CSIR develops technology to turn hazardous foundry sand into eco-friendly bricks

Hazardous sand waste generated by thousands of foundries across India will now be recycled into eco-friendly and cost-effective construction material, with the Council for Scientific and Industrial Research (CSIR) developing technology to manufacture bricks from the industrial by-product.

CSIR’s National Institute for Interdisciplinary Science and Technology (NIIST) has joined hands with the private industry to use the know-how for setting up a unit that will initially produce around 5,000 bricks per day.

The unit will consume about 30 tonnes of sand daily to produce the high-strength bricks, that will comply with the IS - 1077 standards which define the specifications and requirements for common burnt clay building bricks.

India's foundry industry generates a significant amount of waste sand, which, according to various studies, is around three million tonnes annually.

This poses environmental hazards like land and water contamination due to its toxic characteristics and the presence of heavy metals. The dust from waste sand also adds to the particulate matter in the air and creates health risks.

Industry reports state that improper disposal is a major issue, especially for small and medium-sized foundries that lack the resources for proper treatment. To address this issue, there is a growing focus on reusing waste sand in civil engineering applications like construction of roads and buildings and for geotechnical applications.

India is the world’s second largest foundry hub after China, forming a vital element of the nation’s economy. The industry started in India around 1940 from Howrah and at present there are approximately 5,000 units across the country with an annual production of around 12 million tonnes and providing direct and indirect employment to 5,00,000 persons.

Over 85 per cent of these units are small to medium-sized enterprises, producing a wide range of items like vehicle components, machine parts, construction material, metal castings and alloys for the domestic market as well as for export.

There are scores of foundries in north India. In Punjab, the industry is largely concentrated in Ludhiana, Batala and Jalandhar, while in Haryana these are mainly located in Faridabad and Kaithal.

“NIIST has systematically studied the reactivity of the foundry sand waste with cement, lime, gypsum, and polymer modified binders and documented the critical parameters such as strength, density, water absorption properties usually required for building bricks,” a CSIR statement said.

“The continued scientific studies resulted in a process for making bricks through a simple cement bonded compression moulding technique,” the statement added.

The brick products have merits that it completely avoids usage of natural raw materials like clay sand and gravel. The bricks can also be shaped in aesthetically appealing colors for architectural interior design applications, according to CSIR. The NIIST technology also can be used to make paving tiles, hard aggregates and interlocks.