In Dialogue with Tarun Jami - A Path to Cement Free Building Methods

Tarun Jami and his team at Greenjams create eco-friendly construction products using crop leftovers and industrial waste. Over the past year, Solarpunk Futures has collaborated with GreenJams to adapt their product for our projects in Goa, using local waste materials. We spoke to him about their transformative alternative to concrete and their journey so far.

The interview has been edited for length and clarity.

Interview by Shivangini Tandon

Why did you start Greenjams? What problem were you looking to solve?

I started my company because I wanted to work on alternative construction materials in response to the climate crisis. Initially, I began with hempcrete, aiming to introduce it to the Indian construction industry. However, after studying its composition and manufacturing processes, I realised hempcrete wouldn't be well-suited for India for various reasons.

The main challenge was that hempcrete wasn't very strong because of the traditional binders used. While it had great thermal insulation properties and was carbon negative, using it would require specific engineering that most Indian engineers aren't trained for. Our practices are based on set rules and codes, making it difficult to adopt materials that don't fit these established norms.

What led you to develop Agrocrete®?

I ended up creating the world’s strongest hempcrete (self-proclaimed) during my R&D, solving the binder-related challenges. But scaling hempcrete required access to an uninterrupted supply of hemp stalks, which we don’t have. I simultaneously learned about the air pollution issues caused by crop residue burning in India. I thought, "We have so much biomass similar to hemp stalks getting burned. Why don't we see if that's a more accessible resource?" This led me to replace hemp with crop residues like paddy straw, sugarcane bagasse, and cotton stalks.

Can you explain what Agrocrete® is?

Agrocrete® is a type of concrete that uses three main ingredients: BINDR (our proprietary alternative to cement), biomass (agricultural waste), and fillers (industrial waste materials like mining residue, construction and demolition waste, ceramic residue, fly ash etc.). It's similar to regular concrete in that it can be moulded into various shapes and forms, but it has better thermal insulation properties and its carbon emissions are significantly lower. 

Agrocrete Block 30 gm CO2/block

Cement Block 1 Kg CO2/block

14% Bindr 15% cement

16% sawdust 45% aggregates

(from furniture factory)

69% soil 40% sand

(excavated soil)

How does Agrocrete® compare to traditional concrete in terms of strength and sustainability?

In terms of strength, we're pretty much matching or exceeding traditional concrete. Agrocrete® performs better when it comes to weight, density, and thermal insulation. It's also carbon negative, meaning it sequesters more carbon than is emitted during its production. However, it is currently more expensive to manufacture due to the additional processing steps involved.

What are the main challenges you're facing with Agrocrete®?

One of the primary challenges is sourcing raw materials, particularly biomass. Unlike quarrying for stone and sand, sourcing agricultural waste requires building networks with farmers and dealing with seasonal availability.

Manufacturing at scale is another challenge. As we aim to produce larger quantities, we need to solve equipment and quality control challenges, as existing machinery isn't always compatible with biomass processing.

There's also room for product improvement. We're working on parameters like moisture resistance and weathering to make Agrocrete® even more durable.

How do you see policy playing a role in promoting sustainable construction materials like Agrocrete®?

Ideally, we need policies that incentivise low-carbon construction. For example, setting limits on embodied carbon per square metre of construction, with financial incentives for staying below the limit and penalties for exceeding it. This could be implemented through preferential interest rates on construction loans, or reduced regulatory fees or licence costs.

Another approach could be through building approvals, where projects exceeding a certain embodied carbon limit would have to pay a carbon tax.

What's your vision for the future of sustainable construction in India?

With 80% of the buildings that will exist in India in the next decade yet to be built, there's a huge opportunity to focus on reducing embodied carbon (emissions from manufacturing, transportation and installation of building materials). While operational energy efficiency in buildings is important, we can potentially bring operational carbon footprint close to zero through various existing technologies and methods. However, it's much more challenging to bring embodied carbon to zero, which is why focusing on materials like Agrocrete® is crucial.

The key is to continue innovating, scaling up production, and working towards policies that incentivise the use of low-carbon materials. This way, we can significantly reduce the environmental impact of India's rapidly growing construction.

For more info about Greenjams, visit greenjams.org  Learn more about embodied carbon in building: https://www.carboncure.com/concrete-corner/what-is-embodied-carbon/