Bridge deck pavement structure for limiting shrinkage and creep of ultra-high performance concrete

Abstract

The invention belongs to the technical field of bridge engineering, and particularly relates to a bridge deck pavement structure for limiting shrinkage and creep of ultra-high performance concrete, which comprises a slow change layer, a shrinkage induction layer and a buffer anti-cracking layer which are sequentially paved on a bridge deck slab from top to bottom, and the slow change layer comprises a plurality of regular polygon prism supporting shell structures which are sequentially connected; a plurality of mutually crossed elastic supporting frameworks are arranged in the regular polygon prism supporting shell structure, and ultra-high performance concrete is filled between the regular polygon prism supporting shell structure and the elastic supporting frameworks; and the shrinkage induction layer is made of an improved ECC material. The slow change layer is formed through modular assembly connection, shrinkage stress can be dispersed, early shrinkage deformation can be inhibited, and meanwhile the viscous flow effect of weakening creep is synergistically borne. By means of multi-layer paving (an improved ECC shrinkage induction layer and a buffer anti-crack layer composed of basalt fibers), the slow change layer is assisted in reducing shrinkage creep of UHPC and improving the bearing capacity of the paving layer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge engineering, and particularly relates to a bridge deck pavement structure for limiting shrinkage and creep of ultra-high performance concrete. BACKGROUND

[0002] Ultra-high performance concrete (UHPC) is a new type of cement-based composite material with ultra-high mechanical properties and durability. It has a wide application prospect in the fields of national defense engineering, ocean engineering, nuclear industry, etc. due to its ultra-high strength, high toughness and high durability. With the increasing demand for bridge construction and maintenance, due to the characteristics of UHPC such as low water-cement ratio, large amount of cementitious material and high amount of active admixture, its shrinkage strain is relatively large compared with ordinary concrete, which will lead to more prominent problems such as shrinkage stress concentration and shrinkage cracking. Excessive shrinkage strain will lead to non-compact joints and cold joint phenomenon, thereby weakening the durability of the steel bars at the joints. In addition, excessive shrinkage strain will also lead to greater stress concentration, thereby developing more shrinkage cracks, affecting the structural appearance and durability. Therefore, in order to prevent the damage of bridge structure caused by concrete shrinkage and creep, measures must be taken to limit the shrinkage and creep of UHPC to ensure the safety and reliability of the structure.

[0003] Traditional measures to limit the shrinkage and creep of concrete include the use of surface reinforcement materials such as polymer modified asphalt and stone chip pavement, which rely on single functional materials and cannot resist shrinkage and creep effects from the structural level. In addition, the traditional ECC has certain crack resistance, but it still has deficiencies in limiting the shrinkage and creep of concrete. The traditional ECC lacks internal curing measures, has large early autogenous shrinkage, and is prone to produce micro-cracks in the hardening stage. At the same time, its single fiber system for controlling cracks is difficult to cope with multi-scale shrinkage stress, and the crack dispersion capacity is limited. The traditional ECC does not contain effective expansion compensation or shrinkage reduction components, and the stress transmission caused by long-term creep is not weakened enough, and it is difficult to significantly reduce the shrinkage stress of the upper UHPC. These traditional solutions have certain limitations in solving stress concentration and long-term durability, especially under high traffic flow and complex environmental conditions, and it is difficult to achieve ideal long-term stability. Therefore, it cannot be the best measure to limit the shrinkage and creep of concrete. SUMMARY

[0004] The application discloses a bridge deck pavement structure for limiting shrinkage and creep of ultra-high performance concrete, which aims to solve the following technical problems: 1、In the prior art, the bridge pavement layer often uses a single reinforcing material to limit the shrinkage and creep of concrete, such as polymer modified asphalt and stone chip pavement. Although these methods can control the shrinkage and cracks of concrete to some extent, they cannot fundamentally solve the problem of stress concentration caused by shrinkage, and the construction process is complex, the maintenance period is long, and the cost is high. The present application combines a multi-faceted hourglass-shaped three-dimensional structure plate with UHPC to form a slow-changing layer, and the combination of ECC facets and rubber rods significantly reduces the shrinkage and creep of the lower UHPC, while improving the overall bearing capacity, durability and crack resistance of the bridge pavement layer.

[0005] 2、In the prior art, traditional ECC relies on a single high-ductility matrix and PVA fiber system to limit the shrinkage and creep of concrete, which can alleviate crack formation to some extent, but has problems such as large early self-shrinkage, lack of internal curing and expansion compensation mechanism, and difficulty in dispersing multi-scale shrinkage stress. The present application uses a modified ECC shrinkage-inducing layer and a buffer crack-resistant layer (basalt fiber layer) in a superimposed design, combined with internal curing particles, micro-expansion components and a multi-scale fiber system, which not only significantly reduces stress transmission and crack propagation caused by UHPC shrinkage and creep, but also uses the basalt fiber layer to achieve interlayer buffering and crack resistance, further improving the crack resistance and durability of the bridge pavement layer, making the bridge pavement structure more flexible and efficient, and ensuring long-term excellent structural performance.

[0006] 3、In the prior art, many shrinkage control measures rely on a long-term maintenance period, and the construction process is complex and time-consuming. The slow-changing layer in the present application uses a modular design, with the multi-faceted hourglass-shaped three-dimensional structure plate prefabricated in the factory and transported to the construction site, and connected into a bridge slow-changing layer using ECC material, which can be quickly assembled, reducing the time and cost of on-site construction.

[0007] To achieve the above-mentioned purposes, the technical solution of the present application is: A bridge pavement structure for limiting the shrinkage and creep of ultra-high performance concrete, comprising a slow-changing layer, a shrinkage-inducing layer and a buffer crack-resistant layer, which are sequentially laid on the bridge deck from top to bottom, the slow-changing layer comprises a plurality of connected regular polygonal prism support shell structures, the upper and lower ends of the regular polygonal prism support shell structure are open, and a plurality of elastic support skeletons are arranged inside, and ultra-high performance concrete is filled between the regular polygonal prism support shell structure and the elastic support skeleton; the shrinkage-inducing layer is made of modified ECC material.

[0008] Preferably, the regular polygonal prism support shell structure is a regular hexagonal prism shell, and the regular hexagonal prism shells are connected in sequence to form a honeycomb structure; the elastic support skeleton is a rubber rod.

[0009] Preferably, the regular hexagonal shell is prefabricated by the ECC material in the factory, the gaps between the adjacent regular hexagonal shells are filled by the ECC material and then connected into one body, and the two ends of the rubber rod are respectively abutted against the bottom and the sidewall of the regular hexagonal shell and form the diagonal bracing structure.

[0010] Preferably, one end of the diagonal bracing structure is abutted against the bottom of one edge line of the regular hexagonal shell, and the other end is abutted against the top of the opposite edge line along the longitudinal middle surface of the regular hexagonal shell, each edge line top of the open end of the regular hexagonal shell is provided with the diagonal bracing structure between the opposite edge line bottom, and the plurality of diagonal bracing structures are intersected in the regular hexagonal shell and fixedly connected at the intersection positions.

[0011] Preferably, the improved ECC material is composed of the following components in parts by mass: Portland cement (P·O 42.5) 300 parts, fly ash 200 parts, blast furnace slag powder 100 parts, silica fume 25 parts, nano-silicon dioxide 10 parts, fine sand 800 parts, pre-saturated lightweight aggregate 40 parts, mixing water 220 parts, polycarboxylic acid high-efficiency water reducing agent 6 parts, shrinkage reducing agent 3 parts, expansion agent 6 parts, viscosity / dispersion regulator 3 parts, PVA short fiber 20 parts, and polypropylene (PP) short fiber 3 parts, wherein the pre-saturated lightweight aggregate is made of porous lightweight aggregate by saturated immersion, and the total parts of the mixing water include the adsorbed water of the porous lightweight aggregate.

[0012] Preferably, the improved ECC material compensates for the shrinkage of the shrinkage-induced layer in the early service period (the early period generally refers to the period from the completion of pouring of the material to the stable development of the strength and shrinkage of the material. This period is generally between 24 hours and 28 days. This period is the most active period of cement hydration, and the strength of the material grows faster, and the shrinkage changes greatly), the pre-saturated lightweight aggregate serves as a slow-release water source inside the shrinkage-induced layer, provides supplemental water for hydration in the early and middle periods of the service process of the shrinkage-induced layer (the middle period generally refers to the initial service period of the improved ECC material. The strength and volume stability of the concrete gradually increase, and the hydration reaction gradually completes between about 28 days and 6 months), the shrinkage reducing agent reduces the dry shrinkage of the shrinkage-induced layer in the whole service process, the PVA short fiber inhibits the development of microcracks during the long-term creep of the shrinkage-induced layer, and the polypropylene short fiber inhibits the microcracks in the plastic stage and the early shrinkage period of the shrinkage-induced layer.

[0013] Preferably, the buffer anti-cracking layer is a basalt fiber mesh.

[0014] Preferably, the surface of the buffer anti-cracking layer is coated with a waterproof layer or a corrosion-resistant coating layer.

[0015] The bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete has the following beneficial effects: 1. The present application has a reasonable structure and outstanding performance. The present application forms a slow-changing layer structure by combining multi-faceted hourglass-shaped three-dimensional structures into a plate. The structure realizes stress dispersion and energy dissipation buffering at the structural level through the multi-material combination design of ECC facets and rubber rods, significantly reduces the shrinkage and creep effects transmitted to the lower part, thereby improving the overall bearing capacity, durability and crack resistance of the pavement layer. Compared with the traditional bridge pavement layer which often uses a single reinforcing material to limit concrete shrinkage and creep, such as polymer modified asphalt, stone paving, etc. These methods can control the shrinkage and cracking of concrete to some extent, but they cannot fundamentally solve the problem of stress concentration from the structural level, and the construction process is complex, the maintenance period is long, and the cost is high. The present application uses the spatial support of the multi-faceted structure and the gradual change characteristics of the hourglass-shaped geometry to jointly build a continuous, flexible and stable force transmission path, ensuring that the structure still maintains efficient stress release and coordinated deformation ability under load and temperature and humidity changes.

[0016] 2. The present application improves the material innovation and multi-mechanism synergy. Traditional ECC relies on a single matrix and PVA fiber system to limit concrete shrinkage and creep, making it difficult to achieve multi-scale stress control. The present application uses the superposition design of improved ECC shrinkage-induced layer and buffer crack-resistant layer (basalt fiber layer), internal curing particles, expansion agent + shrinkage-reducing agent (SRA) double-control system and double-fiber synergy mechanism. Internal curing particles (pre-saturated lightweight aggregate LWA) continuously release moisture to reduce the drying shrinkage rate; the expansion agent produces micro-expansion in the early stage to compensate for plastic shrinkage, and the SRA reduces the capillary tension in the long term, both of which synergistically inhibit cumulative shrinkage deformation; PVA and PP short fibers work together to achieve multi-level crack bridging and expansion inhibition. At the same time, the basalt fibers in the buffer crack-resistant layer further improve the crack resistance of the structure through interlayer buffering and crack blocking, reducing crack propagation and extending the service life of the structure. Through the above multi-mechanism composite design, the present application significantly weakens the stress concentration and crack propagation caused by UHPC shrinkage and creep, enhancing the crack resistance, durability and long-term service performance of the bridge deck pavement layer.

[0017] 3. The application has high construction efficiency and wide applicability. Many existing concrete shrinkage control measures rely on long-term maintenance cycles, complex construction and high time cost, which is not conducive to the rapid construction and maintenance of bridge engineering. The slow-changing layer proposed by the application adopts a modular design concept, by prefabricating multi-sided sandglass-shaped three-dimensional structure plates in the factory, only ECC material is needed for rapid assembly and connection on site, to form a continuous and integral bridge deck slow-changing layer. This assembly type construction method not only significantly shortens the construction period, reduces the site operation intensity and cost, but also reduces the dependence of traditional wet operation on environment and climate conditions. The standardized production and detachable characteristics of the modular plates make them have wide applicability in new bridge pavement, existing bridge deck repair and rapid maintenance engineering. Through the structural design and construction method of the application, the bridge deck pavement structure realizes the integration of "structural optimization-stress slow change-quick construction", and has excellent popularization and application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic diagram of bridge deck multilayer pavement; Figure 2 is a structural schematic diagram of the elastic support framework; Figure 3 is a schematic diagram of the rubber rod structure inside the positive polygonal prism support shell structure; Figure 4 is a schematic diagram of the slow-changing layer overall framework (several connected positive polygonal prism shell structures and the rubber rods inside them) pavement.

[0019] In the figure, 1, UHPC material; 2, shrinkage inducing layer; 3, buffer anti-cracking layer; 4, bridge deck slab; 5, positive polygonal prism support shell structure; 6, rubber rod; 7, support surface; 8, lower port. DETAILED DESCRIPTION

[0020] The following description is only for the preferred embodiment of the application, and is not intended to limit the protection scope of the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

[0021] The following embodiments can be understood as part of the expression of the partial structure or method of the application, or as the mutual combination of the embodiments to explain the connotation of the structure or method of the application in a larger range.

[0022] The application proposes a composite structure bridge deck multilayer pavement structure for limiting the shrinkage and creep of ultra-high performance concrete (UHPC) bridge deck pavement, to solve the problem that the shrinkage and creep effects may still cause interface damage and structural stress concentration under complex loads and environmental conditions for traditional measures, thereby essentially limiting the shrinkage and creep effects of UHPC and improving the stability and durability of the bridge deck pavement layer.

[0023] The bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete comprises Figures 1-4 as shown, a slow change layer, a shrinkage inducing layer and a buffer anti-cracking layer are sequentially arranged on the bridge deck from top to bottom. The embodiments of the application will be described in detail below.

[0024] Example 1: Slow change layer design and production: The slow change layer adopts a modularized regular polygonal prism support shell structure, the regular polygonal prism support shell structure is made of ECC material, an elastic support framework is arranged in the inside, in this embodiment, the elastic support framework selects a rubber rod. The regular polygonal prism support shell structure and the elastic support framework in the inside are preformed in a factory, the regular polygonal prism support shell structures are tightly connected through ECC material at the construction site, and UHPC is poured into the inner cavity of the regular polygonal prism support shell, so that the regular polygonal prism support shell and the UHPC form a tightly combined composite structure. The design of the slow change layer can effectively disperse the shrinkage stress of the UHPC pavement layer, inhibit the shrinkage deformation, cooperate with the bearing and reduce the creep effect.

[0025] The improved ECC ratio is the initial recommended value of the project, and the actual field construction needs to be checked through small and medium tests and adjusted accordingly (especially the amount of water, water reducing agent, the amount of expansion agent and SRA).

[0026] Example 2: Shrinkage inducing layer production: The shrinkage inducing layer is made of improved ECC material. The following table is the improved ECC mix proportion (per cubic meter, kg) given in this embodiment:

[0027] Example 3: Buffer anti-cracking layer production: Basalt fibers are laid under the shrinkage inducing layer to realize interlayer buffering and crack propagation resistance. The thickness and laying method of the buffer anti-cracking layer need to be adjusted according to the bridge deck design requirements to ensure its good crack resistance and durability, which can effectively alleviate the stress concentration and crack propagation caused by shrinkage and creep, and achieve the best effect of interlayer buffering.

[0028] Example 4: It should be noted that the surface of each layer of material (especially the buffer anti-cracking layer) can be appropriately coated with a waterproof layer or anticorrosive paint to further prolong its service life.

[0029] The working principle and replacement repair method of the application are as follows: The multi-layer pavement structure of the composite structure bridge deck adopts a three-layer structure of a slow change layer, a shrinkage inducing layer and a buffer anti-cracking layer through innovative modular design, and gradually reduces the shrinkage and creep effects of ultra-high performance concrete (UHPC) layer by layer. The slow change layer adopts a regular polygonal prism support shell structure prefabricated from ECC material, with an internal rubber rod elastic framework. The edges of the regular polygonal prism support shell structure can effectively disperse the shrinkage stress of the UHPC in the internal cavity, inhibit the shrinkage deformation, and reduce the creep effect. Meanwhile, the internal rubber rod supports the edges, further strengthening the stability of the slow change layer and preventing the edges from being damaged due to external shrinkage. The shrinkage inducing layer further absorbs and weakens stress transmission through internal curing particles, micro-expansion components and a multi-scale fiber system of the improved ECC material, reducing the risk of crack propagation. The buffer anti-cracking layer adopts basalt fiber, enhancing the interlayer buffer effect, effectively blocking crack propagation, and improving the overall crack resistance. Through layer-by-layer cooperation, the three-layer pavement structure gradually reduces stress and prevents crack development, significantly improving the stability, durability and crack resistance of the bridge deck pavement layer.

[0030] When the composite structure bridge deck pavement structure is seriously damaged locally due to shrinkage and creep or other factors, the individual plate of the slow change layer and the local area of the shrinkage inducing layer or the buffer anti-cracking layer in the damaged area can be first broken. Under the premise of ensuring that the surrounding structure is not damaged, the damaged area is cleaned and the damaged layers are removed. After the surface cleaning is completed, the damaged parts of other pavement layers are checked and replaced, and then each layer is refilled and new modular plates are installed. After the installation process of the new plates, the joints are filled with ECC material to ensure good bonding between the new plates and the surrounding plates, and new UHPC material is poured into the internal cavity of the three-dimensional structure to restore the bearing capacity and normal function of the bridge deck pavement and ensure the long-term stability and durability of the bridge deck pavement.

[0031] The matters needing attention of the present application are as follows: The edge thickness of the multi-edge hourglass-shaped three-dimensional structure in the slow change layer, the diameter of the rubber rod and the size of the honeycomb end face should be customized according to the thickness of the bridge deck pavement and the actual stress requirement to ensure that the shrinkage stress can be effectively dispersed and the structural stability is maintained; The ECC joint interface between the modular plates must be kept clean, dry and have sufficient roughness to ensure that the ECC joint material can form a stable and reliable cooperative stress interface; During transportation, hoisting and on-site assembly, the multi-edge corners, rubber rod support parts and honeycomb end faces should be avoided from being collided. If local damage or edge loss occurs, the ECC or special repair material should be used for repair before installation; When the UHPC is poured into the internal cavity unit of the slow change layer, vibration and compaction should be ensured to prevent voids in the internal cavity of the multi-edge hourglass-shaped three-dimensional structure affecting stress transmission. At the same time, the pouring temperature and humidity should be controlled to reduce the risk of early shrinkage; The overall structure needs to be regularly inspected during long-term service to check whether the modular joints are loose, aged or damaged, and the slabs or protective materials are replaced in time to ensure that the pavement structure maintains good performance.

[0032] It should be particularly noted that the improved ECC has the following characteristics: 1) Internal curing particles: pre-saturated lightweight aggregate (LWA) as an internal slow-release water source provides supplementary water for hydration in the early and middle stages, reduces capillary shrinkage caused by external drying, slows down the development of drying shrinkage and the stress induced thereby, and helps to reduce the adverse evolution of creep on the structure in the long term.

[0033] 2) Expansion agent + shrinkage reducing agent SRA double control: expansion agent produces micro-expansion in the early stage to compensate for plastic / early shrinkage; SRA reduces capillary tension and capillary pumping effect, reduces drying shrinkage rate. The two can inhibit shrinkage at different time scales (expansion agent for early shrinkage, SRA for long-term drying shrinkage), thereby significantly reducing cumulative shrinkage deformation and stress concentration caused thereby, and slowing down the long-term adverse effects induced by creep.

[0034] 3) Dual-fiber system: PVA (polyvinyl alcohol) short-cut fiber provides main control of multiple fine cracks and significant ductility (bridging cracks, controlling crack width), which has an inhibitory effect on the development of micro-cracks during long-term creep; PP (polypropylene) short-cut fiber has an auxiliary means for initial control of micro-cracks in the plastic stage and early shrinkage period, and has low cost and good chemical resistance. The dual-fiber system improves the crack initiation and propagation process, thereby reducing the risk of crack formation and propagation under shrinkage-creep coupling.

Claims

1. A bridge deck pavement structure that limits the shrinkage and creep of ultra-high performance concrete, characterized in that: The bridge deck is constructed from top to bottom as follows: a gradual change layer, a shrinkage induction layer, and a buffer crack-resistant layer. The gradual change layer comprises several sequentially connected regular polygonal prism support shell structures. The regular polygonal prism support shell structures are open at the top and bottom and have several intersecting elastic support skeletons inside. Ultra-high performance concrete is filled between the regular polygonal prism support shell structures and the elastic support skeletons. The shrinkage induction layer is made of modified ECC material.

2. The bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 1, characterized in that: The aforementioned regular polygonal prism support shell structure is a regular hexagonal prism shell, and the regular hexagonal prism shells are connected in sequence to form a honeycomb-shaped composite structure; the aforementioned elastic support skeleton is a rubber rod.

3. A bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 2, characterized in that: The regular hexagonal prism shell is pre-formed in the factory using ECC material. The gaps between adjacent regular hexagonal prism shells are filled with ECC material and then connected as one unit. The two ends of the rubber rod abut against the bottom and side wall of the regular hexagonal prism shell, respectively, forming a diagonal bracing structure.

4. The bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 3, characterized in that: One end of the diagonal bracing structure abuts against the bottom of one edge of the regular hexagonal prism shell, and the other end abuts against the top of the opposite edge along the longitudinal midline of the regular hexagonal prism shell. A diagonal bracing structure is provided between the top of each edge of the regular hexagonal prism shell and the bottom of the opposite edge. Several diagonal bracing structures intersect within the regular hexagonal prism shell and are fixedly connected at the intersection.

5. A bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 4, characterized in that: The modified ECC material is composed of the following components by mass proportion: 300 parts of ordinary silicate cement (P·O 42.5), 200 parts of fly ash, 100 parts of blast furnace slag powder, 25 parts of silica fume, 10 parts of nano silica, 800 parts of fine sand, 40 parts of presaturated lightweight aggregate, 220 parts of mixing water, 6 parts of polycarboxylate-based high-efficiency water-reducing agent, 3 parts of shrinkage reducing agent, 6 parts of expansion agent, 3 parts of viscosity / dispersion regulator, 20 parts of PVA chopped fiber, and 3 parts of polypropylene (PP) chopped fiber. The presaturated lightweight aggregate is made by saturating porous lightweight aggregate with water, and the total amount of mixing water includes the adsorbed water of the porous lightweight aggregate.

6. A bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 5, characterized in that: The modified ECC material compensates for shrinkage in the early service stage of the shrinkage-induced layer using an expanding agent. The pre-saturated lightweight aggregate acts as a slow-release water source within the shrinkage-induced layer, providing supplemental moisture for hydration in the early and middle stages of its service life. The shrinkage-reducing agent reduces drying shrinkage throughout the entire service life of the shrinkage-induced layer. The PVA chopped fibers inhibit the development of microcracks during the long-term creep of the shrinkage-induced layer, and the polypropylene chopped fibers inhibit microcracks during the plastic stage and early shrinkage period of the shrinkage-induced layer.

7. A bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 6, characterized in that: The aforementioned buffer and crack-resistant layer is a basalt fiber mesh.

8. A bridge deck pavement structure for limiting the shrinkage and creep of ultra-high performance concrete as described in claim 7, characterized in that: The surface of the buffer crack-resistant layer is coated with a waterproof layer or an anti-corrosion coating layer.

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