Development History of concrete precast elements in China


The production and application of prefabricated parts in China has a history of nearly 60 years. In these 60 years, the development of prefabricated parts can be described as striking one snag after another .

 

Since the 1950s, China has been in the period of economic recovery and the first Five-Year Plan of the national economy. Under the influence of the construction industrialization of the former Soviet Union, China’s construction industry began to take the road of prefabricated development. The main prefabricated parts in this period include columns, crane beams, roof beams, roof panels, skylight frames, etc. Except for roof panels, some small crane beams and small-span roof trusses, they are mostly site precasting . Even if prefabricated in factories, they are often prefabricated in temporary prefabrication yards established on site. Prefabrication is still a part of construction enterprises.

1. First Step

Since the 1950s, China has been in the period of economic recovery and the first Five-Year Plan of the national economy. Under the influence of the construction industrialization of the former Soviet Union, China’s construction industry began to take the road of prefabricated development. The main prefabricated parts in this period include columns, crane beams, roof beams, roof panels, skylight frames, etc. Except for roof panels, some small crane beams and small-span roof trusses, they are mostly site precasting . Even if prefabricated in factories, they are often prefabricated in temporary prefabrication yards established on site. Prefabrication is still a part of construction enterprises.

2. Second Step

In the late 1960s and early 1970s, with the development of small and medium-sized prestressed components, a large number of prefabricated parts factories appeared in urban and rural areas. Hollow slab, flat plate, purlin and hanging tile plate for civil buildings; Roof panels, F-shaped plates, trough plates used in industrial buildings and V-shaped folded plates and saddle plates used in industrial and civil buildings have become the main products of these component factories, and the prefabricated parts industry has begun to take shape.

3.Third Step

In the mid-1970s, with the strong advocacy of government departments, a large number of large concrete slab factories and frame light slab factories were built, which set off an upsurge of the development of prefabricated parts industry. By the mid-1980s, tens of thousands of prefabrication plants of different sizes had been established in urban and rural areas, and the development of China’s component industry reached the peak. At this stage, the main types of prefabricated parts are as follows. Civil building components: exterior wall slab, prestressed building slab, prestressed circular orifice plate, precast concrete balcony, etc. (as shown in Figure 1);

 

Industrial building components: crane beam, prefabricated column, prestressed roof truss, roof slab, roof beam, etc. (as shown in Figure 2);

 

From a technical point of view, the production of prefabricated parts in China has experienced a development process from low to high, from mainly manual to mechanical mixing, mechanical forming, and then to the assembly line production with a high degree of mechanization in the factory.

4. Forth Step

Since the 1990s, component enterprises have been unprofitable, most of the large and medium-sized component factories in cities have reached the point of unsustainability, and the small components in civil buildings have given way to the production of small component factories in villages and towns. At the same time, the inferior hollow slabs produced by some township enterprises flooded the construction market, which further affected the image of the prefabricated parts industry. Since the beginning of 1999, some cities have successively ordered to prohibit the use of precast hollow floors and use cast-in-situ concrete structures, which has dealt a heavy blow to the prefabricated parts industry, which has reached a critical juncture of life and death.

 

In the 21st century, people began to find that the cast-in-situ structure system is no longer fully in line with the development requirements of the times. For the increasingly developing construction market in China, the disadvantages of cast-in-situ structure system tend to be obvious. In the face of these problems, combined with the successful experience of foreign housing industrialization, China’s construction industry has once again set off a wave of “construction industrialization” and “housing industrialization”, and the development of prefabricated parts has entered a new age .

 

In recent years, under the guidance of relevant policies of government departments, the development situation of construction industrialization is good. This also makes groups, enterprises, companies, schools and scientific research institutions increase their enthusiasm for the research of prefabricated parts. After years of research, they have also achieved certain results.