Preparation method of high-adaptability super-high-strength pipe segment concrete admixture

Abstract

This invention discloses a method for preparing a highly adaptable ultra-high strength tunnel segment concrete admixture, comprising: 16%-20% polycarboxylate superplasticizer mother liquor, 10%-12% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 6%-10% polycarboxylate early-strength mother liquor, 10%-16% polycarboxylate composite mother liquor, 2% polycarboxylate short-term slump-retaining mother liquor, 5%-15% nano-early-strength agent, 0.1% functional defoamer, and 5%-10% temperature-inhibiting and crack-resistant agent. The percentages of the compounds are by weight, with the remainder being water. The method includes the following steps: Step 1: Add the nano-early-strength agent, temperature-inhibiting and crack-resistant agent, functional defoamer, and water to a mixing tank and stir for 10 minutes to obtain a homogeneous solution; Step 2: Sequentially add the polycarboxylate superplasticizer mother liquor, polycarboxylate fast-dispersing viscosity-reducing mother liquor, polycarboxylate early-strength mother liquor, polycarboxylate composite mother liquor, and polycarboxylate short-term slump-retaining mother liquor to the homogeneous solution obtained in Step 1 and stir for 30 minutes to obtain the ultra-high strength tunnel segment concrete admixture. The prepared high-strength concrete exhibits excellent workability, high early strength, and good crack resistance; the prepared tunnel segments have no air bubbles on their surface, resulting in a more aesthetically pleasing appearance and better decorative effect.

Description

Technical Field

[0001] This invention belongs to the field of concrete modifier technology, specifically relating to a method for preparing a highly adaptable ultra-high strength pipe segment concrete admixture. Background Technology

[0002] As modern architecture develops towards higher and more personalized requirements, such as high-rise buildings, long-span bridges, offshore oil platforms, wind turbine tower foundations, and wind turbine hybrid tower segments, C15-C60 concrete can no longer fully meet the needs of these projects. This has led to demands for high-strength and ultra-high-strength concrete. Furthermore, major concrete structural projects operating in harsh environments not only face significant construction challenges, but also demand excellent workability, minimal defects during pouring, and high durability and long service life. Therefore, even higher quality requirements are placed on concrete.

[0003] Wind energy, as a sustainable natural resource, boasts advantages such as wide distribution, safety, cleanliness, and environmental friendliness, leading to rapid industrialization and large-scale development of related projects. With the increasing power output of wind turbine generators and the expansion of their application areas, wind power equipment is constantly being upgraded, posing new challenges to the strength, height, durability, and reliability of its main supporting structure—the concrete tower.

[0004] In the production process of high-strength wind turbine concrete towers, especially for grades C80 and above, many problems are often encountered, such as workability issues like excessive viscosity and rapid loss, making pouring difficult and resulting in high losses; the early strength of the solid does not meet the standards, making it impossible to lift and delaying the construction period; the strength growth is slow, and it is difficult to reach the design strength in 28 days; and there are many cracks in the specimens, which have a certain impact on the safety of the wind tower.

[0005] Cement is an important cementitious material in concrete. There are many cement manufacturers and a variety of grinding aids, mainly alkanolamines. The workability of concrete will vary to different degrees depending on the type of cement and grinding aid. Therefore, admixtures that are highly adaptable to different types of cement and grinding aids have a strong effect on the performance stability of tunnel segment concrete.

[0006] Therefore, it is of great significance to develop an admixture for ultra-high strength concrete that has excellent workability, high early strength, crack resistance, no air bubbles on the surface, good appearance, good decorative effect, and strong adaptability. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing highly adaptable ultra-high strength pipe segment concrete admixtures to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a highly adaptable ultra-high strength pipe segment concrete admixture, comprising 16%-20% polycarboxylate water-reducing mother liquor, 10%-12% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 6%-10% polycarboxylate early-strength mother liquor, 10%-16% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 5%-15% nano-early-strength agent, 0.1% functional defoamer, and 5%-10% temperature-inhibiting and crack-resistant agent, wherein the percentages of the compounds are by weight and the balance is water.

[0009] A method for preparing a highly adaptable ultra-high strength tunnel segment concrete admixture includes the following steps:

[0010] Step 1: Add the nano early strength agent, temperature-inhibiting and crack-resistant agent, functional defoamer and water to the mixing tank, stir for 10 minutes to obtain a uniform solution;

[0011] Step 2: Add the polycarboxylate superplasticizer mother liquor, polycarboxylate fast-dispersing viscosity reducer mother liquor, polycarboxylate early strength mother liquor, polycarboxylate comprehensive mother liquor, and polycarboxylate short-term slump-preserving mother liquor in sequence to the homogeneous solution obtained in Step 1, and stir for 30 minutes to obtain the ultra-high strength segment concrete admixture.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] The highly adaptable ultra-high strength segment concrete admixture prepared in this invention introduces heterocycles into the side chains of the water-reducing agent molecules. This improves steric hindrance, reduces the degree of freedom of the main chain, and enhances the adsorption of small carboxyl groups on cement particles by the side chains of the water-reducing agent, thus facilitating rapid dispersion of the cement paste. The low sensitivity of the polycarboxylate composite mother liquor and the combination of a short-term polycarboxylate slump-retaining mother liquor with the composite mother liquor address early-stage losses and temperature issues. To address the long setting time, the high water reduction rate of the polycarboxylate water-reducing mother liquor and the highly efficient slump-retaining performance of the composite mother liquor combined with the short-term slump-retaining mother liquor are utilized, and the amount of polycarboxylate slump-retaining mother liquor used in the paste is adjusted to shorten the setting time.

[0014] To address the issue of cracks easily occurring at the embedded metal holes, the early strength of the specimens is increased and the risk of thermal shrinkage cracking is reduced, thereby mitigating the strength difference between the embedded holes and the embedded metal and reducing the risk of cracking.

[0015] The polyether-modified organosilicon defoamer and hydrophobic nano-silica in the functional defoamer are used to effectively control the bubbles in concrete. The presence of hydrophobic nano-silica allows the polyether-modified organosilicon to diffuse faster at the air-water interface in the foaming liquid, thereby improving the dispersion efficiency of the polyether-modified organosilicon and the bubble elimination efficiency.

[0016] It should have good adaptability to different types of grinding aids in cement, with small fluctuations in dosage and small differences in loss, so as to meet the stable production of segment concrete.

[0017] When the highly adaptable ultra-high strength segment concrete admixture prepared in this invention is added, the resulting high-strength concrete exhibits excellent workability, high early strength, and good crack resistance; the prepared segments have no air bubbles on their surface. Therefore, they are aesthetically pleasing and have a good decorative effect.

[0018] The method for preparing highly adaptable ultra-high strength pipe segment concrete admixtures in this invention is simple, uses affordable raw materials, and is easy to mass-produce. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0020] A highly adaptable ultra-high strength pipe segment concrete admixture comprises: 16%-20% polycarboxylate water-reducing mother liquor, 10%-12% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 6%-10% polycarboxylate early-strength mother liquor, 10%-16% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 5%-15% nano-early-strength agent, 0.1% functional defoamer, and 5%-10% temperature-inhibiting and crack-resistant agent. The percentages of the compounds are by weight, and the balance is water.

[0021] The polycarboxylate superplasticizer mother liquor is type EPEG-2400-3000, with a water reduction rate ≥32% and a solid content of 50%; the polycarboxylate fast dispersion viscosity reducer mother liquor is type EPEG-1600-2000, with a water reduction rate ≥20% and a solid content of 50%; the polycarboxylate early strength mother liquor is type TPEG-4000-5000, with a water reduction rate ≥25% and a solid content of 50%; the polycarboxylate comprehensive mother liquor is type EPEG-2400-3000, with a water reduction rate ≥20% and a solid content of 50%; and the polycarboxylate short-term slump-retaining mother liquor is type EPEG-2000-2400, with a water reduction rate ≥10%.

[0022] The rapid dispersion and viscosity-reducing mother liquor of polycarboxylic acid includes unsaturated polyether macromonomers, unsaturated heterocyclic carboxylic acid monomers, and the molar ratio of heterocyclic unsaturated carboxylic acid monomers to unsaturated polyether macromonomers is 1.2-1.8:1;

[0023] The general structural formula of polycarboxylate fast dispersion viscosity reducing mother liquor is shown in Formula 1:

[0024]

[0025] Where R is a furan ring or a thiophene ring, and a, b, and c are positive integers, ranging from 1 to 30.

[0026] The nano-early strength agent is a CSH crystal nucleation early strength agent; the functional defoamer is a liquid mixture of polyether modified organosilicon defoamer and hydrophobic nano-silica at a mass ratio of 20-45:55-80.

[0027] A method for preparing a highly adaptable ultra-high strength tunnel segment concrete admixture includes the following steps:

[0028] Step 1: Add the nano early strength agent, temperature-inhibiting and crack-resistant agent, functional defoamer and water to the mixing tank, stir for 10 minutes to obtain a uniform solution;

[0029] Step 2: Add the polycarboxylate superplasticizer mother liquor, polycarboxylate fast-dispersing viscosity reducer mother liquor, polycarboxylate early strength mother liquor, polycarboxylate comprehensive mother liquor, and polycarboxylate short-term slump-preserving mother liquor in sequence to the homogeneous solution obtained in Step 1, and stir for 30 minutes to obtain the ultra-high strength segment concrete admixture.

[0030] Example 1

[0031] A highly adaptable ultra-high strength pipe segment concrete admixture comprises 16% polycarboxylate superplasticizer, 12% polycarboxylate fast-dispersing viscosity-reducing agent, 10% polycarboxylate early-strength agent, 16% polycarboxylate composite agent, 2% polycarboxylate short-term slump-preserving agent, 5% nano-early-strength agent, 0.1% functional defoamer, 5% temperature-inhibiting and crack-resistant agent, and 33.9% water. The percentages of the compounds are by weight.

[0032] A rapid dispersion and viscosity-reducing mother liquor of polycarboxylic acid can be prepared by reacting 35g of furan heterocyclic unsaturated carboxylic acid monomer and 415g of unsaturated polyether EPEG-1800 macromonomer at room temperature for 60 minutes and then holding at room temperature for 60 minutes in an initiator, reducing agent and chain transfer agent system.

[0033] A method for preparing highly adaptable ultra-high strength tunnel segment concrete admixtures includes the following steps:

[0034] Step 1: Add the nano early strength agent, temperature-inhibiting and crack-resistant agent, functional defoamer and water to the mixing tank and stir for 10 minutes;

[0035] Step 2: Add the polycarboxylate superplasticizer mother liquor, polycarboxylate fast-dispersing viscosity reducer mother liquor, polycarboxylate early strength mother liquor, polycarboxylate comprehensive mother liquor, polycarboxylate short-term slump-preserving mother liquor, and water to the homogeneous solution obtained in Step 1 in sequence, and stir for 30 minutes to obtain the highly adaptable ultra-high strength pipe segment concrete admixture.

[0036] Example 2

[0037] Unlike Example 1 above, this is a highly adaptable ultra-high strength segment concrete admixture, comprising 18% polycarboxylate superplasticizer, 12% polycarboxylate fast-dispersing viscosity-reducing agent, 10% polycarboxylate early-strength agent, 14% polycarboxylate comprehensive agent, 2% polycarboxylate short-term slump-preserving agent, 10% nano-early-strength agent, 0.1% functional defoamer, 5% temperature-inhibiting and crack-resistant agent, and 28.9% water. The percentages of the compounds are by weight.

[0038] Example 3

[0039] Unlike Examples 1-2 above, this formula contains 20% polycarboxylate water-reducing mother liquor, 10% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 6% polycarboxylate early-strength mother liquor, 10% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 15% nano-early-strength agent, 0.1% functional defoamer, 10% temperature-inhibiting and crack-resistant agent, and 26.9% water. The percentages of the compounds are by weight.

[0040] Comparative Example 1

[0041] Unlike Examples 1-3 above, this formula contains 18% polycarboxylate water-reducing mother liquor, 12% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 10% polycarboxylate early-strength mother liquor, 14% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 2% nano early-strength agent, 0.1% functional defoamer, 2% temperature-inhibiting and crack-resistant agent, and 41.9% water. The percentages of the compounds are by weight.

[0042] Comparative Example 2

[0043] Leizhi Holdings Group Co., Ltd. produces high-strength concrete admixture I for pipe segments.

[0044] Comparative Example 3

[0045] Jiangsu Subote New Material Co., Ltd. produces high-strength concrete admixture II for pipe segments.

[0046] Test case

[0047] The water-reducing agents used in the examples and comparative examples were subjected to concrete mix design tests. The concrete performance tests were conducted according to GB8076-2008 "Concrete Admixtures". Esheng cement was selected with a water-cement ratio of 0.22%, as shown in Table 1.

[0048] The concrete mix design was C80, and its slump, hydration temperature rise, and appearance of the molded samples were measured. Adaptability to different cements was also assessed, including dosage, state, and strength changes. The fineness modulus of the manufactured sand in the concrete was 2.6, the crushed stone was continuously graded with a particle size of 5-25mm, and the polycarboxylate superplasticizer dosage was 1.7-2.2wt%.

[0049] Table 1. Mix Proportions for C80 Concrete

[0050] cement Microbeads Mineral powder silica ash Manufactured sand aggregate water 380 100 60 50 630 1050 130

[0051] Table 2 Concrete Performance Data C30

[0052]

[0053]

[0054] As can be seen from the concrete performance data in Table 2, the water-reducing agents in Examples 1-3 are all superior to those in Comparative Examples 1-3, mainly in terms of viscosity, 1-day strength, peak hydration temperature rise, and specimen appearance.

[0055] Table 3. Data on the adaptability of different cements

[0056]

[0057]

[0058] As shown in Table 3, when comparing the water-reducing agent in Example 2 with that in Comparative Example 3, concrete tests were conducted using Esheng Cement, Conch Cement, Jidong Cement, Huaxin Cement, and Hongshi Cement, respectively. The dosage variation in Example 2 was 0.1%-0.2%, while that in Comparative Example 3 was 0.1%-0.5%. The admixture in Example 2 was superior to that in Comparative Example 3 in terms of slump performance, workability, and 1-day strength stability, and all requirements were met. This demonstrates that the admixture in this application has good adaptability to different cements.

[0059] This invention introduces heterocycles into the side chains of water-reducing agents, which helps to improve steric hindrance, reduce the degree of freedom of the main chain, and enhance the adsorption of small carboxyl groups on cement particles by the side chain molecules of the water-reducing agent, thus facilitating rapid dispersion of cement paste. Utilizing the characteristics of rapid dispersion and good viscosity reduction of polycarboxylate fast-dispersion paste mother liquor, the mixing time of ultra-high strength concrete is reduced from 300 seconds to 180 seconds, and the concrete collapse time is reduced from 15 seconds to less than 8 seconds.

[0060] Ultra-high strength concrete segments are precast components with low slump requirements, typically 160±20mm. Low-slump concrete is prone to problems such as rapid early-stage loss and high dosage sensitivity. The low sensitivity of polycarboxylate superplasticizer and the combination of short-term polycarboxylate slump-maintaining superplasticizer with superplasticizer address early-stage loss and temperature-related issues. To address the long setting time, the high water reduction rate of polycarboxylate superplasticizer and the efficient slump-maintaining performance of superplasticizer combined with short-term slump-maintaining superplasticizer are utilized, along with the appropriate amount of polycarboxylate slump-maintaining superplasticizer in the slurry, thereby shortening the setting time.

[0061] To address early strength issues, a nano-accelerator is added to increase 16-hour strength, meeting the requirements for lifting and demolding. To address the potential for cracking, a temperature-inhibiting and crack-resistant agent is used to reduce the peak heat of hydration in concrete, decrease temperature shrinkage stress, and lower the risk of temperature rise and shrinkage cracking. Regarding the issue of cracks easily forming at embedded metal holes, increasing the early strength of the specimens and reducing the risk of temperature rise and shrinkage cracking reduces the strength difference between the embedded holes and the embedded metal, thus lowering the cracking risk.

[0062] This study utilizes a functional defoamer, specifically a polyether-modified silicone defoamer and hydrophobic nano-silica, to effectively control air bubbles in concrete. First, the polyether-modified silicone defoamer primarily consists of polyether with strong foam-suppressing ability and dimethyl silicone oil with strong hydrophobicity and rapid foam breaking. It features low surface tension, rapid defoaming, and long foam-suppressing time, effectively eliminating air bubbles in concrete. Second, the hydrophobic nano-silica, due to its small particle size and high surface energy, forms a powerful adsorption force on air bubbles. The "needle-tip" effect of the nano-silica adsorbs and impacts the bubbles, creating weak points and accelerating their rupture. Third, the polyether-modified silicone and hydrophobic nano-silica together attack the air bubbles. The presence of hydrophobic nano-silica accelerates the diffusion of the polyether-modified silicone at the air-water interface in the foaming liquid, improving its dispersion efficiency and thus enhancing bubble elimination efficiency.

[0063] In view of the influence of different grinding aids on the workability of concrete, the ultra-high strength segment concrete admixture of the present invention has good adaptability to different grinding aids, with small dosage fluctuations and small loss differences, so as to meet the stable production of segment concrete.

[0064] This addresses the challenges posed by the poor workability of ultra-high strength concrete, such as difficulties in construction, failure to achieve early strength and subsequent demolding, localized cracks in tunnel segments, and excessive air bubbles in tunnel segments. It improves construction efficiency, reduces production energy consumption, and minimizes or eliminates production quality risks, aligning with the needs of low-carbon and green development.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A highly adaptable ultra-high strength segment concrete admixture, characterized in that, Polycarboxylate superplasticizer mother liquor 16%-20%, polycarboxylate fast-dispersing viscosity reducer mother liquor 10%-12%, polycarboxylate early strength mother liquor 6%-10%, polycarboxylate comprehensive mother liquor 10%-16%, polycarboxylate short-term slump-preserving mother liquor 2%, nano early strength agent 5%-15%, functional defoamer 0.1%, temperature-inhibiting and crack-resistant agent 5%-10%, the percentages of compounds are by weight, and the balance is water; The polycarboxylate superplasticizer mother liquor is type EPEG-2400-3000, with a water reduction rate ≥32% and a solid content of 50%; the polycarboxylate fast dispersion viscosity reducer mother liquor is type EPEG-1600-2000, with a water reduction rate ≥20% and a solid content of 50%; the polycarboxylate early strength mother liquor is type TPEG-4000-5000, with a water reduction rate ≥25% and a solid content of 50%; the polycarboxylate comprehensive mother liquor is type EPEG-2400-3000, with a water reduction rate ≥20% and a solid content of 50%; and the polycarboxylate short-term slump-retaining mother liquor is type EPEG-2000-2400, with a water reduction rate ≥10%. The rapid dispersion and viscosity-reducing mother liquor of polycarboxylic acid includes unsaturated polyether macromonomers, unsaturated heterocyclic carboxylic acid monomers, and the molar ratio of heterocyclic unsaturated carboxylic acid monomers to unsaturated polyether macromonomers is 1.2-1.8:1; The general structural formula of polycarboxylate fast dispersion viscosity reducing mother liquor is shown in Formula 1: ； Where R is a furan ring or a thiophene ring, and a, b, and c are positive integers, with a, b, and c taken from 1 to 30; The nano-early strength agent is a CSH crystal nucleation early strength agent; the functional defoamer is a liquid mixture of polyether modified organosilicon defoamer and hydrophobic nano-silica at a mass ratio of 20-45:55-80.

2. The highly adaptable ultra-high strength segment concrete admixture according to claim 1, characterized in that, The composition includes 16% polycarboxylate water-reducing mother liquor, 12% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 10% polycarboxylate early-strength mother liquor, 16% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 5% nano-early-strength agent, 0.1% functional defoamer, and 5% temperature-inhibiting and crack-resistant agent. The percentages of the compounds are by weight, and the balance is water.

3. The highly adaptable ultra-high strength segment concrete admixture according to claim 2, characterized in that, The composition includes 18% polycarboxylate water-reducing mother liquor, 12% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 10% polycarboxylate early-strength mother liquor, 14% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 10% nano early-strength agent, 0.1% functional defoamer, and 5% temperature-inhibiting and crack-resistant agent. The percentages of the compounds are by weight, and the balance is water.

4. The highly adaptable ultra-high strength segment concrete admixture according to claim 3, characterized in that, The composition includes 20% polycarboxylate water-reducing mother liquor, 10% polycarboxylate fast-dispersing viscosity-reducing mother liquor, 6% polycarboxylate early-strength mother liquor, 10% polycarboxylate comprehensive mother liquor, 2% polycarboxylate short-term slump-preserving mother liquor, 15% nano early-strength agent, 0.1% functional defoamer, and 10% temperature-inhibiting and crack-resistant agent. The percentages of the compounds are by weight, and the balance is water.

5. A method for preparing a highly adaptable ultra-high strength segment concrete admixture according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Add the nano early strength agent, temperature-inhibiting and crack-resistant agent, functional defoamer and water to the mixing tank, stir for 10 minutes to obtain a uniform solution; Step 2: Add the polycarboxylate superplasticizer mother liquor, polycarboxylate fast-dispersing viscosity reducer mother liquor, polycarboxylate early strength mother liquor, polycarboxylate comprehensive mother liquor, and polycarboxylate short-term slump-preserving mother liquor in sequence to the homogeneous solution obtained in Step 1, and stir for 30 minutes to obtain the ultra-high strength segment concrete admixture.

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