Regenerated lightweight concrete and preparation method thereof

Abstract

According to the recycled lightweight concrete and the preparation method thereof provided by the invention, the recycled lightweight concrete is formed by mixing the waste insulation board, the concrete, the water, the cement, the fly ash, the mineral powder and other materials, and is used for preparing non-bearing filling building blocks in a building structure, so that the density of the concrete is remarkably reduced, and the strength of the lightweight concrete is improved; and the resource utilization of building and industrial wastes is realized, the exploitation of natural resources such as natural gravels is effectively saved, the carbon emission of the concrete can be obviously reduced, and the purpose of green and low-carbon development of the concrete is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of green recycled concrete, and specifically relates to recycled lightweight concrete and a preparation method thereof. Background Art

[0002] Infill blocks are a type of material used for building infill walls, usually made of lightweight materials such as autoclaved aerated concrete, lightweight aggregate concrete, etc. At present, the commonly used infill blocks on the market are mostly solid bricks or hollow blocks made of low-strength cement concrete, concrete with ceramsite lightweight aggregate or polystyrene particles, etc. In addition to being heavy, their production costs are also high. For structures with large storeys or volumes, this will undoubtedly increase the extra weight of the structure and the overall construction cost.

[0003] Therefore, the cost and quality of current lightweight concrete still need to be improved. Summary of the invention

[0004] The invention provides a recycled lightweight concrete and a preparation method thereof, which are used to solve the problems of high cost and heavy weight of lightweight concrete in the prior art.

[0005] In a first aspect, the present invention provides a recycled lightweight concrete, wherein the raw materials of the recycled lightweight concrete include, by mass: 180-220 parts of cement, 30-100 parts of mineral powder, 20-60 parts of fly ash, 400-800 parts of aggregate, 160-190 parts of water, and 4-7 parts of waste insulation board particles.

[0006] Compared with the prior art, the advantages of the present invention are as follows: waste insulation boards and concrete are mixed with water, cement, fly ash, mineral powder and other materials to form recycled lightweight concrete, which is used to prepare non-load-bearing filling blocks in building structures, significantly reducing the density of concrete and increasing the strength of lightweight concrete; and realizing the resource utilization of construction and industrial waste, effectively saving the exploitation of natural resources such as natural sand and gravel, while also significantly reducing concrete carbon emissions, achieving the goal of green and low-carbon development of concrete.

[0007] Furthermore, the aggregate is waste concrete particles, and the particle size of the waste concrete particles is not greater than 4.75 mm.

[0008] Furthermore, the waste insulation board particles are scraps or defective products of insulation boards attached to prefabricated concrete wall panels; and / or,

[0009] The waste insulation board particles include at least one of polystyrene, extruded polystyrene and polyurethane.

[0010] Furthermore, the particle size of the waste insulation board particles is 5 to 15 mm; and / or,

[0011] The density of the waste insulation board particles is 0.03-1.1 g / cm 3 and / or,

[0012] The thermal conductivity of the waste insulation board particles is no higher than 0.03w / (mk).

[0013] Furthermore, the cement is 42.5 ordinary Portland cement.

[0014] Furthermore, the mineral powder is S95 grade mineral powder.

[0015] Furthermore, the fly ash is grade II fly ash.

[0016] Furthermore, the compressive strength of the recycled lightweight concrete at 28 days is not less than 1 MPa, the splitting strength is not less than 0.4 MPa, the thermal conductivity is not higher than 0.3 W / (m·K), and the density is not higher than 800 kg / m 3 , the antifreeze index is not less than D25.

[0017] In a second aspect, the present invention provides a method for preparing the recycled lightweight concrete according to the first aspect, comprising the following steps:

[0018] (1) subjecting cement, mineral powder, fly ash and aggregate to a first mixing process to obtain a gel material;

[0019] (2) adding water to the gel material for a second stirring treatment to obtain cement mortar;

[0020] (3) Adding waste insulation board particles into the cement mortar for a third mixing process, and then vibrating and pressing to obtain the recycled lightweight concrete.

[0021] Furthermore, the first stirring process is performed using a single-shaft mixer, with a stirring speed of 40 to 50 rpm and a stirring time of 30 to 40 s; and / or,

[0022] The second stirring treatment is carried out using a single-horizontal shaft mixer, with a stirring speed of 40 to 50 rpm and a stirring time of 90 to 100 s; and / or,

[0023] The third mixing process is carried out using a single-horizontal-shaft mixer with a mixing speed of 40 to 50 rpm and a mixing time of 120 to 130 s. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In a first aspect, the present invention provides a recycled lightweight concrete, wherein the raw materials of the recycled lightweight concrete include, by mass, 180-220 parts of cement, 30-100 parts of mineral powder, 20-60 parts of fly ash, 400-800 parts of aggregate, 160-190 parts of water, and 4-7 parts of waste insulation board particles.

[0026] The recycled lightweight concrete provided by the present invention is formed by mixing waste insulation boards and concrete with water, cement, fly ash, mineral powder and other materials, and is used to prepare non-load-bearing filling blocks in building structures, which significantly reduces the density of concrete and increases the strength of lightweight concrete; and realizes the resource utilization of construction and industrial waste, effectively saves the exploitation of natural resources such as natural sand and gravel, and can also significantly reduce the carbon emissions of concrete, thereby achieving the goal of green and low-carbon development of concrete.

[0027] Furthermore, the aggregate is waste concrete particles, and the particle size of the waste concrete particles is not greater than 4.75 mm.

[0028] By crushing and screening waste concrete and using it as recycled aggregate for recycled lightweight concrete, the cost of concrete can be further reduced and the strength can be improved. By limiting the particle size of the aggregate, the structural quality of the concrete can be further improved, which helps to improve the durability and strength of the concrete. Generally, aggregates include natural aggregates such as crushed stone, pebbles, pumice, and natural sand, as well as artificial aggregates such as coal slag, slag, ceramsite, expanded perlite, and industrial waste slag aggregates (metallurgical slag, etc.).

[0029] Furthermore, the waste insulation board particles of the present invention are scraps or defective products of insulation boards attached to prefabricated concrete wall panels.

[0030] It can be understood that in the actual production process, the prefabricated concrete component factory is affected by factors such as component size, sample self-inspection, and preparation process, and a certain amount of waste insulation board scraps and waste concrete will be generated every day. The commonly used treatment method at present is mainly centralized stacking and external transportation, which is not only time-consuming and labor-intensive, but also causes a lot of resource waste to a large extent. At the same time, the landfill treatment method will also cause environmental, land and groundwater resource pollution to a certain extent. The present invention uses waste insulation boards in lightweight concrete, realizes the resource utilization of construction and industrial waste, effectively saves the exploitation of natural resources such as natural sand and gravel, and further reduces concrete carbon emissions.

[0031] Specifically, the waste insulation board particles include at least one of polystyrene, extruded polystyrene and polyurethane.

[0032] Furthermore, the particle size of the waste insulation board particles is 5 to 15 mm; the density of the waste insulation board particles is 0.03 to 1.1 g / cm 3 ; The thermal conductivity of the waste insulation board particles is not higher than 0.03w / (mk).

[0033] Waste insulation board mainly plays the role of skeleton and filling inside concrete, which is used to reduce the weight of recycled concrete blocks. By further defining the relevant performance parameters of waste insulation board, it is helpful to further reduce the density of concrete and improve the compressive strength of concrete.

[0034] Optionally, the cement is 42.5 ordinary Portland cement, the mineral powder is S95 grade mineral powder, and the fly ash is grade II fly ash.

[0035] Furthermore, the compressive strength of the recycled lightweight concrete at 28 days is not less than 1 MPa, the splitting strength is not less than 0.4 MPa, the thermal conductivity is not higher than 0.3 W / (m·K), and the density is not higher than 800 kg / m 3 , the antifreeze index is not less than D25.

[0036] In a second aspect, the present invention provides a method for preparing the recycled lightweight concrete according to the first aspect, comprising the following steps:

[0037] (1) subjecting cement, mineral powder, fly ash and aggregate to a first mixing process to obtain a gel material;

[0038] (2) adding water to the gel material for a second stirring treatment to obtain cement mortar;

[0039] (3) Adding waste insulation board particles into the cement mortar for a third mixing process, and then vibrating and pressing to obtain the recycled lightweight concrete.

[0040] Furthermore, the first stirring process is performed using a single-horizontal shaft mixer with a stirring speed of 45 rpm and a stirring time of 30 s;

[0041] The second mixing process is carried out using a single-horizontal shaft mixer with a mixing speed of 45 rpm and a mixing time of 90 s;

[0042] The third mixing process is carried out using a single-horizontal-shaft mixer with a mixing speed of 45 rpm and a mixing time of 120 s.

[0043] In a specific embodiment, the required amount of each component is calculated according to the concrete mix ratio, and the weighed cement, mineral powder, fly ash and recycled fine aggregate are first poured into a mixer and mixed evenly; then water is added into the mixer at once and fully mixed with the adhesive and fine aggregate to make cement mortar; finally, the weighed waste insulation board particles are added into the mixer and fully mixed with the cement mortar. When the surface of the insulation particles is evenly coated with mortar, the stirring, discharging, vibrating, pressing and forming can be stopped, and the particles can be naturally cured for 28 days before use in construction.

[0044] Hereinafter, the recycled lightweight concrete provided by the present invention is introduced in detail through specific embodiments.

[0045] Example 1

[0046] (1) 212 parts of cement, 65 parts of mineral powder, 49 parts of fly ash and 500 parts of aggregate (waste concrete particles) are subjected to a first mixing process to obtain a gel material;

[0047] (2) adding 182 parts of water to the gel material and performing a second stirring process to obtain a cement mortar;

[0048] (3) Add 5.8 parts of waste insulation board particles (polystyrene) to the cement mortar, perform a third stirring process, and then perform a vibration and compression molding process to obtain the recycled lightweight concrete

[0049] The particle size of the waste insulation board particles is a continuous gradation of 5-15 mm, and the density of the waste insulation board particles is 0.036 g / cm 3 The thermal conductivity of the waste insulation board particles is 0.02w / (mk).

[0050] Example 2

[0051] The difference between this embodiment and embodiment 1 is that the particle size of the waste insulation board particles is a single-graded particle size of 18 mm.

[0052] Example 3

[0053] The difference between this embodiment and embodiment 1 is that the density of the waste insulation board particles is 1.16 g / cm3 .

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that no waste insulation board particles are added.

[0056] Test Example 1

[0057] The concrete prepared in the above examples and comparative examples was subjected to performance tests, and the test results are shown in Table 1.

[0058] Table 1

[0059]

[0060] The present invention uses waste insulation board particles, recycled fine aggregate, mineral powder, fly ash and other construction and industrial solid wastes in the concrete mix. The materials, production and maintenance processes used are all conventional materials and equipment, and there is no need to transform and upgrade existing production equipment. The applicability and operability are convenient, and while improving the utilization rate of solid waste and reducing carbon emissions, the purpose of reducing costs and increasing efficiency for enterprises is achieved. Compared with traditional concrete blocks, the present invention not only meets the strength required for construction, but is also lighter in weight, and can meet the construction of large-span and super-high-rise buildings or structures with stricter self-weight control.

[0061] The porous waste insulation board particles are mixed in, which not only reduces the weight and the labor intensity of workers, but also has a smaller thermal conductivity coefficient due to the hollow structure, and the overall insulation effect is better than that of the traditional concrete block structure.

[0062] The porous structure of the waste insulation board particles themselves can also provide an adsorption carrier for the subsequent internal addition of functional admixtures that require a slow-release effect. Therefore, the present invention has more in-depth development and research value than ordinary concrete.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the protection scope of the present invention.

Claims

1. A recycled lightweight concrete, characterized in that: The raw materials of the recycled lightweight concrete include, by mass, 180-220 parts of cement, 30-100 parts of mineral powder, 20-60 parts of fly ash, 400-800 parts of aggregate, 160-190 parts of water, and 4-7 parts of waste insulation board particles.

2. The recycled lightweight concrete according to claim 1, characterized in that: The aggregate is waste concrete particles, and the particle size of the waste concrete particles is not greater than 4.75 mm.

3. The recycled lightweight concrete according to claim 1, characterized in that: The waste insulation board particles are scraps or defective products of insulation boards attached to prefabricated concrete wall panels; and / or, The waste insulation board particles include at least one of polystyrene, extruded polystyrene and polyurethane.

4. The recycled lightweight concrete according to claim 3, characterized in that: The particle size of the waste insulation board particles is 5-15 mm; and / or, The density of the waste insulation board particles is 0.03-1.1 g / cm 3 and / or, The thermal conductivity of the waste insulation board particles is no higher than 0.03w / (mk).

5. The recycled lightweight concrete according to claim 1, characterized in that: The cement is 42.5 ordinary Portland cement.

6. The recycled lightweight concrete according to claim 1, characterized in that: The mineral powder is S95 grade mineral powder.

7. The recycled lightweight concrete according to claim 1, characterized in that: The fly ash is grade II fly ash.

8. The recycled lightweight concrete according to any one of claims 1 to 7, characterized in that: The recycled lightweight concrete has a compressive strength of not less than 1 MPa, a splitting strength of not less than 0.4 MPa, a thermal conductivity of not more than 0.3 W / (m·K), and a density of not more than 800 kg / m 3 , the antifreeze index is not less than D25.

9. A method for preparing recycled lightweight concrete according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) subjecting cement, mineral powder, fly ash and aggregate to a first mixing process to obtain a gel material; (2) adding water to the gel material for a second stirring process to obtain cement mortar; (3) Adding waste insulation board particles into the cement mortar for a third mixing process, and then vibrating and pressing to obtain the recycled lightweight concrete.

10. The method for preparing recycled lightweight concrete according to claim 9, characterized in that: The first stirring process is carried out using a single-horizontal shaft mixer with a stirring speed of 40-50 rpm and a stirring time of 30-40 s; and / or, The second stirring process is carried out using a single-horizontal shaft mixer with a stirring speed of 40-50 rpm and a stirring time of 90-100 s; and / or, The third mixing process is carried out using a single-horizontal-shaft mixer with a mixing speed of 40-50 rpm and a mixing time of 120-130 s.

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