Debris is precious,don’t just dump it

KSPCB: it could be replace riverbed sand in construction

It may not be long before the mounds of construction rubble that litter the city’s outskirts are turned into building material, replacing the increasingly scarce and expensive riverbed sand.

The Karnataka State Pollution Control Board (KSPCB) has directed the Bruhat Bengaluru Mahanagara Palike (BBMP) to set up a unit at a site in Mallasandra (on Hessarghatta road), which is already designated as a municipality dump yard for construction waste. A unit here should be able to crush and process 50 lorry-loads of debris everyday, KSPCB chairman Vaman Acharya told The Hindu .

According to estimates of the Central Pollution Control Board, India’s construction industry generates around 14 million tonnes of waste every year. A recycling unit makes imminent sense as it could solve two problems at once, he said. While this will help dispose tonnes of debris dumped illegally everyday, it will also make a sound replacement to river sand, which causes ecological degradation.

The recent clampdown on sand extraction by the National Green Tribunal, and the truckers’ strike, has sent river sand prices soaring, and a single truck load of sand now costs between Rs. 60,000 to Rs. 1 lakh, said R.V. Ranganatha, head of department of Civil Engineering at BMS College of Engineering, and former chairman of Indian Concrete Institute — Karnataka Bangalore Centre.

Ideally suited Bangalore is seeing a wave of new construction projects and is ideally suited for a construction waste recycling unit, he added. The construction industry is beginning to look for alternatives, and processed construction debris can make a good substitute that can also meet durability standards, said Mr. Ranganatha.

Riverbed sand is essentially used as ‘fine aggregates’ — or fine particles to fill voids in material — while making mortar. “Riverbed sand is preferred for fine aggregates because the grains are tiny and spherical,” he said, adding however that construction debris can be crushed to such fine sized particles.

BBMP Commissioner M. Lakshminarayan told The Hindu that it will soon call for “Expression of Interest” to run the processing unit in Mallasandra. He added that although Mallasandra is the designated site for construction debris, it is barely being utilised as debris continues to be dumped clandestinely on road sides and empty plots.

He suggested that the KSPCB and the BBMP work together to create a stronger system that incentivises offloading construction waste at Mallasandra.

“The debris could be segregated, processed and sold at prices much lower than the market rate.” Alternatives to river sand — including manufactured sand, copper slag, processed quarry dust and construction demolition waste — are being increasingly used around the world including in EU countries, the USA and Singapore, said Mr. Ranganatha.