WO2023159450A1 - 梯度功能超高性能混凝土制品及其制备方法和应用 - Google Patents

梯度功能超高性能混凝土制品及其制备方法和应用 Download PDF

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WO2023159450A1
WO2023159450A1 PCT/CN2022/077810 CN2022077810W WO2023159450A1 WO 2023159450 A1 WO2023159450 A1 WO 2023159450A1 CN 2022077810 W CN2022077810 W CN 2022077810W WO 2023159450 A1 WO2023159450 A1 WO 2023159450A1
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ultra
high performance
performance concrete
gradient
parts
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PCT/CN2022/077810
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English (en)
French (fr)
Inventor
刘开志
龙勇
陈露一
彭旭民
王波
侍刚
欧阳华林
田启贤
王天亮
李晨
盖珂瑜
王亚洲
凌刚
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中铁大桥局集团有限公司
中铁大桥科学研究院有限公司
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Priority to PCT/CN2022/077810 priority Critical patent/WO2023159450A1/zh
Publication of WO2023159450A1 publication Critical patent/WO2023159450A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/08—Producing shaped prefabricated articles from the material by vibrating or jolting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/52—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements

Definitions

  • the invention relates to the technical field of ultra-high performance concrete, in particular to a gradient function ultra-high performance concrete product and its preparation method and application.
  • Ultra-high performance concrete is a building structure material with ultra-high strength, ultra-high toughness, and ultra-high durability, which can well meet the needs of engineering structures that are developing toward higher heights, larger spans, and heavier loads. Requirements for material properties. Therefore, ultra-high-performance concrete has attracted great attention from scholars and engineers at home and abroad in the past ten years, and has rapidly become a hot spot in scientific research, and its application in the field of engineering has become increasingly widespread.
  • the ultra-high performance concrete prepared by this method does not consider the influence of fiber distribution and orientation on its performance, and the fiber utilization rate is not high.
  • the improvement of fiber utilization efficiency in ultra-high performance concrete is mainly achieved by controlling the directional distribution of fibers.
  • the patent with the publication number CN108453868A discloses the preparation method and device of fiber-reinforced ultra-high performance concrete products with directional distribution of fibers. Vibration, start the perspective detection, use the external electric field to make the fiber rotate, and use the vibration to reduce the viscous effect of the ultra-high performance concrete slurry on the fiber rotation, so that the fiber is oriented and the utilization rate of the fiber is improved.
  • the purpose of the present invention is to provide a gradient function ultra-high performance concrete product and its preparation method and application.
  • the present invention provides a method for preparing a functional gradient ultra-high performance concrete product, comprising:
  • the above technical scheme vibrates the ultra-high-performance concrete slurry with a specific viscosity under vibration conditions different from the general ultra-high-performance concrete vibration conditions (up and down amplitude ⁇ 1mm, vibration intensity ⁇ 5g), so that the steel fibers in the ultra-high-performance concrete
  • the matrix is in a gradient distribution state, which meets the needs of ultra-high performance concrete products that are tensile at one end and compressed at the other end.
  • the energy of vibration causes the steel fibers to rotate during the movement, making their orientation uniform, and the air bubbles in the matrix shrink. , thus improving the flexural performance of ultra-high performance concrete products.
  • the volume content of the steel fiber is 1% to 3%.
  • the steel fiber-containing ultra-high performance concrete slurry in parts by weight, includes 100 parts of Portland cement, 35-45 parts of microbeads, 10-15 parts of silica fume, and 125-135 parts of quartz sand , 25-35 parts of water, 1-3 parts of water reducing agent, 0.05-0.25 parts of viscosity reducing agent and 10-30 parts of steel fiber.
  • the particle size distribution range of the quartz sand is 0-2 mm.
  • the water reducer is a polycarboxylic acid powder water reducer.
  • the viscosity reducer is a special viscosity reducer for polycarboxylate water reducer.
  • the viscosity of the steel fiber-containing ultra-high performance concrete slurry is 15-20 Pa ⁇ S.
  • the vertical amplitude is 1-5 mm
  • the vibration intensity is 5-20 g
  • the vibration duration is 5-30 min.
  • the present invention provides a functionally gradient ultra-high performance concrete product prepared by the method for preparing a functionally gradient ultra-high performance concrete product.
  • the present invention provides the use of the above-mentioned graded function ultra-high performance concrete product in the construction field.
  • the present invention proposes a technical concept of gradient distribution of steel fibers to achieve functionalization, which overcomes the traditional pursuit of ultra-high performance concrete Homogeneous technical bias; and by vibrating the ultra-high performance concrete slurry and adjusting the vibration conditions, the gradient distribution of steel fibers in ultra-high performance concrete products is realized, and the gradient functional ultra-high performance is prepared easily and efficiently concrete products.
  • the present invention not only can make the steel fibers in the ultra-high performance concrete matrix oriented Migration, reaching the state of gradient distribution, can also use the disturbance effect during the migration process of steel fibers to make the orientation of steel fibers tend to be consistent, and at the same time optimize the pore structure by using the liquefaction effect of the slurry under vibration conditions, so as to obtain high fiber utilization efficiency and compactness.
  • Gradient functional ultra-high performance concrete with good toughness and excellent bending resistance to meet the needs of practical applications.
  • the method provided by the present invention can further optimize the vibration conditions of the ultra-high performance concrete slurry according to the viscosity thereof, so that the steel fibers present a required gradient distribution state, and has the advantages of wide application range and strong controllability.
  • the gradient distribution state of the steel fiber formed by the vibration effect in the present invention is controllable and has strong operability.
  • the method provided by the invention does not need electric field or magnetic field, the preparation process is simple, the cost is lower, and it can better meet the needs of actual production.
  • the steel fibers are distributed in a gradient and have a better orientation, which can not only effectively improve the utilization efficiency of steel fibers, but also reduce the amount of steel fibers to achieve ultra-high performance without vibration.
  • Performance concrete products have the same toughness; it can also make the side with more steel fiber distribution have higher tensile strength, so that the prepared gradient function ultra-high performance concrete products have more excellent bending resistance, and its toughness index I 5 and I 10 can reach 6.8-12.9 and 15.1-25.5 respectively, which has high practical application value.
  • Fig. 1 is the load-displacement curve of the graded functional ultra-high performance concrete prepared in Example 1.
  • Fig. 2 is the cross-sectional photograph of the graded functional ultra-high performance concrete prepared in Example 1.
  • Fig. 3 is a three-dimensional distribution diagram of steel fibers in the functionally graded ultra-high performance concrete prepared in Example 1.
  • FIG. 4 is a three-dimensional distribution diagram of air bubbles in the functionally graded ultra-high performance concrete prepared in Example 1.
  • FIG. 4 is a three-dimensional distribution diagram of air bubbles in the functionally graded ultra-high performance concrete prepared in Example 1.
  • Fig. 5 is the load-displacement curve of the graded functional ultra-high performance concrete prepared in Comparative Example 1.
  • Fig. 6 is a cross-sectional photo of the graded functional ultra-high performance concrete prepared in Comparative Example 1.
  • FIG. 7 is a three-dimensional distribution diagram of steel fibers in the functionally graded ultra-high performance concrete prepared in Comparative Example 1.
  • FIG. 8 is a three-dimensional distribution diagram of air bubbles in the functionally graded ultra-high performance concrete prepared in Comparative Example 1.
  • Fig. 9 is a schematic diagram of the pressure applied when testing the 28d compressive strength of the gradient function ultra-high performance concrete product.
  • Fig. 10 is a schematic diagram of cutting when testing the average fiber area of the cross-section of the gradient function ultra-high performance concrete product.
  • the microbead involved in the following examples is a global shape, continuous particle size distribution, ultrafine, solid, ultrafine fly ash aluminosilicate fine microbead (sinking bead), particle size distribution range (d10 ⁇ 0.5 ⁇ m, d50 ⁇ 3 ⁇ m, d95 ⁇ 10 ⁇ m);
  • the viscosity reducer used is a common polycarboxylate superplasticizer special viscosity reducer on the market;
  • the steel fiber used is a common long straight copper-plated steel fiber.
  • This embodiment provides a preparation method of gradient functional ultra-high performance concrete products, including the following steps:
  • step S1 pour the steel fiber-containing ultra-high-performance concrete slurry obtained in step S1 into a mold of 40mm ⁇ 40mm ⁇ 160mm and pour it into a mold.
  • the vibration was continued for 15 minutes, and then stood still for 24 hours to obtain hardened ultra-high performance concrete.
  • the hardened ultra-high-performance concrete obtained in step S2 is removed from the formwork, and then placed under standard conditions for curing for 28 days to obtain gradient-functional ultra-high-performance concrete products.
  • the viscosity of the steel fiber-containing ultra-high performance concrete slurry obtained in step S1 is 19.1 Pa ⁇ s.
  • the 28d compressive strength of the gradient functional ultra-high performance concrete product obtained in step S3 was measured to be 137.9 MPa, and the 28d flexural strength was 31.5 MPa.
  • the flexural performance of the graded function ultra-high performance concrete product obtained in step S3 is tested to obtain a load-displacement curve, as shown in FIG. 1 . It can be seen from Fig. 1 that the bending resistance line of the prepared graded functional ultra-high performance concrete products can be divided into three stages: elastic stage, strain hardening stage and strain softening stage.
  • the load strength corresponding to the first crack point is 8.4KN.
  • the gradient function ultra-high performance concrete products show obvious strain hardening characteristics. This is because the steel fiber and the ultra-high performance concrete matrix form a load-bearing community.
  • Improve the toughness of graded functional ultra-high performance concrete products When the load reaches the ultimate load of 11.3KN, the graded functional ultra-high performance concrete product enters the strain softening stage, and the steel fibers are gradually pulled out, resulting in an increase in the deflection of the gradient functional ultra-high performance concrete product.
  • the toughness indices I 5 and I 10 of the prepared graded functional ultra-high performance concrete products are 10.7 and 20.3, respectively.
  • the gradient function ultra high performance concrete product obtained by the gradient function ultra high performance concrete product is cut in several sections according to the cutting direction shown in Figure 10, Obtain the cross-sectional photos shown in Figure 2; and use X-ray computed tomography to analyze the three-dimensional distribution of steel fibers and pores in functionally graded ultra-high performance concrete products, and the results are shown in Figures 3 and 4, respectively.
  • the gray part is the ultra-high performance concrete matrix
  • the white part is the steel fiber.
  • the discrete value of the steel fiber distribution is 9.6, and the average fiber area of the cross section is 0.042.
  • the discrete value and cross-sectional average fiber area are used to characterize the distribution state and orientation of steel fibers, respectively.
  • the larger the discrete value the more obvious the gradient distribution; the smaller the cross-sectional average fiber area, the better the orientation.
  • the steel fibers in the prepared ultra-high performance concrete are distributed in a gradient, and the orientation is better, and the distribution is directional. This result shows that the prepared graded functional ultra-high performance concrete products meet the design requirements, and the utilization efficiency of steel fibers is high.
  • Embodiments 2 to 7 and Comparative Examples 1 to 4 respectively provide a preparation method for gradient functional ultra-high performance concrete products. Compared with Embodiment 1, the difference is that the vibration conditions of the vibration table in step S2 are changed, and each The specific vibration conditions corresponding to the embodiment and the comparative example are shown in Table 1, and the rest of the steps and parameters are consistent with the embodiment 1, and will not be repeated here.
  • Table 2 shows the results after testing the performance of the functionally gradient ultra-high performance concrete products prepared in Examples 1-7 and Comparative Examples 1-4.
  • Table 2 The performance of the functional gradient ultra-high performance concrete products prepared in Examples 1 to 7 and Comparative Examples 1 to 4
  • the migration of steel fibers is gradually distributed in a gradient, and the content of steel fibers at the bottom of ultra-high performance concrete products gradually increases, so the tensile and flexural properties of the bottom are enhanced, and the utilization efficiency of steel fibers is also improved.
  • the steel fibers are affected by the disturbance effect during the migration process, and gradually become directional distribution; and the vibration will promote the discharge of air bubbles and optimize their pore structure, which helps to improve the flexural performance and toughness of ultra-high performance concrete products.
  • the 28d compressive strength of ultra-high performance concrete products prepared by simulating conventional UHPC vibration conditions in Comparative Example 1 is higher than that of Examples 1-7, but the flexural strength is low, and the toughness index I 5 and I 10 are significantly lower than those in Examples 1 ⁇ 7.
  • the discrete value of steel fibers decreases, and the average fiber area of cross-section increases.
  • the load-displacement curves, cross-sectional photos, and three-dimensional distribution of steel fibers and pores of the ultra-high performance concrete products prepared in Comparative Example 1 are shown in Figures 5 to 8, respectively, and can be seen by comparing them with Figures 1 to 4.
  • the 28d compressive strength and flexural strength of the ultra-high performance concrete prepared in Comparative Examples 2-4 are lower than those of Examples 1-7, and the toughness indices I 5 and I 10 are also lower than Examples 1-7 in the same direction.
  • the dispersion index of steel fibers increases significantly, while the average steel fiber area of cross-section decreases. This is mainly because the increase of vibration amplitude and vibration intensity, as well as the extension of vibration time, lead to more significant delamination of steel fibers in the prepared ultra-high performance concrete, and the content of steel fibers in the upper ultra-high performance concrete is too low, resulting in overall resistance Compressive strength and flexural strength decreased.
  • Examples 8-11 and Comparative Examples 5-6 respectively provide a method for preparing ultra-high-performance concrete products with gradient functions. Compared with Example 1, the difference is that the silica fume, water reducing agent and The amount of steel fiber, the weight fraction of silica fume and water reducing agent corresponding to each embodiment and comparative example, the volumetric content of steel fiber and the viscosity of the ultra-high performance concrete slurry made are shown in Table 3, and the remaining steps and parameters are consistent with those in Embodiment 1, and will not be repeated here.
  • Table 4 shows the results after testing the performance of the functionally gradient ultra-high performance concrete products prepared in Examples 8-11 and Comparative Examples 5-6.
  • Example 10 and Comparative Example 1 Analyzing Example 10 and Comparative Example 1, it can be seen that the flexural strength and toughness index of the two groups of functionally graded ultra-high performance concrete products are equivalent, but the dosage of steel fibers in Example 10 and Comparative Example 1 are 1.0% and 1.0% respectively. 1.5%, which further shows that the preparation method of the gradient function ultra-high performance concrete product provided by the present invention can effectively improve the utilization efficiency of steel fibers.
  • Comparative Example 6 no silica fume was added, the viscosity of the prepared ultra-high performance concrete slurry was too low, the discrete value of steel fibers was too large under vibration conditions, and the average fiber area of the cross section was large. It shows that the steel fibers in the ultra-high performance concrete prepared in Comparative Example 6 are clearly delaminated and their orientation is disordered. In addition, its compressive strength, flexural strength and corresponding toughness index I 5 and I 10 are also significantly lower than those of the examples with the same steel fiber content, indicating that the too low viscosity of the slurry under the vibration condition is not conducive to the preparation of ultra-high gradient function performance concrete.
  • the present invention can not only make the steel fibers in the ultra-high performance concrete matrix directional migrate to a state of gradient distribution, but also utilize The disturbance effect during the steel fiber migration process optimizes the orientation of the steel fiber, and at the same time optimizes the pore structure by utilizing the liquefaction effect of the slurry under vibration conditions, so as to obtain a gradient function superhigh with high steel fiber utilization efficiency, good compactness, and excellent bending resistance Performance concrete products to meet the needs of practical applications.
  • each raw material weighed can be appropriately adjusted on the basis of Example 1, and each raw material The weight meets 100 parts of Portland cement, 35-45 parts of microbeads, 10-15 parts of silica fume, 125-135 parts of quartz sand, 25-35 parts of water, 1-3 parts of water reducing agent, and 0.05-0.25 parts of reducing agent.
  • the ratio of the adhesive to 10-30 parts of the steel fiber is sufficient, and has little effect on the performance of the final ultra-high performance concrete product, and all belong to the protection scope of the present invention.
  • the present invention provides a functional gradient ultra-high performance concrete product and a preparation method thereof.
  • a predetermined amount of Portland cement, microbeads, silica fume, quartz sand, water, water reducing agent, viscosity reducing agent and steel fiber are fully mixed to make ultra-high performance concrete slurry with a certain viscosity, and then Place it on a vibrating table after pouring and forming, and continue to vibrate for more than 5 minutes under the conditions of up and down amplitude ⁇ 1mm and vibration intensity ⁇ 5g, and then stand until it is completely hardened.
  • the present invention can make use of the effective regulation and control of the vibration condition of the ultra-high performance concrete slurry, so that the steel fibers are in a gradient distribution state in the ultra-high performance concrete matrix, and at the same time optimize the orientation and pore structure of the steel fibers, thereby obtaining a high-performance Gradient function of fiber utilization efficiency for ultra-high performance concrete products to meet the needs of practical applications.

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Abstract

本发明提供了一种梯度功能超高性能混凝土制品及其制备方法和应用，其制备方法包括如下步骤：提供粘度为10～25Pa·S的含钢纤维超高性能混凝土浆体；使所述含钢纤维超高性能混凝土浆体在上下振幅≥1mm、振动强度≥5g的条件下持续振动5min以上，然后静置至硬化；养护，即得梯度功能超高性能混凝土制品。通过上述制备方法，本发明能够使钢纤维在超高性能混凝土基体中呈梯度分布状态，同时优化钢纤维的取向和超高性能混凝土基体内的孔结构，从而得到具有高纤维利用效率的梯度功能超高性能混凝土制品，以满足实际应用的需求。

Description

梯度功能超高性能混凝土制品及其制备方法和应用 技术领域
本发明涉及超高性能混凝土技术领域，尤其涉及一种梯度功能超高性能混凝土制品及其制备方法和应用。
背景技术
超高性能混凝土(UHPC)是一种具有超高强度、超高韧性和超高耐久性的建筑结构材料，可以很好地满足工程结构向高度更高、跨度更大、荷载更重方向发展时对材料性能的要求。因此，超高性能混凝土在近十年引起了国内外广大学者和工程师的高度关注，迅速成为科学研究的热点，并且在工程领域的应用也日益广泛。
在超高性能混凝土的制备过程中，通常会将一定量的纤维直接加入混凝土基体中拌制成型，以增加超高性能混凝土的韧性和强度等性能。但这种方法制备的超高性能混凝土未考虑纤维的分布和取向对其性能的影响，纤维利用率不高。目前，超高性能混凝土中纤维利用效率的提高主要通过控制纤维的定向分布来实现。例如，公开号为CN108453868A的专利公开了纤维定向分布纤维增强超高性能混凝土制品的制备方法及装置，该专利通过将配制的纤维增强超高性能混凝土拌合物浇入试模，再开启电场、振动，启动透视检测，利用外加电场使纤维产生旋转运动，并利用振动减少超高性能 混凝土浆体对纤维旋转运动的粘滞效果，从而使纤维定向排列，提高纤维的利用率。
然而，上述专利公开的方法仅仅能够对纤维的排列方向进行控制，而无法对纤维的分布状态进行调控。实际上，对于一些混凝土工程中的梁式结构，其服役时往往处于一侧受拉而另一侧受压的状态，这类超高性能混凝土结构梁受拉侧的抗拉强度往往决定了其安全载荷，而受压侧的力学性能则远大于实际需求，使得位于超高性能混凝土结构梁受压侧的纤维增强作用未得到充分利用而造成浪费。在此条件下，现有技术中仅仅调整纤维排列方向的方式难以有效提高纤维的利用率。
发明内容
针对上述现有技术的缺陷，本发明的目的在于提供一种梯度功能超高性能混凝土制品及其制备方法和应用。
本发明提供的技术方案具体如下：
第一方面，本发明提供一种梯度功能超高性能混凝土制品的制备方法，包括：
提供粘度为10～25Pa·S的含钢纤维超高性能混凝土浆体；
使所述含钢纤维超高性能混凝土浆体在上下振幅≥1mm、振动强度≥5g的条件下持续振动5min以上，然后静置至硬化；
养护，即得梯度功能超高性能混凝土制品。
以上技术方案在不同于一般超高性能混凝土振捣条件的振动条 件下(上下振幅≥1mm、振动强度≥5g)对特定粘度的超高性能混凝土浆体进行振动，使钢纤维在超高性能混凝土基体中呈梯度分布状态，满足一端抗拉、一端受压的超高性能混凝土制品的需求，振动的赋能使钢纤维在运动过程中产生旋转，使其取向偏一致化，且基体内气泡缩小，从而提高了超高性能混凝土制品的抗折性能。
作为上述技术方案的优选，含钢纤维超高性能混凝土浆体中，钢纤维的体积掺量为1％～3％。
作为上述技术方案的优选，含钢纤维超高性能混凝土浆体，按重量份计，包括100份硅酸盐水泥、35～45份微珠、10～15份硅灰、125～135份石英砂、25～35份水、1～3份减水剂、0.05～0.25份降粘剂和10～30份钢纤维。
作为上述技术方案的优选，石英砂的粒径分布范围为0～2mm。
作为上述技术方案的优选，减水剂为聚羧酸粉体减水剂。
作为上述技术方案的优选，降粘剂为聚羧酸减水剂专用降粘剂。
作为上述技术方案的优选，含钢纤维超高性能混凝土浆体粘度为15～20Pa·S。
作为上述技术方案的优选，上下振幅为1～5mm，振动强度为5～20g，振动持续的时间为5～30min。
第二方面，本发明提供一种由上述梯度功能超高性能混凝土制品的制备方法制备而成的梯度功能超高性能混凝土制品。
第三方面，本发明提供上述梯度功能超高性能混凝土制品在建筑领域中的用途。
本发明的有益效果是：
(1)本发明针对单侧受拉的超高性能混凝土制品中钢纤维利用率较低的问题，提出了将钢纤维梯度分布以达到功能化的技术构思，克服了传统的超高性能混凝土追求匀质的技术偏见；并通过对超高性能混凝土浆体进行振动处理，同时对振动条件进行调控，实现了超高性能混凝土制品中钢纤维的梯度分布，简便高效地制备了梯度功能超高性能混凝土制品。与现有技术中利用电场、磁场等条件使钢纤维定向分布的方式相比，本发明利用对超高性能混凝土浆体振动条件的精确调控，不仅能够使超高性能混凝土基体中的钢纤维定向迁移，达到梯度分布的状态，还能够利用钢纤维迁移过程中的扰动效应使钢纤维的取向趋向一致，同时利用振动条件下浆体的液化效应优化其孔结构，从而得到纤维利用效率高、密实性好、抗弯性能优异的梯度功能超高性能混凝土，以满足实际应用的需求。
(2)本发明提供的方法能够根据超高性能混凝土浆体的粘度进一步优化其振动条件，使钢纤维呈现所需的梯度分布状态，具有适用范围广、可控性强的优点。与现有技术中粘度过低的浆体中钢纤维的离析沉降相比，本发明利用振动效应形成的钢纤维的梯度分布状态可控，操作性强。且本发明提供的方法不需要借助电场或磁场，制备工艺简单，成本更低，更能满足实际生产的需求。
(3)本发明制备的梯度功能超高性能混凝土制品中，钢纤维呈梯度分布，且取向较优，不仅能够有效提高钢纤维的利用效率，降低钢纤维掺量后能达到非振动处理超高性能混凝土制品相同韧性； 还能够使钢纤维分布较多的一侧具有更高的抗拉强度，从而使制得的梯度功能超高性能混凝土制品具有更优异的抗弯性能，其韧性指数I 5和I 10分别可达到6.8～12.9和15.1～25.5，具有较高的实际应用价值。
附图说明
图1为实施例1制备的梯度功能超高性能混凝土的荷载-位移曲线。
图2为实施例1制备的梯度功能超高性能混凝土的横截面照片。
图3为实施例1制备的梯度功能超高性能混凝土中钢纤维的三维分布图。
图4为实施例1制备的梯度功能超高性能混凝土中气泡的三维分布图。
图5为对比例1制备的梯度功能超高性能混凝土的荷载-位移曲线。
图6为对比例1制备的梯度功能超高性能混凝土的横截面照片。
图7为对比例1制备的梯度功能超高性能混凝土中钢纤维的三维分布图。
图8为对比例1制备的梯度功能超高性能混凝土中气泡的三维分布图。
图9为测试梯度功能超高性能混凝土制品28d抗压强度时的施压示意图。
图10为测试梯度功能超高性能混凝土制品截面平均纤维面积时的切割示意图。
具体实施方式
为了使本发明的目的、技术方案和优点更加清楚，下面结合附图和具体实施例对本发明进行详细描述。
在此，还需要说明的是，为了避免因不必要的细节而模糊了本发明，在附图中仅仅示出了与本发明的方案密切相关的结构和/或处理步骤，而省略了与本发明关系不大的其他细节。
另外，还需要说明的是，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。
以下实施例中所涉及的微珠是一种全球状、连续粒径分布、超细、实心、超细粉煤灰硅铝酸盐精细微珠(沉珠)，粒径分布范围(d10≤0.5μm，d50≤3μm，d95≤10μm)；所采用降粘剂为市面上常见的聚羧酸减水剂专用降粘剂；所采用钢纤维为常用长直镀铜钢纤维。
下面结合具体的实施例对本发明提供的梯度功能超高性能混凝土制品的制备方法进行说明。
实施例1
本实施例提供了一种梯度功能超高性能混凝土制品的制备方法，包括如下步骤：
S1、含钢纤维超高性能混凝土浆体的制备
按照重量份计算，称取100份硅酸盐水泥、40份微珠、12份硅灰、129份石英砂、26份水、2份聚羧酸减水剂、0.1份降粘剂和15份钢纤维；其中，钢纤维的重量是根据设定的钢纤维体积掺量为1.5％换算得到。
将称取的硅酸盐水泥、微珠、硅灰、石英砂倒入搅拌锅中，慢速搅拌90s，在慢速搅拌的过程中，将已称取水的70％与全部减水剂和降粘剂形成的混合液缓慢倒入搅拌锅中，直至搅拌锅内的拌合物搅拌成面团状；然后加入剩余的水，继续快速搅拌2min，使胶凝材料与减水剂、降粘剂充分分散并混合均匀；最后在慢速搅拌的状态下缓慢加入称取的钢纤维，待钢纤维全部加入后，继续慢速搅拌1min，得到含钢纤维超高性能混凝土浆体。其中，慢速搅拌的搅拌速率为57～67r/min，快速搅拌的搅拌速率为115～135r/min。
S2、浇筑成型与硬化
将步骤S1得到的含钢纤维超高性能混凝土浆体倒入40mm×40mm×160mm的模具中浇筑成型，在充分插捣后将其表面刮平，覆盖上塑料薄膜后将其整体竖直固定在振动台上，在上下振幅为3mm、振动强度为10g的条件下持续振动15min后，再静置24h，得到硬化的超高性能混凝土。
S3、拆模养护
对步骤S2得到的硬化的超高性能混凝土进行拆模，然后将其置于标准条件下养护28d，得到梯度功能超高性能混凝土制品。
经测试，步骤S1得到的含钢纤维超高性能混凝土浆体的粘度为19.1Pa·s。采用如图9所示的施压方法，测得步骤S3得到的梯度功能超高性能混凝土制品的28d抗压强度为137.9MPa，28d抗折强度为31.5MPa。再对步骤S3得到的梯度功能超高性能混凝土制品的抗弯性能进行测试，得到荷载-位移曲线，如图1所示。由图1可以看出，制备的梯度功能超高性能混凝土制品的抗弯曲线可以分为三个阶段：弹性阶段、应变硬化阶段和应变软化阶段。初裂点对应的载荷强度为8.4KN，随着载荷的增加，梯度功能超高性能混凝土制品表现出明显的应变硬化特征，这是由于钢纤维与超高性能混凝土基体组成一个承载载荷的共同体，提高梯度功能超高性能混凝土制品的韧性。当载荷达到极限载荷11.3KN时，梯度功能超高性能混凝土制品进入应变软化阶段，钢纤维逐渐被拔出，导致梯度功能超高性能混凝土制品挠度增大。所制备的梯度功能超高性能混凝土制品的韧性指数I 5和I 10分别为10.7和20.3。
为了进一步分析步骤S3得到的梯度功能超高性能混凝土制品的钢纤维分布情况，按图10所示切割方向对制得的梯度功能超高性能混凝土制品梯度功能超高性能混凝土制品进行若干段切割，获得如图2所示的横截面照片；并采用X射线计算机断层扫描技术对梯度功能超高性能混凝土制品中钢纤维和气孔的三维分布情况进行分 析，结果分别如图3和图4所示。
在图2中，灰色部分为超高性能混凝土基体，白色部分为钢纤维。通过对图2进行图像分析，可以得到钢纤维分布的离散值为9.6，截面平均纤维面积为0.042。其中，离散值和截面平均纤维面积分别用于表征钢纤维的分布状态和取向，离散值越大，梯度分布越明显；截面平均纤维面积越小，取向越优。由本实施例的分析结果可以得出，制得的超高性能混凝土中钢纤维呈梯度分布，且取向较优，呈定向分布。这一结果表明了所制备的梯度功能超高性能混凝土制品达到所设计的要求，钢纤维的利用效率较高。
由图3、图4可以看出，本实施例制备的梯度功能超高性能混凝土制品内部钢纤维呈现显著的定向分布状态，而且其内部的气泡十分均匀且其尺寸均较小。表明了该振动条件可以很好地优化超高性能混凝土内部钢纤维的取向和孔结构。
实施例2～7及对比例1～4
实施例2～7及对比例1～4分别提供了一种梯度功能超高性能混凝土制品的制备方法，与实施例1相比，不同之处在于改变了步骤S2中振动台的振动条件，各实施例及对比例对应的具体振动条件如表1所示，其余步骤及参数均与实施例1一致，在此不再赘述。
表1实施例1～7及对比例1～4的振动条件
Figure PCTCN2022077810-appb-000001
Figure PCTCN2022077810-appb-000002
对实施例1～7及对比例1～4制备的梯度功能超高性能混凝土制品的性能进行测试后，结果如表2所示。
表2实施例1～7及对比例1～4制备的梯度功能超高性能混凝土制品的性能
Figure PCTCN2022077810-appb-000003
Figure PCTCN2022077810-appb-000004
由表2可以看出，随着振幅、振动强度和振动时间的增加，超高性能混凝土制品的28d抗压强度明显降低，但是抗折强度降低幅度较小。同时钢纤维的离散值逐渐增加，截面平均纤维面积逐渐降低。这表明超高性能混凝土制品内部钢纤维的迁移加剧，这会导致超高性能混凝土制品上层钢纤维的含量过低，受压时更容易被破坏。然而，钢纤维迁移逐渐呈梯度分布，超高性能混凝土制品底部钢纤维的含量逐渐增加，因此底部的抗拉和抗弯性能增强，钢纤维的利用效率也随之提高。同时，钢纤维在迁移过程中受扰动效应的影响，逐渐呈定向分布状态；且振动会促进气泡的排出，优化其孔结构，这有助于提高超高性能混凝土制品的抗折性能和韧性。
对比例1模拟常规的UHPC振捣条件制备的超高性能混凝土制品的28d抗压强度高于实施例1～7，但是抗折强度却偏低，韧性指数I 5和I 10显著低于实施例1～7。同时，钢纤维的离散值降低，截面平均纤维面积增大。对比例1制备的超高性能混凝土制品的荷载-位移曲线、横截面照片及钢纤维和气孔的三维分布情况分别如图5～图8所示，将其与图1～图4分别对比可以看出，对比例1制备的超高性能混凝土制品的应变硬化阶段更加不明显，表明其韧性显著降低，其极限载荷也显著降低，表明其抗弯性能明显下降。同时，对比例1制备的超高性能混凝土制品内部钢纤维呈均匀分布，其分布呈无序状态，且超高性能混凝土内部存在大量的大气泡，表明其孔结构相对更差，这也是导致其抗折强度和韧性降低的重要因素。
对比例2～4制备的超高性能混凝土的28d抗压强度和抗折强度均低于实施例1～7，韧性指数I 5和I 10也同向低于实施例1～7。同时，钢纤维的离散指数显著增大，而截面平均钢纤维面积降低。这主要是因为振动振幅和振动强度的增加，以及振动时间的延长，导致制备的超高性能混凝土内部钢纤维的分层更显著，上层超高性能混凝土内部钢纤维含量过低，导致整体的抗压强度和抗折强度下降。
实施例8～11及对比例5～6
实施例8～11及对比例5～6分别提供了一种梯度功能超高性能混凝土制品的制备方法，与实施例1相比，不同之处在于改变了步骤S1中硅灰、减水剂和钢纤维的用量，各实施例及对比例对应的硅灰与减水剂的重量分数、钢纤维的体积掺量及其制得的超高性能混凝土浆体的粘度如表3所示，其余步骤及参数均与实施例1一致，在此不再赘述。
表3实施例8～11及对比例5～6中硅灰、减水剂和钢纤维的用量以及浆体粘度
Figure PCTCN2022077810-appb-000005
Figure PCTCN2022077810-appb-000006
对实施例8～11及对比例5～6制备的梯度功能超高性能混凝土制品的性能进行测试后，结果如表4所示。
表4实施例8～11及对比例5～6制备的梯度功能超高性能混凝土制品的性能
Figure PCTCN2022077810-appb-000007
由表4可以看出，硅灰掺量较高，减水剂的含量较低时，其含钢纤维超高性能混凝土浆体的粘度较大，振动条件下钢纤维的离散值较小，截面平均纤维面积较大，表明钢纤维的梯度分布和取向不明显，其抗压强度和抗折强度也较高。降低硅灰掺量，提高减水剂掺量，可以降低浆体粘度，促进超高性能混凝土的梯度分布，提高纤维利用效率，增加梯度功能超高性能混凝土制品的韧性。钢纤维的掺入，会轻微提高浆体的粘度，同时，钢纤维掺量的增加，会显著提高超高性能混凝土制品的力学性能和韧性。分析实施例10和对比例1可以看出，两组梯度功能超高性能混凝土制品的抗折强度和韧性指数均相当，但是实施例10和对比例1中钢纤维的掺量分别为1.0％和1.5％，这进一步表明了本发明提供的梯度功能超高性能混凝 土制品的制备方法可以有效提高钢纤维的利用效率。
对比例5中硅灰的含量较高，所制备的超高性能混凝土浆体的粘度过高，振动条件下钢纤维的离散值过小，截面平均纤维面积较大。表明对比例3制备的超高性能混凝土中钢纤维未呈明显的定向取向和梯度分布。此外，其抗压强度、抗折强度及相应的韧性指数I 5和I 10也较同钢纤维掺量实施例降低，表明该振动条件下过高的浆体粘度不利于制备梯度功能超高性能混凝土。
对比例6中未掺入硅灰，所制备的超高性能混凝土浆体的粘度过低，振动条件下钢纤维的离散值过大，截面平均纤维面积较大。表明对比例6制备的超高性能混凝土中钢纤维出现明显分层且取向紊乱。此外，其抗压强度、抗折强度及相应的韧性指数I 5和I 10也较同钢纤维掺量实施例显著降低，表明该振动条件下过低的浆体粘度不利于制备梯度功能超高性能混凝土。
因此，本发明通过对含钢纤维超高性能混凝土浆体进行振动处理，并对振动条件进行调控，不仅能够使超高性能混凝土基体中的钢纤维定向迁移，达到梯度分布的状态，还能够利用钢纤维迁移过程中的扰动效应优化钢纤维的取向，同时利用振动条件下浆体的液化效应优化其孔结构，从而得到钢纤维利用效率高、密实性好、抗弯性能优异的梯度功能超高性能混凝土制品，以满足实际应用的需求。
需要说明的是，本领域技术人员应当理解，在按照本发明提供的方法制备梯度功能超高性能混凝土制品时，称取的各原料的重量 可以在实施例1的基础上进行适当调整，各原料的重量满足100份硅酸盐水泥、35～45份微珠、10～15份硅灰、125～135份石英砂、25～35份水、1～3份减水剂、0.05～0.25份降粘剂和10～30份钢纤维的比例即可，对最终制得的超高性能混凝土制品的性能影响不大，均属于本发明的保护范围。
综上所述，本发明提供了一种梯度功能超高性能混凝土制品及其制备方法。本发明通过将预定量的硅酸盐水泥、微珠、硅灰、石英砂、水、减水剂、降粘剂和钢纤维充分混匀，制成一定粘度的超高性能混凝土浆体，再将其浇筑成型后置于振动台上，在上下振幅≥1mm、振动强度≥5g的条件下持续振动5min以上，再静置至完全硬化，经拆模养护，得到梯度功能超高性能混凝土制品。通过上述方式，本发明能够利用对超高性能混凝土浆体振动条件的有效调控，使钢纤维在超高性能混凝土基体中呈梯度分布状态，同时优化钢纤维的取向和孔结构，从而得到具有高纤维利用效率的梯度功能超高性能混凝土制品，以满足实际应用的需求。
以上实施例仅用以说明本发明的技术方案而非限制，尽管参照较佳实施例对本发明进行了详细说明，本领域的普通技术人员应当理解，可以对本发明的技术方案进行修改或者等同替换，而不脱离本发明技术方案的精神和范围。

Claims (10)

  1. 一种梯度功能超高性能混凝土制品的制备方法，其特征在于，包括：
    提供粘度为10～25Pa·S的含钢纤维超高性能混凝土浆体；
    使所述含钢纤维超高性能混凝土浆体在上下振幅≥1mm、振动强度≥5g的条件下持续振动5min以上，然后静置至硬化；
    养护，即得梯度功能超高性能混凝土制品。
  2. 根据权利要求1所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：所述含钢纤维超高性能混凝土浆体中，钢纤维的体积掺量为1％～3％。
  3. 根据权利要求1所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：所述含钢纤维超高性能混凝土浆体，按重量份计，包括100份硅酸盐水泥、35～45份微珠、10～15份硅灰、125～135份石英砂、25～35份水、1～3份减水剂、0.05～0.25份降粘剂和10～30份钢纤维。
  4. 根据权利要求3所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：所述石英砂的粒径分布范围为0～2mm。
  5. 根据权利要求3所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：所述减水剂为聚羧酸粉体减水剂。
  6. 根据权利要求3所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：所述降粘剂为聚羧酸减水剂专用降粘剂。
  7. 根据权利要求1所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：含钢纤维超高性能混凝土浆体粘度为15～20 Pa·S。
  8. 根据权利要求1所述的梯度功能超高性能混凝土制品的制备方法，其特征在于：所述上下振幅为1～5mm，所述振动强度为5～20g，持续振动的时间为5～30min。
  9. 一种梯度功能超高性能混凝土制品，其特征在于：由权利要求1-8任一项所述的梯度功能超高性能混凝土制品的制备方法制备而成。
  10. 权利要求9所述的梯度功能超高性能混凝土制品在建筑领域中的用途。
PCT/CN2022/077810 2022-02-25 2022-02-25 梯度功能超高性能混凝土制品及其制备方法和应用 WO2023159450A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4062913A (en) * 1975-07-17 1977-12-13 Ab Institutet For Innovationsteknik Method of reinforcing concrete with fibres
CN101913189A (zh) * 2010-07-23 2010-12-15 河北工业大学 制备单向分布钢纤维增强砂浆的方法及其专用设备
CN201769264U (zh) * 2010-07-23 2011-03-23 河北工业大学 制备单向分布钢纤维增强水泥基材料的设备
CN114474302A (zh) * 2022-02-25 2022-05-13 中铁大桥局集团有限公司 梯度功能超高性能混凝土制品及其制备方法和应用

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4062913A (en) * 1975-07-17 1977-12-13 Ab Institutet For Innovationsteknik Method of reinforcing concrete with fibres
CN101913189A (zh) * 2010-07-23 2010-12-15 河北工业大学 制备单向分布钢纤维增强砂浆的方法及其专用设备
CN201769264U (zh) * 2010-07-23 2011-03-23 河北工业大学 制备单向分布钢纤维增强水泥基材料的设备
CN114474302A (zh) * 2022-02-25 2022-05-13 中铁大桥局集团有限公司 梯度功能超高性能混凝土制品及其制备方法和应用

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