Indian Infrastructures to Replace 70% of Sand in Concrete with Shredded Plastic

Indian researchers had thought of a unique method which tackles two of the biggest environmental issues - sand conservation and cutting down plastic.

The team from Sona College of Technology, Salem, Tamil Nadu, developed a novel technology that will both save the nation's second-most used natural resource - sand - and help cut down the landfills created by waste plastic bottles, like hitting to birds with one stone as per The Weather Channel.

To do so, the 'green tech invention' will replace up to 70% sand in concrete with shredded plastic used in building their infrastructures.

"Our invention successfully utilizes recycled plastic waste as a partial replacement for fine aggregate or natural sand in making paver blocks and precast bricks," said lead inventor, Dr. R Malathy, also dean (R&D) and professor in department of civil engineering.

The technology has just been awarded a patent by India's Patent Office.

Converting plastic waste into usable construction material

Sand is a critical ingredient of our lives, and the primary raw material that modern cities are made from, which is why the 21st Century's most important, but least appreciated commodity sparked a "wave of violence" around the world, BBC wrote.

"Believe it or not, the world is facing a shortage of sand," the website said. "How can we possibly be running low on a substance found in virtually every country on earth and that seems essentially limitless?"

In India, nearly 70 million tonnes of sand are consumed annually to meet the nation's infrastructure demands, and this consumption is growing at 7% per annum, India Today reported. "At the same time, over 5 million tons of plastic are consumed each year, with only about a quarter being recycled and the rest ending up in landfills," the website said.

As a basic building block of construction, sand is indeed essential in all parts of the world, and in fact the planet is covered in it. However, extracting billion tonnes of sand per year has aggravating impacts on the planet and thus on people's lives.

Tackling the world's two environmental problems

The Sona College team of inventors developed a technology that converts recycled plastic waste into useable construction material to partially replace the traditional concrete ingredient.

"The breakthrough invention will hopefully check depletion of global sand stock as well as limit plastic waste," said Chocko Valliappa, Vice Chairman, Sona Group of Education Institutions. The researchers including Dr. R Malathy, Dr. SRR Senthil Kumar, N Karuppasamy and K Dhinesh Babu, earned the patent "Effect of recycled plastic wastes as partial replacement for fine aggregate in manufacturing paver blocks" in 2019. The team were awarded the final patent in early 2022.

The waste bottles (poly ethylene terephthalate) collected from Salem were crushed to less than 4.75 mm size in large machines. The engineers achieved 70% replacement of natural sand while matching the strength of tri-arc shaped paver blocks as per IS 15658-2006 codal.

"By utilizing plastic waste and dramatically reducing use of natural sand our patented technology offers significant environmental and cost advantage," said Dr SRR Senthil Kumar, Principal, Sona College of Technology.