Usage of Pre-Stressed Precast Hollow Core Wall
& Slab in Green Field Project
With the current Govt’s focus on Fast tracking of the Mega projects in Power, Steel, Fertilizer, Coal, Warehousing etc., it becomes very essential that a proper solution to construction is found out which can give advantage on the 3Ms of the project i.e reduce manpower, Reduce waste of material, Reduce cost. This is where Precast comes in to picture.
Today, in any green field project, the greatest challenge to the engineers & project managers is to manage time. Delay and hurdle often arises due to non availability of site and sequencing of cast-in-situ concrete limits the construction time flexibility of the construction manager.
For example in early times, a power plant used to take 48 months to build & mostly all activity from fabrication to Civil works was done on site. To cut on time, trend of prefabricated structures started in which steel was prefabricated in shop and brought to site when foundations are ready & erected
Then all the steel beams & columns were erected and given to GCW contractor to put concrete on various levels of floor & hand over the floors to different teams for further works. Often this needs a great coordination and yet all Project Managers were under pressure to deliver and due to movement of unskilled labours, the area also becomes unsafe.
Hollow core Pre-stressed Precast presents a unique model of working and is perfectly feasible in the most economic way to avoid or minimise the cast-in-situ works on the project site. This will also help the project managers to pre plan & do works in parallel, even if site has not been fully acquired & work on casting of floors can commence in parallel with area grading and foundation in a project. This can save a minimum of 30% construction time.
There is a need to change the mindset of the designers to adopt the proven technology which is available and use it innovatively. Another typical example is of large warehouse sheds in that the perimeter wall (which is currently made up of bricks and RCC bands) could be replaced with precast walls. This is very cost effective and fast to implement. Quality of work improves as the product is produced from factory setup.
How to Do This in Green Field Projects
- Plan from the design stage
- Make the design Precast friendly
- Prepare tenders keeping in provision Prestressed Precast hollow core. For walls & slabs
- Set aside a space in plant for the precast yard & factory of about 15 Acres
- Issue the slabs to the contractor on area basis free of cost just like issue of steel
Operation of the plant can be done by manufacturer of the machine.
Spancrete® Hollowcore Advantages
Fast, safe erection with minimal crews.
- Install in excess of 1000m2/10,000 ft2 per day on steel beam, precast, masonry or poured structures.
- All year construction.
- Once in place, Spancrete® hollowcore slabs provide a secure deck that allows other trades to begin working.
- Each slab’s smooth surface can be carpeted or tiled directly with minimal preparation.
- Slabs can be lifted and installed directly from delivery vehicles.
- Horizontal or vertical hollowcore wall panel capabilities.
- Hollowcore spans can be up to 20m/65ft, the world’s longest.
- Fire ratings of up to 4 hours.
- Offers reductions in sound transmission, for a quiet environment.
- Significant energy savings are achieved with Spancrete Insulated Hollowcore wall panels.
- Fast Turnaround
- Compared to site-cast concrete, precast concrete erection is faster and less affected by adverse weather conditions.
- Plant casting allows increased efficiency, high quality control and greater control on finishes.
In addition to the above other advantages are:
Highest Production Rates: The Spancrete machine produces at a rate of 2.5+m/8+ ft.per minute, resulting in 1200+m2/12,000+ft2 per 8 hour shift.
Most Accurate Tolerances: The Spancrete Machines’ hydraulic tamping and troweling mechanisms result in smooth, flat surfaces which can be carpeted or tiled directly with minimal preparation. Unmatched dimensional specifications within +1.5mm / .063in, the highest standards in the industry.
Advantages of Building with Precast, Prestressed Concrete
Architects, engineers, general contractors, developers and owners have been specifying Spancrete® precast products for more than 69 years. These time-honoured architectural and structural precast components combine to form strong, long-lasting fixtures in our everyday lives. Every member involved in the construction project benefits from the many advantages of using precast building products.
Precast Offers Design Versatility
“Versatility” is synonymous with precast. The selection of structural and architectural precast concrete products offers aesthetically pleasing yet economical solutions for many types of construction projects. Precast concrete offers a variety of surface finishes and textures. Choose ribbed, raked, broomed, sandblasted or exposed aggregate finishes. Colour and reveals are available, enhancing the architectural treatment choices. Precast wall panels are not only ideal for new construction projects, but can be matched to existing structures for additions. Precast concrete components can easily be designed to accommodate future growth. Interiors can be reconfigured simply and quickly for the changing needs of the building. Precast products can span over long areas, resulting in large, open interiors without obstructions or expensive support structures.
Nothing combines beauty with versatility, economy, and efficiency like precast concrete. With all the choices of decorative finishes, wall panels combine a custom architectural exterior with a durable interior surface to create an attractive, long-lasting building. The pattern, texture, and color variations are practically unlimited, from exposed aggregate finishes to thin brick patterns.
Durability is the one quality that allows precast, prestressed concrete to outlast competing materials. With its durable design, Precast is exceptionally resistant to impact, corrosion, weathering, and abrasion, rendering it virtually maintenance free.
Project Efficiency/Speed of Construction
Precast concrete offers rapid, all-weather construction. It can be constructed year-round, in all types of weather, making fast-track construction a routine job meaning projects are done faster and occupied sooner, for a quicker return on investment. In addition, insulated wall panels maximize thermal efficiency to save energy costs and conserve natural resources. Durable, fire-resistant precast concrete also lowers maintenance costs and insurance rates, for even greater savings, while plant manufacturing of precast concrete under an established quality assurance program ensures consistent reliability, and saves production costs through repetitive operations. As soon as Spancrete® Hollowcore Plank is secured in place, it becomes a working surface for trades such as mechanical contractors, electricians, and plumbers. This advantage accelerates the entire construction process, facilitating earlier occupancy. Because construction crews work year-round, in all types of weather, Spancrete® projects stay on or ahead of schedule.
Green Building Construction
Precast concrete components reduce energy consumption in several ways: precast construction allows minimal air infiltration, thermal mass delays internal temperature changes and reduces peak heating and cooling loads, and sculpted shapes facilitate the design of shading devices for window areas. Precast components can be cast with insulation attached during manufacturing process, to increase the structure’s R-factor.
Long Term Cost Savings
Low maintenance costs and insurance premiums, coupled with greater occupant satisfaction and higher resale values, are demonstrated benefits of building with precast. The durability of precast, prestressed concrete components means that buildings last longer and look better over the years.
Precast building systems reduce vibration, assist in noise control, and create a safer environment. Occupants can enjoy the inherent quiet and comfort that precast concrete provides. In fact, precast concrete buildings typically have higher occupancy rates, greater tenant satisfaction, better lease rates, and outstanding resale values. One of the most remarkable competitive advantages of precast concrete is its performance on life safety issues. Precast components and precast structural systems have demonstrated added value in fire safety, wind, flood, earthquake protection and noise control for overall occupant comfort.
Precast is unsurpassed in providing fire protection and containment when incorporated into a comprehensive, balanced design. Precast concrete does not burn or give off lethal fumes in even the hottest of fires, and it maintains its structural integrity, giving occupants more time to evacuate safely and extinguish the fire. The fire rating of precast hollowcore plank saves on insurance costs and enhances tenant satisfaction.
Precast concrete provides protection against the winds of hurricanes and thunderstorms, and has recently been cited as an effective barrier to damage from tornadoes as well. Precast concrete also is impervious to termites and dry rot, creating a structure that does not weaken over time.
Low Sound Transmission
Precast is a high-density material that provides excellent, if not unsurpassed, sound reduction, allowing tenants to benefit from a quieter and less disruptive environment. Precast floors, roofs, and walls have high STC ratings and offer superior sound absorption and impact sound reduction.
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