A high-strength concrete for ultra-high pumping and a method for preparing the same

Abstract

The application belongs to the technical field of concrete, and particularly relates to high-strength concrete for super-high pumping and a preparation method thereof. The high-strength concrete for super-high pumping comprises the following raw materials in mass fraction: water 130-160 parts, cement 370-400 parts, mineral powder 60-80 parts, fly ash 80-95 parts, silica ash 20-40 parts, natural sand 740-770 parts, gravel 940-980 parts, and additive 9-12 parts. The concrete has high compressive strength, good initial flow performance, and excellent performance when used for super-high pumping above 600 meters.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete, and particularly relates to high-strength concrete for super-high pumping and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern building technology, super-high-rise buildings, large bridges and complex infrastructure projects are increasing, which poses unprecedented challenges to the performance of concrete materials. High-strength concrete, especially high-strength and high-performance concrete of C80 and above, has become the preferred material for key load-bearing structures such as super-high-rise building core tubes and giant columns due to its excellent load-carrying capacity and durability.

[0003] In actual construction, the vertical pumping height of concrete has generally exceeded 300 meters, and some projects have even broken through 600 meters. However, with the increase of pumping height, the pressure in the pipeline rises sharply, which poses extremely stringent requirements on the working performance, stability and homogeneity of concrete. Existing C80 high-strength concrete often fails to balance the rheological properties and segregation resistance required for super-high pumping on the basis of meeting the 28-day compressive strength of ≥80 MPa.

[0004] Chinese patent CN106977157B provides C80 super-high pumping concrete and a preparation method thereof. The concrete not only has long-distance pumping performance, but also meets the strength requirements of C80 concrete. There are almost no cracks on the surface of the concrete during its hardening process, reducing the safety hazards.

[0005] Chinese patent CN111454033B provides C80 super-high pumping concrete and a preparation method thereof. The C80 super-high pumping concrete has the advantages of good fluidity and easy pumping while ensuring strength.

[0006] However, the products in the prior art are prone to relative movement between the slurry and the aggregate inside the concrete under high pressure during high-pressure, long-distance and multi-bend pumping when the pumping height exceeds 600 meters, resulting in poor rheological properties and poor concrete spreadability, which can easily cause pipe blockage accidents, not only interrupting the construction progress and causing huge economic losses, but also affecting the final strength and structural durability of the concrete. SUMMARY

[0007] The purpose of the present application is to provide high-strength concrete for super-high pumping and a preparation method thereof.

[0008] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0009] A kind of high-strength concrete for super-high pumping, comprising the following mass parts of raw materials: water 130-160 parts, cement 370-400 parts, mineral powder 60-80 parts, fly ash 80-95 parts, silica fume 20-40 parts, natural sand 740-770 parts, gravel 940-980 parts, additive 9-12 parts.

[0010] Preferably, the gravel includes a mass ratio of 1: (0.4-0.7) of the first gravel and the modified second gravel.

[0011] Preferably, the first gravel has a particle size of 15-45 mm and an average particle size of 20-25 mm.

[0012] Preferably, the preparation method of the modified second gravel comprises the following steps:

[0013] (1) mix 5 kg of epoxy acrylic resin, 0.25-0.50 kg of oleic acid, and 0.025-0.04 kg of catalyst titanium tetraisopropoxide, stir and react at 80-90 °C for 1-2 h, mix 0.10-0.25 kg of acrylic acid and 0.15-0.30 kg of hydroxyethyl acrylate, and then drop them into the system, drop for 1 h, and react at 70 °C for 1-2 h to obtain a modified resin;

[0014] (2) spray 2.5 kg of the modified resin and 5.5 kg of glycidyl methacrylate into the second gravel at a rate of 400-450 mL / min, stir (700 rpm) while spraying, continue stirring at 700 rpm for 20-30 min after spraying is completed, and then dry by stirring at 70 °C to obtain the modified second gravel.

[0015] The present application can improve the compressive strength of concrete and improve the slump degree by modifying part of the gravel. Analysis shows that a tough and flexible interface layer (composed of epoxy acrylic resin and long-chain oleic acid) is formed on the surface of the modified resin. When the concrete is under stress, this flexible film can effectively absorb and disperse stress, preventing the easy expansion of micro-cracks. At the same time, by introducing oleic acid to improve steric hindrance, a polymer layer with a certain thickness and flexibility is formed on the surface of the gravel, which plays a lubricating role between particles, making the gravel particles more easily slide in the cement paste, and obtaining better fluidity, i.e. increased slump. At the same time, the large number of carboxyl and hydroxyl groups on the molecular chain of the modified resin can form strong ionic bonds and hydrogen bonds with the cement hydration products.

[0016] Preferably, the second gravel has a particle size of 5-25 mm and an average particle size of 10-15 mm.

[0017] Preferably, the natural sand is medium-fine sand with a modulus of 2.6-3.2.

[0018] Preferably, the admixture includes at least one of polycarboxylate superplasticizer, aliphatic superplasticizer, and SBT-SEA100 concrete synergist.

[0019] Preferably, the admixture includes polycarboxylate superplasticizer, aliphatic superplasticizer, and SBT-SEA100 concrete synergist.

[0020] Preferably, the admixture includes polycarboxylate superplasticizer, aliphatic superplasticizer, and SBT-SEA100 concrete synergist in a mass ratio of (1.2-1.5):1:(0.3-0.5).

[0021] The admixture in the mixed soil system of the present application only adds conventional polycarboxylate superplasticizer, and the spreadability of the concrete is not ideal. The present application can improve the spreadability of the concrete of the system to more than 600 meters after pumping by adding polycarboxylate superplasticizer, aliphatic superplasticizer, and SBT-SEA100 concrete synergist in a specific ratio as an admixture. Analysis under this condition can realize the synergistic optimization of the rheological properties (fluidity, viscosity) and stability (anti-segregation) of the concrete, so that the spreadability can still be good under extreme pumping conditions.

[0022] The preparation method of the high-strength concrete for ultra-high pumping comprises the following steps:

[0023] Step one, weigh the cement, mineral powder, fly ash, silica fume, natural sand, gravel, aliphatic superplasticizer, mix and stir them uniformly to obtain a mixture;

[0024] Step two, mix water, polycarboxylate superplasticizer, and SBT-SEA100 concrete synergist uniformly and add them to the mixture, and stir uniformly to obtain the high-strength concrete for ultra-high pumping.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] 1. The concrete has very high compressive strength, and the compressive strength is stable and reaches more than 80 MPa, fully meeting the requirements of C80 high-strength grade. The high-strength characteristic makes it suitable for key load-bearing parts of super-high-rise buildings, ensures the safety and durability of the structure under a large load, and prolongs the service life of the building.

[0027] 2. The concrete has excellent working performance, high initial slump spread, smooth flow, and no segregation and bleeding. The high slump spread gives the concrete excellent self-filling ability, can easily flow through dense steel reinforcement areas and complex formwork structures, reduces the need for manual vibration, improves construction efficiency and forming quality, and provides strong protection for the smooth pouring of complex structures.

[0028] 3、The concrete of the present application has high pump-out concrete expansion degree retention rate after high-pressure and long-distance pumping, and the paste and aggregate are uniformly distributed without obvious segregation or pipe blockage risk. Through optimization of the gradation of the crushed stone, control of the paste-aggregate ratio, and compounding of functional admixtures, the performance ensures that the concrete can still maintain homogeneity and fluidity under extreme delivery conditions, realizes efficient, continuous, and safe vertical delivery, effectively avoids project delays and economic losses caused by pipe blockage, and meets the stringent requirements of modern super high-rise buildings on the pumping performance of concrete. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0030] The raw materials used in the following embodiments of the present application are all commercially available goods:

[0031] Cement, type P.O42.5.

[0032] Natural sand, medium-fine sand with a modulus of 2.9.

[0033] Mineral powder, Ling County Anda Mineral Powder Factory, mesh size 200-325.

[0034] Fly ash, Ling County Zhaocen Mineral Products Co., Ltd., 200-mesh flue dust.

[0035] Silica fume, Shijiazhuang Qiantong Mineral Products Co., Ltd.

[0036] Polycarboxylic acid water reducer, Shandong Yuncheng Huihuang New Building Material Technology Co., Ltd., solid content: 20%.

[0037] Aliphatic water reducer, Shandong Yuncheng Huihuang New Building Material Technology Co., Ltd., powder.

[0038] Epoxy acrylic resin, Huangshan Aoshengyuan New Material Technology Co., Ltd., W990S water-based epoxy modified acrylic resin.

[0039] Glycidyl methacrylate, CAS: 106-91-2.

[0040] SBT-SEA100 concrete synergist, Jiangsu Subo New Material Co., Ltd.

[0041] Embodiment 1 provides a high-strength concrete for ultra-high pumping, comprising the following mass fractions of raw materials: water 142 parts, cement 389 parts, mineral powder 66 parts, fly ash 90 parts, silica fume 25 parts, natural sand 752 parts, crushed stone 950 parts, and additive 10.26 parts. The additive comprises polycarboxylate superplasticizer, aliphatic superplasticizer, and SBT®-SEA100 concrete synergist in a mass ratio of 1.2:1:0.4. The crushed stone comprises first crushed stone and modified second crushed stone in a mass ratio of 1:0.45. The first crushed stone has a particle size of 15-45 mm and an average particle size of 22 mm.

[0042] The preparation method of the modified second crushed stone comprises the following steps:

[0043] (1) Mix 5 kg of epoxy acrylate resin, 0.30 kg of oleic acid, and 0.03 kg of catalyst titanium tetraisopropoxide, stir and react at 85°C for 1.5 h, mix 0.2 kg of acrylic acid and 0.2 kg of hydroxyethyl acrylate, and then drop them into the system at a drop time of 1 h, and react at 70°C for 1.5 h to obtain a modified resin;

[0044] (2) Spray 2.5 kg of the modified resin and 5.5 kg of glycidyl methacrylate into the second crushed stone at a rate of 420 mL / min, the second crushed stone has a particle size of 5-25 mm and an average particle size of 12 mm; stir (700 rpm) while spraying, continue stirring at 700 rpm for 30 min after spraying, and then dry at 70°C to obtain the modified second crushed stone.

[0045] The preparation method of the high-strength concrete for ultra-high pumping comprises the following steps:

[0046] Step one, weigh and mix cement, mineral powder, fly ash, silica fume, natural sand, crushed stone, and aliphatic superplasticizer, and stir them uniformly to obtain a mixture;

[0047] Step two, mix water, polycarboxylate superplasticizer, and SBT®-SEA100 concrete synergist uniformly and add them to the mixture, and stir them uniformly to obtain the high-strength concrete for ultra-high pumping.

[0048] Embodiment 2 provides a high-strength concrete for ultra-high pumping, comprising the following mass fractions of raw materials: water 147 parts, cement 380 parts, mineral powder 65 parts, fly ash 80 parts, silica fume 25 parts, natural sand 740 parts, crushed stone 940 parts, and additive 11 parts. The additive comprises polycarboxylate superplasticizer, aliphatic superplasticizer, and SBT®-SEA100 concrete synergist in a mass ratio of 1.2:1:0.5. The crushed stone comprises first crushed stone and modified second crushed stone in a mass ratio of 1:0.7. The first crushed stone has a particle size of 15-45 mm and an average particle size of 22 mm.

[0049] The preparation method of the modified second gravel includes the following steps:

[0050] (1) 5 kg of epoxy acrylic resin, 0.30 kg of oleic acid, and 0.03 kg of catalyst titanium tetraisopropoxide are mixed, stirred and reacted at 85°C for 1.5 h, 0.2 kg of acrylic acid and 0.2 kg of hydroxyethyl acrylate are mixed and then added dropwise into the system, the dropping time is 1 h, and the reaction is carried out at 70°C for 1.5 h to obtain a modified resin;

[0051] (2) 2.5 kg of the modified resin and 5.5 kg of glycidyl methacrylate are sprayed into the second gravel at a rate of 420 mL / min, the particle size of the second gravel is 5-25 mm, and the average particle size is 12 mm; stirring is carried out at 700 rpm during spraying, and after spraying, stirring is continued at 700 rpm for 30 min, and then drying is carried out at 70°C to obtain the modified second gravel.

[0052] The preparation method of the high-strength concrete for ultra-high pumping includes the following steps:

[0053] Step one, weigh the cement, mineral powder, fly ash, silica fume, natural sand, gravel, and aliphatic water reducing agent, mix them, and stir them uniformly to obtain a mixture;

[0054] Step two, mix the water, polycarboxylic acid water reducing agent, and SBT®-SEA100 concrete synergist uniformly and add them into the mixture, and stir them uniformly to obtain the high-strength concrete for ultra-high pumping.

[0055] In example 3, a high-strength concrete for ultra-high pumping is provided, which includes the following mass fractions of raw materials: water 160 parts, cement 396 parts, mineral powder 75 parts, fly ash 90 parts, silica fume 20 parts, natural sand 750 parts, gravel 960 parts, and additive 10 parts. The additive includes a mass ratio of 1.5:1:0.3 of polycarboxylic acid water reducing agent, aliphatic water reducing agent, and SBT®-SEA100 concrete synergist. The gravel includes a mass ratio of 1:0.4 of first gravel and modified second gravel. The particle size of the first gravel is 15-45 mm, and the average particle size is 22 mm.

[0056] The preparation method of the modified second gravel includes the following steps:

[0057] (1) 5 kg of epoxy acrylic resin, 0.30 kg of oleic acid, and 0.03 kg of catalyst titanium tetraisopropoxide are mixed, stirred and reacted at 85°C for 1.5 h, 0.2 kg of acrylic acid and 0.2 kg of hydroxyethyl acrylate are mixed and then added dropwise into the system, the dropping time is 1 h, and the reaction is carried out at 70°C for 1.5 h to obtain a modified resin;

[0058] (2) 2.5 kg of the modified resin and 5.5 kg of glycidyl methacrylate were sprayed into the second gravel at a rate of 420 mL / min, the particle size of the second gravel was 5-25 mm, and the average particle size was 12 mm; stirring (700 rpm) was performed while spraying, 700 rpm stirring was continued for 30 min after the spraying was completed, and then drying was performed at 70°C with stirring to obtain the modified second gravel.

[0059] The preparation method of the high-strength concrete for ultra-high pumping comprises the following steps:

[0060] Step one, weigh the cement, mineral powder, fly ash, silica fume, natural sand, gravel, and aliphatic water reducing agent, mix them, and stir them uniformly to obtain a mixture;

[0061] Step two, mix the water, polycarboxylic acid water reducing agent, and SBT®-SEA100 concrete synergist uniformly and add them to the mixture, and stir them uniformly to obtain the high-strength concrete for ultra-high pumping.

[0062] Comparative Example 1

[0063] The difference between this comparative example and Example 1 is that the gravel comprises first gravel and second gravel at a mass ratio of 1:0.45. The particle size of the first gravel is 15-45 mm, and the average particle size is 22 mm. The particle size of the second gravel is 5-25 mm, and the average particle size is 12 mm.

[0064] Comparative Example 2

[0065] The difference between this comparative example and Example 1 is that the preparation method of the modified second gravel comprises the following steps:

[0066] (1) 5 kg of epoxy acrylate resin, 0.30 kg of oleic acid, and 0.03 kg of catalyst titanium tetraisopropoxide were mixed and stirred at 85°C for 1.5 h to obtain a modified resin;

[0067] (2) 2.5 kg of the modified resin and 5.5 kg of glycidyl methacrylate were sprayed into the second gravel at a rate of 420 mL / min, the particle size of the second gravel was 5-25 mm, and the average particle size was 12 mm; stirring (700 rpm) was performed while spraying, 700 rpm stirring was continued for 30 min after the spraying was completed, and then drying was performed at 70°C with stirring to obtain the modified second gravel.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that the preparation method of the modified second gravel comprises the following steps:

[0070] (1) 0.2 kg of acrylic acid and 0.2 kg of hydroxyethyl acrylate were mixed and then added dropwise to 5 kg of epoxy acrylic resin, the dropwise addition took 1 h, and the reaction was kept at 70 °C for 1.5 h to obtain a modified resin;

[0071] (2) 2.5 kg of the modified resin and 5.5 kg of glycidyl methacrylate were sprayed into the second crushed stone at a rate of 420 mL / min, the particle size of the second crushed stone was 5-25 mm, and the average particle size was 12 mm; stirring was carried out at 700 rpm while spraying, and after the spraying was completed, the stirring was continued at 700 rpm for 30 min, and then the second crushed stone was dried by stirring at 70 °C to obtain a modified second crushed stone.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that the admixture comprises a mass ratio of 1:1.2:0.2 of polycarboxylate superplasticizer, aliphatic superplasticizer and SBT®-SEA100 concrete synergist.

[0074] The difference between this comparative example and Example 1 is that the admixture comprises a mass ratio of 1:0.8:0.7 of polycarboxylate superplasticizer, aliphatic superplasticizer and SBT®-SEA100 concrete synergist.

[0075] Comparative Example 6

[0076] This comparative example is the product of Example 1 in Chinese Patent CN106977157B C80 super-high pumping concrete and a preparation method thereof.

[0077] Comparative Example 7

[0078] This comparative example is the product of Example 1 in Chinese Patent CN111454033B, which provides a C80 super-high pumping concrete and a preparation method thereof.

[0079] Performance Test

[0080] 1. The compressive strength of the concrete standard test block at 7 days and 28 days was detected according to the specification in GB / T50010 “Code for Design of Concrete Structures”.

[0081] 2. The spread degree was determined after 621 meters of super-high pumping according to T0532-2020 “Test Method for Slump Flow and Slump Flow Time of Cement Concrete Mixture”.

[0082] 3. The slump degree was determined according to GB / T 50080-2016 “Standard Test Methods for Performance of Ordinary Concrete Mixture”.

[0083] Results The results are shown in Table 1.

[0084] Table 1 Performance Test Results

[0085] Compressive strength 7d (MPa) Compressive strength 28d (MPa) Span (mm) Slump (mm) Example 1 87.4 105.6 691 278 Example 2 86.1 103.5 684 274 Example 3 85.3 104.1 687 275 Comparative Example 1 72.4 87.5 610 241 Comparative Example 2 76.2 92.1 653 258 Comparative Example 3 74.7 90.3 641 263 Comparative Example 4 71.5 86.4 562 249 Comparative Example 5 75.9 91.7 585 256 Comparative Example 6 79.5 99.9 578 272 Comparative Example 7 75.8 97.9 552 265

[0086] From Table 1, it can be seen that the compressive strength of the concrete of Examples 1-3 is high, the initial flow performance is good, and the spread after 621-meter super-high pumping is excellent, which is obviously superior to the product of the prior art.

[0087] From Comparative Examples 1-3, it can be seen that the modified second gravel has an important influence on the compressive strength and slump of the concrete. From Comparative Examples 4-5, it can be seen that the admixture can only ensure excellent spread after 621-meter super-high pumping under a specific composition and ratio.

[0088] The above is the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A high-strength concrete for ultra-high pumping, characterized by, The raw materials include the following components in mass parts: water 130-160 parts, cement 370-400 parts, mineral powder 60-80 parts, fly ash 80-95 parts, silica ash 20-40 parts, natural sand 740-770 parts, crushed stone 940-980 parts, and additive 9-12 parts; The crushed stone includes first crushed stone and modified second crushed stone in a mass ratio of 1:(0.4-0.7); The preparation method of the modified second crushed stone includes the following steps: (1) mixing epoxy acrylic resin, oleic acid and catalyst, stirring and reacting at 80-90℃ for 1-2h, mixing acrylic acid and hydroxyethyl acrylate, and then dropping into the system for reaction, to obtain a modified resin; (2) spraying the modified resin and glycidyl methacrylate onto the second crushed stone while stirring, continuing to stir after spraying is completed, and drying to obtain the modified second crushed stone; The additive includes polycarboxylic acid water reducer, aliphatic water reducer and SBT-SEA100 concrete synergist in a mass ratio of (1.2-1.5):1:(0.3-0.5).

2. High-strength concrete for ultra-high pumping according to claim 1, characterized in that, The first crushed stone has a particle size of 15-45mm and an average particle size of 20-25mm.

3. High-strength concrete for ultra-high pumping according to claim 2, characterized in that, The second crushed stone has a particle size of 5-25mm and an average particle size of 10-15mm.

4. High-strength concrete for ultra-high pumping according to claim 1, characterized in that, The natural sand is medium-fine sand with a fineness modulus of 2.6-3.

2.

5. A method for the preparation of high-strength concrete for ultra-high pumping according to any one of claims 1 to 4, characterized in that, The method includes the following steps: Step one, weighing and mixing cement, mineral powder, fly ash, silica ash, natural sand, crushed stone and aliphatic water reducer, and then stirring to obtain a mixture; Step two, mixing water, polycarboxylic acid water reducer and SBT-SEA100 concrete synergist, and then adding into the mixture and stirring to obtain high-strength concrete for ultra-high pumping.