, anchors were pre-embedded in the concrete base layer, insulation layer, and finishing layer, and were also installed in the concrete base layer, insulation layer, and finishing layer to ensure the integrity of the poured precast exterior wall. Attached Figure Description

[0048] Figure 1 This is a structural schematic diagram of a prefabricated exterior wall used in prefabricated buildings according to an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of anchors in prefabricated exterior walls used in prefabricated buildings, as described in an embodiment of the present invention.

[0050] Figure 3 These are physical images of prefabricated exterior walls used in prefabricated buildings, as described in an embodiment of the present invention.

[0051] [Explanation of Labels in the Attached Image]

[0052] 1. Concrete base layer; 2. Insulation layer; 3. Finishing layer; 4. Anchors; 41. Nuts; 42. Anchor plates; 43. Anchor hooks. Detailed Implementation

[0053] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0055] Example 1

[0056] This embodiment provides a method for preparing a finishing layer for prefabricated buildings, mainly including the following steps:

[0057] (1) Preparation of the first composition: 26 parts by weight of recycled fine aggregate, 30 parts of tailings, 12 parts of modified silica powder, 20 parts of white cement, 1 part of water-reducing agent, 0.4 parts of PTB emulsion, 3 parts of organosilicon modified styrene-acrylic emulsion, 0.6 parts of internal waterproofing agent, 1 part of PVA fiber, and 6 parts of water.

[0058] (2) First, the recycled fine aggregate, tailings, modified silica powder, white cement, and PVA fiber are mixed in a mixer for 120s to obtain dry material; then, the water-reducing agent, PTB emulsion, organosilicon-modified styrene-acrylic emulsion, internal waterproofing agent, and water are mixed in a container for 90s to obtain a mixed solution; then, the mixed solution is poured into the dry material in the mixer and mixed for 180s to obtain the first slurry;

[0059] (3) Fabric preparation: The first slurry obtained in step (2) is evenly distributed in the mold of the finishing layer. Then, the fixing base (a nut is welded to one side of the anchor plate) is pre-embedded in the first slurry. The nut on the anchor plate needs to be sealed with tape in advance to prevent the first slurry from entering the nut and clogging it. Ensure that the edge of the nut is flush with the inner side of the finishing layer, which facilitates the subsequent vacuum pressing.

[0060] (4) Molding: The slurry obtained in step (3) is pressed and molded under vacuum. The vacuum degree is -0.095 MPa and the press holding time is 180s to obtain the decorative layer slab. Then, the molded decorative layer slab is placed in an environment with a temperature of 20℃ and a humidity of 65% for 24h. After the slab has been cured for 24h, it is demolded and subjected to closed spray curing. The curing environment temperature is 25℃ and the humidity is above 90%. The curing time is 14d.

[0061] (5) Processing: After the raw board has reached the required age, it is subjected to fixed-thickness grinding and polishing treatment, and then cut according to the design drawings to obtain the decorative layer board.

[0062] Example 2

[0063] This embodiment provides a method for preparing prefabricated exterior walls for prefabricated buildings, mainly including the following steps:

[0064] (1) Mold preparation: Prepare the molds for wall production (exterior wall molds) according to the drawing requirements.

[0065] (2) Laying the finishing layer: According to the drawing requirements, the finishing layer sub-boards prepared in Example 1 are laid upside down in the mold. Each finishing layer sub-board and the finishing layer sub-boards are fixed with EVA strips to prevent the finishing layer sub-boards from moving in the mold and to prevent the subsequent insulation layer and concrete base slurry from seeping into the finishing layer surface and contaminating the finishing layer; and one end of the anchor hook is screwed into the nut.

[0066] The inner surface of the decorative layer sub-board (the surface facing the insulation layer) is roughened to facilitate subsequent bonding with the insulation layer;

[0067] Additionally, it should be noted that... (See also) Figure 1 The exhibition showcases the three-layer structure of the precast exterior wall, which is constructed and connected sequentially: a concrete base layer 1, an insulation layer 2, and a finishing layer 3. It also demonstrates the location of the anchors 4 within the precast exterior wall.

[0068] See Figure 2 The anchor 4 includes a fixing base and an anchor hook 43. The fixing base consists of a nut 41 welded to one side of the anchor plate 42. The anchor plate 42 and the anchor hook 43 are arranged opposite each other to improve the pull-out resistance of the precast exterior wall and ensure its integrity. For the precast exterior wall as a whole, the anchors are evenly distributed, with 4 anchors per square meter.

[0069] (3) Reinforcing bar binding: According to the drawings, reinforcing bars (ribs of concrete base layer) are bound above the finishing layer.

[0070] (4) The second composition of the insulation layer is prepared by weight as follows: 16 parts slag, 5 parts fly ash, 10 parts steel slag, 5 parts desulfurized gypsum, 45 parts vitrified microspheres, 2 parts sodium silicate (auxiliary activator), 0.4 parts redispersible latex powder, 2 parts acrylic copolymer emulsion, 0.3 parts water retention agent, 0.2 parts PP fiber, and 15 parts water;

[0071] (5) Stir the slag, fly ash, steel slag, desulfurized gypsum, vitrified microspheres and PP fiber in step (4) in a mixer for 60s to obtain the dry material of the insulation layer; then stir sodium silicate (auxiliary activator), redispersible latex powder, acrylic copolymer emulsion, water-retaining agent and water in a container for 60s to obtain a mixed solution; then pour the mixed solution into the dry material in the mixer and stir for 120s to obtain the second slurry;

[0072] (6) Insulation layer pouring: pour the second slurry obtained in step (5) into the mold prepared in step (3), spread it evenly, and cover it with a film for curing for 8 hours;

[0073] (7) The third composition of the concrete base layer is prepared by weight as follows: 32 parts recycled aggregate, 39 parts sand, 10 parts slag, 5 parts steel slag, 3 parts fly ash, 2 parts desulfurized gypsum, 0.2 parts water-reducing agent, 0.4 parts sodium silicate (auxiliary activator), and 8 parts water.

[0074] (8) Mix the recycled aggregate, sand, slag, steel slag, fly ash and desulfurized gypsum in the above step (7) in a mixer for 60s to obtain dry concrete material; then mix the water-reducing agent, activator and water in a container for 60s to obtain a mixed solution; then pour the mixed solution into the dry material in the mixer and mix for 120s to obtain the third slurry.

[0075] (9) Pour the third slurry obtained in (8) into the mold after step (6), cure for 2 days, and then remove the mold to obtain the prefabricated exterior wall of the prefabricated building. Refer to Figure 3 .

[0076] The strength of the prepared decorative layer specimens was tested in accordance with the standards "Test Methods for Synthetic Stone Part 2: Determination of Flexural Strength" (GB / T 35160.2-2017) and "Test Methods for Synthetic Stone Part 3: Determination of Compressive Strength" (GB / T 35160.3-2017). The strength of the prepared thermal insulation layer specimens was tested in accordance with the standard "Building Thermal Insulation Mortar" (GB / T 20473-2021). The strength of the prepared concrete base layer specimens was tested in accordance with the standard "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). The specific test results are detailed in Table 1.

[0077] Example 3

[0078] This embodiment provides a method for preparing prefabricated exterior walls for prefabricated buildings, which differs from Embodiment 2 in that:

[0079] In step (2), the first composition material corresponding to the decorative layer board is prepared as follows: 27 parts recycled fine aggregate, 28 parts tailings, 13 parts modified silica powder, 20 parts white cement, 1 part water-reducing agent, 0.6 parts PTB emulsion, 3 parts organosilicon modified styrene-acrylic emulsion, 0.6 parts internal waterproofing agent, 1 part PVA fiber, and 6 parts water.

[0080] In step (4), the second composition of the insulation layer is prepared by weight as follows: 12 parts slag, 9 parts fly ash, 10 parts steel slag, 5 parts desulfurized gypsum, 45 parts vitrified microspheres, 2 parts sodium silicate (auxiliary activator), 0.4 parts redispersible latex powder, 2 parts acrylic copolymer emulsion, 0.3 parts water-retaining agent, 0.2 parts PP fiber, and 15 parts water.

[0081] In step (7), the third composition of the concrete base layer is prepared by weight as follows: 30 parts recycled aggregate, 41 parts sand, 10 parts slag, 6 parts steel slag, 2 parts fly ash, 2 parts desulfurized gypsum, 0.2 parts water-reducing agent, 0.2 parts sodium silicate (auxiliary activator), and 9 parts water.

[0082] The remaining steps are the same.

[0083] The strength test results are detailed in Table 1.

[0084] Example 4

[0085] This embodiment provides a method for preparing prefabricated exterior walls for prefabricated buildings, which differs from Embodiment 2 in that:

[0086] In step (2), the first composition material corresponding to the decorative layer board is prepared as follows: 27 parts recycled fine aggregate, 28 parts tailings, 13 parts modified silica powder, 20 parts white cement, 1 part water-reducing agent, 0.6 parts PTB emulsion, 3 parts organosilicon modified styrene-acrylic emulsion, 0.8 parts internal waterproofing agent, 1 part PVA fiber, and 6 parts water.

[0087] In step (4), the second composition of the insulation layer is prepared by weight as follows: 12 parts slag, 4 parts fly ash, 9 parts steel slag, 5 parts desulfurized gypsum, 50 parts vitrified microspheres, 1.5 parts sodium silicate (auxiliary activator), 0.6 parts redispersible latex powder, 2 parts acrylic copolymer emulsion, 0.3 parts water-retaining agent, 0.2 parts PP fiber, and 15 parts water.

[0088] In step (7), the third composition of the concrete base layer is prepared by weight as follows: 27 parts recycled aggregate, 42 parts sand, 10 parts slag, 6 parts steel slag, 3 parts fly ash, 2 parts desulfurized gypsum, 0.2 parts water-reducing agent, 0.4 parts sodium silicate (auxiliary activator), and 9 parts water.

[0089] The remaining steps are the same.

[0090] The strength test results are detailed in Table 1.

[0091] Example 5

[0092] This embodiment provides a method for preparing prefabricated exterior walls for prefabricated buildings, which differs from Embodiment 2 in that:

[0093] In step (2), the first composition material corresponding to the decorative layer board is prepared as follows: 28 parts recycled fine aggregate, 25 parts tailings, 15 parts modified silica powder, 20 parts white cement, 1 part water-reducing agent, 0.6 parts PTB emulsion, 3 parts organosilicon modified styrene-acrylic emulsion, 0.8 parts internal waterproofing agent, 1 part PVA fiber, and 6 parts water.

[0094] In step (4), the second composition of the insulation layer is prepared by weight as follows: 10 parts slag, 6 parts fly ash, 8 parts steel slag, 6 parts desulfurized gypsum, 50 parts vitrified microspheres, 1.5 parts sodium silicate (auxiliary activator), 0.6 parts redispersible latex powder, 2 parts acrylic copolymer emulsion, 0.3 parts water-retaining agent, 0.2 parts PP fiber, and 15 parts water;

[0095] In step (7), the third composition of the concrete base layer is prepared by weight as follows: 28 parts recycled aggregate, 42 parts sand, 10 parts slag, 5 parts steel slag, 3 parts fly ash, 2 parts desulfurized gypsum, 0.2 parts water-reducing agent, 0.4 parts sodium silicate (auxiliary activator), and 9 parts water.

[0096] The remaining steps are the same.

[0097] The strength test results are detailed in Table 1.

[0098] Example 6

[0099] This embodiment provides a method for preparing prefabricated exterior walls for prefabricated buildings, which differs from Embodiment 2 in that:

[0100] In step (2), the first composition material corresponding to the decorative layer board is prepared as follows: 30 parts recycled fine aggregate, 23 parts tailings, 15 parts modified silica powder, 20 parts white cement, 1 part water-reducing agent, 0.6 parts PTB emulsion, 3 parts organosilicon modified styrene-acrylic emulsion, 0.8 parts internal waterproofing agent, 1 part PVA fiber, and 6 parts water.

[0101] In step (4), the second composition of the insulation layer is prepared by weight as follows: 10 parts slag, 5 parts fly ash, 10 parts steel slag, 5 parts desulfurized gypsum, 50 parts vitrified microspheres, 1.5 parts sodium silicate (auxiliary activator), 0.6 parts redispersible latex powder, 2 parts acrylic copolymer emulsion, 0.3 parts water-retaining agent, 0.2 parts PP fiber, and 15 parts water;

[0102] In step (7), the third composition of the concrete base layer is prepared by weight as follows: 27 parts recycled aggregate, 45 parts sand, 10 parts slag, 5 parts steel slag, 2 parts fly ash, 2 parts desulfurized gypsum, 0.2 parts water-reducing agent, 0.4 parts sodium silicate (auxiliary activator), and 8.5 parts water.

[0103] The remaining steps are the same.

[0104] The strength test results are detailed in Table 1.

[0105] Test Example 1

[0106] This test example focuses on the prefabricated exterior wall of the prefabricated building prepared in Example 3. Test samples were taken from areas without anchors. The bonding performance between the finishing layer and the insulation layer was tested in accordance with the "Standard for Testing the Bonding Strength of Facing Bricks in Building Engineering" (JGJ 110-2008). The specific test results are detailed in Table 2.

[0107] Test Example 2

[0108] This test example focuses on the prefabricated exterior wall of the prefabricated building prepared in Example 3. The pull-out force of the anchor plate was tested in accordance with the Technical Specification for Post-Anchoring of Concrete Structures (JGJ 145-2013). The specific test results are detailed in Table 2.

[0109] Comparative Example 1

[0110] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that:

[0111] In the first composition corresponding to the decorative layer used in step (2), the modified silica powder is replaced with ordinary 325 mesh silica powder.

[0112] The remaining steps are the same.

[0113] The strength test results are detailed in Table 1.

[0114] Comparative Example 2

[0115] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that:

[0116] In the first composition corresponding to the decorative layer used in step (2), the PTB emulsion is removed and the silicone-modified styrene-acrylic emulsion is replaced with a styrene-acrylic emulsion.

[0117] The remaining steps are the same.

[0118] The strength test results are detailed in Table 1.

[0119] Comparative Example 3

[0120] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that:

[0121] In step (4), sodium silicate (auxiliary activator) is removed.

[0122] The remaining steps are the same.

[0123] The strength test results are detailed in Table 1.

[0124] Comparative Example 4

[0125] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that:

[0126] In step (4), the redispersible latex powder is removed.

[0127] The remaining steps are the same.

[0128] The strength test results are detailed in Table 1.

[0129] Comparative Example 5

[0130] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that:

[0131] In step (4), the acrylate copolymer emulsion is removed.

[0132] The remaining steps are the same.

[0133] The strength test results are detailed in Table 1.

[0134] Comparative Example 6

[0135] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that commercially available ordinary thermal insulation mortar is used to replace the second slurry (thermal insulation layer mortar) in Example 3 of this invention; the remaining steps are the same.

[0136] Areas without anchors were selected as test samples. The bonding performance between artificial stone and insulation layer was tested in accordance with the "Standard for Testing the Bonding Strength of Facing Bricks in Building Engineering" (JGJ 110-2008). The specific test results are detailed in Table 2.

[0137] Comparative Example 7

[0138] This comparative example provides a method for preparing prefabricated exterior walls for prefabricated buildings. The difference between this comparative example and Example 3 is that:

[0139] In the preparation of precast exterior walls, the pre-embedded anchors are removed, and tile adhesive is used to bond the finishing layer and the insulation layer together; the remaining steps are the same.

[0140] Test samples were selected, and the bonding performance between the decorative layer and the insulation layer was tested in accordance with the "Standard for Testing the Bonding Strength of Facing Bricks in Building Engineering" (JGJ 110-2008). The specific test results are detailed in Table 2.

[0141] Table 1 Mechanical performance indicators of prefabricated exterior walls prepared in different embodiments and comparative examples

[0142]

[0143] Table 2 Mechanical performance indicators of prefabricated exterior walls prepared in different test cases and comparative examples

[0144]

[0145] Based on the data in Table 1, the analysis is as follows:

[0146] The finishing layer used in Example 6 exhibited the best performance, with a flexural strength of up to 19.6 MPa, demonstrating the best crack resistance and toughness; its compressive strength reached up to 114.6 MPa, indicating the best density and load-bearing capacity. Furthermore, Example 6 showed the highest flexural strength / compressive strength ratio (i.e., "strength-toughness balance") at 0.171, indicating that this finishing layer balanced both compressive and crack resistance.

[0147] The insulation layer in Example 3 exhibits the best mechanical properties, including the best compressive strength and bonding strength.

[0148] Compared with Comparative Example 1, Example 3 shows that the use of modified silica powder can significantly increase the compressive strength and flexural strength of the finishing layer.

[0149] Compared with Comparative Example 2, Example 3 uses PTB emulsion and silicone-modified styrene-acrylic emulsion for the finishing layer, which can significantly improve the compressive strength and flexural strength of the finishing layer, while also increasing the flexural strength / compressive strength ratio of the finishing layer.

[0150] Compared with Comparative Examples 3 to 5, Example 3 shows that adding appropriate amounts of sodium acid (auxiliary activator), redispersible latex powder and acrylate copolymer emulsion to the insulation layer helps to improve the compressive strength and bonding strength of the insulation layer.

[0151] Based on the data in Table 2, the analysis is as follows:

[0152] As can be seen from the comparison between Test Example 1 and Comparative Example 6, the bonding strength between the thermal insulation slurry (second slurry) used in Example 3 and the finishing layer is much higher than that of commercially available ordinary thermal insulation mortar. The thermal insulation slurry of the present invention has better adhesion to the finishing layer.

[0153] Test Example 2 shows that the 28-day pull-out strength of the anchors embedded in the precast exterior wall is 3.2 MPa, which is 0.8 MPa higher than that of Test Example 1. This indicates that while improving the bonding strength of the insulation mortar, the anchors, through the reverse installation process, tightly connect the finishing layer, insulation layer and concrete base layer together, which greatly improves the adhesion and integrity between the finishing layer and the wall, prevents the finishing material from falling off and improves the appearance quality of prefabricated buildings.

[0154] Comparative Example 7 and Test Example 1 show that the insulation mortar in Example 3 of this invention has a better adhesion to the finishing layer than the tile adhesive. At the same time, the insulation layer also has higher compressive strength.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A finishing layer for prefabricated buildings, characterized in that, The first slurry prepared from the first composition is molded to obtain: The first composition comprises, by weight: 20-30 parts recycled fine aggregate, 20-30 parts tailings, 10-15 parts modified silica powder, 20-30 parts white cement, 0.5-1.5 parts water-reducing agent, 0.4-0.6 parts PTB emulsion, 2-4 parts organosilicon-modified styrene-acrylic emulsion, 0.6-0.8 parts internally added waterproofing agent, 1-2 parts PVA fiber, and 4-8 parts water.

2. A prefabricated exterior wall for prefabricated buildings, characterized in that, It includes a concrete base layer, an insulation layer, and a finishing layer as described in claim 1, which are poured and connected sequentially from the inside out. The insulation layer is formed by casting a second slurry prepared from the second composition onto the inner side of the finishing layer: The second composition comprises, by weight: 10-20 parts slag, 5-10 parts fly ash, 10-15 parts steel slag, 5-10 parts desulfurized gypsum, 40-50 parts vitrified microspheres, 1-2 parts first auxiliary activator, 0.4-0.8 parts redispersible latex powder, 1-2 parts acrylate copolymer emulsion, 0.2-0.5 parts water-retaining agent, 0.1-0.3 parts PP fiber, and 12-20 parts water.

3. The prefabricated exterior wall for prefabricated buildings as described in claim 2, characterized in that, It also includes anchors; The anchors are inserted into the concrete base layer, the insulation layer, and the finishing layer, and connect the finishing layer, the insulation layer, and the concrete base layer.

4. The prefabricated exterior wall for prefabricated buildings as described in claim 3, characterized in that, The number of anchors is 4-8 per square meter.

5. A method for preparing a prefabricated exterior wall for prefabricated buildings as described in any one of claims 2 to 4, characterized in that, Includes the following steps: S1. Preparation of decorative layer board: The first slurry prepared from the first composition is molded, vacuum pressed, cured and processed to obtain the decorative layer board; S2. Prepare the second slurry using the second composition for later use; S3. Lay the decorative layer sub-boards on the bottom of the exterior wall mold according to the preset pattern to form the decorative layer, and then pour the second slurry onto the decorative layer and cure it to form the insulation layer. S4. Prepare a third grout for pouring the concrete base layer, then pour the third grout onto the insulation layer and cure it to form the concrete base layer. At this time, the concrete base layer, insulation layer and finishing layer are poured into an integrated structure. S5. Demolding to obtain the prefabricated exterior wall used in prefabricated buildings.

6. The preparation method according to claim 5, characterized in that, In S1, the preparation process of the first slurry includes: S11. First, the recycled fine aggregate, tailings, modified silica powder, white cement and PVA fiber in the first composition are mixed to obtain a dry material; S12. The water-reducing agent, PTB emulsion, organosilicon-modified styrene-acrylic emulsion, internal waterproofing agent and water are mixed to obtain a mixed solution; the mixed solution is mixed with the dry material to obtain the first slurry.

7. The preparation method according to claim 5, characterized in that, In S1, The vacuum-pressed strips have the following characteristics: vacuum degree of -0.09 to -0.12 MPa, and holding time of 160-200 s; The curing process is as follows: First stage: curing in mold: ambient temperature 20-40℃, humidity 65-80%, curing for 20-24 hours; Second stage: demolding curing: closed spraying, ambient temperature 25-40℃, humidity above 90%, curing for 14-28 days.

8. The preparation method according to claim 5, characterized in that, In S2, the preparation process of the second slurry includes: S21. The slag, fly ash, steel slag, desulfurized gypsum, vitrified microspheres, and PP fiber in the second composition are mixed to obtain a dry material; S22. The first auxiliary activator, redispersible latex powder, acrylate copolymer emulsion, water-retaining agent, and water are stirred in a container for 30-60 seconds to obtain a mixed solution; then the mixed solution is poured into a mixer and stirred for 120-180 seconds to obtain the second slurry.

9. The preparation method according to claim 5, characterized in that, In S1, It also includes anchors, which include a fixed base and an anchor hook; before vacuum pressing, the fixed base is pre-embedded in the first slurry, so that the side of the fixed base that contacts the first slurry in the mold sinks into the first slurry, while the other side is flush with the inner surface of the first slurry in the mold. Furthermore, in S3, before the second slurry is poured onto the finishing layer, the anchor hook is connected to the fixing base; The anchoring hook can extend into the concrete base layer in S4.

10. The preparation method according to claim 5, characterized in that, In S4, the third slurry is prepared from the third composition; The third composition comprises, by weight: 30-40 parts recycled aggregate, 35-45 parts sand, 8-10 parts slag, 4-6 parts steel slag, 1-3 parts fly ash, 1-3 parts desulfurized gypsum, 0.2-0.4 parts water-reducing agent, 0.4-0.6 parts second auxiliary activator, and 6-8 parts water.

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