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The future will demand less energy-intensive, greener cements

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Dr Sujit Ghosh, Executive Director – New Product and R&D, Dalmia Cement (Bharat), discusses the alternative raw materials that can be used in the production of cement and its impact on carbon emissions while underscoring the major challenges faced in using other cementitious materials.

What are the core raw materials used in the production of cement?
The core raw materials used in the production of cement are limestone (calcium carbonate) and clay (a source of silica). First, the limestone is roasted/calcined to create activated lime (CaO) in a calciner and then the activated lime along with siliceous clay is proportioned along with some other minor ingredients into a raw mix design and charged inside a kiln to form cement clinker; which is basically made of complex compounds of calcium-silica-oxides primarily, which when mixed with water, reacts, to form a cementitious gel paste that binds all aggregates together and when dried up provides strength to the concrete/plaster, made with cement and the aggregates.
Limestone (calcium carbonate) and clay (silica), which are both available in nature, are inert materials. Only when they are heat-treated at temperatures above 900oC, they become activated lime (CaO) and activated/amorphous silica (SiO2), and fuse inside the cement kiln in liquid form to form complex calcium-silica-oxides, that is cement or cement clinker.

What are the alternative raw materials that can be used in the production of cement? How does that impact the process of production?
As explained in the previous paragraph, any activated lime (CaO) and/or activated/amorphous silica (SiO2), could be potential sources of cementitious material. These could be alternative raw materials for cement production. Thus far, the most widely found and used sources of alternative materials are primarily ‘fly ash’ and ‘blast furnace slag’. Fly ash is a waste product from the burning of coal (as in a thermal power plant etc). It primarily contains amorphous/activated silica (SiO2), but very little active lime (CaO) in the Indian context. So, it is not reactive on its own, it needs activated lime (CaO) to become cementitious – which is available from cement clinker, when the two are co-processed in a cement manufacturing plant. Blast furnace slag likewise is a waste product from the steel manufacturing process and does contain some activated silica and activated lime, but again, not in the proportion/concentration to itself become cementitious. It also has to be co-processed with a cement clinker in a cement manufacturing plant. Overall, these alternative or supplementary cementitious materials, which are other industry wastes, due to the need for co-processing with cement clinker, may add some costs to the production process, but since the use of such alternative raw materials, reduces the dependence on highly energy-intensive clinker, they are welcome by the cement manufacturing fraternity, that helps lower the carbon footprint of production. These cements are called ‘blended cements’ – either fly ash blended (popularly known as PPC) or slag blended (popularly known as PSC) or fly ash + slag blended (popularly known as PCC).

Can cement maintain its quality standard with the inclusion of supplementary raw materials as against limestone?
Absolutely yes. These blended cements made using supplementary raw materials, have ‘additional’ activated silica (SiO2) and/or activated lime (CaO), which when co-processed with cement clinker, provide ‘additional’ cementitious gel paste (complex calcium-silica-oxide-hydrates) when mixed with water, that renders improved strength and durability to the cement-concrete structure. Decades ago, when such co-processing commenced, the industry went through a learning curve, and then, use of supplementary cementitious materials, although provided improved strengths, the rate of strength gain was markedly slow. This is not the case anymore. With specialised processing and with the use of performance enhancers, blended cements using supplementary raw materials, provide acceptable rate of strength gains, comparable to pure-clinker cement and top-class long-term durability, with lower carbon footprints and at the same time effectively finding value-solution to other industry wastes.

Explain the impact on carbon emission of the production unit when alternative raw materials are used in various proportions.
Processing of alternative raw materials at a cement plant and transportation of such alternative materials from distant places (as they are not available in the adjacent limestone mines of a cement plant), do have associated costs and carbon footprints. However, since the use of alternative raw materials reduces dependency on highly energy-intensive clinker, net-net, there is an overall reduction in carbon footprint, in the production of blended cements using alternative/supplementary cementitious raw materials.

How can the cost of production be reduced by using alternative or supplementary raw materials in cement production?
Since the use of alternative / supplementary cementitious materials has been prevalent in the world and in India, for blended cement production, for the last couple of decades, the demand for such other industry wastes (primarily from thermal power plant or steel plant) has been increasing steadily. This has led to a steep increase in prices for these industry wastes (mainly slags from steel plants) which otherwise were previously dumped in landfills, by opportunistic players and profiteering groups. Also, since steel plants and thermal power plants are not co-located with cement plants geographically, transportation costs of such bulky waste materials have also been increasing. Cost of blended cement production has to reduce or at least maintain at par, as well as, at the same time assist the nation in beneficially getting rid of other-industry-wastes. Cement players can do justice to climate-change by producing less energy intensive blended cements that are in no way inferior in quality to pure-clinker cements. Transport subsidies should also be provided to cement manufacturers by the government as well as at the same time try and administer some polluter-to-pay mechanism (so that these wastes are not conveniently dumped away in nearby landfills by the relevant industries).

What are the major challenges in using other cementitious materials?
Sometimes the quality of other cementitious materials varies significantly, being other industry wastes – hence diligent quality checks of such incoming raw materials become important. And subsequent changes in co-processing with clinker, if necessary, is administered, such that the final product quality is maintained. We see many ready-mix concrete manufacturers, often blend fly ash and/or slag at site with cement, to produce some sort of blended cement concrete. Many times, this leads to questionable quality concrete in our nation – and sometimes earns a bad name to the use of supplementary cementitious raw materials! This is simply because a ready-mix concrete plant just cannot do the necessary processing (namely- polishing, grinding, classification etc) of such industry wastes (fly ash or slag) and neither have the stringent and highly automated factory precision of co-processing and blending, as happens at a cement plant.

What role does technology play in deciding which materials can be used, and than incorporating them in the production process?
Technology plays a very important role in the pre-assessing quality of incoming supplementary cementitious raw materials, with the same rigour, as is mined limestone assessed for its usability in the production process. State-of-the-art, highly automated and high precision expensive types of equipment are deployed along with highly skilled personnel, not only to pre-assess incoming feed quality but also in deciding necessary mix changes, at the production level, to ensure final product quality consistency. Typically, there are highly trained and experienced chemists, chemical engineers, process engineers, doctorates and specialists, who act in unison to produce consistent quality blended cements. Such capabilities and facilities are unfortunately not available to a ready-mix concrete operator or their plant, to try and produce consistent quality by site blending cement with alternative raw materials; and such need to stop. It is therefore recommended that consistent quality blended cements be purchased directly from cement manufacturers by downstream ready-mix-concrete manufacturers.

Does your organisation manufacture a variant of cement made from alternative raw materials? Tell us more about its performance and use.
Yes, we do. We manufacture many variants of cement from alternative raw materials, even some special applications, high-performance ones too! We produce and sell fly ash blended PPC, slag blended PSC, fly ash + slag blended PCC (composite cement), all of which meet all quality criteria of BIS (Bureau of Indian Standards) and are used for regular construction works. We also have blended special application cement like railway sleeper cement and oil well cement – in fact, we are the first manufacturer of such types of cement in India, since decades. Plus, of late, we have highly engineered, proprietary/patented, early strength and high performance blended cement (made using alternative/supplementary cementitious raw materials and special chemicals), that outperforms all cement types including pure-clinker cement, on all performance parameters of strength, crack control, water demand and all durability characteristics, at all ages and can hasten infrastructure construction, by allowing opening of structures within 3 to 7 days, instead of the normal 21 to 28 days. This cement has been in use by the Airports Authority of India at some of their airports’ apron/taxiway construction, for the last several years and is now being also tried for highway construction in the country. Thus, it is evident that blended cement using alternative raw materials, made under factory precision of a cement plant, can clearly outperform pure-clinker energy-intensive normal cement, and is clearly a much greener and environment-friendly alternative.

How do you foresee the future of cement production?
The future will demand less energy-intensive, greener cements, preferably with net zero carbon footprints! Is it possible to produce green cement and yet meet quality requirements? Of course, yes. Continuous research and development initiatives are on at our organisation and likewise, globally. We, as a cement manufacturing organisation, have continuously lowered our carbon footprint over the last decades and are very confident to meet future needs of even greener cements. Hence, we have voluntarily committed at global platforms like the Paris accord, COP26 etc. We recently also signed an MoU with FLSmidth, a major supplier of engineering, equipment, and service solutions to collaborate the research and development of disruptive solutions for next-generation cement manufacturing. All these initiatives are part of our journey to become a net carbon-negative cement company by 2040 and we’re well on our way!

Kanika Mathur

Concrete

India Sets Up First Carbon Capture Testbeds for Cement Industry

Five CCU testbeds launched to decarbonise cement production

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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.

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Concrete

JK Lakshmi Adopts EVs to Cut Emissions in Logistics

Electric vehicles deployed between JK Puram and Kalol units

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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.

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Concrete

Holcim UK drives sustainable construction

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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.

Image source:holcim

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