We’ve been scooping the bottom of our rivers like they’re infinite sandpits. But while our cities rise taller and wider, our rivers face an unprecedented strain and are left gasping for breath. Sand mining in India has gone from necessary to downright destructive, eroding riverbanks, draining aquifers, and bulldozing biodiversity along the way. And the irony? We’re doing this all in the name of building a "sustainable" future.
That’s the intriguing shift explored in the latest edition of Sediment Stories, a dialogue series hosted by Veditum India Foundation. Instead of mining riverbeds, what if we mined our construction waste—those broken bricks, concrete chunks, and leftover tiles that usually get dumped and forgotten?
Enter construction and demolition (C&D) waste—a gritty underdog in the building materials world that's suddenly stepping into the spotlight. The conversation featured a pioneering voice in sustainable construction who is proving that what we discard can actually build us a better, greener tomorrow.
Turns out, we don’t have to wreck rivers to raise walls. By replacing sand with recycled aggregates and industrial leftovers like fly ash, we can cut down on environmental damage while keeping buildings strong and stylish. So maybe it’s time we looked beyond the riverbed—and into the debris pile—because the future of construction might just be hiding in yesterday’s demolition.
The conversation, led by Aishani Goswami from Veditum, featured Keyur Sarda, founder of Kesarjan Building Centre Private Limited. Sarda, a pioneer in sustainable construction, shared insights from decades of experimentation with eco-friendly materials. Beginning in the 1990s with fly ash bricks, his journey later shifted to recycling C&D waste.
“Engineering and environmental consciousness brought me here,” he said. “What we’ve built today is the result of years of collaboration with family, engineers, and professionals.”
Veditum, an organisation dedicated to environmental action, has been fostering awareness about pressing ecological issues, including sand mining and sediment management. Their "India Sand Watch" project aims to protect India's rivers from unsustainable mining. "Sediment Stories" serves as a platform to examine the movement of sediment from its creation to extraction, engaging experts from fields like ecology, geology, hydrology, journalism, and activism.
Sarda, an alumnus of CEPT University, Ahmedabad, recounted his journey into sustainable construction and explained how his facility processes construction and demolition waste.
He says that construction and demolition waste is often segregated at construction sites, making it an ideal source of raw material. "We receive the waste, crush it, and sort it by size. Instead of washing the aggregate, which is costly, we keep the process simple—remixing segregated components to create lean concrete for bricks and blocks. This low-energy approach retains valuable silt, reducing waste and enhancing the product’s quality."
Beyond construction and demolition waste, Kesarjan Pvt. Ltd. also incorporates other pozzolanic materials like finely crushed bricks (surkhi) and ceramic tiles. "These materials react well with lime, forming strong, durable bricks and blocks. The mix of different waste components also results in unique colours, making our products visually appealing," he explains.
These bricks have been used for load-bearing walls, paving blocks, and even domes. “Our bricks test at around 7.5 MPa—nearly double the strength of conventional bricks in Gujarat,” he said. Despite challenges in cost and policy, his team has produced M30-grade self-compacting concrete using 100% recycled aggregates. He says, “Research supports replacing up to 30% of traditional aggregate without compromising quality. The IS codes are beginning to reflect this potential.”
A major theme of the discussion was the challenge posed by sand mining. In many parts of India, river sand is a crucial but over-exploited resource. Sarda highlighted that recycled aggregates could serve as an alternative.
River sand remains cheap—around Rs. 800 per tonne in Ahmedabad—but its environmental cost is immense. Recycling C&D waste is more expensive, especially without subsidies for waste disposal or collection. "If the government offered free or low-cost delivery of C&D waste, recycled products could become more affordable, and we could compete with river sand,” Sarda pointed out.
He also highlighted issues with government tenders by saying, “Many specify foreign technologies that don’t suit the Indian context. For instance, washing aggregates. It is unnecessary in many cases and generates additional sludge disposal challenges."
Despite these hurdles, market awareness of sustainable materials has grown. "People are increasingly interested in these materials, and doubts about their quality have largely been dispelled. Scaling up is less about demand and more about encouraging entrepreneurship in this sector. The government can play a crucial role in this regard," Sarda emphasised.
The conversation also touched upon alternative materials, including lime mortar, which Kesarjan Pvt. Ltd. has been developing. "Lime and pozzolanic materials offer a viable replacement for cement often, significantly reducing the environmental impact of construction. We should look beyond just construction and demolition waste—there is enormous potential in utilising mineral waste in the building industry," Aishani Goswami said.
The discussion focused on practical applications such as production capacity, cost comparison, and performance characteristics of the recycled bricks. Sarda explained that his facility produces around 10,000 bricks per day, with costs ranging from Rs. 9 per standard brick to Rs. 16 for customised colours. "Compared to conventional bricks, our water absorption rates are slightly higher at 15-16%, but we are working to reduce this further. Our bricks have been successfully used in exposed applications, though we recommend applying a water repellent to prevent algae formation."
As regards government policies, Sarda acknowledged the existence of guidelines but pointed out gaps in implementation. "The Central Public Works Department has guidelines for using 20% recycled materials in projects, but actual enforcement is weak. Many recycling plants in India struggle to find markets for their products, even though the demand should be there. Acceptance and regulatory mandates would make a big difference."
Regarding the potential for on-site brick manufacturing, Sarda noted, "It’s possible but challenging due to noise and dust from crushing operations. However, if done in areas without residential constraints, it could be a viable model."
On whether these bricks could be used in cavity wall construction for improved insulation. Sarda affirmed, "Cavity walls can enhance thermal mass, but proper drainage and ventilation are crucial to prevent moisture condensation. This is a highly effective technique in areas with extreme temperatures."
"No special expertise is required. Our bricks are designed to fit standard construction modules, minimising waste. However, for exposed applications, careful placement is necessary to ensure a visually appealing finish," Sarda explained.
Reflecting on his experience, Sarda noted that despite initial scepticism, recycled materials have found their place in mainstream construction. "When we started, people doubted whether recycled bricks could match conventional ones. Now, major projects use them confidently. The shift in mindset has been significant."
The session reinforced the importance of innovative solutions in addressing construction waste, sand mining, and sustainable development. It underscored that addressing sediment overextraction, construction waste, and urban expansion demands more than policy—it calls for innovation, collaboration, and courage to build differently.