In India, the construction sector is developing very rapidly and there is a massive demand for real estate due to which Precast construction has found its way to better quality and faster work.
The adaptation of this technology is becoming very rapid as the availability of skilled labor is getting reduced day-by-day, while as the demand for construction is increasing very rapidly in the country.
This practice of construction is gaining popularity at a fast pace as less labor is required with this process and it saves time. Because of faster completion processes which would enable them to give fast delivery of the project, developers in the construction industry and the government agencies turned out to be optimistic in the use of precast constructions.
Many real estate developers these days are moving away from the traditional type of construction, which is more time-consuming, due to which they are moving to precast construction technology like monolithic construction with aluminum formwork.
This type of technology has quickly caught up the popularity and thus it is widely being used in the construction industry for housing and infrastructure projects.
The Central Government and the state government are also urging contractors to make use of the latest technology for construction. Wherever the precast units are available there the government is floating tender for the construction of the precast structures.
Advantages of precast structures:
- The advantages of the precast are that it has better quality, factory condition production, better finish, and accuracy, and is suitable for all weather conditions.
- This process requires less labor due to which the cost of the construction also gets saved.
- It has a faster cycle time, repeatability, and scalability.
- Offsite and parallel work, standardization of design, engineering, and execution.
Limitations of precast:
- A larger volume of work is required for the viability of precast.
- Lots of equipment is required for this process in case of transportation, erection, and lifting of the structures.
Types of precast system:
There are various categories of precast systems depending on their load-bearing structure. The categories are large panel systems, frame systems, slab column systems with walls, and mixed systems.
The description of the precast system is as mentioned:
Large panel system
The large type of panel consists of multistoried structures of large wall and floor concrete panels connected in vertical and horizontal directions so that the wall spaces have appropriate spaces for rooms inside the building. The panels help in forming a box-like structure.
The vertical and horizontal columns both resist the gravitational load. Typically, the height of the wall panels is one story. The one-way or two-way slabs are formed by horizontal panels.
When the columns are joined properly together the horizontal panels form a diaphragm which transfers the lateral load to the walls. Depending upon the wall layout there are three basic configurations of large panel buildings namely cross wall system, longitudinal wall system, and two-way systems.
Precast Frames
Spatial beam-column assemblages or linear elements can be used to construct such frames. This column has the advantage that the sub-assemblages can be kept away from the critical frame regions.
Spatial elements are filled with difficulties pertaining to their formation, transportation and erection; therefore, they are not as popular as linear elements when it comes to pre-casting. The use of linear elements usually means placing the connecting faces at the beam-column junctions.
The beam-column is accomplished in the way they are hinged. In some cases, rigid beam columns are being used when the continuity of the longitudinal reinforcement of the beam-column joint needs to be ensured.
Mould release Oil is used for releasing the shutters which allows for quick and simple removal of shuttering out of a concrete surface and keeps concrete away from sticking onto it molds.
Slab column system with shear walls
These systems depend on the shear wall to sustain lateral load effect while the slab column structure bears the gravity load.
There are basically two types of systems:
- Lift slab system with walls.
- Pre-stressed slab column system.
In the lift slab type systems, precast concrete columns and slabs serve as the load-bearing structures. Columns that are precast could be as tall as two stories. Precast components are put together using unique connectors.
The reinforced concrete slabs are poured on in a ground form one above the other. The precast concrete floors are lifted from the concrete ground till the final height with the help of cranes.
First, lift the slab panels to the top of the columns; then, move them downwards towards the final position. Until the proper location for the columns is chosen, temporary props will hold the slabs in their respective places. The precast columns of the elements are 1 to 3 floors high.
Once the columns and slabs of a story are erected and then posted, the slabs are prestressed using prestressed tendons which pass through the ducts and columns at the floor level and adjacent slabs.
After the prestressing is done then post that the gaps in between the slabs are filled with in situ concrete the tendons become bonded with the spans between the columns.
The seismic load, which is taken into consideration in earthquake-prone zones, is resisted by the shear walls positioned between the columns at appropriate locations.
Precast concrete structural elements used in industry are as follows:
Wall panels
The walls can be precast in two types:
[1] To full thickness as one panel.
[2] Two leaves are a pair of double-panel concrete leaves which usually measure about 2 x 50-100 mm in thickness, containing special reinforcing supports and lattice girders.
In the first case, the wall panels can be built over a flatbed made of steel mold post which sufficient steam curing is done at a 60-degree angle. It is carried away by gantry girders with one end loading on a truck and further to precast yard or site.
The vertical position could also be accomplished in this way, followed by lifting and storing in a precast area after enough time has elapsed. While manufacturing precast wall panels the mostly used chemicals is superplasticizer. The plasticizer PCE 850 by Sakshi Chem Sciences helps in improving the strength of the precast construction.
Precast Staircases:
The designing of staircases is quite challenging within the standard classification of construction. The shuttering and pouring of the concrete are too cumbersome thus in that case precast staircases are beneficial to be fitted. Precast staircases are easy to manufacture and install.
Industrial structures:
These days even many of the industrial structures are being built as precast construction. There are many different types of industries in which precast construction is being done for quick construction saving time, money, and labor.
In the case of factories, it is very common that steel structures are being used for the construction of factories. Pre-engineered buildings help in providing large column-free structures that are useful to industry for setting up their machines.
The walls are constructed of 3-meter height posts and the sheeting is provided to the roof. The durability of sheeting lasts for 10-15 years post which replacement of sheeting is required. The external walls are made up of precast walls.
External precast RCC walls are also fire resistant, which provides protection against damage. The fixed support is provided for the precast RCC wall panels at the bottom over a beam connecting the column pedestals and, on the height, it is connected to angle-associated structural steel components from PEB.
Car Parking structures:
One of the best options to build a structure for car parking is precast concrete structure. The precast hollow core slabs are 12-15m while the double tee can have a span of 22 meters. The spans are large, especially for the parking spaces due to which it is ideal to make use of precast structures.
Precast RCC frame structures with precast floor slabs can be used for the construction which can be used for parking slots.
Infrastructure: Precast can be used in construction in multiple ways. The construction technique of precast can be used with such items as culverts, drainage channels, manholes, boundary walls, and subterranean tunnels.
More about Precast Construction:
The load-bearing wall panels with precast HCS as flooring is the best option for multi-story residential buildings. These precast walls also have resistance to natural calamities and earthquake and wind resistance.
For structures such as commercial malls, parking spaces, and structures with large column-free spaces, RCC column structures with precast columns and beams are among the ideal solutions.
For the industrial solutions, it is beneficial that the precast structures can be used as large space structures are required.
In the case of infrastructure projects, the precast structures can be used for setting up the culverts, abutments, retaining walls, and drain channels. Etc.
Precast structures are gaining popularity at a faster pace due to their convenience, reliability, and cost-effectiveness. Many real estate developers set up their own precast manufacturing units. It saves their time and labor.
It is expected that many new entrepreneurs may start providing precast solutions in the coming times due to its popularity. These days there are many architects who design structures taking into consideration the precast structures. Any kind of structure can be used for precast construction and reap the benefits of speedy construction and durable structures can be built.
Conclusion:
The Precast construction structures have many applications in the real estate & infrastructure sector. This technology makes it easy to assemble the structures, saves time, saves labor, and improves efficiency.
This technology is amongst the relatively new technologies and is fast gaining popularity in the construction sector. The new designs of the building are taken into consideration as per the precast technology.
The precast system is used in car parking structures, industrial structures, staircases & wall panels. Walls made using this technology are fire-resistant and durable. This technology has gained rapid growth and popularity in the fast-growing real estate & infrastructure sector in India.
The growth of this technology is rapid due to lots of benefits in construction like saving time & labor, being easy to install, and being cost-effective.
This technology has helped make construction easier in densely populated areas as the pre-casting can be done at different places and the structure can be transported to the site with the help of a vehicle.