Usage of Pre-Stressed Precast Hollow Core Wall & Slab in Green Field Project

PRE-CAST TECHNOLOGY

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.

98 CE&CR July 2015

Out Door Plant

Long Span Slabs Ideal for Podium Parks, Covering Over Nallahas, etc

Perimeter walls in Factory Shed, Ware Houses

- 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.

100 CE&CR July 2015

Spancrete 4’ wide (1.2 m) Hollow Core Slabs

Spancrete Floor Slabs Used on Various Structural Elements / Frames

Spancrete Vertical and Horizontal Wall Panels(Insulated and Non-insulated)

PRE-CAST TECHNOLOGY

Beauty

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

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.

Occupant Satisfaction

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.

Fire Safety

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.

Weather Resistance

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.

For more information contact Suresh Tripathi - sctripathi1963@gmail.com

Spancrete Highway Noise Barriers and Perimeter Walls

PRE-CAST TECHNOLOGY

102 CE&CR July 2015