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Science and Application of Grinding Aids

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Dr SB Hegde discusses the importance of grinding aids as essential chemical additives that enhance cement grinding efficiency, reduce energy consumption and improve overall cement quality.

Grinding aids are chemical additives used in the manufacturing of cement to improve the grinding efficiency and performance of the material. These additives have become a critical component of the cement industry, playing a significant role in optimising mill output, reducing energy consumption, and enhancing the quality of cement. However, the adoption of grinding aids varies significantly across regions, influenced by cost considerations, regulatory frameworks, and technical awareness.

Despite their utility, grinding aids remain underutilised in certain regions. For instance, Europe has achieved over 80 per cent penetration of grinding aids due to stringent energy efficiency norms and advanced technologies, while India lags at around 30 per cent penetration, primarily due to cost sensitivity and limited technical expertise. Additionally, inconsistent quality and improper dosing often lead to suboptimal performance, underlining the need for stringent quality control and process optimisation.

The global market for grinding aids is expanding, projected to reach $ 1.2 billion by 2030, with a CAGR of 5.5 per cent. In India, the market is currently valued at `500 crore (2024). Innovations in the chemistry of grinding aids and the push for sustainable, bio-based additives are opening new avenues for adoption. Moreover, real-time monitoring and digital integration in cement plants are poised to revolutionise grinding aid applications by ensuring precise dosing and performance optimisation.

This article delves into the science, chemistry, and application of grinding aids, exploring their role in improving milling efficiency, quality control, and concrete performance. It further addresses market dynamics, challenges in adoption, and the path forward for maximising the benefits of grinding aids in cement manufacturing.

Chemistry of Grinding Aids
Grinding aids are chemical compounds specifically designed to improve the efficiency of the cement grinding process. Their effectiveness arises from their ability to modify the physical and chemical interactions between cement particles during grinding, thereby reducing agglomeration and improving the flowability of the material. This section delves into the nomenclature, chemistry, and scientific characteristics of grinding aids, providing an advanced understanding of their role in cement manufacturing.

2.1. Nomenclature and Classification
Grinding aids are generally categorised based on their chemical composition and functional groups. The most common types include:
1. Amine-based Compounds:

  • Triethanolamine (TEA)
  • Diethanolamine (DEA)
  • Monoethanolamine (MEA)

2. Glycol-based Compounds:

  • Ethylene glycol (EG)
  • Diethylene glycol (DEG)
  • Polyethylene glycol (PEG)

3. Other Organic Compounds:

  • Lignosulfonates
  • Hydroxycarboxylic acids (e.g., citric acid)

4. Hybrid Formulations:

  • Combinations of amines and glycols for enhanced performance
  • Additives with functionalised polymers provide multiple benefits, such as improving hydration kinetics and early strength development.

These compounds are often blended with performance enhancers, such as surfactants or dispersants, to achieve desired operational and material properties.

2.2. Chemical Mechanism of Action
Grinding aids operate at the molecular level by modifying surface properties and reducing inter-particle forces. The primary mechanisms include:

1. Reduction of Surface Energy:

  • Cement particles exhibit high surface energy due to fracture during grinding. Grinding aids adsorb onto particle surfaces, reducing their surface energy and preventing agglomeration.

2. Electrostatic Neutralisation:

  • Many grinding aids neutralise electrostatic charges that cause particles to attract each other, thus improving dispersion.

3. Lubrication Effect:

  • Glycol-based grinding aids act as lubricants at the contact points between particles and grinding media, reducing friction and energy consumption.

4. Improved Particle Size Distribution (PSD):

  • Grinding aids influence PSD by stabilising fine particles and preventing the re-agglomeration of smaller fractions, resulting in improved cement quality.

2.3. Scientific Characteristics and Properties
The effectiveness of grinding aids depends on their physicochemical properties and interactions with cement clinker phases.

1. Molecular Weight and Structure:

  • Low molecular weight compounds, such as TEA, are highly effective in reducing agglomeration but may increase water demand in the final cement.
  • High molecular weight compounds, such as PEG, provide additional benefits like workability and slump retention.

2. Hydrophilicity and Hydrophobicity:

  • Hydrophilic compounds, such as DEG, enhance water compatibility, while hydrophobic additives improve the grinding of clinker with high limestone content.

3. pH and Ionic Strength:

  • Most grinding aids function optimally within a specific pH range (typically 7-9) to ensure effective adsorption on clinker particles.
  • Ionic strength plays a critical role in the interaction of grinding aids with calcium ions present in the clinker.

4. Thermal Stability:

  • The thermal decomposition of grinding aids during the grinding process can influence their effectiveness. For example, amine-based compounds degrade at temperatures above 200°C, whereas glycol-based compounds remain stable under similar conditions.

2.4. Advanced Chemical Interactions with Clinker Phases
Grinding aids interact differently with the primary clinker phases—C3S (alite), C2S (belite), C3A (tricalcium aluminate), and C4AF (ferrite).

1. C3S (Alite):

  • Glycol-based compounds enhance the grinding of alite due to their ability to reduce crystalline hardness.
  • TEA has been shown to accelerate the hydration of C3S, improving early strength.

2. C2S (Belite):

  • Grinding aids have limited direct interaction with belite but indirectly improve its grinding efficiency by stabilising the fine particles in the cement mix.

3. C3A (Tricalcium Aluminate):

  • Amine-based grinding aids are highly effective in modifying the hydration kinetics of C3A, thereby influencing setting time and workability.

4. C4AF (Ferrite):

  • Ferrite phases are less reactive, but grinding aids reduce the grinding energy required for these phases, indirectly contributing to overall mill efficiency.

2.5. Examples of Performance Variation
Performance variations of grinding aids depend on clinker composition, mill type, and operating conditions. For instance:

  • A study revealed that the use of TEA in ball mills improved the grinding efficiency by 15 per cent, while the same compound exhibited a 20 per cent improvement in vertical roller mills.
  • Glycol-based aids showed superior performance with clinker containing higher SO3 content, improving Blaine fineness by 10 per cent compared to amine-based aids.
  • Customised formulations combining TEA and PEG reduced specific power consumption by eight per cent in a cement plant in South India.

2.6. Quality Control and Standardisation
To ensure consistent performance, grinding aids undergo rigorous quality control tests, including:

1. Fourier Transform Infrared Spectroscopy (FTIR): Used to identify functional groups and confirm chemical composition.
2. Gas Chromatography-Mass Spectrometry (GC-MS): Determines the purity and presence of byproducts in grinding aid formulations.
3. Thermogravimetric Analysis (TGA): Assesses thermal stability and decomposition characteristics.
4. Surface Area and PSD Analysis: Evaluates the impact of grinding aids on cement particle size distribution and specific surface area.
5. Mill Trials: Performance is validated under real-world conditions by assessing mill output, specific power consumption, and cement quality metrics like Blaine fineness and compressive strength.

Performance Evaluation of Grinding Aids
The performance evaluation of grinding aids is crucial in determining their efficiency and overall contribution to cement manufacturing processes. A systematic assessment involves analysing key performance indicators (KPIs) such as energy consumption, mill output, and particle size distribution, while also evaluating their impact on cement hydration, setting time, and compressive strength. These evaluations, carried out both in laboratories and real-world industrial settings, provide critical insights into the effectiveness of grinding aids.

3.1. Key Performance Indicators (KPIs)
Energy consumption serves as a primary metric for evaluating grinding aids, as their primary objective is to reduce the energy required for grinding. Studies have revealed that grinding aids can lower specific energy consumption by five to 25 per cent, contingent upon factors such as cement type, mill configuration, and operating parameters. For instance, a South Indian cement plant achieved an eight per cent reduction in specific power consumption with a glycol-based grinding aid in a ball mill, equating to considerable cost savings.
Mill output is another essential parameter. Grinding aids enhance material flowability and reduce agglomeration, leading to increased throughput. For example, polycarboxylate ether (PCE)-based grinding aids have been shown to boost mill output in vertical roller mills by 10 to 15 per cent compared to traditional amine-based formulations. This improvement is due to the superior dispersion and grinding efficiency offered by PCE-based formulations.
Particle size distribution (PSD) is significantly impacted by grinding aids, as they help achieve a finer and more uniform grind. This results in improved packing density and reduced voids in the cement matrix. Laboratory tests with triethanolamine (TEA)-based grinding aids have demonstrated a 12 per cent increase in Blaine fineness, alongside a notable reduction in oversize particles (>45 microns).

3.2. Laboratory Testing Methods for Grinding Aids
To comprehensively evaluate grinding aids, laboratory testing under controlled conditions is indispensable. Standardised methods include:
Grinding Efficiency Tests: Laboratory ball mills simulate industrial grinding conditions. The addition of grinding aids is assessed by measuring power draw, material flow rate, and specific residue levels. These tests provide quantifiable data on grinding efficiency improvements.
Hydration Studies: Techniques like isothermal calorimetry and X-ray diffraction (XRD) monitor hydration kinetics and phase formation. Amine-based grinding aids accelerate calcium silicate
hydrate (C-S-H) formation, contributing to early strength development.
Rheology and Flowability Tests: Grinding aids improve flowability, evaluated using rheometers and flowability indices. Glycol-based additives typically enhance flow properties by 15 to 20 per cent, reducing clogging and promoting smoother mill operations.
Compressive Strength Testing: Cement mortars incorporating grinding aids are subjected to compressive strength tests at various curing ages (e.g., 1, 3, 7, and 28 days). TEA-based grinding aids exhibit a 10 to 15 per cent improvement in early compressive strength, while PCE-based formulations deliver balanced strength gains across all curing ages.

3.3. Effect of Grinding Aids on Cement Hydration, Setting Time, and Compressive Strength Development
Grinding aids play a pivotal role in influencing cement hydration. Amine-based formulations, such as TEA and diethanolamine (DEA), enhance alite (C3S) hydration, leading to accelerated setting and early strength gain. However, excessive dosages can retard ettringite formation, thereby delaying setting time.
Glycol-based additives improve particle dispersion, ensuring uniform hydration. This results in enhanced compressive strength development at all ages. For instance, laboratory experiments demonstrated an eight per cent increase in 28-day compressive strength with ethylene glycol-based grinding aids compared to untreated cement.
Polycarboxylate ether-based grinding aids represent a modern advancement, offering dual benefits of improved grinding efficiency and compatibility with chemical admixtures like superplasticisers. This synergy optimises hydration, resulting in superior strength development. Studies have shown a 12 per cent increase in 28-day compressive strength for PCE-based grinding aids in cement containing supplementary materials like fly ash and slag.

3.4. Examples of Performance Variations with Specific Grinding Aids
Performance variations among grinding aids are influenced by their chemical compositions and the specific characteristics of the grinding process.

For example:

  • A North American cement plant achieved a 15 per cent increase in mill throughput and a 10 per cent reduction in specific energy consumption after transitioning from TEA-based to hybrid amine-glycol grinding aids.
  • Comparative trials revealed that diethylene glycol (DEG) is more effective in reducing grinding energy for clinker with high C3A content, while TEA offers superior performance for clinker with low gypsum levels.
  • A European cement manufacturer observed significant quality improvements with PCE-based grinding aids, particularly for blended cements containing up to 30 per cent fly ash. These cements exhibited narrower PSD and enhanced durability characteristics.

Challenges in Grinding Aid Adoption
Grinding aids, despite their proven benefits in enhancing milling efficiency and improving cement quality, face several challenges in widespread adoption. Understanding these challenges requires a detailed analysis of operational, environmental, and regulatory factors at both global and regional levels, including India. This section delves into the barriers to the extensive use of grinding aids, with a focus on technical, logistical, and market-driven aspects.

4.1. Reasons for Limited Popularity in Some Regions and Plants
The limited adoption of grinding aids in certain regions and plants often stems from economic constraints and lack of awareness. In emerging markets, the upfront cost of grinding aids may deter smaller or cost-sensitive cement producers. For example, in India, many mid-sized plants operate on tight profit margins and prioritise short-term cost reductions over long-term efficiency gains. Globally, smaller plants in Africa and Southeast Asia also exhibit lower adoption rates due to financial constraints and limited technical knowledge about the benefits of grinding aids.
Additionally, plant operators may hesitate to incorporate grinding aids due to the perception that these additives increase operational complexity. Variations in clinker composition and grinding equipment across plants often necessitate customised formulations of grinding aids, which can create challenges in consistency and effectiveness. For instance, cement plants using vertical roller mills (VRMs) often require different grinding aid formulations compared to those with ball mills, leading to variability in performance and discouraging adoption.

4.2. Impact of Raw Material Variability on Grinding Aid Effectiveness
The variability of raw materials, including clinker and gypsum, presents a significant challenge to the consistent performance of grinding aids. Differences in chemical composition, mineralogy, and moisture content of raw materials can influence the reactivity and efficacy of grinding aids. For example, clinkers with high levels of alite (C3S) and belite (C2S) require different formulations compared to those with elevated free lime or alkali content.
In India, raw material variability is particularly pronounced due to the use of diverse limestone sources and blended cements containing fly ash, slag, or other supplementary cementitious materials (SCMs). A study conducted by a leading Indian cement producer revealed that grinding aids optimised for clinker-based cement exhibited suboptimal performance when used for fly ash-blended cement, resulting in inconsistent strength development and mill throughput.
Globally, similar issues arise in regions where raw material quality is inconsistent. Cement plants in Southeast Asia, for instance, frequently encounter challenges due to high moisture content in limestone and clay, which affects grinding efficiency and necessitates frequent adjustments in grinding aid dosage.

4.3. Concerns Over Operational and Maintenance Issues in Cement Mills
Operational and maintenance challenges in cement mills also contribute to the limited adoption of grinding aids. Excessive use of grinding aids can lead to unwanted side effects, such as excessive coating of grinding media and mill internals, which can reduce grinding efficiency and increase maintenance costs. For example, ethylene glycol-based grinding aids, when used at high dosages, may lead to the formation of sticky residues, necessitating frequent cleaning of mill components.
Furthermore, some plant operators report issues related to the compatibility of grinding aids with chemical admixtures or process conditions. In certain cases, the use of amine-based grinding aids has been linked to increased foaming in water-recirculating systems, leading to operational disruptions and higher water treatment costs.
Additionally, the adoption of grinding aids in plants using VRMs is often hindered by the sensitivity of these mills to operating parameters. Variations in grinding aid dosage or clinker properties can significantly affect mill vibrations and stability, creating operational challenges.

4.4. Environmental and Regulatory Challenges Related to Grinding Aids
Environmental concerns and regulatory restrictions represent another significant barrier to the widespread adoption of grinding aids. Many grinding aids contain volatile organic compounds (VOCs), which are subject to stringent environmental regulations in developed markets such as Europe and North America. For instance, amine-based formulations, including triethanolamine (TEA) and diethanolamine (DEA), are classified as hazardous substances in some regions, limiting their usage.
In India, while environmental regulations are less restrictive, there is growing pressure from policymakers and environmental organisations to minimise the carbon footprint of cement manufacturing. Grinding aid manufacturers face the challenge of developing eco-friendly formulations that meet performance requirements while adhering to environmental standards. This has spurred interest in biodegradable and low-VOC grinding aids, although their higher cost remains a deterrent.
Additionally, regulatory approval processes for new grinding aid formulations can be time-consuming and costly, particularly in regions with strict compliance standards. This limits the introduction of innovative products in markets such as the EU, where REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) compliance is mandatory.

About the author:
Dr SB Hegde, a global cement industry leader with over 30 years of experience, is a Professor at Jain College of Engineering, India, and a Visiting Professor at Pennsylvania State University, USA. Recipient of the ‘Global Visionary’ award, Dr Hegde advises India’s think tank CSTEP on hydrogen usage in cement and consults for major cement companies. He also serves on expert panels of key industry bodies and journals globally.

Concrete

Nuvoco Vistas launches Limla cement plant, expands Gujarat footprint

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Nuvoco Vistas opens a 2 MMTPA grinding unit at Limla, entering Gujarat and advancing its target of 35 MMTPA capacity by FY 2028.

Surat (Gujarat)

Nuvoco Vistas Corporation Ltd, a part of Nirma Group and one of India’s leading building materials company, has inaugurated the Limla Cement Plant in Surat (Gujarat), one of Vadraj Cement Limited’s (VCL) principal manufacturing facilities. The commissioning represents a key milestone in Nuvoco’s acquisition and restoration of VCL, while supporting the company’s expansion across the Western Indian cement market.

Vadraj Cement Limited is a subsidiary of Nuvoco Vistas Corporation Limited and has installed cement capacity of 6 MMTPA across its assets. The Limla inauguration therefore represents the first operational step in the acquired platform’s wider revival, while the Kutch facilities provide clinker supply, mineral security and coastal logistics support for the western business.

Nuvoco completed its acquisition of Vadraj Cement Limited, then under the Corporate Insolvency Resolution Process, after paying a consideration of Rs 1,800 crore in June 2025. VCL’s asset portfolio comprises a clinker unit at Kutch and a grinding unit at Limla in Surat. It also includes high-quality captive limestone reserves and a captive jetty at Kutch, supporting more efficient logistics. Following the takeover, Nuvoco began an extensive programme of restoration, refurbishment and expansion at both locations, leading to the commissioning of the Limla plant.

The Limla Cement Plant is expected to support a phased increase in sales volumes across Gujarat. It will also help Nuvoco supply neighbouring markets in Western Maharashtra and release cement capacity from its northern plants, which can consequently be redirected towards markets in North India. The plant will manufacture a full portfolio comprising Ordinary Portland Cement, Portland Slag Cement, Portland Pozzolana Cement and Portland Composite Cement. It will additionally produce the complete Nuvoco Duraguard range, including the premium Nuvoco Duraguard Microfibre product. The acquisition is also expected to generate operational synergies with Nuvoco’s existing plants at Nimbol and Chittorgarh in Rajasthan, improving logistics optimisation and market reach across important regional markets.

The grinding unit at the Limla Cement Plant was completed ahead of schedule, with 2 MMTPA of capacity now inaugurated to expand Nuvoco’s operating scale and customer reach. After Vadraj Cement’s assets become fully operational, plants in North and West India are expected to account for nearly 40 per cent of Nuvoco’s total cement capacity. This will broaden the company’s manufacturing network, strengthen access to high-growth markets and support its plan to increase consolidated cement capacity to 35 MMTPA by FY 2028, reinforcing its longer-term growth strategy.

Commenting on the development, Jayakumar Krishnaswamy, Managing Director, Nuvoco Vistas Corp Ltd, said: “The inauguration of the Limla Grinding Unit in Surat is an important milestone in Nuvoco’s growth journey and demonstrates our commitment to disciplined, value-accretive expansion. Gujarat is strategically significant for Nuvoco, with substantial opportunities arising from infrastructure investment, industrial growth, rapid urbanisation and continuing demand from the housing and construction sectors. The facility strengthens our regional footprint, improves operational flexibility and increases our ability to serve customers across northern and western markets with greater reliability and efficiency.”

He added: “Through the Vadraj acquisition, we have refurbished and restarted a strategically important asset, returning it to operations in record time through strong execution and collaboration between teams. The achievement demonstrates our ability to create value from acquired assets, fulfil our commitments and retain the confidence of stakeholders. It also highlights the strength of our project delivery capabilities and our continued focus on building sustainable, profitable growth over the long term.”

Nuvoco Vistas Corporation Limited is a building materials company whose vision is to build a safer, smarter and more sustainable world. It is among the leading players in East India and has a significant presence across North and West India. Nuvoco began operations in 2014 with a greenfield cement plant at Nimbol, Rajasthan. It later acquired Lafarge India Limited, which had entered India in 1999, followed by Emami Cement Limited in 2020 and Vadraj Cement Limited in April 2025. The company has also announced an expansion in eastern India through a new grinding mill at the Arasmeta Cement Plant, supported by several debottlenecking programmes involving equipment upgrades, process improvements and internal capacity initiatives. These developments place Nuvoco on track to achieve total cement capacity of approximately 35 MMTPA. The company reported total income of Rs 11,362 crore in FY 2025-26, reflecting its continuing growth trajectory.

Nuvoco operates a diversified portfolio across three segments: Cement, Ready-Mix Concrete and Modern Building Materials. Its cement portfolio includes Concreto, Duraguard, Double Bull, PSC, Nirmax and Infracem, covering Ordinary Portland Cement, Portland Slag Cement, Portland Pozzolana Cement and Portland Composite Cement. Its pan-India RMX business provides value-added products under Concreto for performance concrete, Artiste for decorative concrete, InstaMix for ready-to-use bagged concrete, X-Con covering M20 to M60 grades, and Ecodure for specialised green concrete. Nuvoco has supplied materials to projects including the Mumbai-Ahmedabad Bullet Train, Birsa Munda Hockey Stadium in Rourkela, Aquatic Gallery at Science City in Ahmedabad, and metro railway projects in Delhi, Jaipur, Noida and Mumbai.

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Concrete

Green Construction Through Cement Innovation

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Indian Cement Review (ICR) and Fuller Technologies brought industry, policy and technology leaders together to discuss how cement innovation can drive green construction at scale, writes Rakesh Rao.

India is building at a pace few countries can match. Highways, airports, housing, logistics parks, industrial corridors and urban infrastructure are reshaping the country’s economic geography. But beneath this growth story lies a difficult question: can India continue to build at scale without locking itself into a high-carbon future?

That question formed the core of an online panel discussion titled “Driving Green Construction Through Cement Innovation”, organised by Indian Cement Review (ICR) in association with Fuller Technologies as the Presenting Partner on June 25, 2026. The webinar brought together experts from cement technology, R&D, global industry platforms, building performance policy and international development cooperation to examine how low-carbon cement and material innovation can accelerate India’s green construction transition.

The discussion came at a crucial time. India has committed to achieving net-zero emissions by 2070 and reducing the carbon intensity of its economy by 45 per cent by 2030. At the same time, the country’s construction sector is expanding rapidly, driven by urbanisation, infrastructure development, housing demand and industrial growth. Cement, as one of the most widely used construction materials, sits at the heart of this transition. It is indispensable to development, but also central to the challenge of reducing embodied carbon in buildings and infrastructure.

Moderated by Nitika Krishan, Senior Urban Infrastructure and Sustainable Policy Consultant, the panel featured:

  • Kiranmai Sanagavarapu, Director, Low Carbon Solutions, Fuller Technologies;
  • Dr Hemantkumar Aiyer, VP and Head R&D, Nuvoco Vistas Corp Ltd;
  • Devika Wattal, Innovation Lead, Global Cement and Concrete Association (GCCA);
  • Dr Sunita Purushottam, MD, GBPN India (Global Buildings Performance Network); and
  • Vaibhav Rathi, Senior Technical Advisor, GIZ (the German Agency for International Cooperation)

Setting the tone for the discussion, Nitika Krishan underlined the scale of the challenge before the sector. “The question before us is no longer whether we build, but how we build sustainably,” she said. She pointed out that construction accounts for nearly 40 per cent of global energy-related carbon emissions when both operational and embodied carbon are considered. Cement production, she added, remains one of the hardest industrial processes to decarbonise.

For India, this is not merely an environmental issue. It is a development issue, a competitiveness issue and increasingly, a market issue. As one of the world’s largest cement producers and among the fastest-growing construction markets, India’s material choices will influence the carbon trajectory of its built environment for decades. As Krishan observed, sustainability solutions in economies such as India must not remain limited to laboratory success. They must be scalable, commercially viable and practical at national level.

The innovation gap: From technology to market

Experts believe that there is a need to bridge the innovation gaps for making decarbonisation in cement and concrete scalable. Devika Wattal of GCCA, explained, “The starting point must be the core cement manufacturing process itself. The first and foremost is the heart of our process, the heart of cement manufacturing. How do we reduce clinker? That is always a topic where industry is working very intrinsically.”

Clinker reduction remains one of the most important pathways for lowering emissions in cement. Since clinker production is energy-intensive and chemically emits carbon dioxide, reducing the clinker factor through supplementary cementitious materials (SCMs), blended cements and new chemistries can have a significant impact. Wattal also noted that carbon capture, utilisation and storage (CCUS) will have a role, though it may not be the first lever for all markets.

However, she stressed that innovation cannot stop at technology development. A solution that works in the lab must also be adaptable to industry, scalable in production and acceptable in construction practice. “It is important for that innovation to be adaptable, to be scalable, and so that it can be executed in real time,” she said.

Wattal also called for stronger enabling systems around innovation. These include performance-based standards, product-level embodied carbon databases and clearer frameworks for evaluating green materials. Without these, low-carbon cement products may struggle to compete with conventional materials in procurement and design.

R&D must balance carbon, cost and performance

Bringing in the R&D perspective into the discussion, Dr Hemantkumar Aiyer of Nuvoco Vistas emphasised that low-carbon cement development cannot be treated as a single-variable exercise. Cement must perform in real construction conditions. It must deliver strength, durability, consistency and cost competitiveness, while also reducing carbon.

“The root of understanding and balancing all these aspects lies in materials, and knowing the materials,” he said.

According to Dr Aiyer, R&D teams must understand the variability of raw materials such as fly ash, slag and clinker. Different sources produce different material behaviours. This makes mix optimisation, material characterisation and processing-property relationships critical. When performance is affected, cement manufacturers must understand how strength enhancers, admixtures and other performance chemicals interact with the material system.

He also linked material science with process efficiency. Clinkerisation takes place at extremely high temperatures, around 1,400 to 1,450 degrees Celsius. Any improvement in raw mix design, process control or energy optimisation can, therefore, help reduce emissions and cost. Dr Aiyer pointed to artificial intelligence-based optimisation, Cement 4.0 tools and advanced software as important enablers for real-time process and material control.

“The more you understand the materials, the more you can control it,” he said.

LC3: The promise is proven, the sequencing is not

Limestone calcined clay cement, commonly referred to as LC3, has attracted global attention because it can reduce clinker content significantly by using calcined clay and limestone while maintaining performance in many applications. Kiranmai Sanagavarapu of Fuller Technologies said the technology itself has already moved beyond proof of concept. Fuller Technologies has worked with calcined clay technology for nearly two decades and has seen plants running in France and Ghana. These plants, she said, are meeting local and national specifications, while the economics are beginning to make sense.

“The calciner is performing, the economics is stacking up, it is making business sense to produce,” she said.

But if the technology is viable, why has adoption not scaled faster? For Sanagavarapu, the answer lies in project sequencing. Too often, clay characterisation happens after equipment is specified. This, she warned, is a backward approach because calciner design depends on clay mineralogy, kaolinite content, iron levels, reactivity, moisture and other variables.

“If you don’t know what your deposit looks like before you commit for the equipment, you are, in a way, going blind into designing,” she said.

She also identified permitting and plant integration as major bottlenecks. Environmental clearances, mining permissions and local regulatory approvals must begin early. Similarly, calcined clay must be integrated into existing grinding, blending and logistics systems from the design stage, not treated as an afterthought during commissioning.

India already has IS 18189:2023 standard for LC3, but Sanagavarapu pointed out that the standard is not yet visible enough in procurement documents. “The gap between what is technically being permitted and what the procurement is asking is the single biggest bottleneck,” she said.

In her view, successful scale-up depends on getting the sequence right: clay characterisation first, permitting in parallel, standards aligned with construction, and integration built into plant design.

India’s LC3 journey: Progress, but demand remains thin

Providing details of India’s LC3 commercialisation experience, Vaibhav Rathi of GIZ noted that JK Cement carried out the first commercial production of LC3 at its Rajasthan plant, followed by JK Lakshmi Cement three months later. These initiatives were supported by the International Climate Initiative of the Government of Germany, with IIT Delhi contributing deep institutional knowledge on LC3 research and BIS certification.

Rathi said India’s early experience has produced clear lessons. One of the biggest was the need to build capacity among regulators. While BIS certification existed, State Pollution Control Boards were unfamiliar with the technology and unsure about the approval pathway.

“The capacity building is not just needed amongst the producer and the users of the cement, but also the regulators who are working with this technology for the first time,” he said.

He also highlighted the need for better information on China clay deposits. Since China clay is currently classified as a minor mineral, centralised data on availability, quality and location is limited. If cement manufacturers are to adopt LC3 at scale, stronger mineral intelligence will be important.

The third issue is demand. LC3 has already been used in projects such as Palava City in Mumbai and Noida International Airport, but these remain limited examples. “It is in a chicken and egg situation,” Rathi said. “Cement companies are saying we need more demand, and users are saying there is not enough cement available.”

Public procurement, he suggested, could help break this cycle. If agencies such as CPWD and other public bodies begin testing, accepting and specifying LC3, it could create the market confidence needed for cement companies to invest in production and storage.

Building codes must catch up with innovation

Dr Sunita Purushottam of GBPN India argued that material choices will determine built environment emissions over the long term, but India’s current policy signals remain fragmented. Although LC3 has received BIS recognition, she pointed out that building codes, municipal bylaws, schedules of rates and sustainability codes do not yet provide uniform guidance on low-carbon cement.

“The current cement regulations are largely prescriptive and favouring traditional materials,” she said. This limits the ability of alternative materials to compete on performance, durability and emissions.

Dr Purushottam also raised the issue of taxation. Cement, including LC3, currently falls under the same GST bracket as conventional cement. A differentiated tax structure, she argued, could help accelerate market adoption. “In order for the market to demand LC3, that differentiation in the GST could go a long way,” she said.

She noted that green building certifications such as IGBC and GRIHA are already creating demand for low-carbon materials by assigning points for embodied carbon and sustainable material use. However, she said large-scale adoption will require regulatory mandates, particularly through building codes and state-level notifications.

She also cautioned that low-carbon cement alone does not solve the entire building performance problem. A material may reduce embodied carbon, but the operational carbon of a building depends on thermal performance, design, insulation and energy use. “The energy part has two elements,” she said. “One is the embodied carbon of the material itself, and the other is the operational carbon.”

Collaboration is the bridge between invention and impact

Wattal said GCCA sees innovation as a strategic priority and works through platforms that connect industry with academia and start-ups. “There is no way we will decarbonise our sector without innovation,” she said.

However, she stressed that research must be connected to actual industry challenges. Innovations developed in isolation may fail when they encounter real-world barriers such as raw material variability, plant integration, cost, standards and finance. Start-ups, too, need industry mentorship and scale-up pathways.

Wattal also flagged the importance of finance. Even strong technologies may struggle to attract investment if there is no common understanding of bankability. “We have always put projects into, is this a bankable project? But the definition of a bankable project has never been defined,” she said.

For India, she saw strong potential in its academic and start-up ecosystem, but said the challenge lies in alignment and prioritisation. The country has the research base, industrial capacity and market size. What it now needs is a coordinated route from innovation to deployment.

There is a practical concern for cement manufacturers: how can existing plants be adapted for lower emissions without compromising reliability or commercial viability?

Kiranmai Sanagavarapu addressed, “The reliability risk in calcined clay retrofit is definitely real, but it is almost always self-inflicted. The risk arises when a new process is added to an existing circuit without properly redesigning grinding and blending configurations.”

Existing cement plants, she explained, can take two broad routes. The first is external sourcing of calcined clay combined with mill optimisation. This requires lower capital investment and can potentially move in 12 to 18 months if other conditions are in place. It may reduce emissions by around 20 to 30 per cent. The second route is integrated calcination on site, which requires higher capital expenditure and longer lead times, but provides greater control over quality, supply and emissions reduction potential.

For Sanagavarapu, the principle is simple: low-carbon retrofits must be designed with intent. “Design it with an intent properly from the start. Start in the market conditions where the economics are already working,” she said.

Circularity: The overlooked advantage

According to Vaibhav Rathi, fly ash and slag are already well established in cement and construction (C&D), but construction and demolition waste remains underutilised. “C&D waste is a growing business opportunity which not many have taken up,” he said. India’s continuous construction and demolition activity creates huge volumes of waste, much of which contributes to air pollution, land degradation and material inefficiency. With the right processing and standards, this waste can be converted into useful construction products.

Rathi also pointed out that LC3 has a circular economy dimension that is often overlooked. It can use low-grade kaolin-rich clay left behind after high-grade clay is extracted for other applications. “LC3 is not only a low-carbon solution, but also a circular economy solution,” he said.

At the same time, he cautioned that LC3 in India is not yet cheap because it has not reached scale. Site-specific techno-commercial feasibility studies, supported jointly by development agencies and industry, could help companies assess whether LC3 production makes technical and financial sense at a given location.

Dr Purushottam added that India must address both low-carbon cement and construction waste together. “Both low-carbon cement and C&D waste go hand in hand. India does not have an option but to work on both,” she said.

Dr Aiyer called for policy shifts from both government and industry, including preferential purchasing of sustainable materials, minimum supplementary cementitious material requirements in public and public-private projects, and faster regulatory implementation. “If we can fast-track the regulatory standards and their implementation on the ground, that is the way to go,” he said.

From green ambition to green construction

Cement innovation is no longer only about chemistry. It is about systems. Low-carbon cement will scale only when technology, standards, procurement, finance, regulation, education and construction practice move together.

LC3 and other low-carbon technologies have shown promise. India has early commercial examples, strong research capability and growing market interest. But mainstream adoption will depend on whether demand can be created, regulators can be capacitated, standards can be embedded in procurement, and manufacturers can see a clear business case.

For a country building at India’s scale, the opportunity is enormous. Cement will continue to be central to infrastructure and urban development. The challenge now is to ensure that the cement used in India’s growth story carries a lower carbon burden.

  • Rakesh Rao

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Concrete

Indian Railways Plans Green Fly Ash Transport Network

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Specialised rail logistics will move fly ash from power plants to infrastructure industries.

New Delhi

Indian Railways is planning a large-scale green logistics initiative to transport fly ash from thermal power plants to industries where it can be reused in infrastructure and construction activities.

The initiative was discussed during a review meeting chaired by Union Minister for Railways Ashwini Vaishnaw. Union Ministers of State for Railways V Somanna and Ravneet Singh Bittu were also present.

India generates nearly 340 million tonnes of fly ash every year from thermal power plants. The proposed initiative aims to create an efficient rail-based transport system using specialised containers and dedicated logistics arrangements to move fly ash safely from power plants to end-use industries.

Fly ash is widely used in road construction, cement manufacturing, brick production, concrete, blocks and boards. By improving its movement through the railway network, the initiative is expected to support better utilisation of this industrial by-product while reducing environmental concerns linked to storage and disposal.

The move also aligns with India’s circular economy goals by converting waste from thermal power generation into a useful raw material for the construction and infrastructure sectors. Wider availability of fly ash can help reduce material costs in areas such as bricks and cement, supporting more affordable infrastructure and housing development.

Through this initiative, Indian Railways aims to provide a cleaner, safer and more organised transport solution for fly ash, turning an environmental challenge into an infrastructure resource.

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