With the development of reform and opening up and economic construction, pretensioned prestressed concrete pipe piles have been widely used in railway system, and extended to industrial and civil buildings, municipal administration, metallurgy, ports, highways and other fields. In the Yangtze River Delta and the Pearl River Delta, because the geological conditions are suitable for the use of pipe piles, the demand for pipe piles has soared, thus rapidly forming a new industry. According to incomplete statistics, by the end of 2007, there were more than 400 pipe pile manufacturers in China (excluding Taiwan Province Province), producing about 250 million meters of various pipe piles with an output value of more than 30 billion yuan. At the same time, the supporting products supporting the pipe pile industry have an annual output value of nearly 25 billion yuan, making it a dynamic emerging industry. At present, pipe piles have accounted for about 50% of the national cement products industry output value. In the development process of nearly 20 years, the pipe pile project has won the second prize of scientific and technological progress in building materials industry and the third prize of national scientific and technological progress; Pipe pile is listed as a national new product, and the former Ministry of Construction focuses on promoting new products; In 2006, with the joint efforts of relevant units and associations, the pipe pile products of three enterprises (Zhongshan Jianhua Pipe Pile Co., Ltd., Guangdong Sanhe Pipe Pile Co., Ltd. and Ningbo Dong Zhe Building Materials Group) were listed in the catalogue of famous brand products in China, which is another new climax of the development of pipe pile industry in China and won unanimous praise both inside and outside the industry. There is no standard production of pipe pile products, so far there are relatively complete standard systems-GB13476-92 pretensioned prestressed concrete pipe pile, GB 13476- 1999 pretensioned prestressed concrete pipe pile, JC888-200 1 pretensioned prestressed concrete thin-walled pipe pile. T 19496-2004 Test method for testing compressive strength of centrifugal high-strength concrete by core drilling method, JC/T947-2005 end plate for pretensioned prestressed concrete pipe piles, JC/T950-2005 silica sand powder for prestressed high-strength concrete pipe piles, and JC/T948-2005 release agent for concrete products.
Pipe piles are divided into post-tensioned prestressed pipe piles and pre-tensioned prestressed pipe piles, prestressed concrete pipe piles (PC pipe piles), prestressed concrete thin-walled pipe piles (PTC pipe piles) and high-strength prestressed concrete pipe piles (PHC pipe piles).
Pre-tensioned prestressed pipe pile is a hollow cylindrical slender concrete precast member made by pre-tensioned prestress technology and centrifugal forming method, which is mainly composed of cylindrical pile body, end plate and steel hoop.
Pipe piles are divided into prestressed concrete pipe piles (PC pipe piles), prestressed concrete thin-walled pipe piles (PTC pipe piles) and prestressed high-strength concrete pipe piles (PHC pipe piles) according to concrete strength grade and wall thickness. The concrete strength of PC pile is not less than C50 concrete, PTC pipe pile is not less than C60, and PHC pile is not less than C80. PC piles and PTC piles are generally cured by atmospheric steam, which takes 28 days to finish. PHC piles need to be autoclaved after demoulding. After autoclaving at 10 atmospheric pressure and 180 degrees, it takes only three or four days for the concrete strength grade to reach C80.