by Click the blue word} to easily follow! Precast building is the visual expression of the assembly construction link in the construction industrialization.
It is a building assembled from the precast parts produced by the factory on the construction site.
The whole process should be standardized design, factory production, assembly construction, integrated decoration, information management and intelligent application.
Under the current construction technology, precast buildings will become the main force of the construction industry in the future.
Today, Xiaobian sorted out 9 questions that we are most concerned about to answer.
Q1: is the quality and safety of precast buildings guaranteed? Is it strong? In the design process, through the simulation of various calculation models, diversified and all-round entity experiments, and through the practice of a large number of projects at home and abroad, it is proved that the quality and safety of the house can stand the test, and the technology is mature and reliable.
Because a large number of parts and components of precast buildings are produced in factories, the quality control ability is far greater than the traditional on-site wet operation.
Q2: are precast buildings made of concrete? At the present stage, there are three main modes of industrialized production of buildings in China: Precast concrete precast buildings (PC buildings) are built by the combination of precast concrete components as the main components, assembled, connected and partially cast-in-place concrete structures; Steel structure building steel structure is the main structure, combined with industrialized floor slab and internal and external wall system to form a complete building system, which has the advantages of wide application range, light weight, energy conservation and environmental protection; Due to the limitation of resources and environmental conditions, the promotion of wood structure assembled buildings in the whole country has a long way to go.
Q3: can it resist earthquakes? At present, the seismic performance of precast building structures in China is basically equal to that of cast-in-place structures, and even some performance exceeds that of cast-in-place structures, which can meet the fortification requirements of seismic grade 8.
One of the key technologies for earthquake resistance: the connection technology of cast joints.
At present, the technology mainly used in Beijing was born in the United States in the 1970s and introduced into Japan in 72.
The sleeve is precast in the component, and the reinforcement at the other end is connected through high-strength grouting material grouting at the construction site.
In the past century, mortar sleeve connection technology has been widely practiced in Japan and the United States, including sleeve stress-strain curve and cyclic tension fatigue test.
Such a technology has been tested for a long time and tested by strong earthquakes.
Both the United States and Japan believe that it can be safely and boldly used in high-rise buildings.
In addition, the seismic performance of precast buildings can be strengthened by introducing isolation measures.
Q4: in the past, there were large plank houses.
Why should we promote precast buildings now? In the 1980s, the focus of China’s capital construction shifted from production to life.
In order to quickly solve people’s housing needs, precast large slab buildings began to appear and develop rapidly.
Since the early 1990s, large slab buildings have “suddenly disappeared”.
The reasons for this phenomenon are as follows: first, the market requires diversified house types and personalized decoration, and the large plate structure system fails to solve the contradiction between design standardization and diversification, resulting in increased production difficulty and cost; Second, the large slab structure system failed to solve the waterproof problem well, and a large number of leakage occurred in about 15 years after its completion; Third, the rapid development of cast-in-situ concrete construction technology (such as large formwork technology), migrant workers entering the city and low labor cost have accelerated the demise of large slab structure system; Fourth, with the reduction of China’s demographic dividend and the urgency of environmental pollution, the 18th National Congress put forward the requirements of “ecological civilization construction”.
The construction industry must take the road of industrialization to save resources and energy and reduce environmental pollution.
Combined with the experience at home and abroad, the use of precast construction is one of the main means.
Q5: what is the sound insulation effect? The precast building floor slab adopts the composite floor slab, which is different from the previous hollow floor slab.
It reproduces and pours a layer of concrete floor slab on the basis of precast floor slab, so as to form a solid assembled integral floor slab.
Lightweight concrete internal partition wall is usually made of lightweight strips or concrete products, and its material itself has superior sound insulation performance.
The light steel keel partition wall usually adds sound insulation materials such as rock wool or thermal insulation board in the middle, which meets the national standard in terms of sound insulation standard.
In terms of sound insulation standard, it is not only consistent with the cast-in-situ floor slab, but also has good flatness, saves formwork and is convenient for construction.
Q6: the joints of precast buildings are bonded with glue.
How to avoid frost heaving, corrosion, rain and snow leakage? At present, precast buildings solve the problem of water leakage through structural waterproof, structural waterproof and material waterproof.
Structural waterproof: vertical joint cast-in-situ concrete pouring, and the structure is self waterproof.
Structural waterproof: the horizontal joint back sill structure prevents water from entering the room.
Material waterproof: the exterior wall joints are made of “improved silicone glue”.
Q7: is the cost of precast buildings high? In essence, the construction processes of cast and cast-in-situ construction methods are quite different, the construction process is different, the organization and management mode is different, and the economic, social and environmental benefits are also different.
The “cost” between the two should not be simply compared.
Generally speaking, the increased cost of precast buildings mainly includes: precast component products and transportation expenses, on-site installation and hoisting expenses, large machinery rental expenses, joint treatment of wallboard and floor slab and related material expenses.
The cost reduction mainly includes: the reinforcement and concrete works are carried out in the precast component factory, which reduces the on-site masonry cost, plastering labor cost, on-site support and formwork cost.
In addition, at present, the state vigorously promotes precast buildings and will increase policy support to reduce the incremental cost of precast buildings through area reward, implementation of full decoration, shortening the construction period, technical training of industrial workers, reducing labor costs, replacing business tax with value-added tax in the construction industry and reducing construction costs..
