Cement, flyash, ground granulated blast furnace slag(GGBFS) are the key components in the ternary blend used to make concrete. Nagesh Veeturi and Sumanta Sahu of KEC International – Civil Business, shed light on reducing the carbon footprint of cement production by using supplementary cementitious materials.
Cement is prime ingredient in concrete. One tonne of cement produces around 0.8 to 1 MT of carbon dioxide. It’s worth noting that efforts are being made to reduce the carbon footprint of cement production by using supplementary cementitious materials such as flyash and GGBS in concrete. In case of ternary blended concrete, supplementary cementitious materials flyash and GGBS are used in addition to cement, sand, aggregate, water and admixture.
To evaluate the percentage of replacement of cement with flyash and GGBS, one needs to understand the properties of concrete mix with flyash and GGBS as ingredients, structure strength, stripping time and durability requirements.
Properties of Supplementary Cementitious Materials
Flyash
Pulverised coal is used in thermal power plants for electricity generation. A by-product of this combustion reaction is fly ash. The electrostatic precipitators (ESPs) used inside chimneys of the power plants remove flyash before ejecting out the combustion gases into the atmosphere. Fly ash is a very fine particle like residue, which has pozzolanic properties. Hence it is often blended with cement and also used as partial replacement of cement.
Fly ash consists of silica (SiO2), alumina (Al2O3) and calcium oxide (CaO) as its major components. Fly ash can be of two types – C type and F type. C type fly ash is rich in calcium oxide and possesses both cementitious and pozzolanic properties whereas F type fly ash is low in calcium oxide content and possesses only pozzolanic properties.
Due to spherical shape of flyash, water demands in concrete is reduced, concrete becomes more cohesive.
Silica in flyash reacts with calcium hydroxide released from cement to form CSH Gel, Formation of CSH Gel leads to increase in strength of concrete further and make the concrete dense and durable.
35 per cent of cement can be replaced with flyash according to IS specification. However, for mass concrete high volume flyash up to 50 per cent can be used.
Early strength observed to be less for flyash concrete.
Due to slow development of strength of concrete, stripping time gets delayed.
(Flyash produced from Thermal Power Plant)
Ground Granulated Blast Furnace Slag (GGBFS)
Blast furnace slag is a by-product of iron ore during iron extraction process. Amongst all mineral admixtures, blast furnace slag has the highest specific gravity (2.8 to 3.0). Typically, the slag fineness is slightly more than that of the cement.
There are various types of slag available like air cooled slag, expanded or foamed slag, granulated slag. Among these only the granulated slag is commonly used as a mineral admixture. It is a highly reactive form of slag and is usually quenched to form a hardened matter which is then grounded into particles of fineness almost same as that of cement. Hence the material is called as ‘ground granulated blast furnace slag’.
GGBFS possesses both cementitious and pozzolanic properties. An activator is needed to hydrate the slag.
GGBFS increases the initial setting time of the concrete. But it does not alter the workability of the concrete much because its fineness is almost same as that of the cement.
The early rate of strength gain in concrete is diminished by replacement of cement in the concrete with GGBFS.
The final strength is improved by slag cement and also the durability of the concrete is increased.
Concrete uses in marine construction are highly prone to chemical attack and corrosion. GGBFS as a concrete ingredient increases resistance against sulphate and chloride attack.
Normally concrete tends to segregate with GGBS as ingredient,
(GGBFS produced from Steel Plant)\
Concrete with flyash and GGBS as ingredients (Ternary Blend)
Ternary blended concrete is observed to be more cohesive and workable due to presence of flyash in concrete. Early strength gain can be achieved by using both Cement and GGBS in concrete. Concrete with ternary blend is win-win situation in terms of good product quality, optimising the cost of concrete, durability and resistance against chemical attack. Additionally, the use of SCMs in concrete can contribute to sustainability efforts by minimizing the cement content which is associated with significant carbon dioxide emission during its manufacturing process.
The hydration process of ternary blended concrete is divided into primary reaction by OPC and GGBS, pozzolanic reaction of GGBS and flyash as the secondary process. Both materials react with Calcium hydroxide produced by cement hydration to form CSH gel, which gives denser microstructure than conventional OPC concrete. The dense structure improves the durability properties of ternary blended concrete. Process yields to minimise penetration of aggressive chemicals such as sulphate, chloride as compared to conventional concrete mix.
Conclusion
Use of supplementary cementitious materials always improve the durability properties of concrete along with cost optimisation. Selection of supplementary cementitious materials, percentage replacement with cement is taken considering the strength and durability requirements of structure.
The Department of Science and Technology (DST) recently unveiled a pioneering national initiative: five Carbon Capture and Utilisation (CCU) testbeds in the cement sector, forming a first-of-its-kind research and innovation cluster to combat industrial carbon emissions.
This is a significant step towards India’s Climate Action for fostering National Determined Contributions (NDCs) targets and to achieve net zero decarbonisation pathways for Industry Transition., towards the Government’s goal to achieve a carbon-neutral economy by 2070.
Carbon Capture Utilisation (CCU) holds significant importance in hard-to-abate sectors like Cement, Steel, Power, Oil &Natural Gas, Chemicals & Fertilizers in reducing emissions by capturing carbon dioxide from industrial processes and converting it to value add products such as synthetic fuels, Urea, Soda, Ash, chemicals, food grade CO2 or concrete aggregates. CCU provides a feasible pathway for these tough to decarbonise industries to lower their carbon footprint and move towards achieving Net Zero Goals while continuing their operations efficiently. DST has taken major strides in fostering R&D in the CCUS domain.
Concrete is vital for India’s economy and the Cement industry being one of the main hard-to-abate sectors, is committed to align with the national decarbonisation commitments. New technologies to decarbonise emission intensity of the cement sector would play a key role in achieving of national net zero targets.
Recognizing the critical need for decarbonising the Cement sector, the Energy and Sustainable Technology (CEST) Division of Department launched a unique call for mobilising Academia-Industry Consortia proposals for deployment of Carbon Capture Utilisation (CCU) in Cement Sector. This Special call envisaged to develop and deploy innovative CCU Test bed in Cement Sector with thrust on Developing CO2 capture + CO2 Utilisation integrated unit in an Industrial set up through an innovative Public Private Partnership (PPP) funding model.
As a unique initiative and one of its first kind in India, DST has approved setting up of five CCU testbeds for translational R&D, to be set up in Academia-Industry collaboration under this significant initiative of DST in PPP mode, engaging with premier research laboratories as knowledge partners and top Cement companies as the industry partner.
On the occasion of National Technology Day celebrations, on May 11, 2025 the 5 CCU Cement Test beds were announced and grants had been handed over to the Test bed teams by the Chief Guest, Union Minister of State (Independent Charge) for Science and Technology; Earth Sciences and Minister of State for PMO, Department of Atomic Energy, Department of Space, Personnel, Public Grievances and Pensions, Dr Jitendra Singh in the presence of Secretary DST Prof. Abhay Karandikar.
The five testbeds are not just academic experiments — they are collaborative industrial pilot projects bringing together India’s top research institutions and leading cement manufacturers under a unique Public-Private Partnership (PPP) model. Each testbed addresses a different facet of CCU, from cutting-edge catalysis to vacuum-based gas separation.
The outcomes of this innovative initiative will not only showcase the pathways of decarbonisation towards Net zero goals through CCU route in cement sector, but should also be a critical confidence building measure for potential stakeholders to uptake the deployed CCU technology for further scale up and commercialisation.
It is envisioned that through continuous research and innovation under these test beds in developing innovative catalysts, materials, electrolyser technology, reactors, and electronics, the cost of Green Cement via the deployed CCU technology in Cement Sector may considerably be made more sustainable.
Secretary DBT Dr Rajesh Gokhale, Dr Ajai Choudhary, Co-Founder HCL, Dr. Rajesh Pathak, Secretary, TDB, Dr Anita Gupta Head CEST, DST and Dr Neelima Alam, Associate Head, DST were also present at the programme organized at Dr Ambedkar International Centre, New Delhi.
JK Lakshmi Cement, a key player in the Indian cement industry, has announced the deployment of electric vehicles (EVs) in its logistics operations. This move, made in partnership with SwitchLabs Automobiles, will see EVs transporting goods between the JK Puram Plant in Sirohi, Rajasthan, and the Kalol Grinding Unit in Gujarat.
The announcement follows a successful pilot project that showcased measurable reductions in carbon emissions while maintaining efficiency. Building on this, the company is scaling up EV integration to enhance sustainability across its supply chain.
“Sustainability is integral to our vision at JK Lakshmi Cement. Our collaboration with SwitchLabs Automobiles reflects our continued focus on driving innovation in our logistics operations while taking responsibility for our environmental footprint. This initiative positions us as a leader in transforming the cement sector’s logistics landscape,” said Arun Shukla, President & Director, JK Lakshmi Cement.
This deployment marks a significant step in aligning with India’s push for greener transport infrastructure. By embracing clean mobility, JK Lakshmi Cement is setting an example for the industry, demonstrating that environmental responsibility can go hand in hand with operational efficiency.
The company continues to embed sustainability into its operations as part of a broader goal to reduce its carbon footprint. This initiative adds to its vision of building a more sustainable and eco-friendly future.
JK Lakshmi Cement, part of the 135-year-old JK Organisation, began operations in 1982 and has grown to become a recognised name in Indian cement. With a presence across Northern, Western, and Eastern India, the company has a cement capacity of 16.5 MTPA, with a target to reach 30 MT by 2030. Its product range includes ready-mix concrete, gypsum plaster, wall putty, and autoclaved aerated fly ash blocks.
Holcim UK has released a report titled ‘Making Sustainable Construction a Reality,’ outlining its five-fold commitment to a greener future. The company aims to focus on decarbonisation, circular economy principles, smarter building methods, community engagement, and integrating nature. Based on a survey of 2,000 people, only 41 per cent felt urban spaces in the UK are sustainably built. A significant majority (82 per cent) advocated for more green spaces, 69 per cent called for government leadership in sustainability, and 54 per cent saw businesses as key players. Additionally, 80 per cent of respondents stressed the need for greater transparency from companies regarding their environmental practices.