Method for preventing cracking in mass concrete

Abstract

The application discloses a construction method for preventing cracking of mass concrete, which comprises the following steps: S1, construction preparation and research, preparation of concrete mixing proportion, meanwhile, vibration positioning device and supporting reinforcement device are prepared; S2, positioning and line laying, steel bar binding and cooling waterway installation are carried out at the construction site, and then concealed engineering acceptance is carried out; S3, supporting template installation of conventional wall body is carried out, then supporting template installation of the wall body at corner and other weak positions is carried out, supporting reinforcement device is arranged at the positions, and then vibration positioning device is installed according to pouring sequence; S4, concrete quality is controlled while pouring concrete; S5, concrete curing system is used to carry out standard curing operation on the poured concrete structure; and S6, template removal operation is carried out and concrete quality is accepted; the application can effectively improve the construction and forming quality of mass concrete, control the generation of cracks, and meet the requirements of self-waterproofing, radiation-proofing and other special functions.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and specifically to a method for preventing cracking in large-volume concrete. Background Technology

[0002] Currently, waterproofing in buildings remains a persistent and difficult problem to overcome, a common issue in building quality. Research on large-volume concrete structures, particularly those in hospitals and research institutions requiring self-waterproofing and radiation protection, has stalled. While improving the molding quality of large-volume concrete has been a topic of discussion, it has largely focused on reducing cement hydration heat and slowing its release. In-depth analysis and research on improving the self-waterproofing and radiation protection capabilities of concrete structures have been lacking. This is especially true for concrete structures in hospitals and research institutions, which, in addition to load-bearing and enclosure functions, also require radiation protection and waterproofing. Therefore, high-quality molding is crucial, and through-cracks are strictly prohibited. To ensure the construction and molding quality of large-volume concrete with special functional requirements, it is essential to closely monitor each stage of construction, optimizing, improving, and innovating upon conventional large-volume concrete construction methods to enhance the molding quality of concrete in these functional areas.

[0003] Therefore, it is necessary to improve the existing construction methods for large-volume concrete to enhance the construction and forming quality of large-volume concrete, control the generation of cracks, and meet the requirements for special functions such as self-waterproofing and radiation protection. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a construction method for preventing cracking in large-volume concrete, which can effectively improve the construction and forming quality of large-volume concrete and control the generation of cracks, while also meeting the requirements for special functions such as self-waterproofing and radiation protection.

[0005] This invention provides a method for preventing cracking in large-volume concrete, comprising the following steps:

[0006] S1. Construction preparation and research, formulating concrete mix proportions, and manufacturing vibration positioning devices and support reinforcement devices.

[0007] S2. Locate and lay out the lines at the construction site, tie the reinforcing bars and install the cooling water system. After completion, conduct acceptance of the concealed works.

[0008] S3. After completing the installation of the support formwork for the regular wall, install the support formwork for the weak parts of the wall such as corners and set up the support reinforcement device on the support formwork at this location. Then, install the vibration positioning device in all the support formwork in sequence according to the pouring sequence.

[0009] S4. Control the quality of concrete during the concrete pouring process.

[0010] S5. Use a concrete curing system to perform standard curing operations on the poured concrete structure.

[0011] S6. After the curing work is completed, the formwork is removed and the concrete quality is inspected.

[0012] Furthermore, in step S3, the vibration positioning device includes several vibration guide units disposed between templates, and a connecting rod is provided between adjacent vibration guide units. The connecting rod is used to connect and fix several vibration guide units to form a matrix unit between templates. The vibration guide unit includes a guide pipe disposed at a preset rebar cage hole position and a connecting component disposed on the guide pipe. Multiple guide pipes are arranged vertically in the preset rebar cage hole and connected by the connecting component.

[0013] Furthermore, in step S3, the connecting assembly includes a positioning clip disposed at the end of the guide tube and connecting portions distributed around the positioning clip. The positioning clip is used to connect adjacent guide tubes in the vertical direction, and the connecting portions are used to detachably connect with the connecting rod.

[0014] Furthermore, in step S3, the support reinforcement device includes a corner anchor ring disposed on the two walls at the inside corner, a corner anchor ring disposed on the two walls at the outside corner, and a hook tie rod disposed between the corner anchor ring and the outside corner anchor ring and between the outside corner anchor ring and the outside corner anchor ring. The hook tie rod is used to connect the corner anchor rings and the outside corner anchor rings that are perpendicular to each other and to form a diagonal tie structure.

[0015] Furthermore, the external corner anchor ring includes a first external corner anchor ring, a second external corner anchor ring, and a third external corner anchor ring installed on the same wall surface from far to near the corner. The internal corner anchor ring and the second external corner anchor ring are connected by the hook head to the tie rod to form a diagonal tie. The first external corner anchor ring and the third external corner anchor ring on the adjacent wall surface are connected by the hook head to the tie rod to form a diagonal tie structure.

[0016] Furthermore, the supporting template of the conventional wall includes a template, a horizontal main rib set on the outside of the template, a vertical secondary rib set between the template and the horizontal main rib, a tie structure penetrating the template on both sides of the wall, and a supporting component set on the outside of the template for supporting the template. The horizontal main rib is a double-channel steel structure.

[0017] The tie structure includes tie rods and locking elements. The free end of the tie rod passes through the templates on both sides of the wall and then passes through the gaps between adjacent vertical secondary ribs and the gaps in the horizontal main rib structure. It is then locked to the horizontal main rib by the locking elements to form a tie structure.

[0018] Furthermore, one end of the internal corner anchor ring and the external corner anchor ring passes through the template and extends between the two side templates, and the other end of the internal corner anchor ring and the external corner anchor ring passes through the horizontal main rib and extends out. The ends of the internal corner anchor ring and the external corner anchor ring are provided with threaded sections.

[0019] Both the inner corner anchor ring and the outer corner anchor ring have a connecting structure at their ends. The connecting structure includes top plates on both sides of the horizontal main beam width direction and nuts provided on the outer side of the top plates that are threadedly connected to the ends of the inner corner anchor ring and the outer corner anchor ring.

[0020] Furthermore, in step S5, the concrete curing system includes an internal cooling system disposed inside the concrete slab wall and a standard curing system disposed outside the concrete slab wall. The internal cooling system is used to monitor and control the internal concrete temperature of the concrete slab wall, and the standard curing system is used to perform standard curing of the concrete slab wall with the formwork in place.

[0021] Furthermore, the standard curing system includes a water supply pipe installed on the outside of the concrete slab wall and a CNC water stop valve installed on the water supply pipe. The CNC water stop valve is used to monitor the temperature and humidity of the concrete slab wall and control the flow rate of the water supply pipe. The standard curing system also includes a spray unit connected to the water supply pipe. The spray unit includes a spray pipe and several nozzles installed along the length of the spray pipe. Several spray pipes are spliced ​​together longitudinally or vertically to form the spray unit as a whole.

[0022] Furthermore, when the temperature of the outer surface of the concrete slab wall is less than 5°C, the CNC water stop valve controls the water supply pipe to be in a closed state;

[0023] When the temperature of the outer surface of the concrete slab wall is between 5℃ and 35℃, the CNC water stop valve controls the opening angle of the CNC water stop valve and adjusts the flow rate of the water supply pipe by monitoring the moisture of the concrete slab wall.

[0024] When the temperature of the outer surface of the concrete slab wall is greater than 35°C, the CNC water stop valve monitors the temperature of the concrete slab wall to control the opening angle of the CNC water stop valve and adjust the flow rate of the water supply pipe.

[0025] In summary, this application has at least one of the following beneficial effects:

[0026] (1) This invention optimizes the mix proportion of concrete by adding WHDF concrete inorganic nano crack-resistant and seepage-reducing agent to determine the optimal mix proportion, so as to improve the crack resistance and waterproofness of concrete structure;

[0027] (2) The present invention protects the steel mesh by using a set of detachable and splicable vibration positioning devices during the concrete pouring process, so as to prevent the vibrator from touching the steel mesh and ensure that the lower layer of pre-set reinforced concrete structure is not damaged during the pouring of large volume concrete.

[0028] (3) The present invention provides support reinforcement devices for weak support parts such as the corner walls, the parts that are prone to expansion and bursting in the formwork support system, so as to ensure that weak support parts such as corners, the parts that are prone to expansion and bursting are effectively supported, thereby improving the overall molding quality of large volume concrete.

[0029] (4) By setting up a complete set of standard concrete curing system, the present invention ensures that all parts of the formed concrete are effectively cured by standard watering, which effectively prevents concrete cracking; and also sets up a temperature control system in the standard concrete curing system to ensure standardized watering and temperature control curing of concrete components, thus avoiding concrete cracking caused by inadequate curing. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the vibration positioning device in this invention;

[0031] Figure 2 This is a schematic diagram of the structure of the vibration guide unit in this invention;

[0032] Figure 3 This is a top view of the vibratory positioning device in this invention;

[0033] Figure 4 This is a schematic diagram of the planar structure of the support system at the internal and external corners of the wall in this invention;

[0034] Figure 5 This is a schematic diagram of the elevation structure of the support system at the six internal and external corners of the wall in this invention;

[0035] Figure 6 This is a schematic diagram showing the connection between the first external corner anchor ring and the connecting structure in this invention;

[0036] Figure 7 This is a schematic diagram of the hook head and pull rod structure in this invention;

[0037] Figure 8 This is a schematic diagram of the standard maintenance system for wall 6 in this invention.

[0038] Figure 9 This is a schematic diagram of the standard maintenance system for floor slab maintenance in this invention;

[0039] Figure 10 A schematic diagram of the structure of the spray unit in this invention;

[0040] Figure 11A schematic diagram of the internal cooling system in this invention;

[0041] Explanation of reference numerals in the attached drawings: 1-Vibration guide unit; 2-Connecting rod; 3-Guide pipe; 4-Positioning clip; 5-Connecting part; 6-Wall; 7-Formwork; 8-Square steel pipe; 9-Double channel steel; 10-Precision rolled threaded steel tie rod; 11-First external corner anchor ring; 12-Hook tie rod; 13-Steel plate; 14-Nut; 15-Second external corner anchor ring; 16-Third external corner anchor ring; 17-Internal corner anchor ring; 18-W-shaped clip; 19-Water supply pipe; 20-CNC water stop valve; 21-Sprinkler pipe; 22-Sprinkler head; 23-Beam and slab; 24-Cooling water pipe. Detailed Implementation

[0042] The present application will be further described in detail below with reference to the accompanying drawings.

[0043] This invention provides a method for preventing cracking in large-volume concrete, comprising the following steps:

[0044] S1. Construction preparation and research, formulating concrete mix proportions, and manufacturing vibration positioning devices and support reinforcement devices.

[0045] S2. Locate and lay out the lines at the construction site, tie the reinforcing bars and install the cooling water system. After completion, conduct acceptance of the concealed works.

[0046] S3. After completing the installation of the support formwork for the conventional wall 6, install the support formwork for the weak parts of the wall 6 such as corners and set up the support reinforcement device on the support formwork at this location. Then, install the vibration positioning device in all the support formwork in sequence according to the pouring sequence.

[0047] S4. Control the quality of concrete during the concrete pouring process.

[0048] S5. Use a concrete curing system to perform standard curing operations on the poured concrete structure.

[0049] S6. After the curing work is completed, the formwork is removed and the concrete quality is inspected.

[0050] In this embodiment, step S1, construction preparation mainly includes mix proportion optimization design, concrete mixture testing, vibration positioning, and fabrication of support reinforcement devices. The mix proportion optimization design is based on the engineering structure and functional requirements. WHDF inorganic nano-crack-resistant and seepage-reducing agent is added to the original polypropylene fiber concrete to improve the crack resistance, compactness, durability, and workability of large-volume concrete, thereby meeting the crack resistance and seepage prevention requirements of the engineering construction. Simultaneously, the addition of WHDF inorganic nano-crack-resistant and seepage-reducing agent increases the cement hydration rate, reduces cement usage, and controls the problem of excessive internal temperature rise during large-volume concrete construction from the source. It also improves the tensile strength, compressive strength, and ultimate tensile strength of the concrete. The value is achieved by inhibiting the early rapid hydration of tricalcium aluminate, reducing the peak value of early hydration heat, alleviating the temperature difference between the inside and outside of the concrete structure, and avoiding or reducing temperature cracks and drying shrinkage cracks. In this scheme, the vibration positioning device consists of a guide tube 3, a positioning clip 4, and a connecting rod 2. The guide tube 3 is made of 75mm diameter UPVC pipe, the positioning clip 4 is made of stainless steel hose clamp, and the connecting rod 2 is made of ordinary HRB400-14mm hot-rolled ribbed steel bar. Each guide tube 3 is equipped with a positioning clip 4, which is welded to the connecting rod 2. The support reinforcement device consists of 6.5# double channel steel 9 outer ribs, φ15 fine rolled threaded steel hook tie rod 12, φ25 fine rolled threaded steel anchor ring, and a φ30 hole at the centroid of a 100×100×10mm steel plate.

[0051] In step S2, the reinforcement binding must strictly follow the drawing requirements, paying attention to the thickness of the protective layer; excessive thickness will result in exposed reinforcement, which is detrimental to the structural waterproofing requirements. The reinforcement at the construction joints of the side walls must be cleaned after the first pour to ensure it is clean and tidy. During the binding process, all tie wire bends must be bent inwards to reduce water inlet points. Cooling pipes and temperature measuring elements are installed according to the construction plan during the reinforcement binding process. The concealed works acceptance includes: A) the grade, specifications, quantity, and location of longitudinal reinforcing bars; B) the connection method, joint location, number of joints, joint area percentage, lap length, anchorage method, and anchorage length of the reinforcing bars; C) the grade, specifications, quantity, and spacing of stirrups and transverse reinforcing bars, the bending angle of the stirrup hooks, and the length of the straight section; D) the specifications, quantity, and location of embedded parts; E) the material, arrangement, spacing, direction, and quantity of cooling water pipes 24 and temperature measuring devices must meet the plan requirements.

[0052] In step S4, concrete quality control includes the following requirements: a) The thickness of the concrete placement for large-volume concrete should be controlled at 30-50cm, which is more conducive to heat dissipation in the initial stage. Vibration should be performed simultaneously with placement, and the upper layer of concrete should be poured before the lower layer initially sets, preventing cold joints; b) Vibration is crucial during the construction of large-volume concrete. Over-vibration and under-vibration are both necessary. The vibrator inserted into the concrete must be vertical, using a "quick insertion, slow withdrawal" method. The vibration time at each point should be controlled at 15-20 seconds, ideally resulting in a horizontal concrete surface that no longer significantly sinks, no more air bubbles, a slurry-like surface, and minimal air bubbles; c) During vibration, the vibrator should be slightly moved up and down to ensure uniform vibration. Concrete vibration should closely follow the placement. When vibrating the upper layer of concrete, the vibrator should be inserted approximately 3-5cm into the lower layer to ensure better bonding between the upper and lower layers. The insertion points of the vibrator should be relatively regular, using rows, columns, or staggered patterns. The distance between the two vibration points should be 1.5 times the effective radius of the vibrator; d At the same time, if conditions permit, the secondary vibration technology before the initial setting of concrete can be mastered to increase the density of concrete, reduce the generation of internal micro cracks, and improve the strength and impermeability of concrete. The concrete pouring adopts the following method: (1) The large volume concrete pouring adopts the planar layering method, and the concrete layer thickness does not exceed 500mm; (2) The wall 6 is poured in layers with a thickness of 500mm. The pouring progresses from one end of the wall 6 to the other end, back and forth, and the pouring time of the two layers is reasonably controlled to ensure that the upper layer of concrete is poured before the initial setting of the lower layer of concrete. In addition, during the vibration process, the vibrator should penetrate into the lower layer by no less than 50mm to ensure that the bonding surface of the two layers of concrete is well integrated and to avoid cold joints; (3) In order to ensure the compaction, each pouring strip is equipped with 6 (2 more are prepared as spares) immersion vibrators. Insertion vibrators should be inserted quickly and withdrawn slowly. Insertion points should be evenly arranged and moved point by point in sequence to ensure uniform compaction. The vibrator should be moved in a "row-and-column" manner, with a moving distance not exceeding 1.5 times the effective vibration radius (300mm-400mm). (4) Surface treatment: After leveling the surface with a screed according to the elevation control line, compact the surface with a wooden trowel, roll it several times with an iron roller, and then compact and smooth it with an iron trowel. Cover the concrete surface with plastic film and geotextile in a timely manner to prevent the concrete surface from losing water and cracking.

[0053] In step S6, the requirements for dismantling formwork 7 are as follows: ① Dismantling of support frame and bottom formwork: Formwork 7 can be dismantled after the strength of the test blocks cured under the same conditions reaches 100% of the design strength and is maintained for no less than 14 days; ② Dismantling requirements: The support frame of formwork 7 should be dismantled only after confirmation and signing of a dismantling permit by the technical supervisor and the supervisor; ③ Before dismantling the support frame of formwork 7, a designated person should check whether the materials and debris on the support frame of formwork 7 have been cleaned up. A safety zone must be demarcated and warning signs set up before dismantling the support frame of formwork 7; a designated person should be assigned to guard the area, and no other personnel should work below the scaffolding during dismantling; ④ The dismantling sequence of the support frame of formwork 7 should follow the principle of dismantling the last erected structure first and the first erected structure last. Dismantling should proceed layer by layer from the top, and simultaneous dismantling from top to bottom is strictly prohibited, as is throwing. The dismantled scaffolding components and accessories should be dismantled, classified, stacked, packaged, and transported layer by layer in a safe manner, and the safety of on-site items should be protected. Concrete quality acceptance should be carried out from the following aspects: Ⅰ. Hospital radiation protection requirements: no horizontal through cracks are allowed; Ⅱ. Concrete structure design code requires that under environmental category 2a, the crack control level is level three, and the maximum crack width is limited to 0.2mm; Ⅲ. Defects in the appearance quality of cast-in-place structures: cracks extending from the concrete surface to the interior of the concrete; Ⅳ. Concrete compressive strength and impermeability grade meet the design requirements.

[0054] In this embodiment, in step S3, the vibration positioning device includes a plurality of vibration guide units 1 disposed between templates 7, and a connecting rod 2 is disposed between adjacent vibration guide units 1. The connecting rod 2 is used to connect and fix the plurality of vibration guide units 1 and form a matrix unit between templates 7. The vibration guide unit 1 includes a guide tube 3 disposed at a preset rebar cage hole position and a connecting component disposed on the guide tube 3. Multiple guide tubes 3 are arranged vertically in the preset rebar cage hole and connected by the connecting component. In step S3, the connecting component includes a positioning clip 4 disposed at the end of the guide tube 3 and a connecting part 5 distributed around the positioning clip 4. The positioning clip 4 is used to connect adjacent guide tubes 3 in the vertical direction, and the connecting part 5 is used to detachably connect with the connecting rod 2.

[0055] In this design, the guide pipe 3 is a 75mm diameter UPVC pipe. Connecting rods 2 are installed between adjacent guide pipes 3 for connection and fixation, ultimately forming a matrix unit. The guide pipes 3 prevent collisions between the vibrator and the reinforcing cage or formwork 7. The vibrator guide unit 1 in the vibrator positioning device arranges the vibrator according to its effective vibration range and the location of the reinforcing cage openings, thus solving the problems of excessive overlap in vibration range or insufficient vibration. Furthermore, after forming a matrix unit, multiple vibrators can simultaneously vibrate multiple areas. In practical use, four vibrator guide units 1 can be arranged as a group. Five sets can form a matrix positioning device, and two sets are prepared for alternating use. The wall length is divided into several vibration zones according to the single positioning device. During construction, the two positioning devices are first placed on the top surface of the wall in the first and second vibration zones and fixed. Then, the guide pipe 3 is passed through the hose clamp in sequence, with the bottom of the pipe 1500mm from the bottom of the wall and tightened. The vibrator is inserted into the concrete through the guide pipe 3. After the first vibration zone is vibrated to the correct position, the first positioning device is lifted and placed in the third vibration zone. After the second vibration zone is vibrated to the correct position, the second positioning device is lifted and placed in the fourth vibration zone, and so on. After the first layer of concrete is poured and before the second layer of concrete is poured, the hose clamp is loosened in sequence, the guide pipe 3 is lifted one section, removed one section, and then tightened again with the hose clamp, and the pouring process is repeated in sequence.

[0056] The connecting assembly includes a positioning clip 4 disposed at the end of the guide tube 3. The positioning clip 4 is used to connect adjacent guide tubes 3 in the vertical direction. Each guide tube 3 is provided with a positioning clip 4, which is a stainless steel hose clamp. Since the guide tube 3 in the vibrating guide unit 1 can be lengthened in the vertical direction as needed, multiple guide tubes 3 in the vertical direction are connected by positioning clips 4.

[0057] The connecting assembly also includes connecting parts 5 distributed around the positioning card 4. The connecting parts 5 are used for detachable connection with the connecting rod 2. The connecting parts 5 are made of ordinary HRB400-14mm hot-rolled ribbed steel bars and are welded to the outer wall of the stainless steel hose clamp. There are four connecting parts 5. Adjacent connecting parts 5 in the circumferential direction are perpendicular to each other. At the same time, the connecting parts 5 are threaded to the connecting rod 2 to facilitate the assembly and disassembly of the connecting rod 2.

[0058] In this embodiment, in step S3, the support reinforcement device includes a corner anchor ring 17 set on the two walls at the inside corner, a corner anchor ring set on the two walls at the outside corner, and a hook tie rod 12 set between the corner anchor ring 17 and the outside corner anchor ring and between the outside corner anchor ring and the outside corner anchor ring. The hook tie rod 12 is used to connect the corner anchor ring 17 and the outside corner anchor ring, which are perpendicular to each other, and to form a diagonal tie structure. This solution strengthens the tensile strength of the weak support parts, such as the corner of the wall in the conventional formwork support system, and prevents the phenomenon of formwork bursting or bulging during subsequent concrete pouring, thereby improving the overall molding quality of large-volume concrete.

[0059] In this embodiment, the external corner anchor rings include a first external corner anchor ring 11, a second external corner anchor ring 15, and a third external corner anchor ring 16, arranged from far to near the corner on the same wall surface. The internal corner anchor ring 17 and the second external corner anchor ring 15 are connected by the hook head to the tie rod 12 to form a diagonal tie. The first external corner anchor ring 11 and the third external corner anchor ring 16 on the adjacent wall surface are connected by the hook head to the tie rod 12 to form a diagonal tie structure. By setting six diagonal tie structures at the internal and external corners of the wall 6, with three on each side of the wall 6, since the internal corner wall surface is larger than the external corner... Because the wall surface is small, a corner anchor ring 1712 is installed on each side of the inside corner and a second corner anchor ring 15 on the adjacent side template 7 of the opposite template 7 to form a diagonal tie structure through a hook tie rod 127. In order to further enhance the tie strength at the inside and outside corners, a first corner anchor ring 11 and a third corner anchor ring 16 are installed on the left and right sides of the second corner anchor ring 15 on each side of the outside corner. The first corner anchor ring 11 on this side wall and the third corner anchor ring 16 on the adjacent side wall are connected by a hook tie rod 12 to form a diagonal tie structure.

[0060] In this embodiment, the support template 7 of the conventional wall 6 includes a template 7, a horizontal main rib disposed on the outside of the template 7, a vertical secondary rib disposed between the template 7 and the horizontal main rib, a tie structure penetrating the template 7 on both sides of the wall 6, and a support component disposed on the outside of the template 7 for supporting the template 7. The horizontal main rib is a double channel steel 9 structure.

[0061] The tie structure includes tie rods and locking elements. The free end of the tie rod passes through the templates 7 on both sides of the wall 6 and then passes through the gap between adjacent vertical secondary ribs and the gap in the horizontal main rib structure in sequence. It is locked to the horizontal main rib by the locking elements to form a tie structure.

[0062] The horizontal main ribs are double-channel steel 9, and the vertical secondary ribs are square steel pipes 8. Setting horizontal main ribs and vertical secondary ribs on the outside of the formwork 7 is a common structure used in formwork 7 support construction. The support components mainly provide lateral support for the formwork 7. The tie rods are precision-rolled threaded steel tie rods 10, and the locking parts are mountain-shaped clips 18. In this scheme, the formwork 7 uses 915mm×1830mm×15mm (thickness) covered plywood; the support components use 40×40×2.5mm square steel pipes 8@150, vertical... The horizontal main ribs are constructed using two φ48×2.7mm ordinary steel pipes, arranged horizontally and reinforced with φ14 water-stop tie rods (using 50mm×50mm×2mm steel water-stop rings). The vertical spacing of the tie rods is 300mm, and the horizontal spacing is 300mm. The bottom tie rod is 100mm away from the completed side wall concrete surface. The outer side of the side wall is supported at 3000mm intervals, and the inner adjacent wall is reinforced at 1000mm intervals using additional steel pipes and top supports for horizontal mutual support.

[0063] In this embodiment, one end of the internal corner anchor ring 17 and the external corner anchor ring passes through the template 7 and extends between the two templates 7. The other end of the internal corner anchor ring 17 and the external corner anchor ring passes through the horizontal main rib and extends out. The ends of the internal corner anchor ring 17 and the external corner anchor ring are provided with threaded sections.

[0064] The ends of the internal corner anchor ring 17 and the external corner anchor ring are provided with a connection structure. The connection structure includes top plates on both sides of the width direction of the horizontal main rib and nuts 14 provided on the outside of the top plates and threadedly connected to the ends of the internal corner anchor ring 17 and the external corner anchor ring.

[0065] Both the internal corner anchor ring 17 and the external corner anchor ring are φ25 precision rolled threaded steel anchor rings, while the hook head tie rod 12 is also made of φ15 precision rolled threaded steel. The anchor ring passes sequentially through the template 7, nut 14, steel plate (with a φ30 hole at the centroid of the 100×100×10mm steel plate), double channel steel 9, steel plate, and nut 14. The nut 14 and steel plate clamp the double channel steel 9 to prevent the anchor ring from slipping under stress. During installation, first tighten the φ25 precision rolled threaded steel anchor ring nut 14 at the internal corner, then hook the internal and external corner φ25 precision rolled threaded steel anchor ring with the φ15 precision rolled threaded steel hook head tie rod 12, and then tighten the external corner φ25 precision rolled threaded steel anchor ring nut 14. At the external corner, φ20 holes are drilled 100mm from the ends of the two double channel steels 9 in two directions, using φ25 precision rolled threaded steel. The steel and matching nuts 14 are connected and locked; the external corner anchor rings and internal corner anchor rings 17, which are set in the same direction, are located on the same horizontal plane; by setting the external corner anchor rings and internal corner anchor rings 17, which are set in the same direction, on the same horizontal plane, the formed diagonal tie structure only acts in the horizontal direction, avoiding the generation of other decomposed forces in the vertical direction, which would affect the connection strength of the diagonal tie structure; the tie rod of the diagonal tie structure located at the outermost corner of the support reinforcement device is interlocked with the tie rod in the tie structure by 300mm; in order to avoid the diagonal tie structure at the internal and external corners from interfering with the tie structure of the conventional formwork 7 support system, it is necessary to set the tie rod of the diagonal tie structure located at the outermost corner of the internal and external corners to interlock with the tie rod in the tie structure by 300mm.

[0066] In this embodiment, in step S5, the concrete curing system includes an internal cooling system disposed inside the concrete slab wall and a standard curing system disposed outside the concrete slab wall. The internal cooling system is used to monitor and control the internal concrete temperature of the concrete slab wall, and the standard curing system is used to perform standard curing of the concrete slab wall with the formwork in place.

[0067] In this embodiment, the standard curing system includes a water supply pipe 19 installed on the outside of the concrete slab wall and a digitally controlled water stop valve 20 installed on the water supply pipe 19. The digitally controlled water stop valve 20 is used to monitor the temperature and humidity of the concrete slab wall and control the flow rate of the water supply pipe 19. The standard curing system also includes a spray unit connected to the water supply pipe 19. The spray unit includes a spray pipe 21 and several nozzles 22 installed along the length of the spray pipe 21. Several spray pipes 21 are spliced ​​together longitudinally or vertically to form the spray unit as a whole. The CNC stop valve 20 has a structure similar to a butterfly valve, allowing for controlled changes in the valve's opening and closing angle. It also features temperature and humidity sensing capabilities. By placing the CNC stop valve 20 near the concrete structure, the temperature and humidity of the concrete surface can be monitored. This monitoring data is then fed back to the control unit to automatically control the valve's opening and closing angle, thereby controlling the flow rate of the water supply pipe 19. To ensure comprehensive water curing of the outer side of the concrete structure's slab wall, the length of the sprinkler pipe 21 and the number of sprinkler heads 22 are determined based on the actual conditions after the concrete structure is poured. The actual dimensions are determined, and the spray unit units are detachably connected using direct heads or spray branch pipes, which will not be elaborated here; it also includes a control system, which is electrically connected to the temperature measuring element of the internal cooling system and is used to change the temperature of the cooling water in the cooling water pipe 24. The control system is also electrically connected to the CNC stop valve 20 and is used to control the flow rate of the water supply pipe 19; wherein the control system generally uses a central processing unit such as a PLC to collect data from the temperature measuring element and the CNC stop valve 20 and output instructions to the CNC stop valve 20 and the flow controller in the cooling water pipe 24 to control the flow rate of the cooling water pipe 24 and the water supply pipe 19.

[0068] In this embodiment, the standard curing system uses plastic film and geotextile for heat preservation and curing. The heat preservation and moisture retention curing time should not be less than 14 days. During temperature monitoring, an automatic alarm should be triggered when the cooling rate or the temperature difference between the surface and the interior exceeds the following specified values, and the temperature control measures should be adjusted and optimized in a timely manner:

[0069] 1) The cooling rate is greater than 2.0℃ / d or the temperature drops by more than 1.0℃ every 4 hours;

[0070] 2) The temperature difference between the inside and outside of the container is controlled at 25℃.

[0071] When the temperature difference between the highest concrete temperature and the surface temperature exceeds 25℃, the internal cooling system should be activated immediately. The temperature difference between the inlet water and the highest concrete temperature should be controlled by adjusting the inlet water flow rate and temperature of cooling water pipe 24; the temperature difference should ideally be 15℃ to 25℃; the temperature difference between the outlet water and the inlet water should ideally be 3℃ to 6℃; the cooling rate should not exceed 2℃ / day and should not exceed 1℃ / 4h. While the internal cooling system is in operation, the wall panels should be cured using standard formwork curing, as detailed below.

[0072] 1) The standard maintenance system consists of a wall spray unit, a water supply pipe 19, and a CNC water stop valve 20. The wall spray unit can be extended longitudinally or vertically. The CNC water stop valve 20 is set to have a minimum opening time of 2 hours.

[0073] 2) Each wall is equipped with a digitally controlled water stop valve 20, and the opening and closing of the digitally controlled water stop valve 20 is controlled by changes in temperature and humidity.

[0074] 3) The CNC water stop valve 20 adjusts its opening and closing based on the humidity and temperature of the beam and wall surface to ensure that the components to be cured are kept at 95% humidity. When the temperature is <5℃, the CNC water stop valve 20 is closed by temperature control sensing. When the temperature is 5℃≤35℃, the water stop valve is opened by humidity control sensing. When the temperature is >35℃, the water stop valve is opened by temperature control sensing. This ensures that the components to be cured can receive standardized curing, which not only ensures proper curing but also avoids wasting water resources.

[0075] After the initial installation, open the water stop valve for curing and check whether the CNC water stop valves 20 on each component are normal. After the initial curing, determine the time to open the CNC water stop valves 20 for the second time based on the temperature at that time, and check whether the CNC water stop valves 20 are open at that time. If they are all open, no further maintenance is needed until the end of the curing period, and then move the unit to another area to be cured. If the valves are not opened as scheduled, check for problems, troubleshoot, and once the CNC water stop valves 20 are normal, no further maintenance is needed until the end of the curing period, and then move the unit to another area to be cured.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preventing cracking in large-volume concrete construction, characterized in that: Includes the following steps: S1. Construction preparation and research, formulating concrete mix proportions, and manufacturing vibration positioning devices and support reinforcement devices. S2. Locate and lay out the lines at the construction site, tie the reinforcing bars and install the cooling water system. After completion, conduct acceptance of the concealed works. S3. After completing the installation of the support formwork for the regular wall, install the support formwork at the corner and set up a support reinforcement device on the support formwork at that location. Then, install the vibration positioning device in all the support formwork in sequence according to the pouring order. S4. Control the quality of concrete during the concrete pouring process. S5. Use a concrete curing system to perform standard curing operations on the poured concrete structure. S6. After the curing work is completed, the formwork is removed and the concrete quality is inspected. In step S3, the support reinforcement device includes a corner anchor ring set on the two walls at the inside corner, a corner anchor ring set on the two walls at the outside corner, and a hook tie rod set between the corner anchor ring and the outside corner anchor ring and between the outside corner anchor ring and the outside corner anchor ring. The hook tie rod is used to connect the corner anchor ring and the outside corner anchor ring, which are perpendicular to each other, and to form a diagonal tie structure. The external corner anchor ring includes a first external corner anchor ring, a second external corner anchor ring, and a third external corner anchor ring installed on the same wall surface from far to near the corner. The internal corner anchor ring and the second external corner anchor ring are connected by the hook head to the tie rod to form a diagonal tie. The first external corner anchor ring and the third external corner anchor ring on the adjacent wall surface are connected by the hook head to the tie rod to form a diagonal tie structure. The supporting formwork for the conventional wall includes a formwork, a horizontal main rib set on the outside of the formwork, a vertical secondary rib set between the formwork and the horizontal main rib, a tie structure penetrating the formwork on both sides of the wall, and a supporting component set on the outside of the formwork for supporting the formwork. The horizontal main rib is a double-channel steel structure. The tie structure includes tie rods and locking elements. The free end of the tie rod passes through the templates on both sides of the wall and then passes through the gaps between adjacent vertical secondary ribs and the gaps in the horizontal main rib structure. It is then locked to the horizontal main rib by the locking elements to form a tie structure.

2. The construction method for preventing cracking in large-volume concrete according to claim 1, characterized in that: In step S3, the vibration positioning device includes several vibration guide units disposed between templates. A connecting rod is provided between adjacent vibration guide units. The connecting rod is used to connect and fix several vibration guide units to form a matrix unit between templates. The vibration guide unit includes a guide pipe disposed at a preset rebar cage hole position and a connecting component disposed on the guide pipe. Multiple guide pipes are arranged vertically in the preset rebar cage hole and connected by the connecting component.

3. The construction method for preventing cracking in large-volume concrete according to claim 2, characterized in that: In step S3, the connecting assembly includes a positioning clip disposed at the end of the guide tube and connecting parts distributed around the positioning clip. The positioning clip is used to connect adjacent guide tubes in the vertical direction, and the connecting parts are used to detachably connect with the connecting rod.

4. The construction method for preventing cracking in large-volume concrete according to claim 1, characterized in that: One end of the internal corner anchor ring and the external corner anchor ring passes through the template and extends between the two side templates. The other end of the internal corner anchor ring and the external corner anchor ring passes through the horizontal main rib and extends out. The ends of the internal corner anchor ring and the external corner anchor ring are provided with threaded sections. Both the inner corner anchor ring and the outer corner anchor ring have a connecting structure at their ends. The connecting structure includes top plates on both sides of the horizontal main rib width direction and nuts that are threaded to the ends of the inner corner anchor ring or the outer corner anchor ring and located on the outer side of the top plates.

5. The construction method for preventing cracking in large-volume concrete according to claim 1, characterized in that: In step S5, the concrete curing system includes an internal cooling system located inside the concrete slab wall and a standard curing system located outside the concrete slab wall. The internal cooling system is used to monitor and control the internal concrete temperature of the concrete slab wall, and the standard curing system is used to perform standard curing of the concrete slab wall with the formwork in place.

6. The construction method for preventing cracking in large-volume concrete according to claim 5, characterized in that: The standard curing system includes a water supply pipe installed on the outside of the concrete slab wall and a CNC water stop valve installed on the water supply pipe. The CNC water stop valve is used to monitor the temperature and humidity of the concrete slab wall and control the flow rate of the water supply pipe. The standard curing system also includes a spray unit connected to the water supply pipe. The spray unit includes a spray pipe and several nozzles installed along the length of the spray pipe. Several spray pipes are spliced ​​together longitudinally or vertically to form the spray unit as a whole.

7. The construction method for preventing cracking in large-volume concrete according to claim 6, characterized in that: When the temperature of the outer surface of the concrete slab wall is less than 5°C, the CNC water stop valve controls the water supply pipe to be in a closed state; When the temperature of the outer surface of the concrete slab wall is between 5℃ and 35℃, the CNC water stop valve controls the opening angle of the CNC water stop valve and adjusts the flow rate of the water supply pipe by monitoring the moisture of the concrete slab wall. When the temperature of the outer surface of the concrete slab wall is greater than 35°C, the CNC water stop valve monitors the temperature of the concrete slab wall to control the opening angle of the CNC water stop valve and adjust the flow rate of the water supply pipe.

Images