Wednesday, 26 November 2014

Role of Concrete in Building Constructions

 Role of Concrete in Building Constructions
Innovation seems to be leading the way when it comes to usage of construction material. New materials and methods are changing the way we perceive the industry. There are already such innovative materials in use.

Aggregates used in making concrete are either naturally occurring or produced from stone crushers. As natural sources are fast depleting, there is a need to produce aggregates of high quality to make concrete which is durable in all conditions.
Conventional stone crushers tend to produce flaky and elongated aggregates. These are mostly two-stage and three-stage crushing plants. Conventional crushers cannot produce crushed stone of required near cubical shape. The solution can be found in a Vertical Shaft Impact (VSI) crusher as it produces cubical crushed stones, ideal for self-compacting concrete. The greatest use of this crusher is its ability to produce manufactured sand.

Self compacting concrete(SCC) is an advanced type of concrete that can flow through intricate geometrical configurations under its own mass without vibration or segregation. It is made with the same materials which are used for making normal concrete except for high powder content (fly ash or slag along with cement) and use of hyper plasticisers for making flowing concrete.  It has proved beneficial economically because of following reasons :

› Faster construction
› Reduction in site power
› Better surface finishes
› Easier placing
› Improved durability
› Greater freedom in design
› Thinner and complicated section
› Improved working environment at a construction site by reducing noise pollution.

Proper curing is essential in producing acceptable concrete performance. This affects both mechanical properties and durability characteristics, and reduces volume changes due to shrinkage. A truly effective curing approach requires two components : Prevents loss of moisture through evaporation. Supplies additional water for continued hydration. Excessive evaporation from concrete surface must be avoided.  This is done by using curing compounds.  There are two types of curing compounds viz., wax based and resin based. Liquid membrane-forming compounds are suitable for application to concrete surfaces to reduce the loss of water during the early hardening period.
White-pigmented membrane-forming compounds serve the additional purpose of  reducing the temperature rise in concrete exposed to radiation from the sun.  curing compounds are used extensively in large areas such as concrete pavements, canal lining etc.

You might think hat concrete is a boring material. Not at all. You can now find concrete that bends like metal and which is five times as strong as regular concrete without any reinforcing steel bars. Or you can use concrete which doesn't need a vibration machine to remove the air bubbles inside, which can save loss of time during construction.
There are also translucent concrete or concrete incorporating transparent elements, allowing to build floors lit from below. And by adding titanium dioxide to cement, you obtain a self-cleaning concrete that remains the same colour for centuries and can even clean the air by breaking down dangerous pollutants.

Ultra-high performance, fibre reinforced concrete (UHPFRC) is a revolutionary material that offers superior strength, durability, ductility and aesthetic design flexibility. It is significantly stronger than conventional concrete.  Available in a range of colours, it is extremely moldable and replicates form materials with great precision. By utilizing Ductal's combination of superior properties, designers can create thinner sections and longer spans that are lighter, more graceful and innovative in geometry and form, while providing improved durability and impermeability against corrosion, abrasion and impact.

Studying the nano structure of concrete could help reduce carbon dioxide (CO2) emissions during its manufacture, according to work by engineers at the Massachusetts Institute of Technology (MIT).
Around 2.35 billion tons of concrete are produced each year and producing cement, the main component of concrete, accounts for five-ten per cent of the world's total CO2 emissions – an important contribution to global warming.
Franz-Josef Ulm and Georgios Constantinides of MIT have found that concrete is strong, thanks to the way in which the nanoparticles are organised.
“If everything depends on the organizational structure of the nanoparticles that make up concrete, rather than on the material itself, we can conceivably replace it with a material that has concrete's other characteristics – strength, durability, mass availability and low cost – but does not release as much CO2 into the atmosphere during manufacture,” explains Ulm.

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