In the high-tech age of the twenty-first century ,builders and building technology developers in India no longer talk about the cost of building large structures. They are more concerned about their life-cycle cost and environmental sustainability. They emphasize the aesthetic aspect as can be seen from some of the structures which dot the skyline of our metropolitan cities. The growth in knowledge oriented sectors has led to the increase in the economy so that developers are investing huge sums in the infrastructure.
The cost to the environment of materials used is of utmost importance. Pre-engineered buildings are an example in which the construction cost includes environmental cleanup cost. We are familiar with the mess created by energy production facilities. One way to overcome this is through the use of more fly ash for roads and buildings. This can be mixed in ready mixed concrete to reduce waste on site mixing. This also leads to quick settling concrete so that scaffoldings can be quickly stripped for the next operation.
According to the seismic rezoning of the country, a city such as Chennai would be in Zone 3 seismic region. This leads to congestion of reinforcement in the joints, and in order to overcome this, self-compacted concrete with special admixtures are being used. Rebarring technologies are improving so that walls are now stronger. New curing compounds are being utilized to reduce water use.
It is a commonly heard complaint about the big noise pollution at construction sites. To negate this, pre-case in piles are being used by builders for pile driving work.
Corrosion too is a great hazard. All new technologies do not make for seismic safety. The use of high-strength rebars for example may be harmful from the point of view of seismic safety.
Newer technologies are emerging in the use of high tensile steel and post-tensioning technologies are gaining importance. The post-tensioning technology is applied to get over the problem of the sagging of load bearing beams and structures on account of excess weight. VSL India is using it for large slab structures, bridges, stadia and dams. With this the steel reinforcement is lighter and the foundation load is less. This technology which popularizes the most tensioned slab saves both cost and time for the client.
Although high-tensile steel should definitely be used in modern construction of tall buildings and bridges, it is not as ductile as mild steel. Therefore it should be appropriately designed. The key is to use high strength steel which has good ductility. This is possible today with rapid advancement in the manufacture of rebars. Steel which has an adequate uniform elongation for protection against seismic and other dynamic loads is ideal.
These new concepts in building technology are incorporated into the system for economy and affordability as well as seismic safety. They are setting the trend for future construction.