Construction Method for Ultra-High Strength, High Toughness and High Durability Concrete Bridge Deck Pavement

Abstract

The invention discloses a construction method for a super-high-strength, high-toughness and high-durability concrete bridge deck pavement, which relates to the technical field of road and bridge construction. The method steps provided by the invention include roughening the top plate of the steel box girder; laying a steel mesh on the surface of the top plate and welding shear studs; mixing and preparing super-high-strength, high-toughness and high-durability concrete; paving the super-high-strength, high-toughness and high-durability concrete on the surface of the top plate, vibrating it densely and curing it; after the curing is completed, roughening the surface of the super-high-strength, high-toughness and high-durability concrete, and then spraying and paving an asphalt layer and rolling it into shape to complete the bridge deck pavement. The raw materials of the super-high-strength, high-toughness and high-durability concrete provided by the invention include ordinary Portland cement, silica fume, modified fly ash microspheres, fine aggregate, steel fibers and high-performance polycarboxylate water reducing agent; the modified fly ash microspheres are prepared by filling phase change materials in fly ash hollow microspheres. The mechanical strength of the bridge deck after construction by the method of the invention is significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of road and bridge construction, and particularly to a construction method for a super-high-strength, high-toughness, and high-durability concrete bridge deck pavement. Background Art

[0002] Currently, ultra-high performance concrete (UHPC) used for STC steel bridge deck pavement generally adopts UHPC materials of RPC 120 - 140 grade. With the development of the current bridge design and construction industry, in order to design new lightweight and thin-walled structures, ultra-high performance concrete (UHPC) with better performance is required, and the mechanical properties are required to reach RPC 160. On this basis, since the construction site conditions often cannot reach the standard conditions of the laboratory, strength needs to be reserved for construction, which requires the UHPC material strength to exceed RPC 160 and reach about RPC 170.

[0003] Due to the use of cementitious materials with an ultra-low water-binder ratio, UHPC has a large degree of autogenous shrinkage, which is likely to affect the volume stability of UHPC, and then affect the normal use of the bridge and threaten the structural safety. In order to make the strength reach the RPC180 level, if measures such as increasing the total dosage, reducing the water-binder ratio, or increasing the dosage of steel fibers are taken for the raw materials of UHPC, it will inevitably lead to an increase in the shrinkage of the UHPC bridge deck and an increase in the risk of shrinkage cracking. Therefore, in order to effectively control the shrinkage and creep of UHPC, the cementitious material ratio, water-binder ratio, dosage of materials such as steel fibers, or the selection of other functional powder materials of UHPC all need to be further optimized and improved. Summary of the Invention

[0004] Aiming at the above deficiencies of the prior art, the present invention provides a construction method for a super-high-strength, high-toughness, and high-durability concrete bridge deck pavement, which is specifically realized through the following technologies.

[0005] The construction method for a super-high-strength, high-toughness, and high-durability concrete bridge deck pavement includes the following steps:

[0006] S1. Roughen the top plate of the steel box girder of the bridge;

[0007] S2. Lay a steel mesh on the surface of the top plate and weld shear studs; mix and prepare super-high-strength, high-toughness, and high-durability concrete; the raw materials of the super-high-strength, high-toughness, and high-durability concrete include 590 - 630 parts by mass of ordinary Portland cement, 140 - 160 parts of silica fume, 200 - 240 parts of modified fly ash microspheres, 1200 - 1240 parts of fine aggregate, steel fibers, and a high-performance polycarboxylate water reducer; the masses of the steel fibers and the high-performance polycarboxylate water reducer are 19.0 - 24% and 4% of the total weight of the cementitious materials respectively, and the water-binder ratio is 0.15 - 0.18;

[0008] The preparation method of the modified fly ash microspheres is as follows: Take a phase change material with a phase change temperature of 40 - 80°C and heat it to a liquid state. Add fly ash hollow microspheres into it, stir for 0.5 - 1 h under a vacuum degree of 500 - 1500 Pa, and then pressurize to 0.15 - 0.25 MPa and stir for 10 - 20 min; After cooling to room temperature, take it out to obtain granular modified fly ash microspheres; The mass ratio of the phase change material to the fly ash hollow microspheres is (0.5 - 0.75):1;

[0009] S3. Spread ultra-high strength, high toughness and high durability concrete on the surface of the top plate, and vibrate it densely; Carry out moisture conservation and high-temperature steam curing;

[0010] S4. Carry out roughening treatment on the surface of the ultra-high strength, high toughness and high durability concrete after curing, and then spray and spread an asphalt layer and roll it into shape to complete the bridge deck paving.

[0011] The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck paving provided by the present invention is specially designed according to the requirements of the bridge deck structure and mechanical properties of special long-span concrete bridges. In the above paving construction method, the raw materials of the ultra-high strength, high toughness and high durability concrete used are innovated, and silica fume and modified fly ash microspheres are used as active admixtures. A special phase change material is filled into the fly ash hollow microspheres, and the change of the internal temperature of the concrete is effectively controlled during the hydration reaction, avoiding the cracking inside the concrete. The fly ash hollow microspheres can also rupture during vibration, curing and the phase change process of the phase change material, forming sharp edge shapes, inhibiting the formation of air bubbles inside the concrete, and improving the density and strength of the concrete.

[0012] Preferably, the roughening treatment method in step S1 is specifically to adopt the methods of chiseling, milling and / or shot blasting.

[0013] Preferably, in step S2, in the preparation method of the modified fly ash microspheres, after adding the fly ash hollow microspheres, stir for 0.5 h under a vacuum degree of 1000 Pa, and then pressurize to 0.20 MPa and keep it for 20 min;

[0014] The phase change material is at least one of stearic acid, palmitic acid, paraffin wax, lauric acid.

[0015] More preferably, in step S2, the raw materials of the ultra-high strength, high toughness and high durability concrete include 620 parts of ordinary Portland cement, 150 parts of silica fume, 230 parts of modified fly ash microspheres, 1230 parts of fine aggregate, and steel fibers and high-performance polycarboxylate water reducer by mass. The mass of the steel fibers is 22.5% of the total weight of the cementitious materials.

[0016] Further preferably, in step S2, the steel fiber has a diameter of 0.2 - 0.4 mm, a length of 13 - 15 mm, and an aspect ratio of 35 - 75.

[0017] Preferably, in step S2, the layout method of the steel bar mesh is specifically:

[0018] P1. Design the number of lanes and lane widths according to the bridge deck width, simulate and obtain the parts where the tires contact the bridge deck when the vehicle is driving in each lane, lay a dense steel bar mesh at these parts, and lay a common steel bar mesh at other parts; the spacing of the longitudinal steel bars of the dense steel bar mesh along the bridge is 5 - 8 cm, and the spacing of the transverse steel bars along the bridge is 5 - 8 cm; the spacing of the longitudinal steel bars of the common steel bar mesh along the bridge is 10 - 12 cm, and the spacing of the transverse steel bars along the bridge is 10 - 12 cm; the intersections of the longitudinal steel bars along the bridge and the transverse steel bars along the bridge are firmly tied.

[0019] P2. Place cushion blocks in a plum blossom shape on the bottom surfaces of the dense steel bar mesh and the common steel bar mesh, and the adjacent cushion blocks are spaced 0.8 - 1.0 m apart.

[0020] Preferably, the thickness of the top plate of the steel box girder is 8 - 10 mm, and the thickness of the ultra-high strength, high toughness and high durability concrete after curing is 15 - 20 cm.

[0021] Preferably, both sides of the steel box girder are corrugated steel webs, and the corrugated steel webs are connected to the top plate through PBL shear connectors.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a construction method for the ultra-high strength, high toughness and high durability concrete bridge deck pavement. Through the optimization and improvement of the paving technology and the raw materials of the ultra-high strength, high toughness and high durability concrete, the flexural strength of the constructed bridge deck can reach up to 45 MPa at most; the tensile strength can reach up to 16 MPa at most; the elastic modulus is close to 50 MPa; the compressive strength exceeds 182 MPa at most, and most of the ratios are about 180 MPa. Detailed implementation manners

[0023] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0024] In the following examples and comparative examples, the cement used was P·II 52.5R Portland cement produced by Guangdong Qingxin Conch Cement Co., Ltd. The fineness, specific surface area, and water demand ratio of the P·II 52.5R Portland cement produced by this company were tested according to the test methods for the key technical indicators of P·II 52.5R Portland cement in "Common Portland Cement" (GB175-2007). The test results of each index met the specification requirements.

[0025] The silica fume used was silica fume produced by Gansu Yuyang New Materials Co., Ltd., with a specific surface area of 19,500 m2 / kg and a SiO2 content of 96.34%. The technical requirement indicators of the silica fume were tested according to the detection methods specified in "Silica Fume for Mortar and Concrete" (GB / T 27690-2011), and the test results met the requirements.

[0026] The fly ash cenospheres used were fly ash cenospheres produced by Shijiazhuang Jucai Mineral Products Co., Ltd., grade 1, with a density of 1.7 g / cm3 and a particle size of 40 μm;

[0027] The fine aggregate used was quartz sand provided by Dongchuan Tuocheng Longyuan Quartz Sand Factory, with a silica content of ≥96%. The fine aggregate was quartz sand in four gradations of 16-26 mesh, 26-40 mesh, 40-70 mesh, and 200 mesh, and the dosage ratios of the four gradations were 39:8:39:15.

[0028] The steel fibers used were provided by Shanghai Zhenqiang Fibre Co., Ltd., with diameters ranging from 0.2 to 0.4 mm, lengths ranging from 13 to 15 mm, and length-to-diameter ratios ranging from 35 to 75.

[0029] The high-performance polycarboxylate water reducer was provided by Shanghai Sunrui Polymer Materials Co., Ltd. According to the detection methods specified in "Concrete Admixtures" (GB 8076-2008), the test results showed compliance.

[0030] For the ultra-high performance concrete provided in the following examples and comparative examples, if not otherwise specified, it was prepared by the following method: The weighed ordinary Portland cement, fine aggregate, steel fibers, and high-performance polycarboxylate water reducer were mixed evenly, then the active admixture was added and mixed evenly, and finally pure water was added according to a water-binder ratio of 0.15 and mixed evenly to obtain the ultra-high performance concrete.

[0031] For the ultra-high strength, high toughness, and high durability concrete bridge decks in the following examples and comparative examples, the bridge was designed with two-way 8 lanes, the full width of the bridge deck was 41.4 m (1.25 m wind fairing + 38.9 m top width + 1.25 m wind fairing), the center beam height was 3.5 m, and a two-way 2% cross slope was set. The side span main girders were concrete main girders, using an integral single-box three-cell box girder section. The specific paving construction method included the following steps:

[0032] S1. Roughen the top plate of the steel box girder of the bridge by means of chiseling, milling and / or shot blasting, etc.; the thickness of the top plate of the steel box girder is 10 mm, and the two sides of the steel box girder are corrugated steel webs, and the corrugated steel webs are connected to the top plate through PBL shear connectors;

[0033] S2. Lay a steel bar mesh on the surface of the top plate. The specific method is as follows: Design the number of lanes and lane widths according to the bridge deck width, simulate the positions where the tires contact the bridge deck when the vehicle is driving in each lane, lay a dense steel bar mesh at these positions, and lay a common steel bar mesh at other positions; the spacing of the longitudinal steel bars along the bridge direction of the dense steel bar mesh is 5 - 8 cm, and the spacing of the transverse steel bars along the bridge direction is 5 - 8 cm; the spacing of the longitudinal steel bars along the bridge direction of the common steel bar mesh is 10 - 12 cm, and the spacing of the transverse steel bars along the bridge direction is 10 - 12 cm; the intersections of the longitudinal steel bars along the bridge direction and the transverse steel bars along the bridge direction are firmly tied; cushion blocks are arranged in a plum blossom shape on the bottom surface of the dense steel bar mesh and the common steel bar mesh, and the adjacent cushion blocks are spaced 0.8 - 1.0 m apart; shear studs are welded on the top plate of the steel box girder, and the spacing between adjacent shear studs is 12 cm. For special-shaped steel plates, shear studs should be welded after the installation of the special-shaped steel plates is completed. When the designed position of the shear stud conflicts with the splicing weld of the steel box girder, the shear stud should deviate about 2 cm from the weld boundary, and the shear stud cannot be directly welded on the top surface of the splicing weld;

[0034] Mix and prepare ultra-high strength, high toughness and high durability concrete; the raw materials of the ultra-high strength, high toughness and high durability concrete include ordinary Portland cement, silica fume, modified fly ash microspheres, fine aggregate, steel fibers and high-performance polycarboxylate water reducer by mass; the dosage of each raw material depends on different examples and comparative examples, and the water-binder ratio is 0.15;

[0035] The preparation method of the modified fly ash microspheres is as follows: Take the phase change material (stearic acid) and heat it to melt into a liquid state, add fly ash hollow microspheres into it, stir for 0.5 h under a vacuum degree of 1000 Pa, then pressurize to 0.20 MPa and keep it for 20 min; take it out after cooling to room temperature to obtain granular modified fly ash microspheres; the mass ratio of the phase change material to the fly ash hollow microspheres is 0.5:1;

[0036] S3. Spread ultra-high strength, high toughness, and high durability concrete on the surface of the top plate and vibrate it thoroughly; conduct moisture conservation and high-temperature steam curing. For moisture conservation, first spray water mist with a high-pressure water gun, then cover with a moisture conservation film, and then water for moisture conservation. The moisture conservation process closely follows the paving surface step by step. When covering the moisture conservation film, pay attention to pressing it with thin plates at the overlapping positions of the moisture conservation film to prevent the film from being blown up by the wind. For high-temperature steam curing, specifically, first remove the remaining moisture conservation film from the moisture conservation curing, and set up a steam curing heat preservation shed. During the curing period, the heating rate in the heating stage is about 15°C / h, the curing temperature is 80°C, the curing time is less than 72h, and the relative humidity is not less than 95%; after the curing is completed, gradually cool down to the ambient temperature at a cooling rate of 8°C / h. The thickness of the ultra-high strength, high toughness, and high durability concrete after the curing is completed is 20 cm;

[0037] S4. Roughness treatment is carried out on the surface of the ultra-high strength, high toughness, and high durability concrete after the curing is completed, and then an asphalt layer is sprayed, paved, and rolled into shape to complete the bridge deck paving.

[0038] The following conducts research on the raw materials of ultra-high strength, high toughness, and high durability concrete in the construction method.

[0039] Example 1

[0040] The ultra-high strength, high toughness, and high durability concrete provided in this example includes, by mass, 620 parts of ordinary Portland cement, 150 parts of silica fume, 230 parts of modified fly ash microspheres, 1230 parts of fine aggregate, steel fibers, and a high-performance polycarboxylate water reducer; the masses of the steel fibers and the high-performance polycarboxylate water reducer are 22.5% and 4% of the total weight of the cementitious materials respectively.

[0041] Example 2

[0042] The ultra-high strength, high toughness, and high durability concrete provided in this example includes, by mass, 590 parts of ordinary Portland cement, 160 parts of silica fume, 240 parts of modified fly ash microspheres, 1200 parts of fine aggregate, steel fibers, and a high-performance polycarboxylate water reducer; the masses of the steel fibers and the high-performance polycarboxylate water reducer are 24% and 4% of the total weight of the cementitious materials respectively.

[0043] Example 3

[0044] The ultra-high strength, high toughness, and high durability concrete provided in this example includes, by mass, 630 parts of ordinary Portland cement, 140 parts of silica fume, 200 parts of modified fly ash microspheres, 1240 parts of fine aggregate, steel fibers, and a high-performance polycarboxylate water reducer; the masses of the steel fibers and the high-performance polycarboxylate water reducer are 19% and 4% of the total weight of the cementitious materials respectively.

[0045] Test example: Determination of the air content and mechanical properties of ultra-high strength, high toughness, and high durability concrete

[0046] The ultra-high strength, high toughness, and high durability concrete slurries prepared in the above examples and comparative examples were cast and hardened by conventional methods to make compressive strength specimens of 40 mm × 40 mm × 40 mm, flexural specimens of 100 mm × 100 mm × 400 mm, and elastic modulus specimens of 100 mm × 200 mm. After demolding and covering with a film, they were cured in high-temperature steam at 80 °C for 72 ± 1 h until final setting.

[0047] The air content and mechanical properties of the ultra-high strength, high toughness, and high durability concrete were tested by conventional testing methods: the air content was evaluated by referring to the relevant methods for air content in the "Standard Test Method for Performance of Ordinary Concrete Mixtures" (GB / T 50080-2016); the mechanical properties (compressive strength, flexural strength, elastic modulus) were tested according to the "Reactive Powder Concrete" (GB / T 31387-2015) and the "Standard Test Method for Mechanical Properties of Ordinary Concrete" (GB / T 50081-2002). The specific test results are shown in Table 1 below.

[0048] Table 1 Test Results of Air Content and Mechanical Properties of Concrete

[0049]

[0050] It can be seen that by using the construction method and the ultra-high strength, high toughness, and high durability concrete formula of the present invention, significant improvements in compressive, flexural, and tensile strengths can be obtained, and the durability of bridge pavements can be significantly improved.

[0051] The above specific embodiments have described the implementation of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple variations all fall within the protection scope of the present invention.

Claims

1. Construction method of ultra-high strength, high toughness and high durability concrete bridge deck pavement, characterized in that, It includes the following steps: S1. Roughen the top plate of the steel box girder of the bridge; S2. Lay a steel mesh on the surface of the top plate and weld shear studs; Mix and prepare ultra-high strength, high toughness and high durability concrete; The raw materials of the ultra-high strength, high toughness and high durability concrete include 590 - 630 parts by mass of ordinary Portland cement, 140 - 160 parts by mass of silica fume, 200 - 240 parts by mass of modified fly ash microspheres, 1200 - 1240 parts by mass of fine aggregate, steel fibers and high-performance polycarboxylate water reducer; The masses of the steel fibers and the high-performance polycarboxylate water reducer are 19.0 - 24% and 4% respectively of the total weight of the cementitious materials, and the water-cement ratio is 0.15 - 0.18; The preparation method of the modified fly ash microspheres is as follows: Take a phase change material with a phase change temperature of 40 - 80 °C and heat it to a liquid state, add fly ash hollow microspheres into it, stir for 0.5 - 1 h under a vacuum degree of 500 - 1500 Pa, then pressurize to 0.15 - 0.25 MPa and stir for 10 - 20 min; After cooling to room temperature, take it out to obtain granular modified fly ash microspheres; The mass ratio of the phase change material to the fly ash hollow microspheres is (0.5 - 0.75):1; S3. Spread ultra-high strength, high toughness and high durability concrete on the surface of the top plate, vibrate it densely; Carry out moisture conservation and high-temperature steam curing; S4. Roughen the surface of the ultra-high strength, high toughness and high durability concrete after the curing is completed, then spray and spread an asphalt layer and roll it into shape to complete the bridge deck paving.

2. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 1, characterized in that The way of roughening treatment in step S1 is specifically to adopt the methods of chiseling, milling and / or shot blasting.

3. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 1, characterized in that, In step S2, in the preparation method of the modified fly ash microspheres, after adding the fly ash hollow microspheres, first stir for 0.5 h under a vacuum degree of 1000 Pa, then pressurize to 0.20 MPa and keep it for 20 min; The phase change material is at least one of stearic acid, palmitic acid, paraffin wax, lauric acid.

4. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 3, characterized in that In step S2, the raw materials of the ultra-high strength, high toughness and high durability concrete include 620 parts by mass of ordinary Portland cement, 150 parts by mass of silica fume, 230 parts by mass of modified fly ash microspheres, 1230 parts by mass of fine aggregate, and steel fibers and high-performance polycarboxylate water reducer, and the mass of the steel fibers is 22.5% of the total weight of the cementitious materials.

5. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 3 or 4, characterized in that, In step S2, the diameter of the steel fibers is 0.2 - 0.4 mm, the length is 13 - 15 mm, and the aspect ratio is 35 - 75.

6. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 1, characterized in that, In step S2, the specific way of laying the steel mesh is as follows: P1. Design the number of lanes and the lane width according to the bridge deck width, simulate to obtain the parts where the tires contact the bridge deck when the vehicle is driving in each lane, lay a dense steel mesh at this part, and lay an ordinary steel mesh at other parts; The spacing of the longitudinal steel bars along the bridge direction of the dense steel mesh is 5 - 8 cm, and the spacing of the transverse steel bars along the bridge direction is 5 - 8 cm; The spacing of the longitudinal steel bars along the bridge direction of the ordinary steel mesh is 10 - 12 cm, and the spacing of the transverse steel bars along the bridge direction is 10 - 12 cm; The intersections of the longitudinal steel bars along the bridge direction and the transverse steel bars along the bridge direction are tied firmly; P2. The bottom surfaces of the dense steel bar mesh and the ordinary steel bar mesh are provided with cushion blocks in a plum blossom shape, and the adjacent cushion blocks are spaced 0.8 - 1.0 m apart.

7. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 1, characterized in that, The thickness of the top plate of the steel box girder is 8 - 10 mm, and the thickness of the ultra-high strength, high toughness and high durability concrete after curing is 15 - 20 cm.

8. The construction method of the ultra-high strength, high toughness and high durability concrete bridge deck pavement according to claim 1, characterized in that, The two sides of the steel box girder are corrugated steel webs, and the corrugated steel webs are connected to the top plate through PBL shear connectors.

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