UHPC composite structure for repairing bridge deck pavement diseases and construction method

Abstract

The invention discloses a UHPC (Ultra High Performance Concrete) composite structure for repairing bridge deck pavement diseases and a construction method, and aims to solve the technical problems of poor durability, insufficient bearing capacity and the like generally existing after the existing bridge deck pavement pit slot diseases are repaired. The method comprises the core technical links of bridge deck pavement milling, drilling and steel bar planting, steel bar mesh installation, UHPC mixing, pouring, maintenance and the like. By adopting a composite structure composed of the UHPC120 concrete and the asphalt concrete surface layer and matching with the reinforced connection design of the HRB400-grade twisted steel mesh and the implanted erection steel bars, the bonding strength between the repairing layer and the original bridge deck concrete pavement layer is effectively improved, the structural integrity and the anti-cracking performance are enhanced, and the service life of a bridge is remarkably prolonged. The technology is suitable for repairing bridge floor cavities, pit slots and other diseases of various types of bridges, and has wide engineering application prospects.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering maintenance technology, specifically relating to a UHPC composite structure and construction method for repairing bridge deck pavement defects. Background Technology

[0002] With the continuous increase in traffic load and the extension of bridge service life, bridge decks are prone to various defects, among which continuous potholes are one of the main types of defects affecting driving safety. Traditional bridge deck repair methods often use ordinary asphalt concrete or ordinary concrete for filling, but these methods have obvious drawbacks: weak adhesion between the repair layer and the original bridge deck, insufficient structural load-bearing capacity, poor crack resistance, and poor durability, leading to easy re-damage in a short period of time after repair, requiring frequent maintenance work. This not only seriously affects traffic efficiency but also significantly increases bridge maintenance costs. Ultra-high performance concrete (UHPC), a new type of building material with high strength, high toughness, and high durability, is increasingly widely used in bridge engineering. However, how to rationally apply UHPC to the repair of bridge deck defects and solve key technical problems such as effective connection with the original structure, shrinkage crack control, and construction process optimization has become a pressing challenge for the industry. Currently, there is a lack of mature UHPC composite structures and construction methods for repairing bridge deck pavement defects. Especially in core aspects such as rebar connection, rebar mesh layout, and UHPC mixing and curing, the technical parameters are not clear or standardized enough, resulting in inconsistent repair results that fail to meet engineering quality requirements. Summary of the Invention

[0003] The core objective of this invention is to provide a UHPC composite structure and construction method for repairing bridge deck pavement defects, in order to solve the problems of low bonding strength, poor structural integrity, and easy cracking in existing repair technologies, thereby improving the quality of bridge deck repair and structural durability.

[0004] The construction method for the UHPC composite structure used to repair bridge deck pavement defects is as follows: 1. Bridge Deck Milling: First, the damaged areas of the bridge are precisely defined to clarify the scope of closure and treatment. A cut is made at the repair boundary to avoid damage to the surrounding intact bridge deck during milling. A layered milling method is used, sequentially removing the original asphalt concrete surface layer and a 1cm thick concrete structural layer until the original concrete pavement layer is exposed. During milling, close monitoring of the reinforcing steel reinforcement within the original concrete pavement layer is necessary to prevent damage to the original structural steel reinforcement during subsequent construction. After milling, a high-pressure water gun combined with manual cleaning is used to ensure the construction surface is free of debris, dust, and loose structures, laying the foundation for subsequent procedures. 2. Drilling and Rebar Installation: A small electric hammer is used for drilling. The hole diameter is determined to be 16mm based on the anchor bar specifications (10mm diameter threaded steel bars), and the hole depth is consistent with the rebar installation depth (both 10cm). The holes are arranged in a square pattern with 50cm intervals, avoiding the original bridge deck reinforcement bars to ensure straightness. After drilling, use a stiff bristle brush to clean any remaining impurities from the hole walls, then use high-pressure dry air to blow away dust, debris, and moisture from the bottom of the hole, ensuring the hole is dry and clean. Before anchoring the rebar, the insertion section of the rebar should be surface-treated: first, use a steel brush to remove surface dirt and rust, then wipe it clean with acetone and let it dry. Slowly pour the anchoring adhesive from the bottom of the hole to 2 / 3 of the hole depth, then rotate the anchor bar in one direction to the bottom of the hole, ensuring a uniform gap between the rebar and the hole wall, allowing the anchoring adhesive to fully fill the entire hole. Finally, remove any excess adhesive from the hole opening. During the anchoring process, note the following: Rebar should be anchored immediately after drilling to avoid prolonged vacancy; it is strictly forbidden to apply adhesive directly to the surface of the rebar before inserting it into the hole; for blind holes, backfilling with anchoring epoxy adhesive is required after cleaning the hole. 3. Reinforcing Mesh Installation: HRB400 grade Ф10mm coiled steel bars are used to fabricate longitudinal and transverse reinforcing meshes, with material proportions adjusted according to the actual pouring length. During mesh arrangement, the longitudinal bridge reinforcement is located in the lower layer, and the transverse bridge reinforcement is located in the upper layer, with a spacing of 10cm × 10cm. The net protective layer thickness is strictly controlled at 20mm. The reinforcing mesh is installed manually, secured by welding using rebar anchoring. Cooling measures must be implemented simultaneously during welding, and continuous welding of the same rebar is prohibited. A point-by-point, rebar-by-rebar cyclic welding method must be used to prevent the anchoring adhesive from failing due to high temperatures. If the reinforcing mesh conflicts with the drainage pipe location, the rebar arrangement can be adjusted appropriately to ensure structural rationality and construction feasibility. 4. UHPC Mixing and Transportation: The mixing site is located near the bridge construction site, covering an area of ​​approximately 100 square meters. It is equipped with one 1m³ capacity UHPC-specific intelligent high-speed mixer, with a production capacity of 5m³ / h. Before mixing, the mixing equipment must be thoroughly cleaned and wetted to ensure there is no water accumulation inside. Simultaneously, a trial run should be conducted to verify the accuracy of the weighing system and ensure precise batching. The weighed UHPC dry mix is ​​added to the mixer drum. Dry mixing is performed for 30 seconds until the material is fluid. Then, water is added according to the designed ratio, and wet mixing continues for 5 minutes. After the mixture becomes fluid, it is further mixed for 2 minutes. The total mixing time must not be less than 8 minutes to ensure uniform UHPC mixing. The mixed UHPC is transported to the pouring site by concrete trucks. Before transportation, the trucks must be checked for water accumulation and moistened. During transportation, the trucks must maintain a constant speed to prevent segregation of the UHPC. The transportation time must be controlled within 60 minutes to ensure that the workability of the UHPC meets the construction requirements upon arrival. The first batch of mix must be tested on-site for slump (controlled range 180mm~280mm) and spread (controlled range 580mm~630mm). Subsequent batch mixing can only proceed after the tests are passed. 5. Paving and Finishing: Before pouring, the construction surface must be cleaned of debris and moistened with water to ensure no standing water. A wheeled excavator in conjunction with a grader will be used for paving. During paving, the alignment should naturally follow the beam surface alignment to ensure uniform paving layer thickness. The slump of the UHPC should be controlled within the range of 180mm–280mm, and the spread within the range of 580mm–630mm. During paving, the paving thickness should be measured every 3 meters on a cross-section, with at least 3 measurements taken at each cross-section. The measurement results should be recorded in detail to ensure the paving thickness meets design requirements. During the finishing process, areas with localized water shortages should be sprayed with water first before finishing to avoid direct water flow causing damage to the concrete surface. Clumps or other debris in the concrete should be cleaned promptly to ensure the homogeneity of the concrete. If cracks are found on the surface, they should be removed immediately through finishing to ensure that the UHPC layer surface is flat and free of defects. 6. Moisturizing and Curing: Moisturizing and curing work should be carried out immediately after the finishing work. Along the bridge direction, after completing every 2m of finishing work, immediately spray the bridge surface with a high-pressure water gun (with the nozzle facing upwards to avoid direct contact with the concrete surface). Then cover with a water-saving moisturizing membrane, and continue watering to keep the membrane moist. The curing time should not be less than 3 days. During the curing period, a dedicated person should conduct regular inspections. If localized water shortages are found, water should be added promptly. For areas where the moisturizing membrane has bubbled or arched, the bubbles should be punctured and replaced with new moisturizing membrane. If the moisturizing membrane peels off, immediately spray water to moisten the bridge surface and re-cover it to ensure continuous curing. When the ambient temperature is low, steam curing should be used to accelerate the strength development of the concrete and ensure construction quality. 7. Shot Blasting Treatment: After the moisture curing is completed, an automatic shot blasting machine is used to shot blast the surface of the newly laid UHPC layer to thoroughly remove surface oil and laitance, exposing the concrete surface with a uniform "fresh" aggregate color and forming a roughened surface with a roughness depth of 2-3mm. This treatment can significantly improve the interfacial adhesion between the subsequent ultra-thin wear-resistant layer and the UHPC layer, ensuring the integrity of the composite structure.

[0005] 8. Waterproofing layer and asphalt concrete surface layer paving: After the waterproofing layer is completed in accordance with the bridge engineering specifications, the asphalt concrete surface layer is paved to finally form a complete UHPC composite repair structure.

[0006] The present invention has the following beneficial effects: 1. The composite structure composed of UHPC120 concrete and asphalt concrete surface layer, combined with the reinforced connection design of steel mesh and rebar anchoring, significantly improves the load-bearing capacity, crack resistance and durability of the repair layer, fundamentally solving the problems of easy damage and short service life of the repair layer in traditional repair methods.

[0007] 2. The rebar installation process parameters (including hole diameter, hole depth, hole spacing, and adhesive injection method) and the rebar mesh layout were optimized and clarified to ensure a reliable connection between the repair layer and the original bridge deck, greatly enhancing the overall structural integrity.

[0008] 3. The mixing procedure and time control requirements of UHPC were clearly defined and standardized. Through specialized mixing equipment and strict control of the mixing ratio, the working performance and mechanical properties of UHPC were ensured to provide material guarantee for the quality of repair.

[0009] 4. A targeted moisturizing and maintenance plan was developed, which effectively controlled the self-shrinkage and drying shrinkage during the hardening process of UHPC, avoided the risk of cracking, and further improved the repair quality and structural stability.

[0010] 5. The construction process system is complete and easy to operate, requiring no complicated equipment. It is applicable to the treatment of continuous potholes on bridge decks of various types of bridges, such as small box girder bridges, and has broad engineering application prospects and promotion value. Attached Figure Description

[0011] Figure 1 Schematic diagram of the cross-section of a UHPC structure for treating bridge deck pavement defects; Figure 2 Schematic diagram of cross-section of bridge deck pavement defects; Figure 3 : Schematic diagram of the cross-section of the original asphalt concrete surface layer after milling; Figure 4 Schematic diagram of a 1cm section of the original concrete pavement layer after precision milling; Figure 5 : Schematic diagram of the installation of reinforcing bars and steel mesh in UHPC structure for treating bridge deck pavement defects; Figure 6 : Schematic diagram of the UHPC pavement layer for treating bridge deck pavement defects; Figure 7 : Schematic diagram of the sprayed waterproof layer of UHPC structure for treating bridge deck pavement defects; Figure 8 Schematic diagram of the new asphalt concrete surface layer laid by the UHPC structure for treating bridge deck pavement defects.

[0012] The diagram shows the following labels: 1-New asphalt concrete surface layer; 2-Waterproof layer; 3-UHPC pavement layer; 4-Retained original concrete pavement layer; 4'-Original concrete pavement layer; 5-Beam body; 6-Damaged area of ​​bridge deck pavement; 7-Standing steel reinforcement; 8-Steel mesh; 9-Original asphalt concrete surface layer; 10-Milled original asphalt concrete surface layer; 11-1cm original concrete pavement layer finely milled; 12-Damaged area cleaned. Detailed Implementation

[0013] The following is in conjunction with the attached diagram ( Figures 1-8 The specific embodiments of the present invention will be described in further detail below. Example

[0014] like Figures 1-8 As shown in the figure, this embodiment provides a UHPC composite structure and construction method for repairing bridge deck pavement defects. The specific implementation steps are as follows: A. First, define the bridge pavement defect area 6, and cut a joint at the boundary between the defect area and the intact area; then mill the original asphalt concrete surface layer 9, and then finely mill the 1cm thick original concrete pavement layer 11; after milling, use a high-pressure water gun in conjunction with manual cleaning to thoroughly clean the bridge surface to ensure that there are no debris, dust and loose structures on the construction surface. B. Use a small electric hammer for drilling. The holes should be arranged in a square pattern with a spacing of 50cm, avoiding the structural reinforcement of beam 5. After drilling, clean the hole walls to ensure the hole is dry and clean. Wipe the insertion section of the reinforcing bar 7 clean with acetone and let it dry. Pour the anchoring adhesive from the bottom of the hole to 2 / 3 of the hole depth, then rotate the reinforcing bar 7 in one direction to the bottom of the hole, ensuring that the anchoring adhesive is fully filled. C. Install the steel mesh 8. Weld the steel mesh 8 to fix it by erecting steel bars 7. Take cooling measures during the welding process to avoid high temperature affecting the performance of the anchoring adhesive. D. Constructing UHPC pavement layer 3: First, clean and moisten the existing concrete pavement layer 4. During paving, the alignment should follow the beam body 5 to ensure uniform thickness of UHPC pavement layer 3. Measure the pavement thickness on a cross-section every 3 meters to ensure it meets design requirements. For moisture curing, first use a high-pressure water gun to spray and moisten the bridge surface (gun tip facing upwards, avoiding direct sunlight), then cover with a water-saving and moisture-retaining membrane. Curing time should be no less than 3 days. If the outside temperature is low, steam curing can be used to accelerate strength development. E. After curing, use an automatic shot blasting machine to shot blast the surface of UHPC pavement layer 3 to remove surface oil and laitance, forming a roughened surface with a roughness depth of 2-3mm, so as to improve the interfacial adhesion between the new asphalt concrete surface layer 1 and UHPC pavement layer 3 and ensure the integrity of the structure. F. Apply waterproof layer 2 according to specifications. After the waterproof layer has cured, lay the new asphalt concrete surface layer 1 to complete the entire bridge deck repair work.

Claims

1. A construction method for a UHPC composite structure for repairing bridge deck pavement defects, characterized in that, Includes the following steps: A. Bridge deck milling: First, the repair boundary line of the damaged area of ​​the bridge deck pavement is cut. Then, a layer milling method is used to mill the original asphalt concrete surface layer and the 1cm thick concrete structural layer in sequence until the original concrete pavement layer is exposed. During the process, the position of the original structural steel reinforcement needs to be accurately marked. After the milling is completed, the bridge deck debris is thoroughly cleaned to ensure that the construction surface is clean. B. Drilling and Rebar Installation: Use a small electric hammer to drill holes. The holes should avoid the original structural steel bars and be arranged in a square pattern with a spacing of 50cm. After the holes are cleaned and completely dry, inject the rebar installation adhesive to 2 / 3 of the hole depth, and then insert a 10mm diameter HRB400 grade threaded steel bar with a bend to ensure that the gap between the steel bar and the hole wall is uniform. Finally, remove the excess adhesive from the hole opening. C. Reinforcing mesh installation: HRB400 grade Ф10mm coiled steel bars are used to lay longitudinal and transverse reinforcing mesh, with the longitudinal bridge bars located in the lower layer and the transverse bridge bars located in the upper layer. The spacing of the reinforcing bars is 10cm×10cm, and the net protective layer thickness of the reinforcing bars is controlled at 20mm. The reinforcing mesh is fixed by welding with anchor bars. The welding method is used during welding, and cooling measures are taken simultaneously to avoid high temperature affecting the performance of the anchoring adhesive. D. UHPC Mixing and Transportation: Use a dedicated intelligent high-speed mixer for UHPC mixing. First, dry mix the dry mixture for 30 seconds, then add water according to the design ratio and wet mix for 5 minutes. After the mixture has flowed, continue mixing for 2 minutes. The total mixing time shall not be less than 8 minutes. The mixed UHPC shall be transported to the construction site by concrete truck. The transportation time shall be controlled within 60 minutes. During transportation, the truck shall maintain a constant speed to prevent UHPC segregation. E. Paving and Finishing: Before pouring, the construction surface must be moistened to ensure that there is no standing water. A wheeled excavator and a leveling machine are used for paving operations. The slump of UHPC is controlled within the range of 180mm to 280mm and the spread is controlled within the range of 580mm to 630mm. During the paving process, the cross-sectional paving thickness is measured every 3m. If surface defects are found, they must be dealt with in time. When finishing, water is sprayed on local areas with insufficient water before finishing. F. Moisturizing and Maintenance: After the surface coating is completed, cover the surface with a water-saving moisturizing film every 2m along the bridge direction; the maintenance process is as follows: spray with high-pressure water gun to moisten → cover with moisturizing film → continuously water to keep moist, and the maintenance time shall not be less than 3 days; if it is in a low temperature environment, steam maintenance method shall be used. G. Shot blasting: After curing, the UHPC layer surface of the bridge deck is shot blasted using an automatic shot blasting machine to form a roughened surface with a roughness depth of 2-3mm, which enhances the bonding effect of subsequent structural layers. H. Waterproofing layer construction and asphalt concrete pavement: After the waterproofing layer is constructed in accordance with the specifications, the asphalt concrete pavement is laid to form a complete composite repair structure.

2. The construction method of a UHPC composite structure for repairing bridge deck pavement defects according to claim 1, characterized in that, In step B, the drilling diameter is 16mm; before planting the rebar, the surface of the rebar needs to be cleaned of dirt. First, use a steel brush to grind and clean it, then wipe it clean with acetone and let it dry; before the rebar adhesive dries, avoid disturbing the rebar and the water near the hole to ensure the quality of the rebar planting.

3. The construction method of a UHPC composite structure for repairing bridge deck pavement defects according to claim 1, characterized in that, If the position of the steel mesh conflicts with that of the drainage pipe in step C, the position of the steel bars can be adjusted appropriately. The same steel bar should not be continuously welded. A point-by-point, bar-by-bar cyclic welding method should be adopted to prevent the steel bar adhesive from failing due to local high temperature.

4. The construction method of a UHPC composite structure for repairing bridge deck pavement defects according to claim 1, characterized in that, Before using the mixing equipment in step D, it is necessary to clean and wet it, and ensure that there is no water accumulation inside the equipment; at the same time, a trial operation is required to verify the accuracy of the metering and weighing system; the slump and spread of the first batch of mixing material must be tested on site, and batch mixing can only be carried out after the test is qualified.

5. The construction method of a UHPC composite structure for repairing bridge deck pavement defects according to claim 1, characterized in that, Before covering the bridge surface with the moisturizing film in step F, the bridge surface must be moistened with a high-pressure water gun, and the nozzle of the water gun must be facing upwards to avoid direct contact with the concrete surface and damage. During the curing period, a dedicated person should be assigned to conduct regular inspections, replenish moisture in a timely manner, and repair any damaged moisturizing film to ensure the curing effect.

Images