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The rise of carbon negative materials.

The building and construction industry is facing inflationary pressure due to the shortage of raw materials and increasing fuel prices. Steel prices are up 45%, copper has risen to 75%, and aluminum prices are up 50%. The cost of labour has also gone up by approximately 15% since the onset of COVID-19. Building materials are the main component in any construction project and variations in their prices can affect the whole project. Apart from this, what are the repercussions of using these materials that rely so much on the availability of raw materials?

Shortage of raw materials and inflation in prices have dominated the agenda in the construction sector for the entirety of 2021 and it will follow us into 2022. Source

 5% of carbon dioxide emissions are caused by the manufacture of building materials and the space conditioning of buildings. In this article let’s look at two of the most common materials used in construction today ie. AAC blocks and cement. Autoclaved Aerated Concrete (AAC) blocks are the preferred choice of walling material for almost every real estate developer in the market today because they’re cheap and enable faster construction. But they aren’t easy to live with.

The blocks are very porous and absorb huge amounts of water; the expansion and contraction are so much that they eventually crack.  The plaster de-laminates after a few years of construction and the structural integrity gets compromised if the chiseling for concealed conduits is not done accurately. Most importantly, you cannot hammer a nail into the block without shattering it. To overcome all of these difficulties builders end up installing RCC tie beams after every 4 rows of the block-work, using only power drills to fix nails, and so on.

Urbanisation is on a rampant spree around the world. There have been heavy constructions everywhere we see. Now, the building of infrastructure majorly uses cement. If we look closely into this cement, it is a major contributor to the destruction of the environment. The problem becomes evident if we understand the process of making cement. 

The raw materials are crushed and mixed with iron ore or ash and fed to cylindrical kilns at around 1,450 degrees Celsius. The process is called calcination, which splits the mixture into calcium oxide and CO2, giving out a new product called clinker. The new marbled-sized and grey product is cooled and mixed with gypsum and limestone and sent as a ready-mix to concrete companies. Half of the CO2 emissions from cement happen during the process. 

4–8% of the world’s carbon dioxide (CO2) emissions come from the manufacturing of cement, making it a major contributor to global warming. Source

This was a problem that Tarun Jami, founder of GreenJams identified and decided to tackle. He set up GreenJams in 2017, intending to create a carbon-neutral building environment in the construction industry. While GreenJams initially started focusing on the development of hempcrete they also wanted a solution to a bigger social problem. Crop residue burning costs the country almost $27 billion in economic losses and causes more than 10 million premature deaths.

Tarun experienced this first hand and decided to experiment by replacing the hemp with crop residue. This led to the innovation of Agrocrete, made from agricultural residue and industrial by-products. Agrocrete is made by collecting residue from farmers, processing it, and mixing it with another product exclusive to GreenJams called BINDR. Let’s look at these two materials in detail and compare them to AAC blocks and cement.

The company has received more than 1200 sales enquiries totalling a volume of more than 11 million Agrocrete®  blocks in 2021. Source


Agrocrete® bricks/blocks are made from crop residues like paddy straw, cotton stalk, bagasse, etc. and industrial by-products like slags, ashes & lime sludge. The company is currently focusing on the agrocrete hollow blocks owing to their versatility.

The hollow blocks come in 4 sizes however they can be customized as per requirement. The sizes are as follows:

  • 400x150x225mm
  • 400x150x150mm
  • 400x150x125mm
  • 400x150x100mm

 The compressive strength of hollow blocks is more than 5 MPa as compared to 3-4 MPa of AAC blocks. The water absorption of the hollow blocks is 10% against 15% of AAC blocks. Hollow blocks offer 40% lower construction cost, 40% higher thermal insulation, and 20% thinner walls giving more carpet area for the same built-up area. The blocks last around 75 years under favourable conditions. 

THE EMBODIED CARBON OF THE HOLLOW BLOCKS IS -0.15 kg CO2/kg AS COMPARED TO THE 0.24 kgCO2/kg OF FLY ASH BRICKS. This means it absorbs carbon dioxide making it carbon negative. Agrocrete®solid blocks are tested and certified by CSIR-CBRI, Roorkee according to IS 2185 Part 2.

Apart from capturing carbon dioxide from the atmosphere and reversing climate change, Agrocrete® also makes buildings energy efficient by being thermally insulating. Source


BINDR is a low-carbon replacement of Portland cement made of industrial co-products. It is made of 100% upcycled materials and is non-toxic. The block also consumes less water and gives out 80% fewer carbon emissions than Portland cement. It has an embodied carbon of 0.10 kg.CO2/kg. While it is currently not available commercially, the company hopes to introduce it as an add-on purchase in the future.

 BINDR can be used as a non-structural replacement for portland cement.source

Both the products are being patented and are based on low energy, low resource and advanced alkali activation chemical technology. To prove the concept, Tarun built an 1100 sqft load-bearing extension and manufacturing unit to his current office space using agrocrete and BINDR. The extension was built for Rs 1.95 lakh, that would have otherwise cost 5.5 lakhs. The cost of construction was reduced by 30% and in less than 40% of the time required. Less than Rs 200 per square foot was spent on construction as opposed to Rs 500 per square foot, which is a number you can consider if you use the cheapest brick available.

Construction was completed in 4 days, which would otherwise have lasted approximately 12 days. By using all these carbon-negative materials, they were able to capture 3.1 tons of carbon dioxide from the atmosphere. Nobody could have imagined creating building materials made of crop residues and industrial by-products. The company has revolutionised the way building materials are being manufactured keeping in mind the ecological balance that our future generations need. 

GreenJams is an award-winning CleanTech Social Enterprise decarbonizing the built environment. Source


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