IMPORTANT THINGS YOU SHOULD KNOW ABOUT PRECAST CONSTRUCTION.

The concept of precast (also known as “prefabricated”) construction includes those buildings where the majority of structural components are standardized and produced in plants in a location away from the building, and then transported to the site for assembly. 

These components are manufactured by industrial methods based on mass production in order to build a large number of buildings in a short time at low cost. 

This type of construction requires a restructuring of the entire conventional construction process to enable interaction between the design phase and production planning in order to improve and speed up the construction. One of the key premises for achieving that objective is to design buildings with a regular configuration in plan and elevation.

HISTORY

The History of Precast Concrete Forms and its Innovations:-

The history of precast concrete can be traced back as far as the Ancient Roman Era in which the Romans, looking for ways to strengthen their infrastructure throughout the empire, came across concrete as a suitable material to carry out their architecture design plans. Soon thereafter, they began developing forms allowing them to shape the concrete into many sizes and use them throughout their building process. Many of the ancient Roman infrastructures such as their aqueducts, culverts and tunnels were built on the back of this precast innovation. Although not referred to as “precast” by Caesar and his legions, this was the first recorded record of this type of structural design.

Initially accredited with the official precast concrete design in 1905, Liverpool, England city engineer, John Alexander Brodie, was the first to develop and perfect the idea of using precast concrete forms in modern architectural design. Oddly enough, although the use of precast forms took off at an unbelievable pace throughout Eastern Europe, its uses in British architecture never really gained any traction.

As precast concrete moved forward in its evolution, the innovation of pre-stressing these concrete forms came about allowing for much stronger, more durable forms. What pre-stressing does is lays the concrete in the form over stressed cables and allowed to set up. These cables are stressed by stretching them extremely tightly. Once the concrete is hardened and cured, the cables are then cut allowing them to pull back to somewhat of their initial shape. Because the concrete is hardened around them though, this retraction is minimal. Minimal as it may be though it does retract enough to pull the concrete together even more so that is what provides the form its strength and durability.

In addition to strength and durability pre-stressing concrete provides, it is also watertight and due to its structural integrity can hold up to extremely heavy workloads without issue. These pre-stressed forms are also considered crack-free so they not only will remain water tight, but will also maintain their overall aesthetic design under any conditions.

THE MAIN FEATURES OF THIS CONSTRUCTION PROCESS ARE AS FOLLOWS:

• The division and specialization of the human workforce

• The use of tools, machinery, and other equipment, usually automated, in the production of standard, interchangeable parts and products

ADVANTAGES

Withstands everyday use:

All structures and buildings are subject to everyday wear and tear, and this iswhere the use of precast concrete really makes sense. It’s hard, tough surface is extremely resistant to everyday dents and dings.

Weatherproof:

Precast concrete is resistant to rain penetration, flood damage and wind- blown debris. It can also withstand many winters of freeze-thaw cycles unlike other materials, which can deteriorate quickly with such regular exposure to expansion and contraction

Thermally efficient:

Costs associated with heating and cooling can be greatly reduced through concrete’s thermal mass benefits. Reduced peak heating and cooling loads can be achieved because concrete reacts slowly to changes in outside temperature.

Comfortable:

The versatility of precast can be seen in its application as a carrying medium for heating or cooling – by air or fluids. Hollow cores in precast floors can be used or pipes can be cast into slabs. Concrete surfaces radiate very effectively, enabling space to be used without the hindrance of radiators, and the precast protects the heating or cooling system within.

WiFi compatible:

With homes and offices increasingly wired for information technology, it is good news that precast concrete buildings do not interfere with radio signals, local wi-fi or internet networks. This makes precast the most technology-friendly material for homes and places of work.

Resists buoyant forces underground:

With a specific gravity of 2.40, precast concrete resists buoyant forces better than any other material. Once it is installed, it stays put!

Protects against fire:

Precast concrete is fireproof. It protects against the spread of fire between rooms or properties, and it cannot catch fire, burn or drip molten particles

Structurally efficient:

Precast products can be designed with a high span-to-depth ratio, reducing the need for additional columns and supports. Precast can also be designed with lightweight concrete to reduce dead loads and decrease the size of structural members and foundations. 

Dampens vibration:

Structures like sports stadiums and concert halls are particularly susceptible to vibration from noise and crowd movements, which in some cases can be disturbing to people using the facility. Precast concrete can be used to dampen these vibrations due to its mass, which makes it the material of choice for modern stadium and concert hall construction.

Can achieve high strengths:

In civil engineering applications, high-strength concrete is often desirable, and precast components can be cast to meet such demands. If high early strengths are needed, this can be achieved through high-performance concrete, custom mix designs or accelerated curing methods at the plant.

Can support heavy loads:

Where point loads or high bearing stresses are likely, the dense, high-quality reinforced concrete in a precast concrete structure is absolutely critical. Industrial applications, utilities and underground structures are perfect for precast.

Absorbs impacts:

Precast concrete can resist massive impacts, so it makes an ideal material for security around public structures. Whether in day-to-day use as a median barrier or for protecting the perimeter of a building, precast structures can be designed to absorb the impact from vehicles, redirect them and/or slow them down.

Perfectly precise:

The accuracy factory controlled conditions in a precast factory are ideal for producing very precise, sharp details. This relies on the craft based skills of mold makes and through their and through their expertise even minute details become possible.

Resists chemical attack:

For sidewalks and driveways, precast concrete interlocking pavers are an ideal choice, because they are resistant to fuel and oil spills, they can be replaced easily and they are widely available.

Precast Concrete Technology, in an Indian Space can facilitate both speed and quality of the construction and at the same time exploits the advantages that these large scale projects offer in terms of volume turnover and the repetitions.

With the changing face of realty sector in Indian market, the change of construction methodology is inevitable.

This aims at demonstrating how the Precast Concrete Technology can be efficiently and effectively used on various Indian Projects in the light of Projects under execution.

The Advantages that Precast Concrete Technology has to offer can be exploited to the fullest for Mass Housing Projects comprising of small, compact size apartments in large volumes.

This Technology can be implemented on such Projects in two ways,

1. Site based precast Plant

2. Dedicated precast Plant

SITE BASED PRECAST PLANTS VS DEDICATED PRECAST PLANTS

The Site based precast plants forma lucrative option for Indian Market as the excise duty which otherwise gets attracted from Factory made precast components is saved.

Anyhow for adopting site based plant, there has to be sufficient volume of construction to justify the initial cost of setting up.

Also, such plants have lesser efficiency than state of the art plants for obvious reasons.