Preparation method of a multi-layer spaced fabric reinforced foamed concrete material

Abstract

The invention discloses a preparation method of a multi-layer spacer fabric reinforced foamed concrete material, belonging to the technical field of high-performance fiber-reinforced composite materials. The preparation method is as follows: preparing a multi-layer spacer fabric, preparing foamed concrete slurries with different relative foaming volumes, and pouring in layers, and obtaining a finished product through post-treatment. The multi-layer spacer fabric is composed of multiple spacer layers with different densities. When stressed, the stress is evenly dispersed, the strength and compressive capacity are improved, and the foamed concrete is enhanced; the foamed concrete is compounded with the multi-layer spacer fabric by a method of pouring in layers, ensuring that the multi-layer spacer fabric can maintain a good spatial state and has uniform foaming during the compounding process. The multi-layer spacer fabric reinforced foamed concrete material prepared by the invention improves the strength and toughness of the foamed concrete, and also has good heat insulation and heat preservation effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance fiber-reinforced composite materials, and particularly relates to a preparation method of a multi-layer spacer fabric-reinforced foamed concrete material. Background Art

[0002] Foamed concrete is a new type of porous cement-based material. Due to its hollow structure, foamed concrete has advantages such as heat insulation, sound insulation, light weight, good fire resistance, and low cost. However, problems such as poor slurry stability, high brittleness, low strength, and poor toughness limit the application of foamed concrete in the construction industry.

[0003] Currently, fiber-reinforced foamed concrete technology has been widely studied and applied, such as basalt fibers, steel fibers, etc. However, thick fibers are not easily mixed evenly in the slurry, resulting in low fiber utilization rate and poor reinforcement effect. At the same time, more importantly, short fibers do not have a definite direction and cannot enable the material to bear load in a certain definite direction.

[0004] Spacer fabrics have an obvious strengthening and toughening effect on foamed concrete, improving the anti-deformation ability of foamed concrete and changing its failure mode. For example, in the literature "Preparation and Properties of 3D Spacer Connecting Fabric Reinforced Foamed Concrete", the flexural strength, compressive strength, and tensile strength of 3D spacer connecting fabric-reinforced concrete are significantly higher than those of ordinary foamed concrete. However, when pouring from the side of the 3D spacer connecting fabric, the cement slurry is poured into the voids between the core columns by gravity. This side-pouring method cannot control the uniformity during large-piece pouring, restricting the size of the specimens. The specimens poured from the side only fill the cement slurry by gravity, and the internal uniformity of the specimens cannot be controlled. At the same time, foamed concrete cannot be vibrated by a machine to make the slurry fill evenly, which will reduce the internal pores, and thus more pores are not retained, resulting in a reduction in the heat insulation and sound insulation effects of foamed concrete and an increase in the mass of the overall material. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of a multi-layer spacer fabric-reinforced foamed concrete material. The prepared multi-layer spacer fabric-reinforced foamed concrete material has the advantages of good compressive strength and good heat insulation and sound insulation effects.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A preparation method of a multi-layer spacer fabric reinforced foamed concrete material, comprising the following steps: preparing a multi-layer spacer fabric, preparing foamed concrete slurries with different relative foaming volumes, and layered pouring. Among them, the multi-layer spacer fabric is a multi-interval layer structure composed of at least three fabric layers, and each adjacent two fabric layers are connected by a binding yarn. The density of the binding yarn in each interval layer is different and decreases in a gradient from bottom to top; the layered pouring is to pour the foamed concrete slurry with the lowest relative foaming volume in a mold, embed the lowermost fabric layer of the multi-layer spacer fabric, then pour the foamed concrete slurry with the lowest relative foaming volume to completely immerse the lowermost fabric layer. After that, the relative foaming volumes of the foamed concrete slurries poured for each interval layer are different and decrease in a gradient from bottom to top. The fabric layer above each interval layer has the same relative foaming volume as the adjacent interval layer below it. After pouring, the finished product is obtained after post-treatment.

[0007] Further, the density of the binding yarn in each interval layer is 1.5 to 3 times that of the adjacent interval layer above it; the relative foaming volume used in each interval layer is 1.1 to 1.3 times that of the adjacent interval layer above it; the relative foaming volume used in the lowermost fabric layer is 50 to 70% of the relative foaming volume used in the adjacent fabric layer above it.

[0008] Further, the fabric layer is woven from warp and weft yarns in a plain weave, and the interval between two adjacent warp yarns is 1 to 10 mm, and the distance between two adjacent weft yarns is 1 to 10 mm.

[0009] Further, the warp and weft yarns of the fabric layer are POM, PET or UHMEPE filaments; the binding yarn is a POM or PET filament.

[0010] Further, the diameter of the warp and weft yarns is 0.1 to 1 mm, and the diameter of the binding yarn is 2 to 5 times that of the warp yarn.

[0011] Further, the multi-layer spacer fabric is a three-layer spacer fabric, which consists of upper, middle and lower fabric layers. The upper fabric layer and the middle fabric layer are connected by an upper binding yarn, and the middle fabric layer and the lower fabric layer are connected by a lower binding yarn.

[0012] Further, the post-treatment is to cover and seal with a film, demold, and cure for 28 days to obtain the finished product.

[0013] Further, the foamed concrete slurry includes cement, foaming agent, foam stabilizer, water reducing agent; the cement is 42.5 grade rapid hardening sulphoaluminate cement; the foaming agent is hydrogen peroxide.

[0014] A multi-layer spacer fabric reinforced foamed concrete material is prepared by the above method.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) The multi-layer spacer fabric connects at least three fabric layers with at least two spacer layers. The knotting yarn in the spacer layer is made of thick denier high-strength and high-modulus filaments, which can play a better supporting role and form a better overall reinforcement effect. Foamed concrete is light in weight, heat-insulating, and sound-insulating, but has low strength, poor toughness, large shrinkage, and is prone to cracking. The knotting yarn has a relatively thick diameter and good toughness. The knotting yarn divides the space between the upper and lower fabric layers into multiple spaces, which can not only improve the strength and toughness of the foamed concrete, reduce the shrinkage, but also prevent the foamed concrete from being completely broken after being subjected to a strong external force. Even if it is locally broken and collapsed, it can still maintain the overall integrity.

[0017] (2) During the preparation process, the density of the knotting yarn in each spacer layer from bottom to top is different and decreases in a gradient manner. In actual use, the fabric layer for pouring the foamed concrete with the lowest relative foaming volume serves as the direct stress-bearing surface of the entire material. That is, the density of the knotting yarn in the spacer layer closer to the external force is greater, which can disperse the external pressure evenly to the surrounding area faster and distribute it to a larger space. The density of the knotting yarn in the spacer layer farther from the external force is smaller, which can retain a certain number of large pores, resulting in a lower thermal conductivity. Therefore, while increasing the strength of the foamed concrete, it has good heat-insulating and sound-insulating properties.

[0018] (3) Hydrogen peroxide is used as the foaming agent for the foamed concrete, and a foam stabilizer and a water reducer are added at the same time. Chemical foaming facilitates the pouring process. In order to solve the problem that the pores formed after the chemical foaming of the foamed concrete are prone to collapse, the present invention uses a layered pouring method to pour layer by layer, which not only improves the bonding strength between the multi-layer spacer fabric and the foamed concrete, but also improves the uniformity of the foamed concrete in the multi-layer spacer fabric.

[0019] (4) By preparing foamed concrete slurries with different relative foaming volumes and adopting a layered pouring method, first pour the foamed concrete slurry with the lowest relative foaming volume into the mold. The pouring volume is determined by embedding the lowest fabric layer. Apply force to embed the lowest fabric layer, which closely combines with the foamed concrete slurry. Then, the relative foaming volumes of the foamed concrete slurries poured in each intermediate layer are different and decrease in a gradient from bottom to top. The knotting yarn densities of the intermediate layers from bottom to top are different and decrease in a gradient. The foamed concrete slurry with the highest relative foaming volume has good fluidity, which is convenient for the foamed concrete slurry to fill the intermediate layer with the largest knotting yarn density. At the same time, after the initial setting of the foamed concrete slurry, it will experience a certain collapse, ensuring that there are still certain pores left in the foamed concrete. The next pouring can fill the collapse of the previous pouring. At the same time, the knotting yarn densities of the intermediate layers from bottom to top decrease in a gradient. Pour the foamed concrete slurry from the height direction of the multi-layer intermediate fabric downwards, which is convenient for pouring. This pouring method also solves the problem that in the case of integral molding pouring, due to the poor fluidity of the foamed concrete slurry and the density gradient of the intermediate layers of the multi-layer intermediate fabric, especially the intermediate layer with a large knotting yarn density, it is easy to cause insufficient contact between the foamed concrete slurry and the fibers in the multi-layer intermediate fabric, thus affecting the heat insulation performance. In addition, it also improves the problem of poor internal uniformity of the foamed concrete slurry during the pouring process. Moreover, this pouring method does not limit the size of the specimen. Description of the Drawings

[0020] Figure 1 Schematic structural diagram of the multi-layer intermediate fabric reinforced concrete material in Example 1;

[0021] Figure 2 Schematic longitudinal sectional view of the structure of the three-layer intermediate fabric in Example 1;

[0022] Among them, 1 is the three-layer intermediate fabric, 2 is the foamed concrete, 11 is the upper fabric layer, 12 is the middle fabric layer, 13 is the lower fabric layer, 14 is the upper intermediate layer, and 15 is the lower intermediate layer. Detailed Embodiment

[0023] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred examples described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0024] Example 1

[0025] The schematic structural diagram of the multi-layer intermediate fabric reinforced foamed concrete material in this example is as Figure 1 shown. The three-layer intermediate fabric and the foamed concrete are compounded by a layered pouring method. The three-layer intermediate fabric 1 is the framework, and the foamed concrete 2 is filled in the surface layer and internal pores of the three-layer intermediate fabric 1.

[0026] The multi-layer spacer fabric reinforced foamed concrete material of this embodiment is prepared by the following preparation method:

[0027] (1) Prepare a multi-layer spacer fabric

[0028] The multi-layer spacer fabric is a three-layer spacer fabric. As Figure 1 shown, the three-layer spacer fabric consists of an upper fabric layer 11, a middle fabric layer 12, and a lower fabric layer 13. The upper spacer layer 14 is between the upper fabric layer 11 and the middle fabric layer 12. The upper spacer layer 14 is formed by connecting the upper fabric layer 11 and the middle fabric layer 12 with upper binding yarns. The lower spacer layer 15 is between the middle fabric layer 12 and the lower fabric layer 13. The lower spacer layer 15 is formed by connecting the middle fabric layer 12 and the lower fabric layer 13 with lower binding yarns. The warp and weft yarns are POM filaments, and the binding yarns are POM filaments. The diameter of the warp and weft yarns is 0.5 mm, and the diameter of the binding yarns is 2 mm. The interval between adjacent two warp yarns is 2 mm, and the interval between adjacent two weft yarns is 2 mm. The density of the lower binding yarns is twice that of the upper binding yarns. During the weaving process, the warp yarns and the binding yarns are all led out from the creel. The yarn splitting is divided into five layers: upper warp yarns, upper binding yarns, middle warp yarns, lower binding yarns, and lower warp yarns. Among them, the upper, middle, and lower warp yarns are controlled by the heald frames where the three-eye healds are located, and the upper and lower binding yarns are controlled by the heald frames where the double-eye healds are located. The heald frames move up and down alternately to form a fell of cloth. Then, the upper weft yarns are introduced by the rapier weft insertion device. After placing the spacers, the middle weft yarns are beaten into the fell of cloth by the steel foil, and after placing the spacers, the lower weft yarns are beaten into the fell of cloth by the steel foil to realize the interweaving of the three-layer spacer fabric.

[0029] The structural schematic diagram of the three-layer spacer fabric is as Figure 1 and Figure 2As shown, the three-layer spacer fabric is composed of upper, middle and lower fabric layers, and each adjacent two fabric layers are connected by warp binder yarns, with two spacer layers. The weave of the fabric layer is plain weave. The upper warp yarns 1 and 2 are interwoven with the upper weft yarn Ⅰ to form the upper fabric layer 11. The middle warp yarns 3 and 4 are interwoven with the middle weft yarn Ⅱ to form the middle fabric layer 12. The lower warp yarns 5 and 6 are interwoven with the lower weft yarn Ⅲ to form the lower fabric layer 13. After the upper binder yarn a passes through above the upper weft yarn Ⅰ, it then passes through below the middle weft yarn Ⅱ, alternating repeatedly. The upper binder yarn c passes through below the middle weft yarn Ⅱ and then passes through above the upper weft yarn Ⅰ, alternating repeatedly. The lower binder yarn b passes through above the middle weft yarn Ⅱ and then passes through below the lower weft yarn Ⅲ, alternating repeatedly. The lower binder yarn d passes through below the lower weft yarn Ⅲ and then passes through above the middle weft yarn Ⅱ, alternating repeatedly. The density of the lower binder yarn is twice that of the upper binder yarn. The lower binder yarn is interwoven with the middle weft yarn and the lower weft yarn more times. That is, the upper binder yarn continuously passes through above two upper weft yarns and then continuously passes through below two middle weft yarns, forming a smaller binder yarn density. The weft yarn in the binder point exerts a bending moment on the binder yarn. Two adjacent binder points exert a pair of bending moments with opposite directions on the binder yarn, making the binder yarn present an "S" structure, and the "S" shaped structures of adjacent binder yarns are opposite in direction. From the side view of the fabric, it is an "8" shaped structure.

[0030] (2) Prepare foamed concrete slurries with different relative foaming volumes

[0031] The foamed concrete slurry includes cement, foaming agent, foam stabilizer, and water reducer; the cement is 42.5 grade rapid hardening sulphoaluminate cement; the foaming agent is hydrogen peroxide; the foam stabilizer is silicone resin polyether emulsion (MPS); the water reducer is naphthalene-based high-efficiency water reducer.

[0032] Mix 400 kg / m 3 cement, 0.32 kg / m 3 foam stabilizer, 1.92 kg / m 3 water reducer and 240 kg / cm 3 water evenly, and control the slurry temperature, stirring continuously for 3 min; stir in 5%, 7%, 9% hydrogen peroxide and continue stirring for 30 s to obtain foamed concrete slurries with relative foaming volumes of 40.35%, 52.1%, and 61.3% respectively. The relative foaming volume is the ratio of the difference between the volume after foaming and the volume before foaming to the volume before foaming.

[0033] (3) Layered pouring

[0034] Place the lower fabric layer of the three-layer spacer fabric at the bottom of the mold, i.e., the denser spacer layer is at the bottom and the looser spacer layer is at the top in the upper part of the mold to facilitate the downward flow of foamed concrete; pour foamed concrete slurry with a relative foaming volume of 40.35% into the mold, and the pouring volume is determined according to embedding the lower fabric layer. Then pour foamed concrete slurry with a relative foaming volume of 40.35% to completely immerse the lower fabric layer; pour foamed concrete with a relative foaming volume of 61.3% into the lower spacer layer, and after initial setting, immerse the middle fabric layer with foamed concrete with a relative foaming volume of 61.3%; pour foamed concrete with a relative foaming volume of 52.1% into the upper spacer layer, and after initial setting, immerse the upper fabric layer with foamed concrete with a relative foaming volume of 52.1%; after pouring is completed, cover it with a film for sealing, demold, and cure for 28 days to obtain the finished product.

[0035] Example 2

[0036] Same as Example 1, the differences are as follows:

[0037] The warp and weft yarns are PET filaments, and the binding yarn is PET filament. The diameters of the warp and weft yarns are 0.3 mm, and the diameter of the binding yarn is 1.5 mm. The spacing between adjacent two warp yarns is 5 mm, and the spacing between adjacent two weft yarns is 5 mm. The density of the lower binding yarn is 3 times that of the upper binding yarn.

[0038] Comparative Example 1

[0039] This comparative example is prepared by pouring foamed concrete slurry with a relative foaming volume of 52.1% according to the dimensions of Example 1 without using a multi-layer spacer fabric for reinforcement.

[0040] Comparative Example 2

[0041] Same as Example 1, the differences are as follows: The foamed concrete slurry with a relative foaming volume of 52.1% is directly poured without using layered pouring.

[0042] Comparative Example 3

[0043] Same as Example 1, the differences are as follows: The densities of the upper and lower binding yarns are the same and the sum of the densities is equal to the sum of the densities of the upper and lower binding yarns in Example 1.

[0044] Carry out test analysis on the compressive strength and thermal conductivity of Examples 1 - 2 and Comparative Examples 1 - 3. Refer to GB / T11969 - 2008 for compressive strength detection. For a cuboid with dimensions of 100 mm × 50 mm × 30 mm, the fabric layer of the foamed concrete with the lowest relative foaming volume is used as the directly stressed surface; the thermal conductivity is carried out with reference to GB / T 10294 - 2008 "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Guarded Hot Plate Method", and the results are shown in Table 1.

[0045] Table 1 Performance test results of examples and comparative examples

[0046] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Compressive strength / MPa 11.21 10.32 0.318 8.54 9.86 <![CDATA[Thermal conductivity / W·m -1 ·K -1 > 0.079 0.082 0.090 0.121 0.098

[0047] As can be seen from Table 1, in Examples 1-2, a multi-layer spacer structure with a density gradient is adopted, and the spacer fabric-reinforced foamed concrete prepared by pouring foamed concrete slurry with a relative volume gradient of foam by a layered pouring method has high compressive strength and low thermal conductivity.

[0048] Compared with Comparative Example 1, in Example 1, through the selection of fabric yarns and the design of the structure, the compressive strength is increased by more than 1600% compared with pure foamed concrete, and the thermal conductivity is also better than that of pure foamed concrete. Since the POM filaments used in Example 1 have a small thermal conductivity, and at the same time, a large number of pores are avoided from collapsing during the layered pouring process, and the porosity is high.

[0049] Compared with Comparative Example 2, the compressive strength of Comparative Example 2 is small and the thermal conductivity is high. In Comparative Example 2, due to direct pouring, the foamed concrete slurry is prone to collapse, the number of pores becomes less and the pore diameter becomes smaller, resulting in a large increase in the thermal conductivity, thus affecting the heat insulation effect. In addition, in anticipation, the compressive strength is good, but due to the poor fluidity of the concrete slurry and the poor interfacial bonding force between the fabric layer and the concrete slurry, the compressive strength of the whole material decreases.

[0050] Compared with Comparative Example 3, Example 1 has greater compressive strength and lower thermal conductivity. Since the binding yarns are evenly distributed in the whole spacer fabric and the foamed concrete is easier to flow down along the binding yarns during pouring, the filling is relatively uniform and there are no large-pore-sized pores. Therefore, in anticipation, the compressive strength is large. However, in reality, during the three-point bending test, since the density of the lower-layer binding yarns in Comparative Example 3 is less than that of the lower-layer binding yarns in Example 1, and the compressive strength of the area with a small density directly bearing the external force is poor, the compressive strength of the whole Comparative Example 3 decreases; moreover, the thermal conductivity of Comparative Example 3 is high, which may be because when the density of the binding yarns is small, the pores are rounder and higher and are relatively evenly distributed. As the density of the binding yarns increases, the pore uniformity of the foamed concrete becomes worse, and pore collapse occurs. The number of small-pore-sized pores changes little with the increase in the density of the binding yarns, and the number of large-pore-sized pores decreases with the increase in the density of the binding yarns. In Example 1, since the spacer layer with a small density of binding yarns can retain a certain number of large pores, the thermal conductivity is lower.

[0051] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A preparation method of a multi-layer spacer fabric-reinforced foamed concrete material, characterized in that, It includes the following steps: preparing a multi-layer spacer fabric, preparing foamed concrete slurries with different relative foaming volumes, and pouring in layers. Among them, the multi-layer spacer fabric is a multi-interval layer structure composed of at least three fabric layers, and each adjacent two fabric layers are connected by binding yarns. The density of the binding yarns in each interval layer is different and decreases in a gradient from bottom to top; the layer-by-layer pouring is to pour the foamed concrete slurry with the lowest relative foaming volume in a mold, embed the lowermost fabric layer of the multi-layer spacer fabric, then pour the foamed concrete slurry with the lowest relative foaming volume to completely immerse the lowermost fabric layer. After that, the relative foaming volumes of the foamed concrete slurries poured in each interval layer are different and decrease in a gradient from bottom to top. The fabric layer above each interval layer has the same relative foaming volume as the adjacent interval layer below it. After pouring and post-treatment, a finished product is obtained.

2. The preparation method according to claim 1, characterized in that, The density of the binding yarns in each interval layer is 1.5 to 3 times that of the adjacent interval layer above it; the relative foaming volume used in each interval layer is 1.1 to 1.3 times that of the adjacent interval layer above it; the relative foaming volume used in the lowermost fabric layer is 50 to 70% of the relative foaming volume used in the adjacent fabric layer above it.

3. The preparation method according to claim 1, characterized in that, The fabric layer is woven from warp yarns and weft yarns in a plain weave. The interval between two adjacent warp yarns is 1 to 10 mm, and the spacing between two adjacent weft yarns is 1 to 10 mm.

4. The preparation method according to claim 1, characterized in that, The warp yarns and weft yarns of the fabric layer are POM, PET or UHMEPE filaments; the binding yarns are POM or PET filaments.

5. The preparation method according to claim 3, characterized in that, The diameters of the warp yarns and weft yarns are 0.1 to 1 mm, and the diameter of the binding yarns is 2 to 5 times the diameter of the warp yarns.

6. The preparation method according to claim 1, characterized in that, The multi-layer spacer fabric is a three-layer spacer fabric. The three-layer spacer fabric consists of upper, middle and lower fabric layers. The upper fabric layer and the middle fabric layer are connected by upper binding yarns, and the middle fabric layer and the lower fabric layer are connected by lower binding yarns.

7. The preparation method according to claim 1, characterized in that, The post-treatment is to cover and seal with a film, demold, and cure for 28 days to obtain a finished product.

8. The preparation method according to claim 1, characterized in that, The foamed concrete slurry includes cement, foaming agent, foam stabilizer, water reducer; the cement is 42.5-grade rapid-hardening sulphoaluminate cement; the foaming agent is hydrogen peroxide.

9. A multi-layer spacer fabric-reinforced foamed concrete material, characterized in that, It is prepared by using the method according to any one of claims 1 to 8.

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