Which is better for precast concrete and on-site pouring
Concrete is a unique material that can be converted from liquid to solid at room temperature and produces high strength. Therefore, both prefabricated and cast-in-place construction methods are formed.
First, the characteristics:
The cast-in-place concrete large-mold building is a house built on the site by using a large tool-type formwork, and is cast in a cast-in-place concrete load-bearing wall by mechanization. It is suitable for houses and hotels with more interior walls.
Cast-in-place concrete, concrete cast in the formwork at the construction site. Unlike precast concrete, most buildings are constructed using cast-in-place concrete.
Prefabrication is first made into concrete components in the factory, and then transported to the construction site for assembly and connection to form a prefabricated concrete structure; cast-in-place is to directly cast concrete into the molding at the construction site to form an integral concrete structure.
1. Good structural performance, factory-made production can effectively guarantee structural mechanics and small dispersion.
2. The construction speed is fast, the product quality is good, the surface finish is high, and the decorative effect of the clear water concrete can be achieved, so that the structure and the building are unified and coordinated.
3, factory production energy-saving, is conducive to environmental protection, reducing noise on-site construction.
4, good fire performance.
5. The overall performance of the structure is poor, and it is not suitable for buildings with high seismic requirements.
Before the components or structures are put into use, for example, before the permanent load on the floor is up, the bridge construction road surface is before the traffic. Apply a stress to the component that is opposite to the stress caused by the permanent load. The principle of prestressing is to give full play to the material properties, the concrete has good pressure resistance and the steel is tensile. Ordinary reinforced concrete members are often cracked by the concrete in the pull zone, and the concrete stress in the compression zone is still small. Concrete performance did not play. In this case, prestressing is applied to the tension zone so that the permanent load causes the stress to cancel out against the prestressing force. With the same material, the load that can be tolerated is greatly increased. The specific method is to use prestressing tendons. The prestressed tendons are pretensioned before the members are subjected to permanent loads and prestressed against the concrete.
So the difference is in prestressing. It can be a pre-stressed steel bar or a steel strand.
The materials used are different. Prestressed members have prestressed tendons, often high-strength concrete, with low chloride salt content to prevent corrosion pre-stress.
The bearing capacity is different. Prestressed members are certainly much taller at the same size.
The construction method is different. Prestressed members must be pre-stressed by post-tensioning or post-tensioning. Have a fixture, or an anchor. The post-tension method requires a prestressed tube.
It is important to protect against corrosion during use. Prestressing damage will cause an accident.
Three costs and transportation
It is a concrete component prefabricated in concrete mixing station or special concrete prefabricated component factory according to national standard requirements or site site design requirements. When it is used, it will be transported to the site for installation at the end of the curing period.
Cast-in-place concrete members - are mixed into concrete by concrete mixing station (still in the state of the mixture), transported to the site by a special mixer truck, self-unloading or pumping to the site pre-installed template In the middle, the site receives water conservation and curing, and becomes a building component after hardening, and the overall performance is relatively good.
To buy components, the installation fee is one category, and the material and transportation costs are another.
Different component types are different in different regions.
to sum up
Precast concrete, referred to as "Shangyu", commonly known as ash or material: is composed of cement, aggregate, water and admixtures, mineral admixtures, etc., which are blended according to the needs. After the sale and use of the transport vehicle, the concrete mixture is transported to the place of use within the specified time.
Precast concrete, poured elsewhere rather than at the final construction site. (such as cement bricks, cement boards, etc.)
To put it simply: commercial concrete is a semi-finished product, and precast concrete is a finished product.
Nothing is better, only which is more suitable.