Construction method to prevent cracking of steel-concrete composite beam concrete slab
By arranging PPR pipes on the top of the steel box girder and using steam furnaces and U-shaped rubber airbags to control the temperature consistency between the steel formwork and the concrete, the problem of cracking of the concrete slabs of the steel-concrete composite beams in the low temperature environment of northern winter was solved, crack-free construction of the concrete slabs was achieved, and energy consumption was reduced.
Patent Information
- Application Number
- CN202210851477.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-20
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2042-07-20
AI Technical Summary
In the low temperature environment of northern winter, the temperature difference between the steel formwork and the cast-in-place concrete causes the steel-concrete composite beam concrete slab to easily crack during construction.
PPR pipes are arranged and fixed on the top of the steel box girder. Steam is sprayed to the PPR pipes through a steam boiler to control the temperature consistency of the steel formwork and concrete. U-shaped rubber air bags are used to form an insulation cavity for continuous heating. Combined with insulation blanket covering, the temperature of the concrete is ensured to be stable during the solidification process.
It effectively avoids cracking of concrete slabs due to temperature differences, ensures that there are no cracks on the concrete surface, reduces construction costs and improves heating efficiency.
Smart Images
Figure CN115162181B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of bridge casting, in particular to a construction method for preventing cracking of a steel-concrete composite beam concrete slab. Background Art
[0002] Steel-concrete composite beams are now widely used in bridge construction in my country. Construction of these beams is accomplished by pouring concrete into steel formwork. Some bridge construction projects are located in northern China, where winter temperatures are lower. This results in a significant temperature difference between the steel formwork and the concrete being poured during the pour-in-place process. This temperature difference causes the steel formwork and the concrete to shrink differently, creating a temperature field during the concrete slab pouring process. This temperature difference can lead to shrinkage cracks in the concrete slab. Summary of the Invention
[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a construction method for preventing cracking of steel-concrete composite beam concrete slabs, which can keep the steel formwork and concrete temperatures synchronized to avoid cracking of the concrete slabs.
[0004] A construction method for preventing cracking of a steel-concrete composite beam concrete slab according to an embodiment of the present invention includes:
[0005] Step 1: Arrange multiple PPR pipes in parallel on the top of the steel box girder. The PPR pipes are fixed to the top of the steel box girder with steel bars and multiple through holes are punched on the left and right sides of the PPR pipes.
[0006] Step 2: Connect the PPR pipe to the steam furnace, and select the power and number of steam furnaces according to the area of the steel template;
[0007] Step 3: Install a first thermometer at the concrete pump outlet and a second thermometer inside the steel formwork. Before pouring concrete, the steam boiler sprays steam toward the steel formwork through multiple holes on the PPR pipe. Concrete pouring can only be carried out after the temperature detected by the second thermometer is consistent with the temperature detected by the first thermometer.
[0008] Step 4: After the concrete has initially set, cover the concrete surface with a thermal insulation blanket;
[0009] Step 5: The PPR pipe continues to spray steam onto the steel formwork until the concrete has finally set, and the PPR pipe continues to spray steam onto the steel formwork for three days.
[0010] The construction method for preventing cracking of a steel-concrete composite beam concrete slab according to an embodiment of the present invention has at least the following beneficial effects: the temperature of the concrete remains stable from pouring to solidification. Since the temperature of the steel formwork is consistent with that of the concrete, temperature changes caused by temperature differences when the concrete and the steel formwork come into contact are avoided, thereby preventing cracking of the concrete and ensuring that there are no cracks on the concrete surface.
[0011] According to some embodiments of the present invention, in step 3, an inflation hole is opened on the PPR pipe, and an air bag is connected to the outside of the inflation hole. When steam is introduced into the PPR pipe, the steam is sprayed into the air bag from the inflation hole, and the air bag expands upward until the upper end of the air bag is in contact with the left and right ends of the bottom surface of the steel template, so that the air bag and the steel template form an insulation cavity, and the through hole on the PPR pipe sprays steam into the insulation cavity.
[0012] According to some embodiments of the present invention, the inflatable bag is a U-shaped rubber bag. After the U-shaped rubber bag is inflated, the left and right ends of the U-shaped rubber bag expand upward until they are in contact with the bottom surface of the steel formwork.
[0013] According to some embodiments of the present invention, the U-shaped rubber airbag is detachably connected to the inflation hole. After a length of concrete pouring and insulation is completed, the U-shaped rubber airbag is removed from the PPR pipe of the completed section and installed on the PPR pipe of the section to be constructed.
[0014] According to some embodiments of the present invention, in step 1, the interval between each PPR pipe is 1 meter.
[0015] According to some embodiments of the present invention, in step 1, a plurality of through holes are symmetrically arranged on the left and right sides of the PRR pipe, and a distance of 0.5 m is provided between each through hole.
[0016] According to some embodiments of the present invention, in step 2, the steam furnace power is 0.15 MW, and steam is provided by one steam furnace for every 1,200 square meters of steel formwork.
[0017] According to some embodiments of the present invention, in step 3, during the pouring of concrete, thermal insulation blankets are used to seal both sides of the steel formwork along the pouring length direction.
[0018] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0020] Figure 1 1 is a flow chart of a construction method for preventing cracking of a steel-concrete composite beam concrete slab according to an embodiment of the present invention;
[0021] Figure 2 yes Figure 1 Structural diagram of the PPR pipe arrangement;
[0022] Figure 3 yes Figure 1 Schematic diagram of the structure of the U-shaped rubber airbag after inflation;
[0023] Figure 4 yes Figure 3 A partial enlarged view of point A in the middle.
[0024] Reference numerals:
[0025] Steel formwork 100;
[0026] PPR tube 200; through hole 210; inflation hole 220; U-shaped rubber airbag 230;
[0027] Steam oven 300. DETAILED DESCRIPTION
[0028] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.
[0029] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.
[0030] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.
[0031] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.
[0032] refer to Figures 1 to 4 A construction method for preventing cracking of a steel-concrete composite beam concrete slab according to an embodiment of the present invention is described.
[0033] like Figure 1 As shown, the construction method for preventing cracking of a steel-concrete composite beam concrete slab according to an embodiment of the present invention includes:
[0034] Step 1: Arrange multiple PPR pipes 200 in parallel on the top of the steel box girder. The PPR pipes 200 are fixed to the top of the steel box girder by welding with steel bars. Multiple through holes 210 are punched on the left and right sides of the PPR pipes 200.
[0035] Step 2: Connect the PPR pipe 200 to the steam furnace 300, and select the power and number of the steam furnaces 300 according to the area of the steel template 100;
[0036] Step 3: A first thermometer is installed at the concrete pump outlet, and a second thermometer is installed inside the steel formwork 100. Before pouring concrete, the steam boiler 300 sprays steam toward the steel formwork 100 through the multiple through holes 210 on the PPR pipe 200. Concrete pouring is performed only after the temperature detected by the second thermometer is consistent with the temperature detected by the first thermometer.
[0037] Step 4: After the concrete has initially set, cover the concrete surface with a thermal insulation blanket;
[0038] Step 5: The PPR pipe 200 continues to spray steam toward the steel formwork 100 until the concrete is finally set. The PPR pipe 200 continues to spray steam toward the steel formwork 100 for three days.
[0039] like Figure 2 As shown, in step 1, a DN50 PPR pipe 200 is arranged every 1 m on the top of the steel box girder, the PPR pipe 200 is fixed by welding with steel bars, and multiple through holes 210 with a diameter of 1 cm are symmetrically punched on the left and right sides of the PPR pipe 200. The spacing between each through hole 210 is 50 cm, and the through holes 210 facilitate steam ejection.
[0040] In step 2, a steam furnace 300 with a power of 0.15 MW is used. Each 0.15 MW steam furnace 300 is responsible for providing steam to the top plate of the steel formwork 100 with an area of 1,200 square meters.
[0041] In step 3, the temperature of the concrete pumped out by the concrete pump is generally around 20°C, while the temperature of the steel formwork 100 is generally around 5°C. Steam from the steam boiler 300 is passed through the PPR pipe 200 and sprayed onto the steel formwork 100 from the through-holes 210 in the PPR pipe 200, heating the steel formwork 100 and aligning its temperature with that of the concrete. A first thermometer is used to monitor the temperature of the concrete, while a second thermometer is used to monitor the temperature of the steel formwork 100. The output power of the steam boiler 300 is controlled to control the temperature of the steel formwork 100. When the temperature readings of the first and second thermometers match, the temperature of the concrete and the steel formwork 100 are aligned. Concrete pouring can be performed at this time to prevent cracking of the concrete due to the large temperature difference.
[0042] like Figure 3 and Figure 4 As shown, the lower end of the PPR tube 200 has an air filling hole 220, which is connected to a U-shaped rubber airbag 230. When the steam furnace 300 introduces steam into the PPR tube 200, some of the steam enters the U-shaped rubber airbag 230 through the air filling hole 220, causing the U-shaped rubber airbag 230 to expand. After expansion, the U-shaped rubber airbag 230 assumes an overall U-shape, with both ends expanding upward until they contact the bottom surface of the steel formwork 100. The bottom surface of the steel formwork 100 and the U-shaped rubber airbag 230 together form an insulation cavity. Steam ejected from the through hole 210 of the PPR tube 200 enters the insulation cavity, continuously heating and insulating the steel formwork 100. As a result, the steam ejected from the PPR tube 200 is less likely to diffuse outward, improving the steam's heating and insulation effect on the steel formwork 100, reducing the energy consumption of the steam furnace 300, and lowering construction costs.
[0043] In the above technical solution, thermal insulation blankets can be used to seal both sides of the steel template 100 to reduce the heat transfer of the steel template 100 to the outside.
[0044] In step 4, hot steam is continuously sprayed onto the steel formwork 100, and the concrete is waited for initial setting. After initial setting, the concrete surface is covered with a heat-insulating blanket.
[0045] In step 5, hot steam is continuously sprayed toward the steel formwork 100 until the concrete is finally set, and the hot steam is continuously sprayed toward the steel formwork 100 for three days, after which the steam spraying is stopped.
[0046] To sum up, the temperature of concrete remains stable during the pouring and solidification process. Since the temperature of the steel formwork 100 is consistent with the temperature of the concrete, temperature changes caused by temperature differences when the concrete contacts the steel formwork 100 are avoided, thereby avoiding concrete cracking and ensuring that there are no cracks on the concrete surface.
[0047] The construction method for preventing cracking of the steel-concrete composite beam concrete slab is described with a specific construction example:
[0048] Step 1: Place a DN50PPR pipe 200 every 1m on the top of the steel box girder and fix it with steel bars by welding. Punch through holes 210 on the left and right sides and an inflation hole 220 at the lower end every 50cm on the DN50PPR pipe 200, and connect a U-shaped rubber airbag 230 to the inflation hole 220.
[0049] Step 2: The PPR pipe 200 is connected to the steam furnace 300. The power of the steam furnace 300 is 0.15MW. Each 0.15MW steam furnace 300 is responsible for providing steam to the top plate of the steel formwork 100 of 1,200 square meters.
[0050] Step 3: The steam oven 300 passes steam into the PPR tube 200. The steam enters the U-shaped rubber airbag 230 through the inflation hole 220, causing the U-shaped rubber airbag 230 to expand. After expansion, the U-shaped rubber airbag 230 assumes an overall U-shape, with the left and right ends expanding upward until they contact the bottom surface of the steel formwork 100. The bottom surface of the steel formwork 100 and the U-shaped rubber airbag 230 together form an insulation cavity. Steam ejected from the through hole 210 of the PPR tube 200 enters the insulation cavity, continuously heating the steel formwork 100 until the readings of the first thermometer and the second thermometer are consistent. At this time, concrete is poured into the steel formwork 100. Insulation blankets are used to seal both sides of the steel formwork 100 to reduce heat transfer from the steel formwork 100 to the outside.
[0051] Step 4: Continue to spray hot steam onto the steel formwork 100 and wait for the initial setting of the concrete. After the initial setting, cover the concrete surface with a thermal insulation blanket.
[0052] Step 5: Continue to spray hot steam onto the steel formwork 100 for three days after the concrete has finally set, and stop spraying steam after three days.
[0053] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the spirit of the present invention.
Claims
1. A construction method for preventing cracking of steel-concrete composite beam concrete slabs, characterized in that: include: Step 1: Arrange multiple PPR pipes in parallel on the top of the steel box girder. The PPR pipes are fixed to the top of the steel box girder with steel bars and multiple through holes are punched on the left and right sides of the PPR pipes. Step 2: Connect the PPR pipe to the steam furnace, and select the power and number of steam furnaces according to the area of the steel template; Step 3: A first thermometer is set at the outlet of the concrete pump, and a second thermometer is set in the steel formwork. Before pouring concrete, the steam furnace sprays steam to the steel formwork through multiple through holes on the PPR pipe, so that the temperature detected by the second thermometer is consistent with the temperature detected by the first thermometer before pouring concrete; an inflation hole is opened on the PPR pipe, and an inflatable bag is connected to the outside of the inflation hole. When steam is passed into the PPR pipe, the steam is sprayed into the inflatable bag from the inflation hole, and the inflatable bag expands upward until the upper end of the inflatable bag fits with the left and right ends of the bottom surface of the steel formwork, so that the inflatable bag and the steel formwork form an insulation cavity. The through holes on the PPR pipe spray steam into the insulation cavity to continuously heat and insulate the steel formwork. The inflatable bag is a U-shaped rubber airbag. After the U-shaped rubber airbag is inflated, the left and right ends of the U-shaped rubber airbag expand upward until they fit with the bottom surface of the steel formwork; Step 4: After the concrete has initially set, cover the concrete surface with a thermal insulation blanket; Step 5: The PPR pipe continues to spray steam onto the steel formwork until the concrete has finally set, and the PPR pipe continues to spray steam onto the steel formwork for three days.
2. The construction method for preventing cracking of steel-concrete composite beam concrete slab according to claim 1, characterized in that: The U-shaped rubber airbag is detachably connected to the inflation hole. After completing a length of concrete pouring and insulation, the U-shaped rubber airbag is removed from the PPR pipe of the completed section and installed on the PPR pipe of the section to be constructed.
3. The construction method for preventing cracking of steel-concrete composite beam concrete slab according to claim 1, characterized in that: In step 1, the interval between each PPR pipe is 1 meter.
4. The construction method for preventing cracking of steel-concrete composite beam concrete slab according to claim 1, characterized in that: In step 1, multiple through holes are symmetrically arranged on the left and right sides of the PRR pipe, with a spacing of 0.5 m between each through hole.
5. The construction method for preventing cracking of steel-concrete composite beam concrete slab according to claim 1, characterized in that: In step 2, the steam furnace power is 0.15MW, and steam is provided by one steam furnace for every 1,200 square meters of steel formwork.
6. The construction method for preventing cracking of steel-concrete composite beam concrete slab according to claim 1, characterized in that: In step 3, during the concrete pouring process, insulation blankets are used to seal both sides of the steel formwork along the pouring length.