Complex special-shaped structure thin-shell floor support plate sprayed concrete material

Abstract

The invention belongs to the technical field of cement-based materials, and particularly discloses a complex special-shaped structure thin-shell floor support plate sprayed concrete material which comprises the following components in parts by weight: 450-550 parts of river sand, 150-200 parts of gravel, 180-220 parts of Portland cement, 20-25 parts of mineral powder, 10-15 parts of silica fume, 10-15 parts of microbead fly ash, 20-25 parts of an expanding agent and 12-18 parts of redispersible rubber powder. The concrete is prepared from the following components in parts by weight: 0.4 to 0.6 part of polycarboxylate superplasticizer, 0.5 to 1.0 part of cellulose ether, 0.15 to 0.20 part of plastic expanding agent, 0.25 to 0.35 part of defoaming agent, 0.75 to 1.0 part of retarder and 100 to 110 parts of water. According to the invention, the river sand with good grading is adopted, so that the material still has good pumping performance under small slump, the microbead fly ash is added to improve the fluidity, the silica fume is adopted to improve the compactness and impermeability of the material, and the rubber powder is added to improve the adhesive property and bending strength of the material. The thin-shell floor support plate sprayed concrete material with the complex special-shaped structure, provided by the invention, has excellent comprehensive performance.

Description

Technical Field

[0001] The invention belongs to the technical field of cement-based materials, and in particular relates to a sprayed concrete material for a thin-shell floor deck with a complex and special-shaped structure. Background Art

[0002] Shotcrete for thin shell floor slabs with complex and special-shaped structures is a new type of building material with excellent construction performance, mechanical properties and durability. It is a material made of high-performance powder, minerals and chemical additives, and can be used for a variety of special-shaped structures and reinforced structures that are not easy to support formwork.

[0003] Domestic shotcrete is often used to pour tunnel linings, walls, ceilings and other thin-walled structures or other structural linings as well as protective layers of steel structures. This type of shotcrete is added with an accelerator during spraying, so that the concrete solidifies instantly when it is sprayed onto the sprayed surface, generating strength to achieve the purpose of fixing it on the sprayed surface. However, the disadvantages of this type of shotcrete are low strength, difficulty in spraying densely, and the surface cannot be modified.

[0004] The sprayed concrete of thin-shell floor slab with complex and special-shaped structure is a kind of sprayed concrete without adding accelerating agent. Its slump is small, and its performance is best when the slump is 70-90mm. It is fixed on the sprayed surface by its own bonding performance. Its aggregate gradation requirements are high, and it is supplemented by adding materials such as micro beads to promote its sliding performance, so that it has excellent pumping performance at a small slump. When the concrete is sprayed to the sprayed surface, it will not solidify instantly because no accelerating agent is added. At this time, the sprayed concrete has good sliding performance and can fill the gaps in the steel bars under the spraying pressure to achieve good density.

[0005] The sprayed concrete of thin shell floor slab with complex and special-shaped structure can be used as a kind of structural sprayed concrete. Because of its reasonable aggregate gradation and the use of several cementitious materials with different particle sizes, it has high density and better durability than conventional concrete. In China, this type of sprayed concrete is used less frequently. In foreign construction, this type of sprayed concrete is widely used in various constructions such as residential, factory, and transportation. Art works such as sculptures and rockery are also widely used. Since sprayed concrete has the advantages of fast construction and is suitable for the construction of complex structures, with the development of construction needs, this type of sprayed concrete will be widely used in various constructions. Summary of the invention

[0006] Based on the advantages and application prospects of shotcrete for thin-shell floor decking with complex and special-shaped structures, the purpose of the present invention is to provide a new type of shotcrete material for thin-shell floor decking with complex and special-shaped structures with excellent comprehensive performance, so as to provide more high-quality choices for the use of such materials in various constructions. The shotcrete material for thin-shell floor decking with complex and special-shaped structures provided by the present invention has a small slump of the mixture, and is fixed on the sprayed surface by the bonding properties of the material itself during the spraying construction. By improving the aggregate grading and adding cementitious materials that can improve the flow properties, the concrete material still has good pumping performance at a smaller slump, adding retarders to achieve a slump-preserving effect, and adding glue powder to improve the bonding properties and flexural strength of the material.

[0007] In order to achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0008] A shotcrete material for a thin-shell floor deck with a complex and special-shaped structure, comprising the following components in parts by weight:

[0009]

[0010] The micro-bead fly ash is a kind of ultra-fine fly ash, and its particles are in the shape of round glass, and have a ball effect to improve the flowability of the material. The mixture of the retarder, cellulose ether, redispersible latex powder, defoamer, and plastic expansion agent is added as an admixture, which can ensure that the material does not have early plastic cracking on the basis of meeting the strength and construction performance.

[0011] Preferably, the river sand is composed of 50-150 mesh river sand and 0-5mm continuously graded river sand mixed in a ratio of 1:5.

[0012] Preferably, the crushed stone is 5-10 mm continuously graded crushed stone with rounded particles, which helps to improve the concrete pumping performance.

[0013] Preferably, the silicate cement is PO 42.5 ordinary silicate cement.

[0014] Preferably, the mineral powder is S95 mineral powder.

[0015] Preferably, the SiO 2 The content reaches 95%, and its particles are finer, about 50 times finer than cement, and the specific surface area can reach 15000m 2 / kg, which can fill the gaps between cement and increase the density and cohesion of the material.

[0016] Preferably, the expansion agent is a UEA expansion agent, which can compensate for the shrinkage of the material after hardening and is not prone to cracking.

[0017] Preferably, the redispersible latex powder is a water-soluble white or off-white flowable powder, a copolymer of ethylene and vinyl acetate, with polyvinyl alcohol as a protective colloid, and the compressive strength ratio of the tested mortar is not less than 70%, the tensile bonding strength ratio is not less than 140%, and the chloride ion penetration resistance is not more than 25%. The latex powder can improve the bonding performance of gypsum materials.

[0018] Preferably, the water reducer is a polycarboxylic acid high performance water reducer with a water reduction rate ≥ 25%, a 1d compressive strength ratio ≥ 170%, a 3d compressive strength ratio ≥ 160%, and a 28d compressive strength ratio ≥ 140%.

[0019] Preferably, the cellulose ether is a polymer compound with an ether structure made of cellulose, specifically hydroxymethyl cellulose ether, which has water retention, can increase the anti-sagging performance of gypsum self-leveling, and has a viscosity of 400 Pa.s.

[0020] Preferably, the plastic expansion agent is polyurethane, which can generate tiny bubbles in the plastic stage of concrete, causing it to expand slightly.

[0021] Preferably, the defoaming agent is an organosilicon defoaming agent, specifically polydimethylsiloxane, the defoaming time should be no more than 60s, and the antifoaming performance should be ≤200S.

[0022] The present invention has the following beneficial effects:

[0023] (1) The shotcrete material of the thin-shell floor slab with complex special-shaped structure of the present invention is a mixture of 50-150 mesh river sand and 0-5mm continuously graded river sand in a ratio of 1:5. The reasonable grading plays a major role in the pumping performance of the shotcrete.

[0024] (2) The sprayed concrete material of the thin-shell floor slab with complex special-shaped structure of the present invention adopts micro-bead fly ash, which is a kind of ultra-fine fly ash. Its particles are in the shape of round glass and have a ball effect, which can improve the flowability of the material.

[0025] (3) The sprayed concrete material of the thin-shell floor slab with complex special-shaped structure of the present invention adopts silica fume, which can increase the density of the material and improve the durability of the material such as impermeability.

[0026] (4) The sprayed concrete material of the thin-shell floor slab with complex special-shaped structure of the present invention adopts glue powder, which can increase the bonding performance and flexural strength of the material on the basis of meeting the strength and construction performance.

[0027] (5) The addition of cellulose ether to the sprayed concrete material of the thin-shell floor slab with complex special-shaped structure of the present invention can increase the water retention of the material and improve the cohesiveness of the material on the basis of meeting the basic performance requirements.

[0028] (6) Adding a defoaming agent to the sprayed concrete material of the thin-shell floor slab with a complex and special-shaped structure of the present invention can eliminate bubbles inside the material, improve the density of the material, and increase the strength.

[0029] In summary, the complex and special-shaped thin-shell floor decking sprayed concrete material of the present invention is green and environmentally friendly, has strong bonding strength, small shrinkage, convenient construction, good workability, good water retention and workability, fast strength growth, and can save construction time. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments.

[0031] The raw materials and parameters used in the following examples and comparative examples are as follows:

[0032] River sand: 50-150 mesh river sand and 0-5mm continuous graded river sand are mixed in a ratio of 1:5;

[0033] Crushed stone: 5-10mm continuous graded crushed stone;

[0034] Portland cement: PO 42.5 ordinary Portland cement;

[0035] Mineral powder: S95 mineral powder;

[0036] Silica fume: SiO 2 The content reaches 95% and the specific surface area reaches 15000m 2 / kg;

[0037] Expanding agent: UEA expander;

[0038] Redispersible rubber powder: The compressive strength ratio of the tested mortar shall not be less than 70%, the tensile bond strength ratio shall not be less than 140%, and the chloride ion penetration resistance shall not be greater than 25%;

[0039] Polycarboxylate water reducer: water reduction rate ≥ 25%, 1d compressive strength ratio ≥ 170%, 3d compressive strength ratio ≥ 160%, 28d compressive strength ratio ≥ 140%;

[0040] Cellulose ether: hydroxymethyl cellulose ether, viscosity 400Pa.s;

[0041] Plastic expansion agent: polyurethane;

[0042] Defoaming agent: polydimethylsiloxane, defoaming time is not more than 60s, antifoaming performance is ≤200S.

[0043] In the following examples, the raw materials are mixed and stirred evenly to obtain the shotcrete material of the thin shell floor slab with complex special-shaped structure. The specific operation steps are: first add fine aggregate (river sand), then add cementitious materials (Portland cement, mineral powder, silica fume, micro-bead fly ash) in sequence, stir for 1 minute, then add admixtures (expansion agent, redispersible rubber powder, polycarboxylic acid water reducer, cellulose ether, plastic expansion agent, defoamer, retarder) in sequence, stir for 5 minutes, then add coarse aggregate (crushed stone), stir for 1 minute, then add water, and stir for 3 minutes.

[0044] Example 1

[0045] The shotcrete material of the complex special-shaped thin-shell floor deck of this embodiment includes the following components in parts by weight:

[0046]

[0047]

[0048] Example 2

[0049] The shotcrete material of the complex special-shaped thin-shell floor deck of this embodiment includes the following components in parts by weight:

[0050]

[0051] Example 3

[0052] The shotcrete material of the complex special-shaped thin-shell floor deck of this embodiment includes the following components in parts by weight:

[0053]

[0054] Example 4

[0055] The shotcrete material of the complex special-shaped thin-shell floor deck of this embodiment includes the following components in parts by weight:

[0056]

[0057] Example 5

[0058] The shotcrete material of the complex special-shaped thin-shell floor deck of this embodiment includes the following components in parts by weight:

[0059]

[0060] The component contents of the shotcrete materials of the thin shell floor slabs with complex special-shaped structures in various embodiments are summarized in Table 1 below:

[0061] Table 1

[0062]

[0063]

[0064] The physical property test results of the shotcrete materials of the thin shell floor decking with complex and special-shaped structures in various embodiments are shown in Table 2 below:

[0065] Table 2

[0066] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Standard requirements 1h slump loss (mm) 50 30 20 20 10 ≤20 Compressive strength(Mpa) 39 40 41 42 36 ≥35 Bond strength(Mpa) 1.2 1.4 1.6 1.6 1.7 ≥1.5 Flexural strength(Mpa) 4.1 4.2 4.5 4.5 4.6 ≥4.2 Shrinkage rate (%) -0.36 -0.18 -0.12 +0.15 +0.30 ≥0

[0067] In Example 1, no retarder is added, and the slump loss in 1 hour is large; in Example 2, 0.5 parts of tartaric acid retarder are added, and the slump loss in 1h is reduced, but it does not meet the design requirements; in Example 3, 0.75 parts of retarder are added, and the slump loss in 1 hour is 20mm, which meets the design requirements; the data show that when 12 parts or more of rubber powder are added, the bonding strength and flexural strength meet the design requirements. The test data of Example 4 show that when 25 parts of UEA expansion agent and 0.20 plastic expansion agent are added, the concrete shrinkage value is positive, that is, it does not shrink. The area of ​​the thin shell structure reaches, the concrete thickness is small, and the concrete does not shrink, so as to ensure that the thin shell structure sprayed concrete does not crack. The test results of Example 5 show that when the retarder in the material is increased, the slump loss in 1h is lower, but the strength is also reduced. When the amount of rubber powder is increased, the bonding strength and flexural strength are improved. When the amount of expansion agent is increased, its shrinkage value is also reduced. Examples 3 and 4 belong to the formulations within the protection scope of the present invention. Compared with the other three comparative examples 1, 2 and 5, the comprehensive performance is better, and Example 4 has the best performance.

[0068] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A shotcrete material for thin-shell floor decking with complex and special-shaped structures, characterized by: It includes the following components in parts by weight:

2. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1 is characterized by: The river sand is composed of 50-150 mesh river sand and 0-5mm continuously graded river sand mixed in a ratio of 1:

5.

3. The complex and special-shaped thin-shell floor deck sprayed concrete material according to claim 1 is characterized by: The crushed stone is 5-10 mm continuously graded crushed stone.

4. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1 is characterized by: The silicate cement is PO 42.5 ordinary silicate cement; the mineral powder is S95 mineral powder.

5. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1 is characterized by: The SiO2 content of the silica fume reaches 95% and the specific surface area reaches 15000m 2 / kg.

6. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1 is characterized by: The expansion agent is a UEA expansion agent, and the plastic expansion agent is polyurethane.

7. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1 is characterized by: The redispersible latex powder is a copolymer of ethylene and vinyl acetate, and its compressive strength ratio of the tested mortar is not less than 70%, its tensile bonding strength ratio is not less than 140%, and its chloride ion penetration resistance is not more than 25%.

8. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1 is characterized by: The polycarboxylate water reducer has a water reduction rate of ≥25%, a 1d compressive strength ratio of ≥170%, a 3d compressive strength ratio of ≥160%, and a 28d compressive strength ratio of ≥140%.

9. The complex and special-shaped thin-shell floor deck sprayed concrete material according to claim 1 is characterized by: The cellulose ether is hydroxymethyl cellulose ether, and the viscosity is 400 Pa.s.

10. The complex and special-shaped thin-shell floor slab sprayed concrete material according to claim 1, characterized in that: The defoaming agent is an organosilicon defoaming agent, specifically polydimethylsiloxane, the defoaming time is no more than 60s, and the antifoaming performance is ≤200S.

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