A large flow state super high-rise pumping ceramsite concrete

Abstract

The application relates to the field of green building materials, and discloses a large-flow-state super-high-rise pumped ceramsite concrete, which comprises 487 parts of shale ceramsite, 731 parts of river sand, 555 parts of cementing material, 180 parts of water and 14 parts of polycarboxylic acid type water reducing agent, the shale ceramsite has a bulk density of 758.1 kg / m3, an apparent density of 1430.1 kg / m3 and a maximum particle size of 16 mm. The large-flow-state super-high-rise pumped ceramsite concrete is prepared by using shale ceramsite, the use amount of natural coarse aggregate can be effectively reduced, and the environmental problems such as water and soil loss, dust pollution and vegetation destruction caused by excessive mining of natural coarse aggregate can be relieved.

Description

Technical Field

[0001] This invention relates to the field of green building materials, specifically to a high-flow-rate, ultra-high-rise pumped ceramsite concrete. Background Technology

[0002] Lightweight aggregate concrete (LEC) possesses advantages such as light weight, good durability, fire resistance, and seismic resistance, and is now widely used in high-rise buildings, large-span structures, and offshore platforms with special requirements. However, globally, there are few application cases of LEC in super high-rise buildings, and the pumpability of LEC remains controversial in various countries. Limited research, insufficient experience, and high failure rates are the main problems in pumping LEC in super high-rise buildings. To improve the pumpability of LEC, a common practice is to pre-wet the LEC for 24 hours before mixing. However, experimental results show that the water absorption rate of LEC after 24 hours of pre-wetting is far lower than that under pumping pressure. During pumping, the LEC absorbs excessive water, leading to increased slump loss and eventually pipe blockage. Therefore, we propose a high-flow-rate pumping method for LEC in super high-rise buildings. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a high-flow-rate, ultra-high-rise pumped ceramsite concrete, which solves the aforementioned problems.

[0005] (II) Technical Solution

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a high-flow-rate ultra-high-rise pumpable ceramsite concrete, comprising 487 parts of shale ceramsite, 731 parts of river sand, 555 parts of cementitious material, 180 parts of water, and 14 parts of polycarboxylate superplasticizer.

[0007] The bulk density of shale ceramsite is 758.1 kg / m³. 3 The apparent density is 1430.1 kg / m³. 3 The maximum particle size is 16mm.

[0008] Preferably, the water reduction rate of the polycarboxylate superplasticizer is 20-40%.

[0009] Preferably, the volume of the shale ceramsite accounts for 34.1% of the total volume.

[0010] Preferably, the cementitious material comprises 370 parts cement, 39 parts silica fume, 78 parts mineral powder, 29 parts fly ash, and 39 parts microspheres.

[0011] Preferably, the mass ratio of water to cementitious material is 0.324.

[0012] Preferably, the preparation method of the high-fluidity ultra-high-rise pumped ceramsite concrete is as follows:

[0013] S1: Dissolve the polycarboxylate superplasticizer in water and stir until homogeneous to form a superplasticizer solution;

[0014] S2: Mix the cementitious materials river sand, cement, silica fume, mineral powder, fly ash and microspheres to obtain a mixture, and then mix it with natural river sand to obtain mixture two;

[0015] S2. Add mixture 2 to the mixer, add the water-reducing agent aqueous solution and stir for 30 seconds, then add it to the mixer and stir for 3 minutes. Next, pour the shale ceramsite into the mixing pot and stir for 30 seconds.

[0016] (III) Beneficial Effects

[0017] Compared with the prior art, the present invention provides a high-flow-rate, ultra-high-rise pumped ceramsite concrete, which has the following beneficial effects:

[0018] 1. This high-flow-rate ultra-high-rise pumped ceramsite concrete uses shale ceramsite to prepare concrete, which can effectively reduce the amount of natural coarse aggregate used and alleviate environmental problems such as soil erosion, dust pollution, and vegetation destruction caused by excessive mining of natural coarse aggregate.

[0019] 2. This high-flow-rate ultra-high-rise pumped ceramsite concrete uses shale ceramsite, an engineering material with excellent comprehensive performance. Thanks to its small and non-interconnected internal pores, shale ceramsite is lightweight, high-strength, has excellent impermeability, and low water absorption. It is not easily damaged by pumping pressure during high-pressure pumping, and the increased water absorption of ceramsite under pumping pressure will not cause a significant loss in the flowability of the concrete.

[0020] 3. This high-flow-rate ultra-high-rise pumped ceramsite concrete, based on the excellent performance of shale ceramsite, simultaneously meets the requirements of low density and high strength, making it an excellent choice for the construction of high-rise and ultra-high-rise buildings. It can not only reduce the burden on the substructure, but also expand the functionality of high-rise buildings.

[0021] 4. This high-flow-rate, ultra-high-rise pumped ceramsite concrete is not only of great guiding significance for the development of lightweight aggregate concrete, but also of great significance for improving construction efficiency, mastering new engineering construction methods, promoting the advancement of construction technology, and realizing the lightweight and multifunctional nature of building structures. Attached Figure Description

[0022] Figure 1 This is a macroscopic morphology diagram of the shale ceramsite described in Example 1;

[0023] Figure 2 This is a microscopic morphology diagram of the shale ceramsite described in Example 1;

[0024] Figure 3 This is a diagram of the fresh state of Comparative Example 1 under normal pressure;

[0025] Figure 4 This is a diagram of the fresh state of Comparative Example 2 under normal pressure;

[0026] Figure 5 This is a diagram of the fresh state under normal pressure.

[0027] Figure 6 This is a comparison diagram of the fresh state after full-size field pumping (Example 1).

[0028] Figure 7 This is a comparison diagram of the fresh state after full-size field pumping (Example 2).

[0029] Figure 8 This is a fresh state diagram of the implementation after full-size on-site pumping. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment is a high-flow-rate ultra-high-rise pumpable ceramsite concrete. The raw materials and proportions for the preparation of this material are shown in Table 1, by weight.

[0033] Table 1. Raw material ratios used in Example 1

[0034]

[0035] The shale ceramsite used in this embodiment was produced by Hubei Huiteng Light Aggregate Environmental Protection Products Co., Ltd., with a bulk density of 758.1 kg / m³. 3 The compressive strength of the cylinder is 6.0 MPa; its macroscopic and microscopic morphologies are shown in the attached figures. Figure 1-2 As shown; from the appendix Figure 1 It can be seen from the attached image that the ceramsite has a broken, polygonal morphology; Figure 2 The microscopic morphology diagram shows that most of the pores inside the ceramsite are independent structures, while the outer layer has a protective layer with smaller pores and a denser structure, which can reduce the water absorption rate of the ceramsite to a certain extent.

[0036] In this embodiment, the water-cement ratio refers to the mass ratio of water to cementitious materials, which are cement, silica fume, mineral powder, fly ash, and microspheres.

[0037] In this embodiment, the amount of shale ceramsite used is 34.1% of the concrete volume.

[0038] In this embodiment, the maximum particle size of the shale ceramsite is 16 mm.

[0039] The water-reducing agent used in this embodiment is a polycarboxylate-type high-performance water-reducing agent formulated by Guangzhou Wanyou Concrete Structure Components Co., Ltd., with a water reduction rate of 20-40%.

[0040] The preparation method of high-fluidity ultra-high-rise pumped ceramsite concrete in this embodiment includes the following steps:

[0041] S1. Dissolve 14 parts of polycarboxylate superplasticizer in 180 parts of water, and stir until homogeneous to form a superplasticizer solution;

[0042] 731 parts river sand, 370 parts cement, 39 parts silica fume, 78 parts mineral powder, 29 parts fly ash, and 39 parts microspheres were mixed together.

[0043] S2. Add the mixture of all cement and natural river sand to the mixer. Add the water-reducing agent solution after stirring for 30 seconds and stir for 3 minutes. Then pour the shale ceramsite into the mixing pot and stir for 30 seconds.

[0044] Comparative Example 1

[0045] This comparative example is a shale ceramsite concrete. The raw materials and proportions for the preparation of this material are shown in Table 2 for the mix design.

[0046] Table 2. Raw material ratios used in Comparative Example 1

[0047]

[0048] The shale ceramsite, cement, silica fume, mineral powder, fly ash, microspheres, natural river sand, and water-reducing agent are the same as in Example 1;

[0049] In this comparative example, the amount of shale ceramsite used is 35.0% of the concrete volume.

[0050] The preparation method of the shale ceramsite concrete includes the following steps:

[0051] S1. Dissolve 14 parts of polycarboxylate superplasticizer in 150 parts of water and stir evenly to form a superplasticizer solution; mix 750 parts of river sand, 380 parts of cement, 40 parts of silica fume, 80 parts of mineral powder, 30 parts of fly ash, and 40 parts of microspheres.

[0052] S2. Add the mixture of all cement and natural river sand to the mixer. After stirring the water-reducing agent solution for 30 seconds, add it to the mixer and stir for 3 minutes. Then pour the shale ceramsite into the mixing pot and stir for 30 seconds.

[0053] Comparative Example 2

[0054] This comparative example is a shale ceramsite concrete. The raw materials and proportions for the preparation of this material are shown in Table 3 for the mix design.

[0055] Table 3. Raw material ratios used in Comparative Example 2

[0056]

[0057] The shale ceramsite, cement, silica fume, mineral powder, fly ash, microspheres, natural river sand, and water-reducing agent are the same as in Example 1;

[0058] In this comparative example, the amount of shale ceramsite used is 35.0% of the concrete volume.

[0059] The preparation method of the shale ceramsite concrete includes the following steps:

[0060] S1. Dissolve 14 parts of polycarboxylate superplasticizer in 195 parts of water and stir evenly to form a superplasticizer solution; mix 724 parts of river sand, 367 parts of cement, 39 parts of silica fume, 77 parts of mineral powder, 29 parts of fly ash, and 39 parts of microspheres.

[0061] S2. Add the mixture of all cement and natural river sand to the mixer. Add the water-reducing agent solution after stirring for 30 seconds and stir for 3 minutes. Then pour the shale ceramsite into the mixing pot and stir for 30 seconds.

[0062] Experimental Example

[0063] 1. Performance under normal pressure

[0064] Laboratory workability tests were conducted on Comparative Example 1, Comparative Example 2, and Example 1. The tests included slump tests, spread tests, and observation of segregation and bleeding in the fresh concrete. The workability test results of the concrete obtained from the examples and comparative examples are shown in Table 4.

[0065] Table 4. Test results of workability of shale ceramsite concrete under normal pressure

[0066]

[0067] The slump values ​​in Comparative Example 1, Comparative Example 2, and Example 1 were 240 mm, 250 mm, and 270 mm, respectively, while the slump spreads were 500 mm, 620 mm, and 680 mm, respectively. (See attached image) Figure 3-5 The images show the fresh state of the shale ceramsite concrete in Scale 1, Comparative Scale 2, and Example 1. (See attached image.) Figure 3 It was found that the components of the shale ceramsite concrete in Comparative Example 1 were evenly distributed, with no segregation or bleeding, but the slump expansion was smaller, decreasing by 20.0% compared to the Example 1; while from the attached... Figure 4 Observations revealed that although the slump expansion of Comparative Example 2 was 9.7% higher than that of the Example, slight segregation and significant bleeding occurred, indicating excessive free water and insufficient adhesion of the mortar to the coarse aggregate surface. (See attached image) Figure 5 The example of fresh shale ceramsite concrete under normal pressure is shown, demonstrating excellent flowability while exhibiting uniform mixture distribution, no segregation, and slight bleeding. Firstly, this is due to the increased mortar film thickness resulting from the increased water-cement ratio, thus reducing friction between aggregates. Secondly, the dilution of the cement paste reduces the yield stress, making fresh shale ceramsite concrete more susceptible to deformation and diffusion under gravity.

[0068] 2. Performance after on-site pumping

[0069] Comparative Example 1, Comparative Example 2, and Example 1 underwent on-site full-scale pumping and post-pumping workability tests at ultra-high-rise buildings. A ZLJ5180THBJE truck-mounted concrete pump manufactured by Zoomlion was used for the pumping tests. The performance of the shale ceramsite concrete during pumping was observed. Workability tests included slump tests, as well as segregation and bleeding of the fresh concrete. The workability test results of the concrete obtained in the examples and comparative examples are shown in Table 5.

[0070] Table 5. Test results of pumping performance and post-pumping workability of shale ceramsite concrete.

[0071]

[0072] Comparative Examples 1, 2, and 1 (Example 1) exhibited different properties during pumping. For Comparative Example 1, the shale-ceramic concrete at the pipe outlet showed good workability in the first 1-2 minutes after pumping began, spreading rapidly across the test site. After 2-3 minutes, the consistency of the shale-ceramic concrete increased, and the slump loss gradually increased. In this case, with the continuous increase of pumping pressure, the workability of the concrete deteriorated rapidly. Even when the hydraulic cylinder pressure input displayed on the pump truck control panel reached 32 MPa, no improvement was observed. Ultimately, the concrete lost all fluidity, the pipe became clogged, as shown in the attached diagram. Figure 6 As shown. For Comparative Example 2, no pipe blockage occurred during pumping. The shale ceramsite concrete could pass through the pipe quickly and smoothly, and after flowing out of the outlet, it could pass through the reinforcing steel laid in the test site. According to tests, its slump could reach 250 mm. However, as shown in the attached... Figure 7As shown, a large amount of shale ceramsite floats and accumulates on the surface, which is a typical segregation phenomenon. The shale ceramsite is unevenly distributed in the concrete; the low-density ceramsite and excess unabsorbed free water aggregate to the upper layer of the mixture under pressure, while the high-density cementitious materials and natural river sand aggregate to the lower layer. This will lead to unstable mechanical properties of the concrete, making it unsuitable for use in the construction industry. For Example 1, the outlet shale ceramsite concrete maintains a stable flow rate, as shown in the attached diagram. Figure 8 As shown, the shale aggregate rapidly diffuses at the point of impact. After pumping, the concrete surface exhibits good uniformity and smoothness, with only a small amount of expanded clay floating. This indicates that the viscosity between the coarse aggregate and mortar is sufficient to resist buoyancy. During pumping, the maximum pressure reached 13.8 MPa. The slump of the shale expanded clay concrete sample obtained from the test site was 220 mm, and the expanded clay and mortar were uniformly mixed. This indicates that the pumping test of the shale expanded clay concrete in Example 1 was successful. According to sampling tests, the 28-day compressive strength of the shale expanded clay concrete in Example 1 can reach over 60 MPa.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-flow-rate, ultra-high-rise pumpable ceramsite concrete, characterized in that, It includes 487 parts of shale ceramsite, 731 parts of river sand, 555 parts of cementitious materials, 180 parts of water, and 14 parts of polycarboxylate superplasticizer; The bulk density of shale ceramsite is 758.1 kg / m³. 3 The apparent density is 1430.1 kg / m³. 3 The maximum particle size is 16mm; The water reduction rate of the polycarboxylate superplasticizer is 20-40%; The volume of the shale ceramsite accounts for 34.1% of the total volume; The cementitious material includes 370 parts cement, 39 parts silica fume, 78 parts mineral powder, 29 parts fly ash, and 39 parts microspheres. The mass ratio of water to cementitious material is 0.

324.

2. The high-flow-rate, ultra-high-rise pumped ceramsite concrete according to claim 1, characterized in that: The preparation method of high-flow-rate ultra-high-rise pumped ceramsite concrete is as follows: S1: Dissolve the polycarboxylate superplasticizer in water and stir until homogeneous to form a superplasticizer solution; S2: Mix the cementitious materials river sand, cement, silica fume, mineral powder, fly ash and microspheres to obtain a mixture, and then mix it with natural river sand to obtain mixture two; S3: Add mixture 2 to the mixer, add the water-reducing agent solution after stirring for 30 seconds, stir for 3 minutes, then pour the shale ceramsite into the mixing pot and stir for 30 seconds.

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