Rib protection type super-early-strength high-fracture-resistance concrete as well as preparation method and application thereof

Abstract

The invention relates to rib protection type super-early-strength high-fracture-resistance concrete as well as a preparation method and application thereof. The preparation method comprises the following steps: weighing the following raw materials in parts by weight: 390 to 420 parts of a cementing material, 260 to 280 parts of a rib protecting mixed material, 850 to 875 parts of fine aggregate, 570 to 600 parts of coarse aggregate, 8 to 10 parts of a water reducing agent, 3.1 to 3.6 parts of a retarder, 0.6 to 0.9 part of a defoaming agent, 0.08 to 0.1 part of a thickening agent, 110 to 125 parts of steel fibers and 190 to 200 parts of water; the preparation method comprises the following steps: putting a cementing material, a rib protecting mixed material, fine aggregate, coarse aggregate, a water reducing agent, a retarder, a defoaming agent and a thickening agent into a stirring machine, and premixing until the materials are uniform; adding 3 / 4 of the total water amount into the stirrer, and uniformly stirring; adding steel fibers into the stirrer; adding the rest water into the stirrer at one time, and continuously stirring; and after pouring is completed, a water spraying kettle is used for spraying water mist to the surface of the concrete for curing, and the concrete strength is enhanced to reach the expectation.

Description

Technical Field

[0001] The present disclosure relates to the fields of civil engineering and transportation technology, and more specifically to a reinforcing steel bar type ultra-early strength high flexural strength concrete for repairing an expansion joint anchoring zone, and a preparation method and application thereof. Background Art

[0002] Expansion joints are an important component of structures such as bridges and tunnels. They are used to adapt to deformation of the structure caused by factors such as temperature changes and loads. They are usually connected to the bridge deck through concrete in the anchorage area. From a structural point of view, a large number of steel bars are arranged inside the concrete in the anchorage area of the expansion joint to ensure structural performance; from a force point of view, the concrete in the anchorage area of the expansion joint mainly bears the bending and tensile loads generated by vehicle rolling. During long-term use, the concrete in the anchorage area of the expansion joint often cracks, falls off, and the steel bars are exposed and rusted, which seriously affects the integrity and durability of the structure. Therefore, the concrete in the anchorage area of the expansion joint not only needs to meet the design indicators, but also needs to have sufficient flexural strength and reinforcement protection capabilities.

[0003] Conventional repair methods usually use ordinary concrete, but there are problems such as long setting time, slow strength growth, low flexural strength, easy cracking, etc., which are difficult to meet the requirements of rapid repair and high strength. In recent years, technologies have been developed using special cements such as sulphoaluminate cement to develop rapid repair concrete, which has high early strength (4h compressive strength 30MPa) characteristics. However, sulphoaluminate cement concrete has the characteristics of low alkalinity of hardened concrete (pH about 9.5~11.5, silicate cement concrete pH about 12~13) and less CSH gel products, which is not conducive to protecting the passive film of steel bars and preventing steel bar corrosion.

[0004] In addition, in order to meet the design requirements of flexural strength of concrete in the expansion joint anchorage area, steel fibers are usually required. When the CSH gel product is less, the bonding ability of concrete with steel bars and steel fibers will be significantly reduced, affecting the material and structural strength, and easily inducing problems such as unsatisfactory repair effects and reduced structural safety. The use of steel bar rust inhibitors or steel bar surface treatment methods in existing technologies requires the introduction of more complex construction processes and the use of special mixing equipment, which will not only significantly increase construction costs, but may also reduce the mechanical properties of concrete and prolong maintenance time, which does not meet the expectations of rapid repair projects. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide a reinforcing steel type ultra-early strength high flexural concrete for repairing the anchoring area of an expansion joint and a preparation method and application thereof, so as to solve the current problems of low alkalinity and less CSH gel product in sulphoaluminate cement concrete.

[0006] According to one aspect of the present disclosure, there is provided a method for preparing a steel-bar-reinforced ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage areas, including:

[0007] S1: Weigh raw materials according to the following parts by weight: 390 - 420 parts of cementitious materials, 260 - 280 parts of steel-bar-reinforced admixture, 850 - 875 parts of fine aggregate, 570 - 600 parts of coarse aggregate, 8 - 10 parts of water-reducing agent, 3.1 - 3.6 parts of retarder, 0.6 - 0.9 parts of defoaming agent, 0.08 - 0.1 parts of thickening agent, 110 - 125 parts of steel fiber, and 190 - 200 parts of water;

[0008] S2: Put the cementitious materials, steel-bar-reinforced admixture, fine aggregate, coarse aggregate, water-reducing agent, retarder, defoaming agent, and thickening agent in the raw materials into a mixer and premix until uniform;

[0009] S3: Add 3 / 4 of the total water consumption to the mixer and stir until uniform;

[0010] S4: Add steel fiber to the mixer. The steel fiber has passed through a stainless steel square-hole sieve to prevent the steel fiber from agglomerating;

[0011] S5: Add the remaining water to the mixer at one time and continue to stir to obtain the steel-bar-reinforced ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage areas;

[0012] S6: Use the steel-bar-reinforced ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage areas for pouring. After pouring, use a watering can to spray water mist on the surface of the concrete for curing to enhance the concrete strength to reach the expected value.

[0013] According to an embodiment of the present disclosure, the cementitious material described in step S1 is sulfoaluminate cement, and the sulfoaluminate cement clinker includes anhydrous calcium sulfoaluminate 60 - 75% by mass percentage, dicalcium silicate 10 - 30%, and tetracalcium ferroaluminate 2 - 8%.

[0014] According to an embodiment of the present disclosure, the steel-bar-reinforced admixture described in step S1 is obtained by mixing silica fume, fly ash, slag powder, and calcium oxide according to a mass ratio of 1:3:5:0.4, where:

[0015] The silicon dioxide content of silica fume ≥ 92%, and the specific surface area is 480 - 500m 2 / kg;

[0016] The fly ash is desulfurized first-class ash, and the specific surface area is 320 - 380m 2 / kg;

[0017] The slag powder is of S95 grade, and the specific surface area is 350 - 400m 2 / kg;

[0018] The calcium oxide is industrial pure calcium oxide with a purity of ≥90%.

[0019] According to an embodiment of the present disclosure, the fine aggregate described in step S1 is quartz sand, which is composed of four particle sizes of 10 - 20 mesh, 20 - 40 mesh, 40 - 70 mesh, and 70 - 140 mesh mixed in a mass ratio of 5:5:7:4.

[0020] According to an embodiment of the present disclosure, the coarse aggregate described in step S1 uses continuously graded crushed stone with a particle size of 4 - 6 mm.

[0021] According to an embodiment of the present disclosure, the water - reducing agent described in step S1 uses at least one of polycarboxylate superplasticizer, naphthalene - based water - reducing agent, anthracene - based water - reducing agent, and lignosulfonate water - reducing agent.

[0022] According to an embodiment of the present disclosure, the setting retarder described in step S1 uses at least one of borax, boric acid, citric acid, sodium gluconate, or tartaric acid.

[0023] According to an embodiment of the present disclosure, the defoaming agent described in step S1 is a polyether - type high - molecular compound; the thickening agent described in step S1 is a high - molecular compound such as cellulose; the steel fibers described in step S1 are composed of two types of steel fibers, Φ0.3mm×16mm end - hooked type and Φ0.4mm×20mm end - hooked type, mixed in a mass ratio of 4:5; the water described in step S1 is mixing water.

[0024] According to an embodiment of the present disclosure, the mixer described in step S2 uses a forced mixer, and the time required for premixing is 2 - 3 min.

[0025] According to an embodiment of the present disclosure, adding 3 / 4 of the total water consumption to the mixer and stirring until uniform includes: adding 1 / 2 of the total water consumption to the mixer at one time, starting to stir, and then starting to slowly add mixing water to the mixer after 1 min. The water - adding time lasts for 0.5 - 1 min, and a total of 1 / 2 of the remaining water consumption is added during this process. Then stir for 1.5 - 2 min until the state is uniform.

[0026] According to an embodiment of the present disclosure, the aperture of the stainless - steel square - hole sieve described in step S4 is 8 mm - 10 mm, and the time for adding steel fibers is within 1.5 - 2.5 min.

[0027] According to an embodiment of the present disclosure, the time required for continuous stirring in step S5 is 1 - 2 min.

[0028] According to an embodiment of the present disclosure, in step S6, spraying water mist on the concrete surface for curing with a watering can means spraying water mist on the concrete surface for curing with a watering can every 3 - 5 minutes. The curing time is calculated starting from the spraying moment, and the strength can reach the expected requirements after curing for 2.5 - 3 hours.

[0029] According to another aspect of the present disclosure, there is provided a steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas prepared by the method described above.

[0030] According to still another aspect of the present disclosure, there is provided an application of a steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas prepared by the method described above in bridge, tunnel, emergency repair of expressway, and post - earthquake emergency reinforcement engineering of building structures.

[0031] The steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas provided by the present disclosure, its preparation method and application have the following beneficial effects compared with the prior art:

[0032] (1) The present disclosure uses low - cost conventional materials and conventional mixing equipment, solves the problems of low alkalinity and less C - S - H gel products in current sulphoaluminate cement concrete, and can also prepare ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas with stronger steel - bar - protecting ability without using special materials such as rust inhibitors and other special admixtures without increasing material costs.

[0033] (2) The steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas provided by the present disclosure and its preparation method have the outstanding effect of using less cement content, larger amounts of steel - bar - protecting admixtures with different hydration rates, and steel fibers of different specifications to prepare steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete, which is of positive significance for reducing carbon emissions and is also an important way for concrete to achieve green and low - carbon.

[0034] (3) The steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas provided by the present disclosure and its preparation method have the outstanding effect of developing steel - bar - protecting admixtures to replace techniques such as steel - bar rust inhibitors and steel - bar surface treatment in conventional technical means, significantly simplifying the technological process in on - site implementation, and also eliminating the problem of repeatedly adjusting the concrete mix ratio for specifically developing and adding steel - bar rust inhibitors.

[0035] (4) The steel - bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas provided by the present disclosure and its preparation method simplify the traditional construction process, refine the usage process of mixing water, make the concrete have good workability and plasticity, facilitate construction and vibration, improve construction efficiency and quality, significantly reduce the time required for expansion joint anchorage area repair projects, and have positive significance for quickly restoring traffic. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above content and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0037] Figure 1 A method flow chart for preparing steel bar-reinforced ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage areas according to an embodiment of the present disclosure is shown. Specific Embodiments

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0039] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0040] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0041] To solve the problems of low alkalinity and few C-S-H gel products in current sulfoaluminate cement concrete, as Figure 1 shown, Figure 1 A method flow chart for preparing steel bar-reinforced ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage areas according to an embodiment of the present disclosure is shown. The method includes the following steps:

[0042] S1: Weigh raw materials according to the following parts by weight: 390 - 420 parts of cementitious materials, 260 - 280 parts of steel bar-reinforced admixture, 850 - 875 parts of fine aggregate, 570 - 600 parts of coarse aggregate, 8 - 10 parts of water reducer, 3.1 - 3.6 parts of retarder, 0.6 - 0.9 parts of defoamer, 0.08 - 0.1 parts of thickener, 110 - 125 parts of steel fiber, and 190 - 200 parts of water;

[0043] In this step, the cementitious material is sulfoaluminate cement. The clinker of sulfoaluminate cement includes calcium anhydrous sulfoaluminate 60 - 75% by mass percentage, dicalcium silicate 10 - 30% and tetracalcium aluminoferrite 2 - 8%, and the specific surface area is about 500 - 520m 2 / kg. At this time, the calcium anhydrous sulfoaluminate in the sulfoaluminate cement has a relatively fast hydration rate and can hydrate to form ettringite within a short time (such as within 3h) to reach the expected strength. At the same time, conventional technical means use a large amount of sulfoaluminate cement to ensure early strength, late strength and alkalinity (reinforcement protection ability) at the same time. In the present disclosure, only a small amount of sulfoaluminate cement is required to ensure early strength, and a large amount of reinforcement protection admixture is used to ensure the reinforcement protection ability and late strength of the concrete. This is one of the innovations.

[0044] The reinforcement protection admixture is obtained by mixing silica fume, fly ash, slag powder and calcium oxide according to the mass ratio of 1:3:5:0.4. Among them: the silica content of silica fume is ≥92%, and the specific surface area is 480 - 500m 2 / kg; the fly ash is desulfurized grade - 1 ash, and the specific surface area is 320 - 380m 2 / kg; the slag powder is S95 grade, and the specific surface area is 350 - 400m 2 / kg; the specific surface areas of silica fume, slag powder and fly ash form a gradient, which can not only construct a staged hydration reaction process, but also improve the density of hardened concrete.

[0045] The calcium oxide is industrial pure calcium oxide with a purity of ≥90%.

[0046] In the existing public and conventional mix proportions of high - strength concrete, auxiliary cementitious materials such as silica fume, fly ash, and slag powder mainly play the role of reducing cement consumption and reducing heat of hydration, and calcium oxide is used as an expansive agent or shrinkage compensating agent. The technical route adopted in the present disclosure is completely different. The reinforcement protection admixture realizes a staged hydration reaction by using the different specific surface areas and different activities of powder materials, increases the total amount of C - S - H gel and alkalinity in the concrete, and improves the reinforcement protection ability of the concrete throughout its life cycle. This is one of the innovations.

[0047] Using a small amount of highly active and large - specific - surface - area silica fume to match the hydration process of sulfoaluminate cement, it reacts with calcium ions in the hydration products to form C - S - H gel in a short time. On the one hand, it can solve the problem that almost no C - S - H gel is generated in the early stage of sulfoaluminate cement hydration. On the other hand, it can consume free calcium ions in the paste to promote the cement hydration reaction, accelerate the hydration process, and promote strength development.

[0048] The calcium ions generated by the hydration of extremely low calcium oxide dosage can make up for the calcium ions consumed by the hydration of silica fume, ensuring that the total amount of calcium sulfonate products produced by the hydration of sulphoaluminate cement will not decrease; at the same time, the hydroxide ions generated by the hydration of calcium oxide can provide an alkaline environment to promote the hydration of slag powder and fly ash. Compared with fly ash, slag powder has higher activity. Under the same specific surface area conditions, the hydration reaction of slag powder is faster than that of fly ash. It consumes hydroxide ions and generates CSH gel, which increases the total amount of CSH gel and promotes the hardening and early strength of concrete. At this time, the concrete has begun to develop structural strength, and calcium oxide has been consumed in large quantities. Therefore, it does not play the role of an expansion agent, but instead assists in achieving the reinforcement capacity in the early stage of hydration hardening.

[0049] When the concrete reaches a certain age, the dicalcium silicate in the sulphoaluminate cement begins to hydrate and provide a hydration reaction environment for the fly ash, further increasing the amount of CSH gel generated. This process often occurs in long-aged concrete, thereby achieving an improvement in the reinforcement protection capacity during the long-term service stage.

[0050] Therefore, by utilizing the specific surface area and activity combination of common concrete raw materials, a staged hydration reaction process is constructed to improve the reinforcement protection capacity of concrete throughout its life cycle, highlighting its innovation.

[0051] The fine aggregate is quartz sand, which is mixed with four particle sizes of 10-20 mesh, 20-40 mesh, 40-70 mesh and 70-140 mesh in a mass ratio of 5:5:7:4. This ratio can help concrete obtain optimal fluidity.

[0052] The coarse aggregate is a continuously graded crushed stone with a particle size of 4 to 6 mm.

[0053] The water reducer is at least one of polycarboxylic acid high-performance water reducer, naphthalene water reducer, anthracene water reducer and lignin sulfonate water reducer. In the existing public and conventional mixes, the water reducer is only used to disperse cement and mineral admixture particles to achieve the effect of reducing water consumption, and the water reducer dosage is usually specified not to exceed 1% of the total cementitious material dosage to prevent excessive dosage from causing slow setting of concrete. The present disclosure, however, does the opposite, and just takes advantage of this characteristic of the water reducer, uses a large amount of water reducer in the mix, so that the water reducer dosage reaches 2% to 5% of the total cementitious material dosage, and uses the slow setting effect of excessive addition of water reducer to control the setting time of concrete to 50 to 55 minutes, ensuring sufficient time for pouring during on-site implementation, while assisting various admixtures to ensure early strength, so as to achieve the purpose of preparing finished concrete with conventional mixing equipment.

[0054] The retarder is at least one of borax, boric acid, citric acid, sodium gluconate or tartaric acid, and is used to further prolong the setting time.

[0055] The defoamer is a polyether polymer compound, which is used to eliminate the large bubbles introduced into the concrete due to over-dosage of water reducer, improve the compactness of the concrete, and thus improve the concrete strength.

[0056] The thickener is a polymer compound such as cellulose, which is used to improve the cohesiveness of fresh concrete and facilitate construction.

[0057] The steel fibers are composed of two types of steel fibers, Φ0.3mm×16mm end-hooked type and Φ0.4mm×20mm end-hooked type, mixed in a mass ratio of 4:5; this ratio matches the hydration process of the reinforcing bar protecting cementitious material. When there is less C-S-H gel in the early age of concrete, due to the poor bonding performance between the A-H gel formed by the hydration of sulfoaluminate cement and the steel fibers, the Φ0.4mm×20mm end-hooked steel fibers are required to ensure the early flexural strength. When the reinforcing bar protecting admixture fully reacts to increase the total amount of C-S-H gel, the Φ0.3mm×16mm end-hooked steel fibers begin to play a role, and the two together improve the later flexural strength.

[0058] The water mentioned is mixing water.

[0059] S2: Put the cementitious material, reinforcing bar protecting admixture, fine aggregate, coarse aggregate, water reducer, retarder, defoamer and thickener in the raw materials into a mixer and premix until uniform.

[0060] In this step, the mixer used is a compulsory mixer, and the premixing time required is 2 - 3 min.

[0061] S3: Add 3 / 4 of the total water consumption to the mixer and stir until uniform.

[0062] In this step, adding 3 / 4 of the total water consumption to the mixer and stirring until uniform includes: adding 1 / 2 of the total water consumption to the mixer at one time, starting to stir, and then starting to slowly add mixing water to the mixer after 1 min. The water addition time lasts for 0.5 - 1 min, and a total of 1 / 2 of the remaining water consumption is added during this process, and then stir for 1.5 - 2 min until the state is uniform.

[0063] S4: Add steel fibers to the mixer. The steel fibers have passed through a stainless steel square-hole sieve to prevent the steel fibers from agglomerating.

[0064] In this step, the aperture of the stainless steel square-hole sieve is 8 mm - 10 mm, and the time for adding steel fibers is within 1.5 - 2.5 min.

[0065] S5: Add the remaining water to the mixer at one time, and continue to stir to obtain the reinforcing bar protecting type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area.

[0066] In this step, the required time for continuous stirring is 1 to 2 minutes.

[0067] S6: Pour using the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repair of expansion joint anchorage zones. After pouring, use a watering can to spray water mist on the concrete surface for curing to enhance the concrete strength to reach the expected level.

[0068] In this step, when using a watering can to spray water mist on the concrete surface for curing, spray water mist on the concrete surface with a watering can every 3 to 5 minutes. The curing time is calculated starting from the spraying moment. The strength can reach the expected requirements after curing for 2.5 to 3 hours.

[0069] From Figure 1 the preparation method of the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repair of expansion joint anchorage zones shown in the embodiments, it can be known that for the method of preparing the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repair of expansion joint anchorage zones in the embodiments of the present disclosure, there are no special requirements for mechanical equipment in the whole preparation process, and the whole stirring time is controlled within 7.5 to 10 minutes, which is beneficial to the requirements for timeliness in emergency repair projects. This technology is also one of the significant innovations of the present disclosure.

[0070] Based on Figure 1 the method of preparing the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repair of expansion joint anchorage zones according to the embodiments of the present disclosure shown, the following combines Examples 1 - 2 to detail the method of preparing the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repair of expansion joint anchorage zones provided by the present disclosure.

[0071] Example 1:

[0072] This example includes the following raw material components in parts by weight: 398 parts of sulfoaluminate cement, 268 parts of steel-bar-protecting admixture, 862 parts of fine aggregate, 588 parts of coarse aggregate, 198 parts of water, 8.8 parts of water reducer, 3.4 parts of retarder, 0.66 parts of defoamer, 0.086 parts of thickener, and 112 parts of steel fiber.

[0073] Prepare the above raw materials according to Figure 1 the preparation method shown to obtain the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repair of expansion joint anchorage zones.

[0074] Example 2:

[0075] This example includes the following raw material components in parts by weight: 415 parts of sulfoaluminate cement, 275 parts of steel-bar-protecting admixture, 871 parts of fine aggregate, 595 parts of coarse aggregate, 192 parts of water, 9 parts of water reducer, 3.1 parts of retarder, 0.82 parts of defoamer, 0.095 parts of thickener, and 120 parts of steel fiber.

[0076] Prepare the above raw materials according to Figure 1The reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas is prepared by the preparation method shown above.

[0077] Table 1 Physical and mechanical properties of the reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete in the examples

[0078]

[0079] It can be seen that the preparation method of the reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas provided by the present disclosure uses a small amount of cement, a large amount of reinforcing bar - protecting admixtures with different hydration rates, and steel fibers of different specifications to solve the problems of low alkalinity and few C - S - H gel products in current sulfoaluminate cement concrete. At the same time, it can also prepare the ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas with stronger reinforcing bar - protecting ability without using special materials such as rust inhibitors and other special admixtures without increasing the material cost.

[0080] Furthermore, the present disclosure develops reinforcing bar - protecting admixtures to replace technologies such as steel bar rust inhibitors and steel bar surface treatment in conventional technical means, significantly simplifies the technological process in on - site implementation, and also eliminates the problem of repeatedly adjusting the concrete mix ratio for the targeted development and addition of steel bar rust inhibitors.

[0081] Furthermore, the present disclosure simplifies the traditional construction process and refines the usage process of mixing water, making the concrete have good workability and plasticity, facilitating construction and vibration, improving construction efficiency and quality, significantly reducing the time required for the expansion joint anchorage area repair project, and having a positive significance for quickly restoring traffic.

[0082] Furthermore, based on the above - mentioned preparation method of the reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas, the present disclosure also provides a reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas prepared by the said method. This reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas uses a small amount of cement, a large amount of reinforcing bar - protecting admixtures with different hydration rates, and steel fibers of different specifications to achieve the preparation of the reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete, which has a positive significance for reducing carbon emissions and is also an important way for concrete to achieve green and low - carbon.

[0083] Furthermore, based on the above - mentioned preparation method of the ultra - early - strength and ultra - high - strength concrete for rapid repair projects, the present disclosure also provides an application of the reinforcing bar - protecting type ultra - early - strength and high - flexural - strength concrete for repairing expansion joint anchorage areas prepared by the said method in bridge, tunnel, highway emergency repair, and post - earthquake building structure emergency reinforcement projects.

[0084] Those skilled in the art will appreciate that the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0085] The embodiments of the present disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments have been described separately above, this does not mean that the measures in the respective embodiments cannot be used advantageously in combination. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present disclosure.

Claims

1. A preparation method of a steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage areas, characterized in that, Including: S1: Weigh the raw materials according to the following parts by weight: 390 - 420 parts of cementitious material, 260 - 280 parts of steel bar protection admixture, 850 - 875 parts of fine aggregate, 570 - 600 parts of coarse aggregate, 8 - 10 parts of water reducing agent, 3.1 - 3.6 parts of retarder, 0.6 - 0.9 parts of defoaming agent, 0.08 - 0.1 parts of thickening agent, 110 - 125 parts of steel fiber and 190 - 200 parts of water; S2: Put the cementitious material, steel bar protection admixture, fine aggregate, coarse aggregate, water reducing agent, retarder, defoaming agent and thickening agent in the raw materials into a mixer and premix until uniform; S3: Add 3 / 4 of the total water consumption to the mixer and stir until uniform; S4: Add steel fiber to the mixer. The steel fiber has passed through a stainless steel square hole sieve to prevent the steel fiber from agglomerating; S5: Add the remaining water to the mixer at one time and continue to stir to obtain the steel bar protection type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area; S6: Use the steel bar protection type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area for pouring. After pouring, use a watering can to spray water mist on the concrete surface for curing to enhance the concrete strength to reach the expected value.

2. The preparation method of the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, wherein, The cementitious material described in step S1 is sulfoaluminate cement. The sulfoaluminate cement clinker includes 60 - 75% of anhydrous calcium sulfoaluminate, 10 - 30% of dicalcium silicate and 2 - 8% of tetracalcium ferroaluminate by mass percentage.

3. The preparation method of the steel bar protecting type ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage zones according to claim 1, characterized in that, The steel bar protection admixture described in step S1 is obtained by mixing silica fume, fly ash, slag powder and calcium oxide according to a mass ratio of 1:3:5:0.4, where: The silicon dioxide content of silica fume is ≥92%, and the specific surface area is 480 - 500 m 2 / kg; The fly ash is the first-class ash for desulfurization, with a specific surface area of 320 - 380 m 2 / kg; The slag powder is of S95 grade with a specific surface area of 350 - 400 m 2 / kg; The calcium oxide is industrial pure calcium oxide with a purity of ≥90%.

4. The preparation method of the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, characterized in that, The fine aggregate described in step S1 is quartz sand, which is composed of four particle sizes of 10 - 20 mesh, 20 - 40 mesh, 40 - 70 mesh and 70 - 140 mesh mixed according to a mass ratio of 5:5:7:

4.

5. The preparation method of the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, characterized in that, The coarse aggregate described in step S1 uses continuously graded gravel with a particle size of 4 - 6 mm.

6. The preparation method of the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage zones according to claim 1, characterized in that, The water reducing agent described in step S1 uses at least one of polycarboxylate high-performance water reducing agent, naphthalene-based water reducing agent, anthracene-based water reducing agent, and lignosulfonate water reducing agent.

7. The preparation method of the reinforcement-protecting type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, characterized in that, The retarder described in step S1 uses at least one of borax, boric acid, citric acid, sodium gluconate or tartaric acid.

8. The preparation method of the steel bar protection type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, characterized in that The defoaming agent described in step S1 is a polyether-based polymer compound; The thickening agent described in step S1 is a polymer compound such as cellulose; The steel fiber described in step S1 is composed of two types of steel fibers, Φ0.3mm×16mm end-hooked type and Φ0.4mm×20mm end-hooked type, mixed according to a mass ratio of 4:5; The water described in step S1 is mixing water.

9. The preparation method of the reinforcing bar-protecting type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, characterized in that, The mixer described in step S2 uses a forced mixer, and the premixing time required is 2 - 3 min.

10. The preparation method of the steel bar protection type ultra-early-strength and high flexural strength concrete for repairing the expansion joint anchorage area according to claim 1, characterized in that, Adding 3 / 4 of the total water consumption to the mixer and stirring until uniform described in step S3 includes: Add 1 / 2 of the total water consumption to the mixer at one time and start stirring. After 1 min, continue to slowly add mixing water to the mixer. The water addition time lasts for 0.5 - 1 min. During this process, a total of 1 / 2 of the remaining water consumption is added. Then stir for 1.5 - 2 min until the state is uniform.

11. The preparation method of the steel bar protecting type ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage zones according to claim 1, characterized in that, The aperture of the stainless - steel square - hole sieve described in step S4 is 8 mm - 10 mm, and the time for adding steel fibers is within 1.5 - 2.5 min.

12. The preparation method of the steel bar protecting type ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage zones according to claim 1, characterized in that, The time required for continuous stirring described in step S5 is 1 - 2 min.

13. The preparation method of the steel-bar-protecting type ultra-early-strength and high flexural strength concrete for repairing expansion joint anchorage zones according to claim 1, characterized in that, In step S6, spraying water mist on the concrete surface with a watering can for curing means spraying water mist on the concrete surface with a watering can every 3 - 5 min. The curing time is calculated starting from the spraying moment. After curing for 2.5 - 3 h, the strength can reach the expected requirements.

14. A steel - bar - protected type ultra - early - strength and high - flexural - strength concrete for repairing the expansion joint anchorage area prepared by the method according to any one of claims 1 to 13.

15. The application of a steel - bar - protected type ultra - early - strength and high - flexural - strength concrete for repairing the expansion joint anchorage area prepared by the method according to any one of claims 1 to 13 in bridge, tunnel, emergency repair of expressway, and post - earthquake building structure emergency reinforcement projects.

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