A kind of concrete composite material for road and bridge and its preparation method

Abstract

This invention belongs to the field of concrete technology, specifically relating to a concrete composite material for roads and bridges and its preparation method. Its raw material composition includes: a cementitious material system, an aggregate system, a hybrid fiber system, a liquid-stabilizing lightweight aggregate, and an admixture system. This invention uses cement, fly ash, and silica fume to construct the cementitious material system. High-strength lightweight aggregate is absorbed into a composite internal curing liquid and then subjected to surface stabilization treatment to obtain a liquid-stabilizing lightweight aggregate. Through the synergistic effect of the components in the composite internal curing liquid, the internal moisture retention capacity and early-age shrinkage state of the concrete are improved. Furthermore, a multi-scale hybrid fiber reinforcement system is constructed by combining steel fibers and PVA fibers. A process involving PVA fiber surface activation treatment, staged wet mixing with water, and low-speed addition of the liquid-stabilizing lightweight aggregate in the later stages is employed to improve fiber dispersion uniformity and reduce the risk of premature liquid loss of the lightweight aggregate during the mixing stage, thereby achieving comprehensive improvement.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to a concrete composite material for road and bridge construction and its preparation method. Background Technology

[0002] Concrete used in road and bridge engineering typically withstands long-term vehicle loads, temperature changes, wet-dry cycles, freeze-thaw cycles, and external corrosive media during its service life. Therefore, it not only requires high compressive strength but also good crack resistance, flexural toughness, fatigue durability, and long-term service stability. Especially in bridge deck pavement, road surface layers, bridge connections, and other low water-cement ratio high-performance concrete structures, the material's internal free water is relatively insufficient. During the continuous hydration of cement, significant self-drying occurs, which can induce large volume shrinkage and early-age cracks, affecting the structural integrity and service life.

[0003] In existing road and bridge concrete, techniques such as reducing the water-cement ratio, adding fly ash and silica fume, introducing water-reducing agents, and compounding fibers are commonly used to improve mechanical properties and durability. Among these, while low water-cement ratios and mineral admixture systems are beneficial for improving paste density and later-stage strength, they can also exacerbate early-age internal water loss and shrinkage sensitivity to some extent. When relying solely on external watering or covering for curing, it is difficult to replenish moisture to the concrete interior in a timely manner. This is especially true for bridge deck paving, large-area road surface layers, or construction environments with limited curing conditions, where internal water loss is more pronounced, easily leading to shrinkage cracks, interface damage, and localized decreases in durability.

[0004] To address the aforementioned shortcomings, existing technologies have proposed pre-wetting lightweight aggregates for internal curing, where water is stored in the aggregates and gradually released during the hardening process to alleviate internal self-drying. Other approaches utilize steel fibers, polymer fibers, or a combination of multiple fibers to improve crack resistance and toughness. Research and applications have also focused on optimizing admixture systems and mixing processes to improve workability and fiber dispersion. However, existing technologies still have the following limitations: First, conventional pre-wetted lightweight aggregates are prone to premature liquid loss during mixing, resulting in insufficient effective liquid release after the actual hardening stage, leading to unstable internal curing effects. Second, single-water-storage internal curing methods primarily focus on water replenishment, offering limited improvement in shrinkage control and localized humidity maintenance in low water-cement ratio systems. Third, while using a single fiber can improve crack resistance or toughness to some extent, it is insufficient for controlling the entire process from microcrack initiation to macrocrack propagation in road and bridge concrete. Fourth, fibers, especially fine-diameter polymer fibers, are prone to agglomeration, uneven distribution, and insufficient localized encapsulation in concrete, resulting in significant fluctuations in reinforcement effects. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a concrete composite material for road and bridge construction and its preparation method. To address the problems of rapid internal water loss leading to high early-age shrinkage cracking risk in existing low-water-cement ratio concrete for road and bridge applications, insufficient liquid retention stability of lightweight aggregate internal curing systems during mixing, poor fiber dispersion uniformity, and difficulty in synergistically improving crack resistance and toughening properties, this invention constructs a cementitious material system using cement, fly ash, and silica fume. High-strength lightweight aggregate is absorbed into a composite internal curing liquid and then subjected to surface liquid stabilization treatment to obtain a liquid-stabilized lightweight aggregate. Through the synergistic effect of the components in the composite internal curing liquid, the concrete's internal moisture retention capacity and early-age shrinkage state are improved. Furthermore, a multi-scale hybrid fiber reinforcement system is constructed by combining steel fibers and PVA fibers. PVA fiber surface activation treatment, staged wet mixing with water, and a low-speed addition process to the liquid-stabilized lightweight aggregate in the later stages are employed to improve fiber dispersion uniformity and reduce the risk of premature liquid loss during mixing. This achieves comprehensive improvement in internal moisture regulation, shrinkage control, multi-scale crack suppression, flexural toughening, and long-term durability, making it particularly suitable for road and bridge engineering structures such as bridge deck pavement, road surface layers, and bridge connection parts.

[0006] The technical effects described in this invention are achieved through the following technical solution: a concrete composite material for roads and bridges, the raw material composition of which includes: a cementitious material system, an aggregate system, a hybrid fiber system, a liquid-stabilizing lightweight aggregate and an admixture system;

[0007] Preferably, the cementitious material system comprises the following components by weight: 280-320 parts P.O52.5 cement, 50-80 parts fly ash, and 15-25 parts silica fume;

[0008] Preferably, the aggregate system comprises the following components by weight: 680-750 parts fine aggregate and 1000-1100 parts coarse aggregate;

[0009] Preferably, the fine aggregate is medium sand with a fineness modulus of 2.3 to 3.0;

[0010] Preferably, the coarse aggregate is continuously graded crushed stone with a particle size of 5-15 mm;

[0011] Preferably, the hybrid fiber system comprises the following components by weight: 10-18 parts steel fiber and 1.2-2.5 parts PVA fiber;

[0012] Preferably, the steel fiber is any one of copper-plated steel fiber, corrugated steel fiber, or end-hooked steel fiber;

[0013] Preferably, the PVA fiber is a polyvinyl alcohol fiber with a length of 6-12 mm and a diameter of 20-50 μm;

[0014] Preferably, the composition of the liquid-stabilizing lightweight aggregate includes the following components by weight: 90-150 parts high-strength lightweight aggregate, 30-60 parts composite internal conditioning liquid, and 10-30 parts surface liquid stabilization treatment system.

[0015] Preferably, the liquid-stabilizing lightweight aggregate is obtained by absorbing the composite internal curing liquid through high-strength lightweight aggregate and then coating the surface with a surface liquid-stabilizing treatment system.

[0016] Preferably, the high-strength lightweight aggregate is high-strength shale ceramsite with a particle size of 5-10 mm;

[0017] Preferably, the raw materials for preparing the composite internal health-preserving solution include the following components in parts by weight: 9-15 parts of polyether shrinkage-reducing agent, 80-90 parts of distilled water, 1-2.5 parts of moisturizing and migration-regulating component, and 1-3 parts of active auxiliary component;

[0018] The polyether shrinkage reducer refers to a polyether compound that has the function of reducing the surface tension of concrete, preferably a commercially available concrete shrinkage reducer such as polyoxyethylene-polyoxypropylene block polyether or polyethylene glycol monobutyl ether.

[0019] Preferably, the moisturizing migration-regulating component is any one of glycerin, polyethylene glycol, or hydroxyethyl cellulose;

[0020] Preferably, the active auxiliary component is any one of silica sol, nano-silica, or sodium metasilicate;

[0021] Preferably, the raw materials for preparing the surface liquid stabilization treatment system include the following components by weight: 6-9 parts silica sol, 3-6 parts water glass, 8-12 parts ultrafine mineral powder, and 80-90 parts distilled water;

[0022] Preferably, the ultrafine mineral powder is any one of silica fume, ultrafine fly ash, or ultrafine mineral powder;

[0023] Preferably, the surface liquid stabilization treatment system is prepared by conventional stirring and dispersion methods;

[0024] Preferably, the additive system comprises the following components by weight: 5-8 parts of polycarboxylate superplasticizer and 100-140 parts of mixing water;

[0025] Another aspect of the present invention is to provide a method for preparing concrete composite materials for roads and bridges, specifically including the following steps:

[0026] S1: Add the polyether shrinkage reducing agent to distilled water and stir at room temperature for 10-20 minutes until well mixed to obtain a shrinkage reducing base solution; add the moisturizing and migration regulating component to the shrinkage reducing base solution and continue stirring for 15-30 minutes to disperse it evenly; then add the active auxiliary component and stir at 300-500 rpm for 20-40 minutes to obtain a composite internal conditioning solution.

[0027] S2: After cleaning the high-strength lightweight aggregate, dry it at 80-105℃ to constant weight; place the dried high-strength lightweight aggregate in a sealed container, evacuate it to -0.06 to -0.095 MPa, and maintain it for 10-30 minutes to remove air from the pores of the lightweight aggregate; then introduce the composite internal curing liquid prepared in step S1 to completely immerse the high-strength lightweight aggregate; after releasing the vacuum, continue to immerse it at normal pressure for 30-60 minutes; after immersion, take it out and drain off the surface free liquid to obtain liquid-absorbing lightweight aggregate;

[0028] S3: Mix silica sol, water glass, ultrafine mineral powder and distilled water, and stir at 400-700 rpm for 20-30 min to obtain a surface liquid stabilization treatment solution; add the liquid-absorbing lightweight aggregate obtained in step S2 to the surface liquid stabilization treatment solution and mix for 5-15 min to form a uniform thin layer on its surface; then dry the treated lightweight aggregate at a low temperature of 40-60℃ for 1-3 h to obtain a liquid-stabilized storage lightweight aggregate;

[0029] S4: Place the PVA fiber in a low-temperature plasma treatment device and perform surface activation treatment in a vacuum environment. The treatment power is 80-120W and the treatment time is 100-180s. After treatment, seal and store for later use.

[0030] S5: Add cement, fly ash, silica fume, fine aggregate and coarse aggregate into the mixing equipment and dry mix to pre-disperse the cementitious materials and aggregates evenly to obtain a basic dry material system;

[0031] S6: Add 60-75% of the total mixing water to the polycarboxylate superplasticizer after pre-mixing evenly, then add it to the basic dry material system prepared in step S5, and stir for 60-120 seconds to form the initial slurry coating state;

[0032] S7: After the initial slurry is formed in step S6, steel fibers are added slowly first, followed by PVA fibers pretreated in step S4. Stirring is carried out while adding the fibers, and the stirring time is 60-180 seconds, so that the steel fibers and PVA fibers are evenly dispersed in the slurry.

[0033] S8: Add the remaining 25-40% of the mixing water to the mixture obtained in step S7, add the remaining water-reducing agent, and continue stirring for 60-120 seconds to further optimize the rheological state of the slurry and obtain a basic concrete mixture with uniform fiber dispersion.

[0034] S9: Add the liquid-stabilized lightweight aggregate prepared in step S3 to the basic concrete mixture obtained in step S8 after the mixing stage, and stir at a low speed of 20-40 rpm for 60-90 s to make the liquid-stabilized lightweight aggregate uniformly dispersed in the concrete system to obtain the concrete composite material.

[0035] Preferably, in step S4, the PVA fiber is used within 24 hours after treatment;

[0036] Preferably, in step S6, the purpose of adding water for the first time is to form a slurry environment with a certain adhesive capacity, so as to provide conditions for subsequent fiber dispersion.

[0037] Preferably, in steps S6 and S8, the polycarboxylate superplasticizer is added as follows: 60-80% is added in step S6 by mixing with the first mixing water, and the remaining 20-40% is added in step S8.

[0038] The beneficial effects of this invention are as follows:

[0039] This invention pre-absorbs a composite internal curing liquid into high-strength lightweight aggregates and further treats the surface with a liquid-stabilizing agent. This first endows the lightweight aggregates with good liquid storage capacity and liquid retention stability during the mixing stage at the material level. Based on this, a low-speed addition process is used in the later stages to reduce the adverse effects of high-shear mixing on the surface liquid stability and internal liquid storage state of the lightweight aggregates. This allows the composite internal curing liquid in the absorbent lightweight aggregates to continue to be gradually released after casting. The combination of these material and process characteristics facilitates a continuous internal water supply during the early stages of concrete curing. Furthermore, it leverages the synergistic regulatory effects of polyether shrinkage reducers, moisture-retaining migration regulators, and active auxiliary components on internal humidity and shrinkage development. This maintains a relatively stable humidity environment inside the concrete, reducing shrinkage stress concentration caused by rapid internal water loss, thereby reducing the volume shrinkage and early cracking tendency of low water-cement ratio road and bridge concrete.

[0040] This invention employs a hybrid fiber system constructed from steel fibers and PVA fibers. Steel fibers facilitate bridging, force transmission, and energy dissipation during the development of larger cracks, while PVA fibers provide dispersion and constraint during the initiation and propagation of microcracks. Furthermore, the gradual release of the composite internal curing liquid from the liquid-absorbing lightweight aggregate improves the humidity maintenance conditions within the concrete, particularly in the slurry region surrounding the lightweight aggregate, mitigating the localized shrinkage inconsistencies caused by rapid water loss from the slurry around the fibers. Thus, this internal curing and humidity regulation characteristic provides a more stable matrix environment for the hybrid fiber system. This improved matrix environment further enhances the multi-scale crack suppression effect, creating a continuous crack control network within the concrete covering the initiation of microcracks, the propagation of fine cracks, and the development of larger cracks. Consequently, cracks are less likely to rapidly penetrate under bending and repeated loading, improving the load-bearing capacity and energy dissipation capacity after cracking, achieving a synergistic improvement in early-age crack resistance and later-age toughening.

[0041] This invention employs a low-temperature plasma surface activation treatment on PVA fibers during the preparation process. This treatment improves the surface wettability of the PVA fibers, making them easier to uniformly wet and encapsulate upon entering the slurry, thereby reducing the possibility of fiber entanglement and local agglomeration. Building upon this, a staged water-addition wet mixing process is used. The first water addition creates an initial slurry environment with a certain adhesive capacity, providing the necessary dispersion medium for fiber addition. A second water addition further adjusts the rheological state of the mixture and the fiber suspension stability. Thus, the improved fiber surface condition creates more favorable dispersion conditions for the staged wet mixing process, which in turn ensures that the activated fibers can be uniformly dispersed in a suitable slurry environment. This mutual promotion improves the dispersion uniformity and spatial distribution stability of steel and PVA fibers in the slurry, reduces performance fluctuations caused by fiber agglomeration, segregation, or insufficient encapsulation, and allows the crack resistance and toughening effect of the fiber-reinforced system to be more fully realized.

[0042] This invention employs a cementitious material system composed of cement, fly ash, and silica fume. Fly ash helps improve the workability and particle size distribution of the mixture, while silica fume helps enhance the density of the slurry and the interfacial bonding. These matrix material characteristics provide a suitable load-bearing environment for fiber dispersion and the effective function of liquid-absorbing lightweight aggregates. Furthermore, a composite internal curing system improves internal humidity conditions in the early stages, a hybrid fiber system enhances crack control and energy dissipation capacity, and a staged low-damage mixing process ensures that each functional component enters the system and performs its function at the appropriate stage. Thus, a synergistic relationship is formed between the cementitious material system, the liquid-absorbing lightweight aggregate internal curing system, the hybrid fiber system, and the staged mixing process, resulting in comprehensive improvements in flexural strength, crack resistance, toughness, and durability. This makes the material more suitable for road and bridge engineering scenarios with high requirements for crack resistance and long-term service stability, such as bridge deck paving, road surface layers, and bridge connection parts. Attached Figure Description

[0043] Figure 1 The graphs show the changes in the autogenous shrinkage rate of concrete over age obtained in Examples 1-3 and Comparative Examples 1, 2, and 5.

[0044] Figure 2 This is a comparison chart of the liquid loss rate during the mixing stage of the liquid-absorbing lightweight aggregates obtained in Examples 1-3 and Comparative Examples 2 and 5;

[0045] Figure 3 The figures show the three-point bending load-deflection curves of the concrete specimens obtained in Examples 1-3 and Comparative Examples 3 and 4. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0047] Example 1: A concrete composite material for road and bridge use, the raw material composition of which includes: a cementitious material system, an aggregate system, a hybrid fiber system, a liquid-stabilizing lightweight aggregate and an admixture system;

[0048] The cementitious material system comprises the following components by weight: 300 parts PO 52.5 cement, 65 parts fly ash, and 20 parts silica fume;

[0049] The aggregate system comprises the following components by weight: 720 parts fine aggregate and 1050 parts coarse aggregate;

[0050] The hybrid fiber system comprises the following components by weight: 14 parts steel fiber and 1.8 parts PVA fiber;

[0051] The composition of the liquid-stabilizing lightweight aggregate includes the following components by weight: 120 parts high-strength lightweight aggregate, 45 parts composite internal curing liquid and 20 parts surface liquid stabilization treatment system.

[0052] The additive system comprises the following components by weight: 6.5 parts polycarboxylate superplasticizer and 120 parts mixing water;

[0053] The ingredients for the compound internal health-preserving solution include the following components by weight: 12 parts polyether shrinkage-reducing agent, 85 parts distilled water, 1.8 parts moisturizing and migration-regulating components, and 2 parts active auxiliary components.

[0054] The raw materials for the surface stabilization treatment system include the following components by weight: 7.5 parts silica sol, 4.5 parts water glass, 10 parts ultrafine mineral powder and 85 parts distilled water;

[0055] The high-strength lightweight aggregate is high-strength shale ceramsite with a particle size of 8mm.

[0056] The fine aggregate is medium sand with a fineness modulus of 2.6;

[0057] The coarse aggregate is continuously graded crushed stone with a particle size of 10 mm;

[0058] The PVA fiber is a polyvinyl alcohol fiber with a length of 9 mm and a diameter of 30 μm;

[0059] The preparation method of the concrete composite material for road and bridge construction specifically includes the following steps:

[0060] S1: Add polyoxyethylene-polyoxypropylene block polyether to distilled water and stir at room temperature for 15 minutes to mix evenly to obtain a shrinkage-reducing base solution; add polyethylene glycol to the shrinkage-reducing base solution and continue stirring for 25 minutes to disperse it evenly; then add nano silica and stir at 400 rpm for 30 minutes to obtain a composite internal conditioning solution;

[0061] S2: After cleaning the high-strength lightweight aggregate, dry it at 95℃ to constant weight; place the dried high-strength lightweight aggregate in a sealed container, evacuate to -0.08MPa, and maintain for 20 minutes to remove air from the pores of the lightweight aggregate; then introduce the composite internal curing solution prepared in step S1 to completely immerse the high-strength lightweight aggregate; after releasing the vacuum, continue to immerse at normal pressure for 45 minutes; after immersion, remove the aggregate, drain off the surface free liquid, and obtain liquid-absorbing lightweight aggregate;

[0062] S3: Mix silica sol, water glass, silica fume and distilled water, and stir at 600 rpm for 25 min to obtain a surface liquid stabilizing treatment solution; add the liquid-absorbing lightweight aggregate obtained in step S2 to the surface liquid stabilizing treatment solution and mix for 10 min to form a uniform thin layer on its surface; then dry the treated lightweight aggregate at a low temperature of 50℃ for 2 h to obtain a liquid-stabilizing storage lightweight aggregate;

[0063] S4: Place the PVA fiber in a low-temperature plasma treatment device and perform surface activation treatment in a vacuum environment. The treatment power is 100W and the treatment time is 140s. After treatment, seal and store for later use.

[0064] S5: Add cement, fly ash, silica fume, fine aggregate and coarse aggregate into the mixing equipment and dry mix to pre-disperse the cementitious materials and aggregates evenly to obtain a basic dry material system;

[0065] S6: After pre-mixing 70% of the total mixing water with 70% of the total amount of allyl polyoxyethylene ether type polycarboxylate superplasticizer, add it to the basic dry material system prepared in step S5, stir for 90s, and form an initial slurry coating state.

[0066] S7: After the initial slurry is formed in step S6, copper-plated steel fibers are slowly added first, followed by the pretreated PVA fibers from step S4. The fibers are added while stirring for 120 seconds to ensure that the steel fibers and PVA fibers are evenly dispersed in the slurry.

[0067] S8: Add the remaining 30% of the mixing water to the mixture obtained in step S7, add the remaining allyl polyoxyethylene ether type polycarboxylate superplasticizer, and continue stirring for 90 seconds to further optimize the rheological state of the slurry and obtain a foundation concrete mixture with uniform fiber dispersion.

[0068] S9: Add the liquid-stabilized lightweight aggregate prepared in step S3 to the basic concrete mixture obtained in step S8 after the mixing stage, and stir at a low speed of 30 rpm for 75 s to make the liquid-stabilized lightweight aggregate evenly dispersed in the concrete system to obtain the concrete composite material.

[0069] Example 2: A concrete composite material for road and bridge use, the raw material composition of which includes: a cementitious material system, an aggregate system, a hybrid fiber system, a liquid-stabilizing lightweight aggregate and an admixture system;

[0070] The cementitious material system comprises the following components by weight: 320 parts PO 52.5 cement, 80 parts fly ash, and 25 parts silica fume;

[0071] The aggregate system comprises the following components by weight: 750 parts fine aggregate and 1100 parts coarse aggregate;

[0072] The hybrid fiber system comprises the following components by weight: 18 parts steel fiber and 2.5 parts PVA fiber;

[0073] The composition of the liquid-stabilizing lightweight aggregate includes the following components by weight: 150 parts high-strength lightweight aggregate, 60 parts composite internal curing liquid and 30 parts surface liquid stabilization treatment system.

[0074] The additive system comprises the following components by weight: 8 parts polycarboxylate superplasticizer and 140 parts mixing water;

[0075] The raw materials for the preparation of the composite internal health-preserving solution include the following components in parts by weight: 15 parts polyether shrinkage-reducing agent, 90 parts distilled water, 2.5 parts moisturizing and migration-regulating components, and 3 parts active auxiliary components.

[0076] The raw materials for the surface liquid stabilization treatment system include the following components by weight: 9 parts silica sol, 6 parts water glass, 12 parts ultrafine mineral powder and 90 parts distilled water;

[0077] The high-strength lightweight aggregate is high-strength shale ceramsite with a particle size of 10mm.

[0078] The fine aggregate is medium sand with a fineness modulus of 2.3;

[0079] The coarse aggregate is continuously graded crushed stone with a particle size of 15 mm;

[0080] The PVA fiber is a polyvinyl alcohol fiber with a length of 12 mm and a diameter of 20 μm;

[0081] The preparation method of the concrete composite material for road and bridge construction specifically includes the following steps:

[0082] S1: Add polyoxyethylene-polyoxypropylene block polyether to distilled water and stir at room temperature for 10 minutes to mix evenly to obtain a shrinkage-reducing base solution; add glycerol to the shrinkage-reducing base solution and continue stirring for 15-30 minutes to disperse it evenly; then add silica sol and stir at 500 rpm for 20 minutes to obtain a composite internal conditioning solution;

[0083] S2: After cleaning the high-strength lightweight aggregate, dry it at 80℃ to constant weight; place the dried high-strength lightweight aggregate in a sealed container, evacuate to -0.06MPa, and maintain for 30 minutes to remove air from the pores of the lightweight aggregate; then introduce the composite internal curing liquid prepared in step S1 to completely immerse the high-strength lightweight aggregate; after releasing the vacuum, continue to immerse at normal pressure for 60 minutes; after immersion, remove the aggregate, drain off the surface free liquid, and obtain liquid-absorbing lightweight aggregate;

[0084] S3: Mix silica sol, water glass, ultrafine fly ash and distilled water, and stir at 400 rpm for 30 min to obtain a surface liquid stabilizing treatment solution; add the liquid-absorbing lightweight aggregate obtained in step S2 to the surface liquid stabilizing treatment solution and mix for 15 min to form a uniform thin layer on its surface; then dry the treated lightweight aggregate at a low temperature of 40℃ for 3 h to obtain a liquid-stabilizing storage lightweight aggregate;

[0085] S4: Place the PVA fiber in a low-temperature plasma treatment device and perform surface activation treatment in a vacuum environment. The treatment power is 80W and the treatment time is 180s. After treatment, seal and store for later use.

[0086] S5: Add cement, fly ash, silica fume, fine aggregate and coarse aggregate into the mixing equipment and dry mix to pre-disperse the cementitious materials and aggregates evenly to obtain a basic dry material system;

[0087] S6: After pre-mixing 60% of the total mixing water with 80% of the total amount of allyl polyoxyethylene ether type polycarboxylate superplasticizer, add it to the basic dry material system prepared in step S5, stir for 120s to form the initial slurry coating state.

[0088] S7: After the initial slurry is formed in step S6, corrugated steel fibers are slowly added first, followed by pre-treated PVA fibers from step S4. The fibers are added while stirring for 180 seconds to ensure that the steel fibers and PVA fibers are evenly dispersed in the slurry.

[0089] S8: Add the remaining 40% of the mixing water to the mixture obtained in step S7, add the remaining allyl polyoxyethylene ether type polycarboxylate superplasticizer, and continue stirring for 120 seconds to further optimize the rheological state of the slurry and obtain a foundation concrete mixture with uniform fiber dispersion.

[0090] S9: Add the liquid-stabilized lightweight aggregate prepared in step S3 to the basic concrete mixture obtained in step S8 after the mixing stage, and stir at a low speed of 20 rpm for 90 s to make the liquid-stabilized lightweight aggregate evenly dispersed in the concrete system to obtain the concrete composite material.

[0091] Example 3: A concrete composite material for road and bridge use, the raw material composition of which includes: a cementitious material system, an aggregate system, a hybrid fiber system, a liquid-stabilizing lightweight aggregate and an admixture system;

[0092] The cementitious material system comprises the following components by weight: 280 parts PO 52.5 cement, 50 parts fly ash, and 15 parts silica fume;

[0093] The aggregate system comprises the following components by weight: 680 parts fine aggregate and 1000 parts coarse aggregate;

[0094] The hybrid fiber system comprises the following components by weight: 10 parts steel fiber and 1.2 parts PVA fiber;

[0095] The composition of the liquid-stabilizing lightweight aggregate includes the following components by weight: 90 parts high-strength lightweight aggregate, 30 parts composite internal curing liquid and 10 parts surface liquid stabilization treatment system.

[0096] The additive system comprises the following components by weight: 5 parts polycarboxylate superplasticizer and 100 parts mixing water;

[0097] The raw materials for the preparation of the composite internal health-preserving solution include the following components by weight: 9 parts polyether shrinkage-reducing agent, 90 parts distilled water, 1 part moisturizing and migration-regulating component, and 1 part active auxiliary component.

[0098] The raw materials for the surface liquid stabilization treatment system include the following components by weight: 6 parts silica sol, 3 parts water glass, 8 parts ultrafine mineral powder and 80 parts distilled water;

[0099] The high-strength lightweight aggregate is high-strength shale ceramsite with a particle size of 5mm.

[0100] The fine aggregate is medium sand with a fineness modulus of 3.0;

[0101] The coarse aggregate is continuously graded crushed stone with a particle size of 5 mm;

[0102] The PVA fiber is a polyvinyl alcohol fiber with a length of 6 mm and a diameter of 50 μm;

[0103] The preparation method of the concrete composite material for road and bridge construction specifically includes the following steps:

[0104] S1: Add polyoxyethylene-polyoxypropylene block polyether to distilled water and stir at room temperature for 20 minutes to mix evenly to obtain a shrinkage-reducing base solution; add polyethylene glycol to the shrinkage-reducing base solution and continue stirring for 15 minutes to disperse it evenly; then add sodium metasilicate and stir at 500 rpm for 20 minutes to obtain a composite internal conditioning solution;

[0105] S2: After cleaning the high-strength lightweight aggregate, dry it at 105℃ to constant weight; place the dried high-strength lightweight aggregate in a sealed container, evacuate it to -0.095MPa, and maintain it for 10 minutes to remove air from the pores of the lightweight aggregate; then introduce the composite internal curing solution prepared in step S1 to completely immerse the high-strength lightweight aggregate; after releasing the vacuum, continue to immerse it at normal pressure for 30 minutes; after immersion, take it out and drain off the surface free liquid to obtain liquid-absorbing lightweight aggregate;

[0106] S3: Mix silica sol, water glass, ultrafine mineral powder and distilled water, and stir at 700 rpm for 20 min to obtain a surface liquid stabilizing treatment solution; add the liquid-absorbing lightweight aggregate obtained in step S2 to the surface liquid stabilizing treatment solution and mix for 5 min to form a uniform thin layer on its surface; then dry the treated lightweight aggregate at a low temperature of 60℃ for 1 h to obtain a liquid-stabilizing storage lightweight aggregate;

[0107] S4: Place the PVA fiber in a low-temperature plasma treatment device and perform surface activation treatment in a vacuum environment. The treatment power is 120W and the treatment time is 100s. After treatment, seal and store for later use.

[0108] S5: Add cement, fly ash, silica fume, fine aggregate and coarse aggregate into the mixing equipment and dry mix to pre-disperse the cementitious materials and aggregates evenly to obtain a basic dry material system;

[0109] S6: After pre-mixing 75% of the total mixing water with 60% of the total amount of allyl polyoxyethylene ether type polycarboxylate superplasticizer, add it to the basic dry material system prepared in step S5, stir for 60 seconds, and form the initial slurry coating state.

[0110] S7: After the initial slurry is formed in step S6, the hook-shaped steel fibers are slowly added first, and then the pretreated PVA fibers in step S4 are slowly added while stirring. The stirring time is 60 seconds, so that the steel fibers and PVA fibers are evenly dispersed in the slurry.

[0111] S8: Add the remaining 25% of the mixing water to the mixture obtained in step S7, add the remaining allyl polyoxyethylene ether type polycarboxylate superplasticizer, and continue stirring for 120 seconds to further optimize the rheological state of the slurry and obtain a foundation concrete mixture with uniform fiber dispersion.

[0112] S9: Add the liquid-stabilized lightweight aggregate prepared in step S3 to the basic concrete mixture obtained in step S8 after the mixing stage, and stir at a low speed of 40 rpm for 60 s to make the liquid-stabilized lightweight aggregate evenly dispersed in the concrete system to obtain the concrete composite material.

[0113] Comparative Example 1: The raw material composition and process flow of Comparative Example 1 are basically the same as those of Example 1. The main difference is that no polyether shrinkage reducer is added when preparing the composite internal curing liquid in step S1 of Comparative Example 1. The other components and process conditions remain unchanged. It is used to investigate the effect of shrinkage reducer on the internal humidity retention, early-age shrinkage development and crack resistance of concrete.

[0114] Comparative Example 2: The raw material composition and process flow of Comparative Example 2 are basically the same as those of Example 1. The main difference is that the surface liquid stabilization treatment is omitted in step S3 of Comparative Example 2. That is, the liquid-absorbing lightweight aggregate obtained in step S2 is used directly in the subsequent step S9 without surface liquid stabilization treatment, in order to examine the effect of surface liquid stabilization treatment on the liquid retention capacity, early liquid loss control and subsequent internal curing effect of the liquid-absorbing lightweight aggregate during the mixing stage.

[0115] Comparative Example 3: The raw material composition and process flow of Comparative Example 3 are basically the same as those of Example 1. The main difference is that the low-temperature plasma surface activation treatment of PVA fiber is omitted in step S4 of Comparative Example 3. PVA fiber is directly added to the system without activation treatment to investigate the effect of PVA fiber surface activation treatment on fiber wetting and dispersion state, slurry encapsulation effect and crack resistance and toughening stability.

[0116] Comparative Example 4: The raw material composition of Comparative Example 4 is basically the same as that of Example 1. The main difference is that the low-temperature plasma surface activation treatment of PVA fiber is retained in Comparative Example 4, but the staged water addition process is cancelled during the mixing process and replaced with one-time water addition and wet mixing. This is used to investigate the effect of the staged water addition process and the PVA fiber surface activation treatment on the fiber dispersion state and crack resistance and toughening effect.

[0117] Comparative Example 5: The raw material composition of Comparative Example 5 is basically the same as that of Example 1. The main difference is that although the liquid-absorbing lightweight aggregate in Comparative Example 5 has undergone surface liquid stabilization treatment, it is added at the same time as other components in the early stage of concrete mixing. The low-speed addition process in step S9 is not used. This is to investigate the effect of the low-speed addition process on the liquid retention stability of the liquid-absorbing lightweight aggregate after surface liquid stabilization treatment and the subsequent internal curing effect.

[0118] Performance testing: To verify the improved performance of the concrete composite material for road and bridge applications of the present invention in terms of workability, mechanical properties, shrinkage crack resistance and durability, performance tests were conducted on the concrete obtained in Examples 1-3 and Comparative Examples 1-5.

[0119] The slump (mm) and slump loss over time (mm / 1h) of the concrete obtained in Examples 1-3 and Comparative Examples 1-5 were measured in accordance with GB / T 50080-2016 to evaluate the initial workability, plasticity retention performance, and the effects of different fiber dispersion methods, water addition processes, and lightweight aggregate addition methods on the rheological stability of the concrete mixture.

[0120] The 28-day compressive strength (MPa) and 28-day flexural strength (MPa) of the concrete obtained in Examples 1-3 and Comparative Examples 1-5 were measured in accordance with GB / T 50081-2019 to evaluate the basic load-bearing capacity and flexural performance of concrete under the combined action of cementitious material system, internal curing system and hybrid fiber system.

[0121] The early autogenous shrinkage rate (με) of concrete obtained in Examples 1-3 and Comparative Examples 1, 2, and 5 corresponding to Example 1 was measured according to GB / T 50082-2024 at 1 day, 3 days, 7 days, and 14 days. This was used to evaluate the effects of shrinkage-reducing components in the composite internal curing solution, surface stabilization treatment, and the subsequent low-rate addition process on the internal moisture retention capacity and shrinkage development process of low water-cement ratio concrete. Since Comparative Examples 3 and 4 mainly focused on the effects of PVA fiber surface activation treatment and staged water addition process on fiber dispersion and toughening, their correspondence with the autogenous shrinkage development process was relatively weak, and therefore they were not included in the autogenous shrinkage rate-age curve test.

[0122] Furthermore, referring to GB / T 50082-2024, the early crack resistance of concrete obtained in Examples 1-3 and Comparative Examples 1-5 was measured. The cracking time, number of cracks, maximum crack width, and crack area per unit area were used as evaluation indicators to investigate the inhibitory effect of the composite internal curing system, the steel fiber / PVA fiber hybrid reinforcement system, and the staged mixing process on the risk of early cracking.

[0123] In addition, referring to GB / T 50082-2024, the chloride ion penetration resistance of concrete obtained in Examples 1-3 and Comparative Examples 1, 2, and 5 corresponding to Example 1 was measured. Electric flux (C) was used as the evaluation index to examine the effects of shrinkage-reducing components, surface stabilization treatment, and the subsequent low-rate addition process on the internal structural stability and resistance to media intrusion of the concrete. Since Comparative Examples 3 and 4 mainly reflect the surface state of the fibers and the effects of the staged water addition process on fiber dispersion and crack-resistant toughening properties, they were not the focus of the chloride ion penetration resistance test.

[0124] To further evaluate the liquid retention stability of the liquid-absorbing lightweight aggregate during the mixing stage, Examples 1, 2, and 3, as well as Comparative Examples 2 and 5 corresponding to Example 1, were used. The mass change of the liquid-absorbing lightweight aggregate before and after its addition to concrete was measured, and the liquid loss rate (%) during the mixing stage was calculated. This was used to investigate the effects of surface liquid stabilization treatment and the subsequent low-speed addition process on the liquid retention capacity of the liquid-absorbing lightweight aggregate.

[0125] To further evaluate the post-cracking load-bearing and toughening capacity of the hybrid fiber system, three-point bending loading tests were conducted on Examples 1-3 and Comparative Examples 3 and 4 corresponding to Example 1, referring to the flexural strength test method in GB / T 50081-2019. Load-deflection curves were recorded to examine the synergistic effect between PVA fiber surface activation treatment, staged water addition process and steel fiber / PVA fiber hybrid reinforcement system.

[0126] The test results are shown in Tables 1 to 4 and 4 respectively. Figures 1-3Table 1 shows the test results of the workability of fresh concrete, Table 2 shows the test results of the mechanical properties of hardened concrete, Table 3 shows the test results of the early crack resistance, and Table 4 shows the test results of the chloride ion penetration resistance. Figure 1 This is a curve showing the change in self-shrinkage rate over age. Figure 2 This is a comparison chart of liquid loss rates during the mixing stage of liquid-absorbing lightweight aggregates. Figure 3 This is a diagram of the three-point bending load-deflection curve.

[0127] Table 1. Test results of workability of fresh concrete in the examples and comparative examples

[0128]

[0129] Table 2. Test results of mechanical properties of hardened concrete in the examples and comparative examples

[0130]

[0131] Table 3. Test results of early crack resistance of concrete in the examples and comparative examples

[0132]

[0133] Table 4. Test results of chloride ion penetration resistance in the examples and comparative examples

[0134]

[0135] From Table 1, Figure 1 , Figure 2 As shown in Table 4, Examples 1-3 are generally superior to Comparative Examples 1, 2, and 5 in terms of slump retention, self-shrinkage control, liquid loss rate during the mixing stage of liquid-absorbing lightweight aggregate, and resistance to chloride ion penetration. Example 1 shows the best overall performance, indicating a good synergistic relationship between the composite internal curing solution, surface stabilization treatment, and the low-speed addition in the later stages. In Comparative Example 1, after removing the polyether shrinkage reducer, the changes in slump and slump loss over time were relatively limited, but the self-shrinkage rate at each age increased significantly, and the electrical flux also increased simultaneously. This indicates that the shrinkage reducer does not have a significant direct impact on the fluidity of the mixture, but it has a significant regulatory effect on the internal humidity retention and shrinkage development in the early stages, further affecting the later structural density and resistance to media intrusion. In Comparative Example 2, after removing the surface stabilization treatment, the slump loss over time increased, and both the self-shrinkage rate and electrical flux deteriorated significantly. Figure 2The significantly increased liquid loss rate during the mixing stage indicates that if the liquid-absorbing lightweight aggregate lacks surface liquid-stabilizing protection, it is more prone to premature liquid loss during the mixing stage. This leads to a reduction in the internal curing components that can be continuously released after entering the hardening stage, thereby weakening the shrinkage control and durability improvement effects. Comparative Example 5 retained the surface liquid-stabilizing treatment but eliminated the low-speed addition in the later stage. Although its liquid loss rate was lower than that of Comparative Example 2, it was still significantly higher than that of Example 1. The self-shrinkage rate and electrical flux also deteriorated simultaneously, indicating that the low-speed addition in the later stage can reduce the damage to the liquid storage state of the liquid-absorbing lightweight aggregate caused by the high-shear mixing in the early stage, and together with the surface liquid-stabilizing treatment, ensure that the composite internal curing liquid continues to play a role after casting. Figure 2 This further verifies Table 1. Figure 1 The intrinsic relationship between Table 4 and the reaction is that the higher the liquid loss rate during the mixing stage, the greater the subsequent self-shrinkage, and the worse the final resistance to chloride ion penetration.

[0136] From Table 2, Table 3 and Figure 3 It is evident that Examples 1-3 outperformed Comparative Examples 3 and 4 in terms of flexural strength, early crack resistance, and post-cracking load-bearing capacity. Example 1 demonstrated the best overall performance, indicating a significant synergistic effect between the PVA fiber surface activation treatment, the staged water addition process, and the steel fiber / PVA fiber hybrid reinforcement system. In Comparative Example 3, after omitting the low-temperature plasma surface activation treatment of the PVA fibers, the compressive strength remained relatively stable, but the flexural strength decreased significantly. Simultaneously, the cracking time shortened, the maximum crack width increased, and the crack area per unit area significantly increased. This suggests that the surface activation treatment has a limited impact on the matrix's load-bearing capacity but a significant influence on the wetting and dispersion of the PVA fibers, slurry encapsulation, and interfacial bonding, thus directly affecting the constraint effect during the microcrack initiation and fine crack propagation stages. Figure 3 The load-deflection curve of Comparative Example 3 showed a lower peak value and a faster decline after the peak, further indicating that the fiber bridging effect and post-cracking load-bearing capacity were weakened in the absence of surface activation treatment. In Comparative Example 4, after removing the staged water addition process while retaining surface activation treatment, the flexural and crack resistance properties further deteriorated. Figure 3 The load-deflection curve showed the smallest peak value and area, indicating that improving the fiber surface state alone is insufficient to fully realize its reinforcing effect. Staged water addition is also needed to provide a more suitable dispersion and suspension environment for the fibers. In other words, surface activation treatment mainly improves the contact conditions between individual fibers and the slurry, while staged water addition mainly improves the rheological environment and distribution state of the fiber group after entering the system. Only through the combination of both can the macro-micro hybrid crack control effect of steel fibers and PVA fibers be more fully realized. Example 1 is superior to Examples 2 and 3, and in... Figure 3The results show that the peak load is higher, the post-peak decline is smoother, and the curve area is larger. This indicates that in the raw material process of Example 1, the matching between the amount of steel fiber and PVA fiber, the activation conditions, and the staged water addition ratio is more coordinated, which is more conducive to the formation of a stable and continuous multi-scale crack suppression system, thus showing the best comprehensive level in terms of flexural strength, crack resistance, and post-cracking toughening.

[0137] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A concrete composite material for a road bridge, characterized by comprising: a plurality of reinforcing fibers; a plurality of inorganic fibers; and a cementitious material. Its raw material composition includes: cementitious material system, aggregate system, hybrid fiber system, liquid-stabilizing lightweight aggregate and admixture system; The cementitious material system comprises the following components: PO 52.5 cement, fly ash, and silica fume; The aggregate system comprises the following components: fine aggregate and coarse aggregate; The hybrid fiber system comprises the following components: steel fibers and PVA fibers; The composition of the liquid-stabilizing lightweight aggregate includes the following components: high-strength lightweight aggregate, composite internal curing liquid, and surface liquid stabilization treatment system; The raw materials for the preparation of the composite internal health-preserving solution include the following components: polyether shrinkage-reducing agent, distilled water, moisturizing and migration-regulating components, and active auxiliary components; The raw materials for the surface liquid stabilization treatment system include the following components: silica sol, water glass, ultrafine mineral powder, and distilled water; The additive system comprises the following components: polycarboxylate superplasticizer and mixing water; The composition of the liquid-stabilizing lightweight aggregate includes the following components by weight: 90-150 parts high-strength lightweight aggregate, 30-60 parts composite internal curing solution, and 10-30 parts surface liquid-stabilizing treatment system; the high-strength lightweight aggregate is high-strength shale ceramsite with a particle size of 5-10 mm. The raw materials for the compound internal conditioning solution include the following components by weight: 9-15 parts polyether shrinkage reducing agent, 80-90 parts distilled water, 1-2.5 parts moisturizing and migration regulating component, and 1-3 parts active auxiliary component; the moisturizing and migration regulating component is any one of glycerin, polyethylene glycol, or hydroxyethyl cellulose; the active auxiliary component is any one of silica sol, nano silica, or sodium metasilicate; the raw materials for the surface stabilizing treatment system include the following components by weight: 6-9 parts silica sol, 3-6 parts water glass, 8-12 parts ultrafine mineral powder, and 80-90 parts distilled water; the ultrafine mineral powder is any one of silica fume, ultrafine fly ash, or ultrafine mineral powder. The preparation of the concrete composite material for road and bridge construction includes the following steps: S1: Preparation of composite internal conditioning solution: Polyether shrinkage reducing agent, moisturizing and migration regulating component and active auxiliary component are added to water in sequence and mixed and stirred; S2: Preparation of liquid-absorbing lightweight aggregate: After drying the high-strength lightweight aggregate, vacuum it and introduce the composite internal curing liquid obtained in step S1 for impregnation, and drain off the surface free liquid. S3: Preparation of liquid-stabilizing lightweight aggregate: Silica sol, water glass, ultrafine mineral powder and water are mixed to prepare a surface liquid-stabilizing treatment solution. The liquid-absorbing lightweight aggregate obtained in step S2 is immersed in the treatment solution and then dried at low temperature. S4: Fiber pretreatment: PVA fibers are subjected to low-temperature plasma surface activation treatment; S5: Dry mixing and pre-dispersion: Dry mixing of the cementitious material system and the aggregate system; S6: Initial slurry preparation: Add part of the mixing water and part of the water-reducing agent to the product of step S5, and stir to form the initial slurry; S7: Fiber dispersion: Add steel fibers and PVA fibers treated in step S4 to the product of step S6 in sequence, and stir to disperse; S8: Flow optimization: Add the remaining mixing water and the remaining water-reducing agent, and continue stirring; S9: Lightweight aggregate mixing: Add the liquid-stabilized lightweight aggregate obtained in step S3 to the product in step S8, and mix at low speed to obtain concrete composite material. In step S2, the drying temperature of the high-strength lightweight aggregate is 80–105℃; the vacuum degree is -0.06–-0.095 MPa, and the holding time is 10–30 min; after the vacuum is released, the atmospheric pressure impregnation time is 30–60 min; in step S3, the stirring speed of the surface liquid stabilizing treatment solution is 400–700 rpm; the contact treatment time between the liquid-absorbing lightweight aggregate and the surface liquid stabilizing treatment solution is 5–15 min; the low-temperature drying temperature is 40–60℃, and the drying time is 1–3 h; In step S4, the low-temperature plasma surface activation treatment is carried out in a vacuum environment with a treatment power of 80-120W and a treatment time of 100-180s; in step S6, the amount of mixing water added is 60-75% of the total mixing water, and the amount of polycarboxylate water-reducing agent added is 60-80% of the total water-reducing agent.

2. The concrete composite material for road and bridge construction according to claim 1, characterized in that, The cementitious material system comprises the following components by weight: 280-320 parts of PO 52.5 cement, 50-80 parts of fly ash, and 15-25 parts of silica fume.

3. The concrete composite material for road and bridge construction according to claim 1, characterized in that, The aggregate system comprises the following components by weight: 680-750 parts fine aggregate and 1000-1100 parts coarse aggregate; the fine aggregate is medium sand with a fineness modulus of 2.3-3.0; and the coarse aggregate is continuously graded crushed stone with a particle size of 5-15 mm.

4. The concrete composite material for road and bridge construction according to claim 1, characterized in that, The hybrid fiber system comprises the following components by weight: 10-18 parts steel fiber and 1.2-2.5 parts PVA fiber; the steel fiber is any one of copper-plated steel fiber, corrugated steel fiber or end-hooked steel fiber; the PVA fiber is polyvinyl alcohol fiber with a length of 6-12 mm and a diameter of 20-50 μm.

5. A concrete composite material for road and bridge construction according to claim 1, characterized in that, The additive system comprises the following components by weight: 5-8 parts of polycarboxylate superplasticizer and 100-140 parts of mixing water.

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