Construction method for improving UHPC surface roughness

Abstract

The invention discloses a construction method for improving UHPC (Ultra High Performance Concrete) surface roughness, which belongs to the technical field of pavement construction of construction projects, and comprises the following steps: step 1, preparing raw materials, preparing UHPC, and paving a pavement base layer; secondly, a UHPC layer is poured and laid on the pavement base layer; and thirdly, UHPC forming and curing are conducted, and after the strength reaches 60% or reaches 50 MPa, the local uneven area of the UHPC surface is polished. According to the construction method for improving the UHPC surface roughness, the grooving position is determined by snapping the line on the UHPC surface layer, grooving construction is conducted on the surface of the UHPC component in cooperation with a grooving machine, braking and braking are conducted in time, the stability of a vehicle during turning is ensured, the vehicle is prevented from slipping, and the driving safety is improved; meanwhile, the friction force between vehicle tires and the road surface is increased through the high friction coefficient, the good road surface friction coefficient can reduce road surface damage and traffic accident loss caused by vehicle slipping or out-of-control, and then the service life of the UHPC road surface is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of construction engineering pavement construction, and particularly relates to a construction method for improving the surface roughness of UHPC. Background Art

[0002] UHPC, the full name of which is Ultra High Performance Concrete, is a new type of cement-based composite material with excellent performance. It has a strength far higher than that of ordinary concrete and excellent durability. It can withstand high loads and has excellent compressive and tensile strength. With its excellent performance and broad application prospects, it is widely used in bridge engineering, construction engineering, road engineering and other fields.

[0003] In cement concrete pavement construction, the friction coefficient of the pavement is directly related to the braking performance of the vehicle. A pavement with a high friction coefficient can provide greater braking force and shorten the braking distance, thereby improving driving safety. When a vehicle is turning, the lateral friction can be used to maintain the stability of the vehicle body and avoid skidding or loss of control. A pavement with a high friction coefficient can provide better lateral adhesion to ensure the stability of the vehicle when turning. Therefore, in order to improve driving safety and ensure vehicle controllability, and to make cement concrete pavements meet road use requirements, cement concrete pavements often need to ensure a sufficiently high friction coefficient. In order to make cement concrete pavement meet the technical standard requirements for pavement friction coefficient, it is also necessary to take necessary construction processes and measures to groove the surface of the cement concrete pavement to improve the pavement's anti-skid performance and friction coefficient. However, due to the high strength of UHPC concrete, it would be difficult to carry out grooving construction after its strength is fully up. In addition, there are relatively few cases of using high-strength concrete such as UHPC for surface construction, which makes it difficult to improve the friction coefficient of UHPC pavement, affecting the driving safety and anti-skid performance of UHPC pavement. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for improving the surface roughness of UHPC, aiming to solve the above-mentioned problems existing in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A construction method for improving the surface roughness of UHPC comprises the following steps: Step 1: Prepare raw materials and UHPC, and lay the road base; Step 2: pouring and laying the UHPC layer on the pavement base; Step 3: UHPC molding and curing; Step 4: UHPC is cured at room temperature for three days. After the strength reaches 60% or 50MPa, the uneven areas on the UHPC surface are polished; Step 5: Design and prepare the UHPC grooves. Design the shape, depth, width and spacing parameters of the grooves. After the UHPC surface is polished, use a shot blasting machine to blast the UHPC molding surface to remove the slurry on the UHPC surface. Step 6: UHPC grooving construction: first clean the surface of the UHPC component, then determine the grooving position by marking the line on the UHPC surface layer, and then use a grooving machine to perform grooving construction on the surface of the UHPC component to form a grooving; Step 7: Post-processing and inspection of UHPC grooving. After the grooving construction is completed, the road surface groove is polished and trimmed with a grinder, and then rinsed with water. The direction, depth, width, and spacing parameters of the groove are measured and inspected and observed regularly.

[0006] In a preferred embodiment of the present invention, in the UHPC preparation link of step 1, cement, ultrafine powder, fine aggregate and steel fiber are mixed and stirred, and the mixing ratio based on the mass of cement as the base percentage or multiple is cement: ultrafine powder: fine aggregate: steel fiber = 1: (0.3-0.6): 1: (2-3), and the stirring time is 5-10 minutes. After the stirring is completed, the concrete is left to stand and vibrated.

[0007] In a preferred embodiment of the present invention, if the pouring process of the UHPC layer in step 2 needs to be interrupted, the joint needs to be processed, a rectangular joint is set, and the joint area is roughened.

[0008] In a preferred embodiment of the present invention, the UHPC layer laid in step 2 has a thickness of 4.5-6 cm.

[0009] In a preferred embodiment of the present invention, for the maintenance and reinforcement project of the existing road base, it is only necessary to plant reinforcement on the existing foundation, and then lay the steel mesh for UHPC paving, and step one can be omitted and step two can be performed directly.

[0010] In a preferred embodiment of the present invention, during the UHPC pouring and laying process in step 2, the forming mold is lubricated.

[0011] In a preferred embodiment of the present invention, during the UHPC forming process in step three, a sunshade is built or a sunshade cloth is covered for shading, and heat insulation cotton or plastic film is used to reduce heat dissipation on the concrete surface.

[0012] In a preferred embodiment of the present invention, in the UHPC groove design of step five, the groove direction is set perpendicular to the driving direction, the groove depth is 0.8~1.2mm, the groove width is 3mm, the single groove spacing is 2cm, the groove machine uses a saw blade group with 14 blades, the single groove width is 30cm, and the groove spacing between each group is 12cm.

[0013] In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects: The construction method for improving the surface roughness of UHPC of the present invention is as follows: after UHPC is poured and laid to form, in order to avoid increasing the difficulty of implementing grooving after UHPC is completely hardened, after the strength of UHPC reaches 60% or 50MPa, the local uneven area on the surface of UHPC is polished to ensure that the surface of UHPC is flat, which is convenient for subsequent grooving operations; then, the grooving position is determined by marking lines on the surface of UHPC, and a grooving machine is used to perform grooving construction on the surface of UHPC components to form grooves, thereby improving the surface roughness and friction coefficient of the UHPC pavement layer, and improving the anti-skid property of the UHPC pavement. The performance of UHPC pavement can provide greater braking force and better lateral adhesion, shorten the braking distance, brake and stop in time, ensure the stability of the vehicle when turning, thus preventing the vehicle from skidding and improving driving safety; at the same time, the high friction coefficient is used to increase the friction between the vehicle tires and the road surface, so that the vehicle can maintain good handling at all speeds, reduce the bumps and vibrations of the vehicle during driving, and improve ride comfort; a good road friction coefficient can also reduce road damage and traffic accident losses caused by vehicle skidding or loss of control, thereby extending the service life of the UHPC pavement. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the implementation process of the construction method of the present invention. DETAILED DESCRIPTION

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0016] Example: like Figure 1 As shown, this embodiment provides a construction method for improving the surface roughness of UHPC, comprising the following steps: Step 1: Prepare raw materials and UHPC, and lay the road base; Step 2: pouring and laying the UHPC layer on the pavement base; Step 3: UHPC molding and curing; Step 4: UHPC is cured at room temperature for three days. After the strength reaches 60% or 50MPa, the uneven areas on the UHPC surface are polished; Step 5: Design and prepare the UHPC grooves. Design the shape, depth, width and spacing parameters of the grooves. After the UHPC surface is polished, use a shot blasting machine to blast the UHPC molding surface to remove the slurry on the UHPC surface. Step 6: UHPC grooving construction: first clean the surface of the UHPC component, then determine the grooving position by marking the line on the UHPC surface layer, and then use a grooving machine to perform grooving construction on the surface of the UHPC component to form a grooving; Step 7: Post-processing and inspection of UHPC grooving. After the grooving construction is completed, the road surface groove is polished and trimmed with a grinder, and then rinsed with water. The direction, depth, width, and spacing parameters of the groove are measured and inspected and observed regularly.

[0017] In a specific application scenario, after UHPC is poured and laid, in order to avoid increasing the difficulty of grooving after UHPC is completely hardened, after the UHPC strength reaches 60% or 50MPa, the local uneven areas on the UHPC surface are polished to ensure that the UHPC surface is flat, which is convenient for subsequent grooving operations. Then, the grooving position is determined by drawing lines on the UHPC surface layer, and a grooving machine is used to perform grooving construction on the surface of the UHPC component to form grooves, thereby improving the surface roughness and friction coefficient of the UHPC pavement layer, and improving the anti-skid performance of the UHPC pavement. The following is a further description of the construction method for improving the surface roughness of UHPC in the present invention in conjunction with this application scenario.

[0018] Further, refer to Figure 1 In the UHPC preparation process of step one, cement, ultrafine powder, fine aggregate and steel fiber are mixed and stirred. The mixing ratio based on the mass of cement is cement: ultrafine powder: fine aggregate: steel fiber = 1: (0.3-0.6): 1: (2-3). The stirring time is 5-10 minutes. After the mixing is completed, the concrete is left to stand and vibrated.

[0019] In this embodiment, the mixing ratio of UHPC is a highly sophisticated design process, in which cement is the main component of the cementitious material, so other raw materials are mixed in a certain percentage or multiple based on the mass of cement. In this construction method, the mixing ratio adopted is cement: ultrafine powder: fine aggregate: steel fiber = 1: (0.3-0.6): 1: (2-3), in which the addition of ultrafine powder (such as silica fume, fly ash, etc.) can significantly improve the density and strength of concrete, fine aggregate (such as fine sand) is used as a filling material in concrete, and steel fiber is used to enhance the tensile strength and toughness of concrete; At the same time, the mixing time of UHPC is longer than that of traditional concrete. The mixing time is set to 5-10 minutes to ensure that various materials can be evenly mixed. After mixing, the concrete is left to stand and vibrate in order to eliminate the pores and air in the UHPC and improve the density and strength of the UHPC.

[0020] For more details, see Figure 1 If the pouring process of the UHPC layer in step 2 needs to be interrupted, the joint needs to be processed, a rectangular joint is set and the joint area is roughened.

[0021] In this embodiment, since the pouring process of the UHPC layer in step 2 has an uncertain construction period and is difficult to complete in one go, when the pouring process is interrupted, in order to protect the already poured UHPC layer and prevent it from being damaged or contaminated, and to facilitate subsequent construction, it is necessary to set a rectangular joint after stopping the pouring and roughen the joint area, which can increase the bonding force between the new and old concretes and ensure the strength and durability of the joints. The roughening process can be performed mechanically or manually, such as using tools such as high-pressure water jets, pneumatic picks, chisels, etc., and avoid damaging the hardened concrete matrix.

[0022] More preferably, referring to Figure 1 The UHPC layer in step 2 is laid with a thickness of 4.5-6cm.

[0023] In this embodiment, UHPC has extremely high strength and durability, and can provide sufficient structural support even at a relatively thin thickness. Therefore, the laying thickness of the UHPC layer is set to 4.5-6 cm. First, its structural strength can be guaranteed. At the same time, within this thickness range, the UHPC layer can effectively realize its waterproof and heat-insulating functions, and it is also convenient for template installation, pouring and post-processing during the construction process, ensuring the quality and performance of the UHPC layer.

[0024] More preferably, referring to Figure 1 For the maintenance and reinforcement projects of existing road bases, it is only necessary to plant reinforcement on the existing foundation, and then lay steel mesh for UHPC paving. Step one can be omitted and step two can be carried out directly.

[0025] In this embodiment, since roads and other transportation infrastructure may have projects for repair and reinforcement based on existing pavement, in order to shorten the construction period and enhance the pavement bearing capacity, rebar can be directly planted on the basis of the existing pavement base, and then steel mesh can be laid for UHPC paving, and step 1 can be omitted and step 2 can be directly performed. The durability and service life of the road are improved.

[0026] Furthermore, refer to Figure 1 In step 2, during the UHPC pouring and laying process, the forming mold is lubricated.

[0027] In this embodiment, when UHPC is poured and laid, UHPC adheres to the forming mold, and extra time and manpower are required to clean the mold, which increases the construction period and cost, especially after the UHPC has hardened, it is more difficult to completely remove it. The UHPC attached to the mold may affect the surface quality of the subsequently poured UHPC layer, resulting in an uneven surface or defects. If the attached objects form protrusions or depressions on the mold surface, these defects may be transmitted to the UHPC components, affecting their appearance and performance. Long-term or improper attachment may cause wear or damage to the mold surface and shorten the service life of the mold. Strong tools or chemical solvents used in the cleaning process may also damage the mold. In addition to direct cleaning costs and mold maintenance costs, attachment problems may also indirectly lead to other cost increases, such as the cost of components that need to be reworked or scrapped due to product quality problems. Therefore, the forming mold needs to be lubricated to reduce the adhesion between the UHPC and the mold, thereby facilitating demoulding and cleaning, and improving the efficiency and quality of UHPC pouring and laying.

[0028] Furthermore, refer to Figure 1 In step three, during the UHPC molding process, a sunshade is built or covered with a sunshade cloth for shading, and thermal insulation cotton or plastic film is used to reduce the heat dissipation of the concrete surface.

[0029] In this embodiment, since it is necessary to strictly control environmental conditions and take necessary maintenance measures during the UHPC molding and curing process to avoid excessively high or low temperatures, so as to prevent the curing and hardening process of the UHPC from being adversely affected, in summer, it is necessary to pay attention to cooling to prevent the UHPC from overheating. For this purpose, a sunshade is built or covered with a sunshade cloth to provide shade to avoid direct sunlight exposure and prevent the concrete surface temperature from rising too quickly to cause cracking, especially within 24 hours after the pouring is completed. This is one of the most critical stages in the curing process; in winter, it is necessary to strengthen insulation measures to prevent the UHPC from freezing, and use insulation cotton or cover with plastic film to reduce the heat dissipation of the concrete surface, thereby promoting the molding and strength development of the UHPC.

[0030] More specifically, see Figure 1In the UHPC groove design of step five, the groove direction is set perpendicular to the driving direction, the groove depth is 0.8~1.2mm, the groove width is 3mm, the single groove spacing is 2cm, and the groove machine uses a saw blade group with 14 blades. The single groove width is 30cm and the groove spacing of each group is 12cm.

[0031] In this embodiment, the grooves can not only improve the performance of the UHPC material, but also enhance its ability to combine with other materials or structures. The roughness of the UHPC surface can be increased by setting the grooves. The direction of the grooves should also be coordinated with the main force direction of the structure. Therefore, setting the groove direction perpendicular to the driving direction is helpful for drainage and increasing the anti-skid performance of the surface, and can also improve the safety and comfort of driving. Since the groove depth should not be too shallow to ensure sufficient adhesion, and should not be too deep to avoid damaging the overall performance of the UHPC structure, the groove depth is set to 0.8~1.2mm. In order to facilitate drainage and anti-skid, the groove width should also be moderate, set to 3mm, and the spacing between single grooves is limited to 2cm to maintain the stability of the UHPC surface.

[0032] Working principle: The construction method of the present invention for improving the surface roughness of UHPC: Step 1: Prepare raw materials and UHPC, and lay the pavement base. Before construction, prepare UHPC first. Mix and stir cement, ultrafine powder, fine aggregate, and steel fiber. The mixing ratio based on the mass of cement is cement: ultrafine powder: fine aggregate: steel fiber = 1: (0.3-0.6): 1: (2-3), which significantly improves the density and strength of concrete, and uses steel fiber to enhance the tensile strength and toughness of concrete; then stir the raw materials for 5-10 minutes. After stirring, let the concrete stand and vibrate to eliminate the pores and air in the UHPC, improve the density and strength of the UHPC, and then lay the pavement base or directly plant reinforcement based on the existing pavement base, and then lay the steel mesh and then lay the UHPC; Step 2: Pour and lay the UHPC layer on the pavement base. Since UHPC has extremely high strength and durability, it can provide sufficient structural support even at a thin thickness. Therefore, the thickness of the UHPC layer is set to 4.5-6cm. First, its structural strength can be guaranteed. At the same time, within this thickness range, the UHPC layer can effectively achieve its waterproof and heat-insulating functions, and it is also convenient for formwork installation, pouring and post-processing during the construction process, ensuring the quality and performance of the UHPC layer. Step 3: UHPC molding and maintenance. First, lubricate the molding mold to reduce the adhesion between UHPC and the mold, so as to facilitate demoulding and cleaning, improve the efficiency and quality of UHPC casting and laying, and avoid UHPC adhering to the molding mold. It takes extra time and manpower to clean the mold, especially after the UHPC has hardened. It is more difficult to completely remove. UHPC attached to the mold may affect the surface quality of the subsequently cast UHPC layer, resulting in uneven surface or defects. Step 4: UHPC is cured at room temperature for three days. In order to avoid increasing the difficulty of grooving after UHPC is completely hardened, the local uneven areas on the UHPC surface are polished after the strength reaches 60% or 50MPa to ensure that the UHPC surface is flat and convenient for subsequent grooving operations. Step 5: Design and prepare UHPC grooves. Design the shape, depth, width and spacing parameters of the grooves. Grooving can not only improve the performance of UHPC materials, but also enhance its ability to combine with other materials or structures. The roughness of the UHPC surface can be increased by setting grooves. The direction of the grooves should also be coordinated with the main force direction of the structure. Therefore, setting the groove direction perpendicular to the driving direction is conducive to drainage and increasing the anti-skid performance of the surface, and can also improve driving safety and comfort. Since the groove depth should not be too shallow to ensure sufficient adhesion, and should not be too deep to avoid damaging the overall performance of the UHPC structure, the groove depth is set to 0.8~1.2mm. In order to facilitate drainage and anti-skid, the groove width should also be moderate, set to 3mm, and limit the spacing of a single groove to 2cm to maintain the stability of the UHPC surface. After the UHPC surface is polished, the UHPC molding surface is shot blasted with a shot blasting machine to remove the floating slurry on the UHPC surface to ensure the quality of the groove construction. Step 6: UHPC grooving construction: first clean the surface of the UHPC component, then determine the grooving position by marking the line on the UHPC surface layer, and then use a grooving machine to perform grooving construction on the surface of the UHPC component to form the grooves, ensuring the uniformity and consistency of the grooves. At the same time, avoid damage or destruction to the UHPC components, thereby improving the friction coefficient of the UHPC surface and enhancing the driving safety and anti-skid performance of the UHPC pavement; Step 7: Post-processing and inspection of UHPC grooving. After the grooving construction is completed, the road surface groove is polished and trimmed with a grinder, and then rinsed with water. The direction, depth, width, and spacing parameters of the groove are measured and checked and observed regularly. The debris and garbage generated by the groove are cleaned in time to keep the surface of the UHPC component clean. The quality and effect of the groove are inspected to ensure that the groove meets the design requirements and usage requirements.

[0033] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A construction method for improving the surface roughness of UHPC, characterized in that: The following steps are involved: Step 1: Prepare raw materials and UHPC, and lay the road base; Step 2: pouring and laying the UHPC layer on the pavement base; Step 3: UHPC molding and curing; Step 4: UHPC is cured at room temperature for three days. After the strength reaches 60% or 50MPa, the uneven areas on the UHPC surface are polished; Step 5: Design and prepare the UHPC grooves. Design the shape, depth, width and spacing parameters of the grooves. After the UHPC surface is polished, use a shot blasting machine to blast the UHPC molding surface to remove the slurry on the UHPC surface. Step 6: UHPC grooving construction: first clean the surface of the UHPC component, then determine the grooving position by marking the line on the UHPC surface layer, and then use a grooving machine to perform grooving construction on the surface of the UHPC component to form a grooving; Step 7: Post-processing and inspection of UHPC grooving. After the grooving construction is completed, the road surface groove is polished and trimmed with a grinder, and then rinsed with water. The direction, depth, width, and spacing parameters of the groove are measured and inspected and observed regularly.

2. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: In the UHPC preparation process of step one, cement, ultrafine powder, fine aggregate and steel fiber are mixed and stirred. The mixing ratio based on the mass of cement is cement: ultrafine powder: fine aggregate: steel fiber = 1: (0.3-0.6): 1: (2-3). The stirring time is 5-10 minutes. After the mixing is completed, the concrete is left to stand and vibrated.

3. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: If the pouring process of the UHPC layer in step 2 needs to be interrupted, the joint needs to be processed, a rectangular joint needs to be set, and the joint area needs to be roughened.

4. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: The UHPC layer in step 2 is laid with a thickness of 4.5-6 cm.

5. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: For the maintenance and reinforcement projects of existing road bases, it is only necessary to plant reinforcement on the existing foundation, and then lay steel mesh for UHPC paving. Step one can be omitted and step two can be carried out directly.

6. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: During the UHPC pouring and laying process in step 2, the forming mold is lubricated.

7. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: In step three, during the UHPC molding process, a sunshade is built or covered with a sunshade cloth for shading, and thermal insulation cotton or plastic film is used to reduce heat dissipation on the concrete surface.

8. The construction method for improving the surface roughness of UHPC according to claim 1, characterized in that: In the UHPC notching design of step five, the notching direction is set perpendicular to the driving direction, the notching depth is 0.8~1.2mm, the notching width is 3mm, the spacing between single notches is 2cm, and the notching machine uses a saw blade group with 14 blades. The width of a single notch is 30cm, and the spacing between each notch is 12cm.

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