Inverted prefabrication method of UHPC (Ultra High Performance Concrete) curb

Abstract

The invention relates to an inverted prefabrication method of UHPC (Ultra High Performance Concrete) curbs, which comprises the following steps of: S1, manufacturing molds according to the size of the curbs, including an openable outer mold matched with the outer contour side and an inner mold matched with the inner contour side; s2, preparing a UHPC material; s3, the blended UHPC material is put into a stirring machine to be stirred; s4, whether the performance of the stirring material meets the pouring requirement or not is detected; s5, stirring materials meeting the pouring requirement are distributed in the mold, and assembling is completed; s6, the mold and the UHPC material poured into the mold according to the step S5 are vibrated; s7, the mold and the curb which is preliminarily formed in the mold after vibration according to the step S6 are subjected to film covering and moisturizing maintenance; and S8, the mold is dismantled, and hot curing or natural curing is completed on the prefabricated UHPC curb obtained through treatment in the step S7. The quality of the curb obtained through prefabricating is improved, the construction procedures are reduced, the construction difficulty can be reduced, the construction period can be shortened, and the working efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of UHPC (Ultra High Performance Concrete) industrial construction, more particularly to an inverted prefabrication method of UHPC curb. BACKGROUND

[0002] The commonly used curbs in the current engineering are cement concrete curbs and natural stone curbs. The cement concrete curb has high strength and durability, can withstand the pressure of vehicles and pedestrians, and is not easy to deform in long-term use; the installation process is relatively simple, and can be accurately installed by manual or mechanical equipment, thereby shortening the construction period and reducing the cost. The raw material price is relatively low, and the production cost is also low, so the price is relatively affordable; but it is easy to break and damage, although it is solid as a whole, but when subjected to a large external force, cracks or fragmentation may occur; and the texture is relatively single, and the architectural aesthetic effect needs to be improved; in the northern region where snow-melting salt is frequently used, the durability needs to be improved.

[0003] The natural stone curb has natural texture and color, and the appearance is elegant and generous, which can improve the grade of the road and landscape; has good durability, high hardness and wear resistance, and can withstand long-term wind and sun exposure and vehicle rolling, and has a long service life; has high compressive strength and can withstand a large external impact; but the stone cost of the natural stone curb is relatively high, so the price of the stone curb is also relatively expensive, which is not suitable for large-scale road construction; and the stone is heavy, and the installation is cumbersome. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an inverted prefabrication method of UHPC curb, which can significantly improve the quality of the curb, reduce the construction difficulty, and shorten the construction period.

[0005] The technical scheme adopted by the present application to solve the technical problem is: constructing an inverted prefabrication method of UHPC curb, comprising the following steps: S1, a mold is made according to the size of the curb, including an openable outer mold set in accordance with the outer contour side, and an inner mold set in accordance with the inner contour side; S2, configuring UHPC material; S3, placing the mixed UHPC material in the mixer for mixing; S4, detecting whether the performance of the mixed material meets the pouring requirements; S5, placing the mixed material meeting the pouring requirements obtained in step S4 in the mold and completing the assembly; S6, vibrating the mold and the UHPC material poured in the mold in step S5; S7, coating and moisturizing the mold and the curb preliminarily formed in the mold after vibrating in step S6. S8, remove the mold, and complete the heat curing or natural curing of the prefabricated UHPC curb stone obtained through step S7.

[0006] According to the above scheme, the outer mold top is provided with a plurality of buckles, and the buckles are closed to complete the closing of the outer mold.

[0007] According to the above scheme, in the heating stage of the heat curing in step S8, the heating speed should not be greater than 15℃ / h; after the curing is completed, the cooling speed should not be greater than 15℃ / h; when the curing temperature is 50℃-70℃, the curing time should not be less than 96h; when the curing temperature is 70℃-90℃, the curing time is preferably 48h; and the relative humidity of the curing should not be less than 95%. According to the above scheme, the shell thickness of the prefabricated UHPC curb stone obtained in step S8 is 10-30mm. According to the above scheme, the cross-sectional width of the prefabricated UHPC curb stone obtained in step S8 is 150-300mm.

[0008] According to the above scheme, the cross-sectional height of the prefabricated UHPC curb stone obtained in step S8 is 150-300mm.

[0009] According to the above scheme, the length of the prefabricated UHPC curb stone obtained in step S8 is 1.4-2.0m.

[0010] According to the above scheme, the step S5 specifically includes: S501, place the mold on the ground with the bottom of the curb stone upward and the top upward; S502, keep the pouring surface horizontal; S503, open the top buckle of the outer mold, loosen the screws on both sides of the inner mold, and take demolding measures on the inner surface of the outer mold; remove the internal core mold, and take demolding measures on the outer surface of the internal core mold; S504, hoist the internal core mold to the designated position, install the screws on both sides of the inner mold, and close the top buckle of the outer mold; S505, start pouring from one side of the mold during pouring, and complete pouring at one time, with slight auxiliary vibration during the process; the free height of the mixture pouring should not exceed 1m, and auxiliary tools such as string barrels, chutes, and pipes should be added when the falling height is greater than 1m.

[0011] According to the above scheme, in step S6, the mold and the UHPC material inside the mold are hoisted as a whole on the vibration table for overall vibration.

[0012] According to the above scheme, the method for removing the mold in step S8 includes: S801, open the top buckle of the outer mold, and loosen the screws on both sides of the inner mold; S802, remove the internal core mold.

[0013] The upside-down prefabrication method of the UHPC curb stone of the application has the following beneficial effects: 1. The upside-down prefabrication process is used instead of the traditional concrete material, traditional formwork and vertical pouring process, the quality of the prefabricated curb stone is improved, the construction process is reduced, which helps to reduce the construction difficulty, shorten the construction period and improve the work efficiency.

[0014] 2. The UHPC material has the characteristics of high strength, durability, corrosion resistance and impact resistance, which can not only meet the erosion of deicing salt in northern areas, but also meet the long-term scouring requirements of cleaning machines, and the early strength of UHPC grows rapidly, which can meet the requirements of rapid demolding, lifting and transportation, and greatly improve the production and construction efficiency.

[0015] 3. The UHPC raw material has rich color system and various textures, and the appearance is beautiful and elegant, the UHPC component can perfectly blend with the surrounding environment, has high architectural aesthetic value, and can improve the grade of roads and landscapes. BRIEF DESCRIPTION OF DRAWINGS

[0016] The application will be further described below in combination with the drawings and examples, and the drawings are as follows: Figure 1 is a prefabricated product diagram of the UHPC curb stone of the application; Figure 2 is a flowchart of the upside-down prefabrication method of the UHPC curb stone of the application; Figure 3 is a schematic diagram of the mold in the upside-down prefabrication method of the UHPC curb stone of the application; Figure 4 is a schematic diagram of the opening state of the mold in the upside-down prefabrication method of the UHPC curb stone of the application; Figure 5 is a schematic diagram of another angle of the opening state of the mold in the upside-down prefabrication method of the UHPC curb stone of the application. DETAILED DESCRIPTION

[0017] In order to have a clearer understanding of the technical features, objects and effects of the application, the specific embodiments of the application will be described in detail with reference to the drawings.

[0018] The upside-down prefabrication method of the UHPC curb stone of the application includes the following steps: S1, mold making: according to the size requirements of the curb stone, the mold is made; the mold includes an openable outer mold 101 arranged in accordance with the outer contour side, an inner mold 102 arranged in accordance with the inner contour side, a plurality of buckles 1011 arranged at the top, and a plurality of screws 1021 arranged at the ends of the two sides. Referring to Figure 3 , the outer mold 101 is opened, the top buckle 1011 of the outer mold 101 is opened, the two side screws 1021 of the inner mold are loosened, the inner surface of the outer mold 101 is taken out of the mold, the outer surface of the inner core mold 102 is taken out of the mold, the inner core mold 102 is hoisted to the designated position, the two side screws 1021 of the inner mold are installed, and the top buckle 1011 of the outer mold 101 is closed; S2, UHPC material configuration: according to the product appearance color, texture and other configurations UHPC material; all materials must be well accepted before use, and only after acceptance can it be allowed to enter the production, and the raw materials should be well sealed during storage to prevent the raw materials from being damp and appearing clumps, and to ensure the quality of the raw materials. S3, UHPC stirring: stirring should be reasonably equipped according to the engineering scale (poured volume), construction technology and progress requirements, preferably using forced mixer, and the stirring amount should not be more than 70% of the rated stirring amount; before stirring, the state of the stirring equipment should be checked, and the stirring equipment should be ensured clean and dry before stirring. Before the first disc of the mixer is mixed, the mixer should be wetted and no clear water should be left; the mixed UHPC material is placed in the mixer for mixing; the water-cement ratio of the UHPC material should be according to the product performance requirements, the corresponding proportioning is provided according to the test results, and the proportioning is followed; after all the premixed materials are poured into the mixer, the water is added while stirring, and the state is changed after about 7 minutes of stirring, then the steel fibers are evenly added while stirring, and the mixing is about 5 minutes to be uniform and discharged; the quality of the out-of-machine mixing compound is uniform, and there should be no fiber clumps.

[0019] S4, UHPC detection: whether the performance of the stirred material meets the pouring requirements; after stirring, the flow performance and slump of the freshly mixed concrete should be measured in time, the fluidity should be within the specified range, otherwise the water reducing agent dosage or water amount should be adjusted to meet the requirements. S5, pouring: check the tightness of the formwork joint before pouring, ensure that the formwork does not leak during pouring, and sprinkle water on the surface of the formwork, but do not accumulate water. The stirred material obtained according to step S4 meets the pouring requirements and is placed in the mold and assembled; the free height of the pouring and pouring should not exceed 1m, when the pouring height is greater than 1m, auxiliary tools such as string drum, chute and pipe should be added; it is appropriate to start pouring from one side of the formwork, and once the pouring is completed, the process can be assisted by vibration; S6, vibrate the mold and the UHPC material poured into the mold according to step S5 and perform vibration treatment; the vibration is preferably performed by using a flat vibrator and an external mold vibrator, and segregation and stratification should be avoided while ensuring vibration compaction. In addition to ensuring the compaction of the concrete, the vibration machinery and method should also ensure uniform distribution of the fibers; the displacement interval of the surface vibrator should be such that the vibrator plate can cover the already vibrated part by not less than 100 mm; the vibration time of each vibration point should not exceed 20 s, and when the surface of the mixture appears to be slurry, it can be considered to be compacted; S7, film covering and moisture curing: based on the temperature difference, consider covering and moisture curing the mold and the curbstone preliminarily formed in the mold after vibration according to step S6; after pouring is completed, spray water mist in time to keep the surface of the curbstone poured in place in a wet state, and cover it with a film in time for moisture curing; S8, demolding and curing: remove the mold, and complete the thermal curing or natural curing of the precast UHPC curbstone obtained after step S7, and pay attention to the surface and corner treatment. During the heating stage of thermal curing, the heating speed should not be greater than 15℃ / h; after the curing is completed, the cooling speed should not exceed 15℃ / h; when the curing temperature is 50℃-70℃, the curing time should not be less than 96h; when the curing temperature is 70℃-90℃, the curing time is preferably 48h; the relative humidity during curing should not be less than 95%. The natural curing time is not less than 7d, and the internal and external temperature difference of the component should not be greater than 20℃, and when the internal and external temperature difference is greater than 20℃, insulation curing measures should be taken.

[0020] Further, the outer shell thickness of the precast UHPC curbstone obtained in step S8 is 10-30mm.

[0021] Further, the cross-sectional width of the precast UHPC curbstone obtained in step S8 is 150-300mm.

[0022] Further, the cross-sectional height of the precast UHPC curbstone obtained in step S8 is 150-300mm.

[0023] Further, the length of the precast UHPC curbstone obtained in step S8 is 1.4-2.0m.

[0024] Further, the specific implementation measures of step S5 are: S501, place the mold on the ground with the bottom of the curbstone facing upwards and the top facing upwards; S502, keep the pouring surface level; S503, open the buckle at the top of the outer mold, loosen the screws on both sides of the inner mold, and take demolding measures on the inner surface of the outer mold; remove the inner core mold, and take demolding measures on the outer surface of the inner core mold; S504, hoist the internal core mold to the designated position, install the screws on both sides of the inner mold; close the top buckle of the outer mold; S505, when pouring, start pouring from one side of the formwork, and once pouring is completed, slightly assist in vibrating during the process. Further, in step S6, the mold and the UHPC material inside the mold are hoisted as a whole on the vibration table for overall vibration.

[0025] Further, in step S7, the mold and the prefabricated UHPC curbstone are coated and moisture cured.

[0026] Further, in step S8, the prefabricated UHPC curbstone is completed heat curing or natural curing.

[0027] Further, the removal of the mold in step S8 specifically includes: S801, open the top buckle of the outer mold, loosen the screws on both sides of the inner mold; S802, remove the internal core mold.

[0028] Embodiment Referring to Figure 1 , the prefabricated product diagram of the UHPC curbstone of the present application is shown in Figure 1 .

[0029] Referring to Figure 2 , the specific preparation steps of the inverted prefabrication method of the UHPC curbstone of the present application are described as follows.

[0030] S1, according to the size requirements of the curbstone, a mold is made; In this step S1, the mold includes an openable outer mold fitted to the outer contour side, an inner mold fitted to the inner contour side, a plurality of buckles and a plurality of screws; Referring to Figures 3-5 , in the mold, the top buckle 1011 of the outer mold 101 is opened, the screws 1021 on both sides of the inner mold are loosened, the inner surface of the outer mold 101 adopts demolding measures; the internal core mold 102 is removed, the outer surface of the internal core mold 102 adopts demolding measures; the internal core mold 102 is hoisted to the designated position, and the screws 1021 on both sides of the inner mold are installed; the top buckle 1011 of the outer mold 101 is closed.

[0031] S2, configure light gray UHPC material according to product appearance color, texture, etc.; all materials must be well inspected before use, and only after inspection is qualified can they be allowed to enter the production, waterproof sealing work should be done well during the storage process of raw materials to prevent raw materials from being damp and appearing lump phenomenon, to ensure the quality of raw materials; S3, the stirring should be according to the project scale (poured volume), construction technology and progress requirements reasonable equipped with stirring equipment, preferably using forced stirrer, and the stirring amount is not more than 70% of the rated stirring amount; Before stirring, the state of the stirring equipment should be checked, and the stirring equipment should be ensured clean and dry before stirring. Before the first disc of the stirring machine is mixed, the stirring machine should be wetted and no clear water should be left; The UHPC material after blending is placed in the stirring machine for mixing; The water-cement ratio of UHPC material should be according to the performance requirements of the product, the corresponding proportioning is provided according to the test results, and stirring is carried out according to the proportioning; After all the premixed materials are poured into the stirring machine, the water is added while stirring, and the stirring is carried out for about 7 minutes until the state changes, then the steel fibers are evenly added while stirring, and the stirring is carried out for about 5 minutes until the mixture is uniform and the material is discharged; The quality of the mixture discharged from the machine is uniform, and there should be no fiber clumps; S4, detect whether the performance of the stirred material meets the pouring requirements; After stirring is completed, the flow performance and slump of the freshly mixed concrete should be determined in time, and the fluidity should be within the specified range, otherwise the water reducing agent dosage or water amount should be adjusted to meet the requirements; S5, check the tightness of the formwork joint before pouring, ensure that the formwork does not leak during pouring, and sprinkle water on the surface of the formwork for wetting, but there should be no standing water. The stirred material obtained according to step S4 is placed in the mold and assembled; The free height of the mixture pouring should not exceed 1m, when the pouring height is greater than 1m, auxiliary tools such as string drum, chute and chute pipe should be added; The specific implementation steps of this step S5 are: S501, place the mold on the ground with the curbstone bottom facing up and the top facing up; S502, keep the pouring surface level; S503, open the buckle at the top of the outer mold, loosen the screws on both sides of the inner mold, and take off the inner core mold, and the outer surface of the inner core mold is taken off; S504, hoist the inner core mold to the specified position, install the screws on both sides of the inner mold, and close the buckle at the top of the outer mold; S505, start pouring from one side of the formwork, and complete the pouring at one time, with slight vibration during the process.

[0032] S6, vibrate the mold and the UHPC material poured in the mold according to step S5; The vibration should use flat plate vibrator and mold outside vibrator, which should avoid segregation and stratification while ensuring compaction. In addition to ensuring the compaction of the concrete, the vibration machinery and method should also ensure uniform distribution of the fibers; The displacement interval of the surface vibrator should be such that the vibrator plate can cover the vibrated part not less than 100mm; The vibration time of each vibration point should not exceed 20s, and when the surface of the mixture appears to be splashed, it can be considered as compacted; Then the mold and the UHPC material in the mold are hoisted as a whole on the vibration table for overall vibration.

[0033] S7, based on the temperature difference, consider coating and moisture curing for the mold and the curb stone preliminarily formed inside the mold after vibrating according to step S6; after pouring is completed, spray water mist in time to keep the surface of the curb stone poured completed in a wet state, and cover with a film in time for moisture curing; S8, remove the mold, and complete the heat curing or natural curing of the precast UHPC curb stone obtained by the treatment of step S7, and pay attention to the surface and corner treatment. The heat curing temperature is 90℃, the curing time is 48h, the curing relative humidity is 95%, so that the strength of the preliminarily formed curb stone rapidly increases in a short time and reaches 90% of the design strength. Or take natural curing measures, and the curing time is not less than 7d, the internal and external temperature difference of the component should not be greater than 20℃, and when the internal and external temperature difference is greater than 20℃, insulation curing measures should be taken; The mold removal in this step S8 specifically includes: S801, open the top buckle of the outer mold, and loosen the two side screws of the inner mold; S802, remove the internal core mold.

[0034] After the curing treatment of this step S8, the strength of the precast UHPC curb stone finally reaches the design strength, that is, the precast product with the same quality as the conventional UHPC curb stone precast method or even better quality is obtained.

[0035] In addition, it also needs to be explained that, since the strength of the curb stone after step S8 has reached 90% and above of the design strength, the structural strength of the curb stone in this state meets the hoisting and transportation requirements.

[0036] In this embodiment, before pouring the UHPC curb stone, the top buckle of the outer mold is opened, the two side screws of the inner mold are loosened, the inner surface of the outer mold takes demolding measures, the internal core mold is removed, the outer surface of the internal core mold takes demolding measures, the internal core mold is hoisted to the specified position, the two side screws of the inner mold are installed, the top buckle of the outer mold is closed, and the mold closing is completed. The shell thickness of the precast UHPC curb stone is 10mm, the cross-sectional width is 220mm, the cross-sectional height is 220mm, and the length of the curb stone is 2.0m. The mechanical properties of the crash barrier plate are as follows: the standard value of compressive strength is 120MPa, and the standard value of tensile strength is 5MPa.

[0037] Performance test: The UHPC curb stone with different design strengths is precast by using the above-mentioned inverted precast method, and the strength, appearance quality and precision of the UHPC curb stone are tested during the precast process.

[0038] Compared with the prior art, the inverted prefabrication method of the UHPC curbstone can not only meet the erosion of the snow-melting salt in the northern region, but also meet the long-term scouring requirement of the sweeper, by using the high strength, durability, abrasion resistance, impact resistance and other characteristics of the UHPC material; the higher strength makes the UHPC curbstone component lighter in weight, has a more superior and advanced structure type; and the UHPC has a faster early strength growth, can meet the requirement of rapid demolding, lifting and transportation, and greatly improves the production and construction efficiency.

[0039] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative but not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, which are all within the protection of the present application.

Claims

1. A method for inverted prefabrication of UHPC curb stones, characterized in that, Includes the following steps: S1. Make a mold according to the size of the curbstone, including an openable outer mold that matches the outer contour side and an inner mold that matches the inner contour side; S2. Configure UHPC materials; S3. Place the prepared UHPC material into a mixer and mix it. S4. Check whether the performance of the mixing material meets the pouring requirements; S5. Place the mixed material that meets the casting requirements obtained in step S4 into the mold and complete the assembly. S6. Vibrate the mold and the UHPC material poured into the mold according to step S5. S7. Cover the mold and the curbstone that has been initially formed inside the mold after vibration in step S6 with a film and keep it moist. S8. Remove the mold and perform heat curing or natural curing on the precast UHPC curbstone obtained after step S7.

2. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, The top of the outer mold is provided with several buckles, and the outer mold is closed when the buckles are engaged.

3. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, In step S8, during the heating phase of heat curing, the heating rate should not exceed 15℃ / h; after curing, the cooling rate should not exceed 15℃ / h; when the curing temperature is between 50℃ and 70℃, the curing time should not be less than 96 hours; when the curing temperature is between 70℃ and 90℃, the curing time should preferably be 48 hours; and the relative humidity during curing should not be lower than 95%.

4. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, The outer shell thickness of the prefabricated UHPC curbstone obtained in step S8 is 10~30mm.

5. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, The cross-sectional width of the precast UHPC curbstone obtained in step S8 is 150~300mm.

6. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, The cross-sectional height of the precast UHPC curbstone obtained in step S8 is 150~300mm.

7. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, The length of the precast UHPC curbstone obtained in step S8 is 1.4~2.0m.

8. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, Step S5 specifically includes: S501. Place the mold on the ground with the bottom of the curbstone facing up and the top facing up. S502. The pouring surface must be kept level. S503. Open the top buckle of the outer mold, loosen the screws on both sides of the inner mold, and take demolding measures on the inner surface of the outer mold; remove the inner core mold, and take demolding measures on the outer surface of the inner core mold. S504. Hoist the internal core mold to the designated position and install the screws on both sides of the internal mold; close the top buckle of the outer mold. S505. When pouring, start pouring from one side of the formwork and complete the pouring in one go, with slight vibration during the process; the free height of the mixture falling should not exceed 1m. When the falling height is greater than 1m, add a tremie pipe, chute and sluice.

9. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, In step S6, the mold and the UHPC material inside the mold are hoisted onto a vibrating table for overall vibration.

10. The inverted prefabrication method for UHPC curb stones according to claim 1, characterized in that, The method for removing the mold in step S8 includes: S801. Open the top clip of the outer mold and loosen the screws on both sides of the inner mold; S802, Remove the internal core mold.

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