Poor quality materials pose risk to strength of buildings
BENGALURU: Wednesday’s building collapse and similar incidents in the past have led to many questioning the quality of buildings constructed in the city.
One of the reasons for poor quality is the use of filter sand in construction because it is cheaper. River sand is expensive and supply is low. Sources say the use of poor quality material, including sand, may have been the reasons for the building collapse in Bellandur.
Farooq Mahmood, chairman and managing director of Silverline Realty, said, “Filter sand is not good for construction. Although riverbed sand is the best for such purposes, today there are many other options in the form of manufactured sand that is certified by the government and many builders use them. M-sand, produced by Ultra Tech, is eco-friendly, user-friendly and has zero impurities. Besides, it is almost 40 per cent cheaper than riverbed sand. Some developers use robo-sand. Of late, manufactured sand has been preferred because of its easy availability and relatively lower cost.”
He added, “It is difficult to state if poor quality sand was the reason for the collapse in this case. It could be wrong planning, inadequate foundation, loose soil, insufficient steel used or even lack of professional knowledge with respect to construction work. All possible parameters will have to be taken into consideration while zeroing in on the real cause of the disaster.”
What is filter sand?
Filter sand is extracted by washing the earth. The silt slurry is allowed to flow down while the separated top layer called “filter sand” is stacked. A few vendors even sell filter sand mixed with river sand.
Sandeepan Goswami, an engineer in a private company, said, “Sand acts as a binding agent in concrete. River sand forms naturally. It has various combinations like particles of rock, clay and silica. If the sand has more clay in comparison with other elements, concrete will not be firm.”