Construction method of bridge deck continuous structure of ultrahigh-ductility fiber concrete bridge

Abstract

The invention discloses a construction method of an ultrahigh ductility fiber concrete bridge deck continuous structure, which belongs to the technical field of bridge engineering, and comprises the following steps: step 1, preparing an ECC (Engineered Cementitious Composite) base material and designing the proportion; 2, interface processing; 3, the modular formwork is installed; fourthly, ECC base material pouring is conducted; 5, laying an elastic buffer layer; sixthly, an asphalt pavement layer is laid; step 7, maintenance and acceptance inspection; the invention discloses a construction method of a bridge deck continuous structure capable of meeting the high ductility requirement and the long-term durability requirement of a bridge deck connecting structure.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and in particular to a construction method for a continuous structure of an ultra-high ductility fiber concrete bridge deck. Background Art

[0002] Continuous structures on bridge decks (such as expansion joints and wet joints) are the weakest link in bridge structures. Their performance directly affects the safety, durability, and driving comfort of the bridge throughout its life cycle. Traditional designs often use conventional concrete (NC) or steel fiber reinforced concrete (SFRC) as wet joint materials, but these have certain drawbacks and limitations, including:

[0003] 1. Brittle cracking: Low tensile strength (2-5MPa), ultimate tensile strain less than 0.01%, prone to through-cracks (width 0.5-2mm), leading to water seepage, steel corrosion and freeze-thaw damage;

[0004] 2. Insufficient durability: Crack expansion accelerates chloride ion penetration and carbonization reaction, resulting in a service life of only 30-50 years;

[0005] 3. High maintenance cost: Repairs require frequent traffic closures, resulting in huge economic losses.

[0006] Existing technologies, such as patent CN109914229A, focus on the ECC material ratio but do not involve coordinated design with the bridge structure. Patent CN220364874U uses ordinary concrete formwork and cannot solve the fundamental cracking problem. Therefore, existing technologies cannot simultaneously meet the high ductility requirements (accommodating main beam deformation) and long-term durability requirements (anti-seepage, anti-carbonization, and anti-fatigue) of the continuous bridge deck structure. Summary of the Invention

[0007] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to propose a construction method for a continuous structure of a bridge deck that can meet the high ductility requirements and long-term durability requirements of the bridge deck connection structure.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a construction method for a continuous structure of an ultra-high ductility fiber concrete bridge deck, comprising the following steps:

[0010] Step 1: ECC matrix material preparation and ratio design;

[0011] Prepare ECC matrix materials, including cement, accounting for 30%-40%, wherein the cement is P·O42.5 grade silicate cement; Grade I fly ash, accounting for 40%-50%; fine aggregate, accounting for 20%-30%, wherein the fine aggregate is machine-made sand with a particle size of ≤0.6 mm; fiber, accounting for 2%-2.5%, wherein the fiber is ultra-high molecular weight polyethylene fiber (UHMWPE), wherein the UHMWPE has a length of 12 mm and a diameter of 39 μm; and water reducer, accounting for 0.8%-1.2%, wherein the water reducer is a polycarboxylic acid high-efficiency water reducer;

[0012] Step 2: Interface processing;

[0013] Apply epoxy resin adhesive between the ECC matrix and the beam-slab interface to ensure that the interface bonding strength is ≥2.5MPa;

[0014] Step 3: Modular template installation;

[0015] The template includes a top connecting plate, a bottom connecting plate and a quick-connect assembly. According to the design size of the continuous structure of the bridge deck, the quick-connect assembly is quickly assembled with the top connecting plate and the bottom connecting plate through a mortise and tenon structure or a screw.

[0016] Step 4: pouring ECC matrix material;

[0017] Mix the prepared ECC matrix material according to the designed ratio to ensure uniform mixing; pour the mixed ECC matrix into the installed modular formwork, and vibrate and compact it during the pouring process to eliminate bubbles in the concrete and ensure the density of the concrete;

[0018] Step 5: Laying the elastic buffer layer;

[0019] After the ECC base layer is initially solidified, an elastic buffer layer is laid; the elastic buffer layer is laid with a thickness of 2-5 cm;

[0020] Step 6: Laying the asphalt pavement layer;

[0021] After the elastic buffer layer has finally set, the bridge deck pavement layer is constructed. 6-8cm thick asphalt concrete is laid and compacted to ensure a smooth and solid bridge deck and provide good driving comfort.

[0022] Step 7: Maintenance and acceptance;

[0023] After the construction is completed, the ECC base layer, elastic buffer layer and asphalt pavement layer are maintained. The maintenance time is determined according to the material properties and environmental conditions to ensure that each layer of material meets the design strength and performance requirements. After the maintenance is completed, acceptance is carried out in accordance with relevant standards and design requirements to check the strength, crack width, anti-seepage performance and other indicators of the structure.

[0024] The preferred technical solution of the present invention is that the performance indicators of the ECC matrix are: compressive strength ≥80 MPa, tensile strength ≥8 MPa, ultimate tensile strain ≥6%, and crack width ≤50 μm.

[0025] The preferred technical solution of the present invention is that the mass of the template block is less than or equal to 50 kg, and the assembly error of the quick-connect assembly is less than or equal to 1 mm.

[0026] A preferred technical solution of the present invention is that a glass fiber grid is pre-buried between the elastic buffer layer and the ECC matrix, and the spacing between the glass fiber grids is ≤10 cm.

[0027] The preferred technical solution of the present invention is that before the ECC matrix is cast, it is necessary to pre-embed positioning steel bars in the gap between the beams and slabs. The spacing of the positioning steel bars is 15-20 cm. For areas where crack resistance needs to be enhanced, such as the negative bending moment area of the continuous beam bridge, double-layer bidirectional steel bars are arranged in the ECC matrix layer.

[0028] A preferred technical solution of the present invention is that the thickness of the ECC substrate is 15-30 cm.

[0029] A preferred technical solution of the present invention is that the top connecting plate, the bottom connecting plate and the quick-connect assembly are all made of high-strength plastic or aluminum alloy, and the surface of the template is coated with a release agent.

[0030] A preferred technical solution of the present invention is that the elastic buffer layer can be made of modified fiber-reinforced polymer high-strength mortar or polyurethane elastomer.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention uses ECC matrix material to achieve a significant improvement in material ductility, with an ultimate tensile strain of ≥6%. Compared with the ultimate tensile strain of ≤0.01% of traditional solutions, the deformation capacity is significantly improved, which can better adapt to the deformation requirements of bridge structures and reduce the occurrence of cracks.

[0033] 2. This invention uses ECC matrix material to achieve multiple cracking, with crack widths ≤ 50 μm. Compared with the traditional solution of single cracking with a width ≥ 1 mm, the risk of water seepage is reduced by 95%, effectively improving the durability of the structure.

[0034] 3. Through the application of modular formwork, the time required to assemble the formwork is shortened to 3 days compared to the 10 days required for traditional wooden formwork, shortening the construction period by 70%, thereby improving construction efficiency and reducing construction costs.

[0035] 4. The service life of the present invention is ≥100 years, which reduces maintenance costs by 80% compared to the 30-50 years of traditional solutions, and has significant economic and social benefits;

[0036] 5. Although the initial cost of the present invention is 15% higher than that of the traditional solution, the whole life cost is reduced by 40%, and the cost performance is significantly improved. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0038] A construction method for a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck comprises the following steps:

[0039] Step 1: ECC matrix material preparation and ratio design;

[0040] Prepare an ECC matrix material, which includes cement, accounting for 30%-40%, wherein the cement is P·O42.5 grade silicate cement; Grade I fly ash, accounting for 40%-50%; fine aggregate, accounting for 20%-30%, wherein the fine aggregate is machine-made sand with a particle size of ≤0.6 mm; fiber, accounting for 2%-2.5%, wherein the fiber is ultra-high molecular weight polyethylene fiber (UHMWPE), wherein the UHMWPE has a length of 12 mm and a diameter of 39 μm; and a water reducer, accounting for 0.8%-1.2%, wherein the water reducer is a polycarboxylate high-efficiency water reducer, to ensure that the performance indicators of the ECC matrix meet the following requirements: compressive strength ≥80 MPa, tensile strength ≥8 MPa, ultimate tensile strain ≥6%, and crack width ≤50 μm;

[0041] By combining the above materials, the ductility of the ECC matrix material is effectively improved, the stress is dispersed to form multiple cracks, so that the crack width is ≤50μm, and the anti-permeability grade is improved at the same time.

[0042] Step 2: Interface processing;

[0043] Apply epoxy resin adhesive between the ECC matrix and the beam-slab interface to ensure that the interface bonding strength is ≥2.5MPa; epoxy resin adhesive has good bonding properties and can effectively enhance the bonding strength between the ECC matrix and the beam-slab interface, prevent cracking and slippage caused by insufficient interface bonding, and improve the stability and reliability of the overall structure.

[0044] Step 3: Modular template installation;

[0045] The template includes a top connecting plate, a bottom connecting plate, and a quick-connect assembly. According to the design dimensions of the continuous structure of the bridge deck, the quick-connect assembly is quickly assembled with the top and bottom connecting plates through a mortise and tenon structure or a screw. The top and bottom connecting plates and the quick-connect assembly are all made of high-strength plastic or aluminum alloy. The surface of the template is coated with a release agent.

[0046] Modular formwork is made of high-strength plastic or aluminum alloy, which is lightweight and easy to carry and install. The quick-connect components with mortise and tenon structures or bolt connections enable rapid assembly of the formwork, greatly shortening the formwork installation time. Compared with the traditional wooden formwork that takes 10 days, the modular formwork assembly takes only 3 days, shortening the construction period by 70%, significantly improving construction efficiency.

[0047] Step 4: pouring ECC matrix material;

[0048] The prepared ECC matrix material is stirred according to the designed ratio to ensure uniform mixing; the stirred ECC matrix is poured into the installed modular formwork, and vibrated and compacted during the pouring process to eliminate bubbles in the concrete and ensure the density of the concrete. The thickness of the ECC matrix is 15-30 cm;

[0049] The ECC matrix material has the characteristics of high ductility and multi-crack formation, with an ultimate tensile strain of ≥6% and a crack width of ≤50μm. Through reasonable casting and vibration processes, the performance advantages of the ECC matrix material can be fully utilized.

[0050] Step 5: Laying the elastic buffer layer;

[0051] After the ECC base layer is initially solidified, an elastic buffer layer is laid; the elastic buffer layer is laid with a thickness of 2-5 cm;

[0052] The elastic buffer layer can absorb the residual stress caused by the deformation of the main beam, reduce the deformation of the ECC matrix layer, and thus further control the generation and expansion of cracks; through the setting of the elastic buffer layer, it adapts to the deformation of the main beam, blocks the water seepage path, and improves the durability and reliability of the structure.

[0053] Step 6: Laying the asphalt pavement layer;

[0054] After the elastic buffer layer has finally set, the bridge deck pavement layer is constructed. 6-8cm thick asphalt concrete is laid and compacted to ensure a smooth and solid bridge deck and provide good driving comfort.

[0055] The asphalt concrete bridge deck pavement layer has good wear resistance, skid resistance and driving comfort, and can protect the underlying structure from vehicle loads and erosion by the natural environment; at the same time, the asphalt pavement layer works together with the elastic buffer layer and ECC base layer to form a complete bridge deck continuous structural system, further improving the overall performance of the bridge.

[0056] Step 7: Maintenance and acceptance;

[0057] After construction is completed, the ECC base layer, elastic buffer layer and asphalt pavement layer are cured. The curing time is determined according to the material properties and environmental conditions to ensure that each layer of material meets the design strength and performance requirements. After the curing is completed, the structure is inspected and accepted in accordance with relevant standards and design requirements to check the strength, crack width, anti-seepage performance and other indicators of the structure.

[0058] Reasonable maintenance measures can ensure that the strength and durability of the materials are fully developed and the construction quality is guaranteed; through strict acceptance procedures, it can be ensured that the continuous structure of the bridge deck meets the design requirements, has good mechanical properties and durability, and provides protection for the safe operation of the bridge.

[0059] As a possible implementation of this solution, preferably, the mass of a single template is ≤50kg, and the assembly error of the quick-connect component is ≤1mm. The small assembly error can ensure the accuracy of the template and the molding quality of the ECC substrate layer.

[0060] As a possible implementation of this solution, preferably, a glass fiber grid is embedded between the elastic buffer layer and the ECC matrix, and the spacing between the glass fiber grids is ≤10 cm. The embedded glass fiber grid can enhance the bonding force between the elastic buffer layer and the ECC layer, prevent interlayer slippage, and improve the integrity of the structure.

[0061] As a possible implementation method of this scheme, preferably, before pouring the ECC matrix, it is necessary to pre-embed positioning steel bars in the gap between the beams and slabs. The spacing of the positioning steel bars is 15-20 cm. For areas where crack resistance needs to be enhanced, such as the negative bending moment zone of the continuous beam bridge, double-layer bidirectional steel bars are set in the ECC matrix layer.

[0062] Positioning steel bars can fix the position of the ECC matrix layer to ensure that it does not move during construction; the setting of double-layer bidirectional steel bars can improve the crack resistance of the ECC matrix layer in complex stress areas such as negative bending moment areas; through the synergistic effect of steel bars and ECC matrix materials, the overall stiffness and bearing capacity of the structure are enhanced, effectively inhibiting the generation and expansion of cracks.

[0063] As a possible implementation of this solution, preferably, the elastic buffer layer can be made of modified fiber-reinforced polymer high-strength mortar or polyurethane elastomer, which can absorb the residual stress caused by the deformation of the main beam.

[0064] Table 1

[0065]

[0066]

[0067] The present invention utilizes the characteristics of high-modulus, high-strength, ultra-high molecular weight polyethylene fiber ECC, which has an ultimate tensile strain of ≥6% and multi-crack cracking (crack width ≤50μm), to replace traditional brittle materials; by constructing a three-level collaborative system of "ECC layer + elastic buffer layer + bridge deck pavement layer", it adapts to the deformation of the main beam and blocks the water seepage path; and develops modular ECC wet joint templates to achieve rapid construction and precise forming.

[0068] Example 1: Continuous Deck Structure of Small and Medium Span Simply Supported Beam Bridges

[0069] Construction parameters: bridge span 20m, ECC base layer thickness 20cm, elastic buffer layer uses modified fiber reinforced polymer high-strength mortar with a thickness of 3cm, and asphalt pavement layer thickness 8cm.

[0070] Construction process:

[0071] 1. Apply epoxy resin adhesive to the beam-slab interface, and quickly assemble the modular formwork through the mortise and tenon structure before installation;

[0072] 2. Pre-embed Φ10 positioning steel bars in the gap between beams and slabs, with a spacing of 15 cm between the positioning steel bars. Stir the prepared ECC matrix material thoroughly and pour it into the formwork. Vibrate and compact it. Perform surface treatment after initial setting.

[0073] 3. Lay modified fiber-reinforced polymer high-strength mortar to form an elastic buffer layer with a thickness of 3cm and pre-embed glass fiber grid;

[0074] 4. After the elastic buffer layer is finally set, lay asphalt concrete and compact it to a thickness of 8cm;

[0075] 5. Maintain the structure and conduct acceptance inspection after maintenance.

[0076] Performance verification: When loaded to 1.5 times the design load, the number of cracks in the ECC matrix layer is ≥15 / m, and the maximum crack width is 50μm; after experiencing 1 million fatigue loadings, the interlayer bond strength attenuation rate is ≤10%, indicating that the structure has good crack resistance and fatigue performance.

[0077] Example 2: Negative bending moment zone structure of continuous beam bridge

[0078] Structural parameters: ECC base layer thickness is 25cm, with double-layer bidirectional Φ12 steel bars inside, with a spacing of 15cm, elastic buffer layer made of polyurethane elastomer, with a thickness of 5cm, and asphalt pavement layer thickness of 10cm.

[0079] Construction process:

[0080] 1. Apply epoxy resin adhesive on the beam-slab interface, and quickly assemble the modular formwork with bolts before installation;

[0081] 2. Pre-embed Φ12 positioning steel bars in the gap between beams and slabs, with a spacing of 20 cm between positioning steel bars, and tie and set double-layer bidirectional Φ12 steel bars with a spacing of 12 cm. After fully mixing the prepared ECC matrix material, pour it into the formwork, vibrate and compact it, and perform surface treatment after initial setting;

[0082] 3. Lay polyurethane elastomer to form a buffer layer with a thickness of 5cm and pre-embed fiberglass grid;

[0083] 4. After the elastic buffer layer is finally set, lay asphalt concrete and compact it to a thickness of 10cm;

[0084] 5. Maintain the structure and conduct acceptance inspection after maintenance.

[0085] Performance verification: The crack resistance in the negative bending moment area is improved by 300%, and the crack width is stable at ≤30μm; the water resistance grade is ≥P12 (the traditional NC structure is only P6), indicating that the structure's crack resistance and water resistance are significantly improved, and its durability is good.

[0086] As shown in Examples 1 and 2, this invention is widely applicable to the reconstruction of expansion joints and wet joints in small and medium-span bridges, strengthening the crack resistance of the negative bending moment zone in continuous beam bridges, and improving the durability and lifecycle management of old bridges. Through collaborative innovation in materials, structures, and processes, it significantly improves the mechanical properties and durability of continuous bridge deck structures, providing technical support for green bridge construction under the "dual carbon" goals.

[0087] The present invention is described through preferred embodiments. Those skilled in the art will appreciate that various modifications or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. The present invention is not limited to the specific embodiments disclosed herein; other embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A construction method for a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck, characterized by: The following steps are involved: Step 1: ECC matrix material preparation and ratio design; Prepare ECC matrix materials, including cement, accounting for 30%-40%, wherein the cement is P·O42.5 grade Portland cement; Grade I fly ash, accounting for 40%-50%; fine aggregate, accounting for 20%-30%, wherein the fine aggregate is machine-made sand with a particle size of ≤0.6 mm; fiber, accounting for 2%-2.5%, wherein the fiber is ultra-high molecular weight polyethylene fiber (UHMWPE), wherein the UHMWPE has a length of 12 mm and a diameter of 39 μm; and water reducer, accounting for 0.8%-1.2%, wherein the water reducer is a polycarboxylic acid high-efficiency water reducer; Step 2: Interface processing; Apply epoxy resin adhesive between the ECC matrix and the beam-slab interface to ensure that the interface bonding strength is ≥2.5MPa; Step 3: Modular template installation; The template includes a top connecting plate, a bottom connecting plate and a quick-connect assembly. According to the design size of the continuous structure of the bridge deck, the quick-connect assembly is quickly assembled with the top connecting plate and the bottom connecting plate through a mortise and tenon structure or a screw. Step 4: pouring ECC matrix material; Mix the prepared ECC matrix material according to the designed ratio to ensure uniform mixing; pour the mixed ECC matrix into the installed modular formwork, and vibrate and compact it during the pouring process to eliminate bubbles in the concrete and ensure the density of the concrete; Step 5: Laying the elastic buffer layer; After the ECC base layer is initially solidified, an elastic buffer layer is laid; the elastic buffer layer is laid with a thickness of 2-5 cm; Step 6: Laying the asphalt pavement layer; After the elastic buffer layer has finally set, the bridge deck pavement layer is constructed. 6-8cm thick asphalt concrete is laid and compacted to ensure a smooth and solid bridge deck and provide good driving comfort. Step 7: Maintenance and acceptance; After the construction is completed, the ECC base layer, elastic buffer layer and asphalt pavement layer are maintained. The maintenance time is determined according to the material properties and environmental conditions to ensure that each layer of material meets the design strength and performance requirements. After the maintenance is completed, acceptance is carried out in accordance with relevant standards and design requirements to check the strength, crack width, anti-seepage performance and other indicators of the structure.

2. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: The performance indicators of the ECC matrix are: compressive strength ≥80 MPa, tensile strength ≥8 MPa, ultimate tensile strain ≥6%, and crack width ≤50 μm.

3. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: The mass of a single template block is less than or equal to 50 kg, and the assembly error of the quick-connect components is less than or equal to 1 mm.

4. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: A glass fiber grid is pre-buried between the elastic buffer layer and the ECC matrix, and the spacing between the glass fiber grids is ≤10 cm.

5. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: Before pouring the ECC matrix, it is necessary to pre-embed positioning steel bars in the gap between the beams and slabs. The spacing between the positioning steel bars is 15-20 cm. For areas where crack resistance needs to be enhanced, such as the negative bending moment area of continuous beam bridges, double-layer bidirectional steel bars are set in the ECC matrix layer.

6. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: The thickness of the ECC substrate is 15-30 cm.

7. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: The top connecting plate, the bottom connecting plate and the quick-connect assembly are all made of high-strength plastic or aluminum alloy, and the surface of the template is coated with a release agent.

8. The construction method of a continuous structure of an ultra-high ductility fiber reinforced concrete bridge deck according to claim 1, characterized in that: The elastic buffer layer can be made of modified fiber reinforced polymer high-strength mortar or polyurethane elastomer.

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