Formwork engineering refers to the formwork of the newly poured concrete and the complete set of construction systems supporting the formwork. Among them, the structural part that contacts the concrete and controls the predetermined size, shape and position is called a formwork. The supporting and fixing means, the truss, the connecting piece, the metal fitting, the working bridge and the like constitute a supporting system. For the sliding formwork, the self-lifting formwork is equipped with lifting power, lifting frame and platform. Formwork engineering is a temporary structure in concrete construction.
Currently applied formwork types
Since the 1990s, due to the continuous emergence of new materials, there are more and more types of forms, and the following are mainly used.
1) Wood glued formwork: At present, a lot of wood formwork is used, and the veneer glued formwork should be advocated.
2) Steel formwork: In addition to the combined steel formwork, wide-width steel formwork, all-steel large formwork, light large steel formwork, 63-type steel frame steel face mold, etc. have been developed.
3) Bamboo glued formwork: The earliest used bamboo plywood formwork has been developed, and coated bamboo plywood formwork, bamboo plywood formwork, covered wood or covered bamboo plywood formwork have been developed.
4) Plastic formwork: At present, many companies have developed various plastic formwork, such as hard and stubborn plastic formwork, wood-plastic composite formwork, GMT plastic formwork, floor plastic formwork and modular plastic formwork system. With the continuous improvement of the technical level of formwork engineering, the template specifications are being serialized and systematically developed, and many formwork systems suitable for different construction projects have emerged, such as modular group large template, hydraulic sliding formwork, hydraulic climbing formwork, Table molds, drum molds, bridge templates, stencils, cantilever templates, etc.
Ⅰ. wood glued formwork
Since 1998, wood plywood formwork has been widely promoted and applied in some domestic construction projects. In just a few years, the development has been very rapid, which has greatly promoted the development of plywood enterprises and the length of plywood. The formwork has light material, low cost, suitable for processing large-surface formworks, etc., can meet the requirements of fair-faced concrete construction. Moreover, this type of formwork has the lowest price and the most used formwork for construction companies. However, there are still some problems in the actual application and production process of wood gluing templates, mainly in the following aspects.
1) The product quality and grade are low, and the waste of wood resources is serious. At present, there are many domestic wood glue formwork manufacturers, but there are not many manufacturers that can produce qualified wood glued building formwork and quality control, and there are fewer manufacturers that can produce overmolded wood plywood formwork. Most manufacturers produce plywood templates with plain urea-formaldehyde glue, which are of poor quality, low grade, low price and low usage times. Generally, they can only be used 3 to 5 times. Compared with foreign wood plywood formworks, the difference is very large. For example, the Visa formwork produced by the British company can be used 10~20 times. If 400g/m2 coated paper is used, it can be used more than 30 times. Plywood formwork, which can be used 25~50 times for single-sided high-density veneer formwork and 50 times for system forming work.
China’s timber resources are extremely poor, but the utilization rate of wood is only one tenth of foreign countries, and the waste of wood resources is too serious. In recent years, with the increasing market share of wood veneer stencils, more and more manufacturers, and market competition has become increasingly fierce. Some manufacturers have seized the market, neglected product quality, and competed at low prices. Some manufacturers’ production equipment and technical conditions are still not complete, and they are eager to put into production, resulting in a decline in product quality.
2) The production process and equipment are backward and the technical management level is low.
The plywood production plants in developed countries have basically adopted mechanized and automated advanced production lines. The production technology and equipment have high technical content, can guarantee product quality, and pay great attention to technology and equipment investment, and constantly research and develop new products. improve product quality. Most of China’s plywood factory’s production equipment is simple, low degree of mechanization, basic manual operation, product quality is difficult to control, technical strength is weak, and it does not pay attention to attract talents. There are few formal wood processing talents and lack of new technology development capabilities. The quality awareness of managers is also poor, the quality management system is not perfect, there is a lack of strict quality supervision measures, quality inspection methods are also backward, and product quality is difficult to improve.
3) There are too many wood plywood manufacturers, and the production scale is too small.
The number of plywood enterprises in developed countries is small, but most of them have formed large-scale production. There have been more than 7,000 wooden plywood manufacturers in China. In the past two years, due to the impact of the international financial crisis, wood gluing formwork manufacturers have closed, stopped, and transferred. At present, there are more than 4,500 plywood manufacturers, and there are still too many manufacturers. And most of the enterprises are small in scale, simple in equipment, extensive in management, low in technology level, only 200 enterprises with an annual production capacity of 10,000 cubic meters of plywood, and only more than 10 enterprises with an annual production capacity of 100,000 cubic meters or more. The average size is only 33% of the world average. Among them, there are more than 600 manufacturers that can produce wood plywood formwork. There are too many manufacturers, and the production capacity is excessive. The market competition is fierce, which is not conducive to the improvement of production technology and improvement of product quality. The scale of production is small, and the production process and equipment are backward, which restricts technological progress. The economic strength and technical strength are weak, and they cannot form large-scale production, which is not conducive to participating in market competition, and is even less able to go to the international market.
In this case, we must take the development path of large-scale production and group management.
To be continue…BOFU plastic formwork system