Construction method and advantages and disadvantag

2022-08-18
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Aluminum formwork construction methods and advantages and disadvantages

Aluminum formwork is fully known as aluminum alloy formwork for construction. It is a new generation of formwork system after wood formwork and steel formwork. The aluminum formwork is designed according to the module, extruded by special equipment, and can be freely combined according to different structural dimensions. The emergence and improvement of aluminum alloy template technology is the choice of market economy. Compared with other forms of templates, it contains high scientific and technological components and is relatively cost-effective

Aluminum formwork construction method

the aluminum formwork construction process is divided into multiple steps, and the fine operation of each step is related to the final project quality of Zui. According to the characteristics of Fujian Vanke Putian Yuhu new city block B project, the shear wall, beam, column, floor formwork and support system of B13, 15, 16 and 17 standard floors of the project adopt aluminum alloy formwork construction technology. Next, combined with the specific construction of aluminum alloy formwork, several key steps are analyzed

1.1 formwork selection

according to the structural characteristics of the project and the actual situation on site, the formwork selection of each part is as follows:

1.2 measurement and setting out

(1) measurement and setting out of shear wall control line. It is required to pop up the shear wall control line on the concrete floor 300mm outward from the shear wall position line, so as to facilitate the correction and recheck of the shear wall formwork position after the formwork installation

(2) survey and setting of 1000mm elevation line and plate thickness control line. There are two specific requirements for this step: ① after the lower concrete is poured, the 1m elevation line must be marked on the shear wall reinforcement in time, and the elevation point of each shear wall corner reinforcement must be given. This is conducive to the accurate marking of 1000mm elevation line. ② The slab thickness control line shall be marked on the reinforcement according to the floor elevation, and three or more floor elevation points shall be measured on each side of the shear wall. This step is the key to the measurement of plate thickness control line

1.3 installation of wall thickness positioning reinforcement

after the floor concrete pouring is completed, the installation of wall thickness positioning reinforcement also begins. First, we need to weld the wall thickness positioning reinforcement. The welding point of welding the positioning reinforcement of the wall thickness is on the vertical reinforcement of the wall 50-100mm high from the floor, and the horizontal spacing of the positioning reinforcement is 800mm. The length of the positioning reinforcement is determined according to the wall thickness, and its welding position is determined according to the popped wall line. The deviation between the reinforcement and the wall line control line should be less than 3mm, so as to ensure the accuracy of the wall thickness and position at the lower part of the shear wall during formwork installation

1.4 formwork design

(1) shear wall formwork. When both ends of the shear wall are L-shaped, in order to make the formwork easy to remove after pouring, the easy to remove formwork is configured for the inner wall. When the wall and elevator shaft are equipped with formwork, the upper horizontal formwork is 50mm higher than the floor to prevent overflow of the external wall formwork when pouring floor concrete

(2) column formwork. The column formwork adopts all aluminum alloy formwork. The back ribs are clamped by split bolts at the two outer ends of the column as the column hoop. The back ribs and the split bolts are staggered as a column hoop. The distance between the column hoop and the bottom is about 300mm, and the distance between the two column hoops is about 600mm

(3) beam formwork. The beam bottom and beam side formwork are all aluminum alloy formwork. The beam side formwork is connected with the beam bottom formwork by aluminum external angle formwork, the primary and secondary beam side formwork is connected by aluminum internal angle formwork, and the beam side formwork is connected with the floor formwork by aluminum internal angle formwork

(4) floor formwork. The floor slab bottom adopts all aluminum alloy formwork, equipped with early dismantling support system to improve the turnover efficiency of the formwork, and uses independent steel support, with a support spacing of 1300mm × 1300mm。

1.5 beam and slab support system

the independent steel support of this system turns off the oil return valve support. It is an early dismantling support system with obvious technical and economic effects. It has been applied to the corners of building engineering, and plays an important role in the vertical support of horizontal structure of buildings, bearing the dead weight and construction load of beam and slab structure, as well as diagonal bracing and horizontal bracing

the floor height of this project is 2.9m, and it is directly supported by 2000-3500 single supports, as shown in the following figure:

the main features of this support system are as follows:

(1) this system is a support system that can realize early disassembly in a real sense. When the concrete reaches the formwork removal strength, except for the single support top and early removal head, the rest can be removed, which not only ensures the continuous construction of the superstructure, but also accelerates the turnover and use of the formwork, which can greatly save the one-time input of the formwork and reduce 1/3-1/2 of the formwork allocation

(2) it has a wide range of applications, and the support rod is not constrained by the fixed plane size. Therefore, it can be used freely for irregular building planes. The spacing of the support rod and the spacing of the longitudinal and transverse beams can be adjusted in time according to the beam plate load, and is not constrained by the connecting rod, which is more convenient than the application of the bowl buckle frame

(3) under the condition of the same formwork area, the steel consumption of this system is only equivalent to 30% of the steel consumption of the bowl buckle frame. This can reduce the vertical transportation of materials on the one hand, and increase the speed of formwork erection on the other hand. Take tower housing as an example. It takes only half a day to support the formwork area of 600-800m2 on each floor, which is one half to one third of the time of other support systems

(4) after removing the aluminum alloy formwork and steel support, they can be centralized on the unloading platform and transported by tower crane. Of course, they can also be transported manually, which is more flexible

advantages and disadvantages of aluminum formwork construction

aluminum formwork has gradually been widely used in engineering construction. At present, the proportion of wood formwork in building formwork engineering is still large. However, in order to save wood and respond to the requirements of energy conservation and environmental protection, people began to try to use various metal templates, such as all steel or all aluminum. Practice has proved that the use of all steel formwork has greatly reduced wood consumption and greatly shortened the construction period, but it also brings challenges to the construction. Compared with wood formwork, it is self-supporting, so it particularly relies on vertical transportation and is inconvenient to operate. The use of aluminum alloy formwork solves this problem well. It is much lighter than all steel formwork. Therefore, after being introduced, it has been rapidly promoted and gradually improved. At present, a complete set of all aluminum alloy formwork construction technology has been formed

2.1 technically

(1) advantages: first, aluminum is a metal with low density, and its self weight is relatively light, but its bearing capacity is quite good, especially suitable for mechanized operation; The same type of components can be mixed with standard plates, so the assembly limit is small, the speed is fast, the formwork is stereotyped and modular, and the formwork can be combined and assembled between left and right, up and down, and vertical and horizontal. The formwork has good versatility and interchangeability, and can be used for large formwork projects of various building plane shapes; Several different templates are directly connected with the help of pins, which is very convenient for installation and does not need a lot of effort when disassembling; If the horizontal component formwork is designed with the help of "early disassembly", only some parts may produce sparks due to vibration and friction, and it can be disassembled after only 36 hours; After the concrete strength reaches the design strength, the aluminum alloy formwork can be completely removed. At this time, it can be seen that the concrete surface quality is very good; In order to ensure construction safety, movable multi-level operation platforms will be set during the installation of aluminum alloy formwork, which can reduce safety risks. In general, aluminum alloy formwork has light weight, convenient construction and reliable quality

(2) disadvantages: compared with other formwork, aluminum alloy formwork has higher requirements for construction level. There are four main requirements for the installation quality of aluminum alloy formwork: ① the positioning of formwork axis, overall dimension and horizontal elevation should be accurate. ② The board surface shall be flat and clean, and the joints shall be tight without mortar leakage. ③ The installation shall be firm and stable to ensure no displacement and formwork expansion during construction. ④ The deviation of formwork installation shall be controlled within the allowable range of the specification. Five points need to be paid attention to in the process of using the formwork: ① the pre fabricated formwork such as wall, column formwork and beam side and beam bottom formwork should be numbered and managed, and the formwork should be stacked by classification for ease of use. ② During the installation and removal of the formwork, it shall be lifted and placed gently, and no collision is allowed. It is not allowed to knock the formwork hard to avoid the deformation of the formwork. ③ The removed formwork shall be cleaned in time. In case of warpage and deformation, it shall be repaired in time, and the damaged plate surface shall be repaired in time. ④ The formwork to be assembled also makes the sample slip during the experiment. There should be a relatively flat and compacted storage site. If it is placed horizontally, Zui it is better to use a wooden square cushion frame. If it is placed vertically, Zui can set up some classification formwork frames, and when it touches the bottom, put wooden squares on it, which can ensure that the formwork does not deform to a great extent. It is not allowed to pile these pre assembled templates or put other scattered materials on them. ⑤ Where the formwork has been installed, it is not allowed to collide with other formworks during the construction process, nor can it be used as a temporary lean to prevent the formwork from deformation or vertical deviation. The plane formwork installed on the working face cannot be used as a temporary stacking and operation platform to ensure the stability of the support and prevent the deviation of the plane formwork elevation and flatness. In addition, there are many requirements for demolition. Once the technology is not in place, there will be common quality problems such as pockmarked concrete surface, honeycomb, missing edges and corners

2.2 economically

(1) advantages: first, compared with wood formwork, aluminum alloy formwork is not easy to deform, so it can be used repeatedly. Taking this project as an example, the combined all aluminum alloy formwork used for shear wall formwork can be used for more than 200-250 times, with small amortization cost and obvious economic benefits each time. Practice has proved that aluminum alloy formwork can be used more frequently than steel formwork, and this advantage is more obvious in high-rise buildings. According to accounting, the amortization cost of aluminum alloy formwork is almost the same as that of wood formwork as long as it reaches more than 50 times. Secondly, the use of aluminum alloy formwork can speed up the project and shorten the construction period. At the same time, it can also reduce unnecessary large-scale equipment rent during the construction process, which is more convenient and fast. Thirdly, qualified and high-quality aluminum alloy formwork construction can make the structural surface show the effect of clear water concrete, which saves the material and labor costs required for plastering and leveling during decoration. Therefore, from the perspective of the whole construction process, the use of aluminum alloy formwork can reduce the project cost, save the consumption of cement, sand and other raw materials on the one hand, and save the labor cost required for plastering on the other hand

(2) disadvantages: the addition cost of aluminum alloy formwork is relatively high. Although its amortization expense is relatively low, it is also diluted due to its many times of turnover and use. Compared with wood formwork, the early investment of aluminum alloy formwork for construction will be very large. After comprehensive comparison and analysis, the project still decides to adopt aluminum alloy formwork, which not only reduces the comprehensive amortization cost of formwork, but also improves the surface quality of concrete and reduces the plastering cost, which is also very beneficial to wood conservation, energy conservation and environmental protection

in a word, aluminum alloy formwork has experienced more than 50 years of application practice abroad, and now a set of construction technology has been formed. In addition to strictly implementing the specification requirements, a series of aluminum alloy formwork construction management measures have been formulated for the project, including safety, quality, finished product protection measures, etc

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