As the cement industry prioritises sustainability and performance, Supplementary Cementitious Materials (SCMs) are redefining standards, explains Tushar Khandhadia, General Manager – Production, Udaipur Cement Works.

What role do supplementary cementitious materials (SCMs) play in enhancing the performance and sustainability of cement and concrete?
SCMs play a crucial role in enhancing the performance and sustainability of cement and concrete. These materials are added to concrete to improve its properties such as strength, durability, and workability, as well as to reduce the environmental impact of cement production. The addition of SCMs to cement reduces the amount of Portland cement required to manufacture concrete, reducing the carbon footprint of the concrete. These materials are often industrial waste products or by-products that can be used as a replacement for cement, such as fly ash, slag and silica fume.
SCMs also reduce the amount of water required to produce concrete, which reduces the environmental impact of concrete production. This is achieved through their ability to improve the workability of concrete, allowing the same amount of work to be done with less water.
In addition, SCMs improve the durability of concrete by reducing the risk of cracking and improving resistance to chemical attack and other forms of degradation.

How has your company integrated SCMs into its production process, and what challenges have you encountered?
The integration of SCMs into cement and concrete production may pose certain challenges in the areas of sourcing, handling and production optimisation.

• Sourcing: Finding an adequate and reliable supply of SCMs can be a challenge. Some SCMs, such as fly ash and slag, are readily available by-products of other industrial processes, while others such as silica fume or metakaolin may be more difficult to source.
• Handling: The storage, handling, and transportation of SCMs require special considerations due to their physical and chemical properties. For instance, some SCMs are stored in moist conditions to prevent them from drying out and becoming airborne, which could pose a safety risk to workers.
• Production optimisation: The addition of SCMs into the mix may require adjustments to the production process to achieve the desired properties of cement and concrete. For example, the use of SCMs may affect the setting time, workability, strength gain, and other properties of the final product, which may require reconfiguration of the production process.
• Quality control: The addition of SCMs may introduce variability in the properties of cement and concrete, and rigorous quality control measures are necessary to ensure the final product meets the required specifications and standards.

Proper planning, handling and production optimisation are essential in overcoming the challenges encountered during the integration process.

Can you share insights on how SCMs such as fly ash, slag and silica fume impact the durability and strength of concrete in different environmental conditions?

• Fly ash is a by-product of coal combustion and is widely used as an SCM in the production of concrete. When added to concrete, fly ash reacts with the calcium hydroxide present in the concrete to form additional cementitious materials, resulting in improved strength and durability. Fly ash increases the durability of concrete by improving its resistance to sulphate and acid attacks, reducing shrinkage and decreasing the permeability of concrete. Fly ash also enhances the workability and pumpability of concrete while reducing the heat of hydration, which reduces the risk of thermal cracking. In cold climates, fly ash helps to reduce the risk of freeze-thaw damage.
• Slag is a by-product of steel production and is used as an SCM because of its high silica and alumina content. When added to concrete, slag reacts with the calcium hydroxide present in the concrete to form additional cementitious materials, resulting in improved strength and durability. Slag increases the durability of concrete by improving its resistance to sulphate and acid attacks, reducing shrinkage and improving the strength of concrete over time. Slag also enhances the workability of concrete, reduces the heat of hydration, and improves the resistance of concrete to chloride penetration.
• Silica fume is a by-product of the production of silicon and ferrosilicon alloys and is used as an SCM because of its high silica content. When added to concrete, silica fumes react with the calcium hydroxide present in the concrete to form additional cementitious materials, resulting in improved strength and durability. Silica fume increases the durability of concrete by improving its resistance to sulphate and acid attacks, reducing permeability, and improving abrasion resistance. Silica fume also enhances the workability of concrete, reduces the heat of hydration, and improves the resistance of concrete to chloride penetration.

Overall, the use of SCMs such as fly ash, slag and silica fume can significantly improve the durability and strength of concrete in different environmental conditions. Their impact on concrete varies depending on the availability, physical and chemical properties of the specific SCM being used and proper testing and engineering analysis should be done for each mix design in order to optimise the final product.

With the global push for sustainability, how do SCMs contribute to reducing the carbon footprint of cement production?
SCMs provide an environmentally friendly alternative to traditional Portland cement by reducing the amount of clinker required to produce cement. Clinker is the main ingredient in Portland cement and is produced by heating limestone and other raw materials to high temperatures, which releases significant GHG emissions. Thus, by using SCMs, less clinker is required, thereby reducing GHG emissions, energy use and the environmental impact of cement production. Some SCMs such as fly ash and slag are by-products of other industrial processes, meaning that their use in cement production reduces waste and enhances resource efficiency. Moreover, the use of SCMs can enhance the properties of concrete, thereby increasing its durability and service life which helps to further reduce the overall embodied carbon of the structure.
In short, the use of SCMs contributes to reducing the carbon footprint of cement production by improving the efficiency of resource utilisation and reducing greenhouse gas (GHG) emissions during the production process. This has led to an increased demand for SCMs in the construction industry, as environmental concerns and sustainable development goals have become more prominent factors in the selection of building materials.

What strategies or innovations has your company adopted to ensure a consistent and reliable supply of SCMs, given their reliance on industrial by-products?

• Developing partnerships with suppliers: Many cement and concrete manufacturers establish long-term partnerships with suppliers of SCMs. These partnerships provide a reliable supply of high-quality SCMs, improve supply chain efficiency, and often provide access to new sources of SCMs.
• Advanced SCM processing techniques: Many companies are investing in advanced processing techniques to unlock new sources of high-quality SCMs. Advanced processing techniques include new separation processes, calcination techniques, and chemical activation methods.
• Alternative SCM sources: Many companies are exploring alternative SCM sources to supplement or replace traditional SCMs. Examples include agricultural by-products such as rice hull ash or sugar cane bagasse ash, which can be used in place of fly ash.
• Quality control measures: Strict quality control measures are necessary to ensure consistent quality of SCMs. Many companies use advanced testing methods, such as particle size analysis, chemical analysis, and performance testing, to validate the quality of SCM materials used in production.
• Supply chain diversification: Diversifying suppliers and SCM sources is another way to ensure a reliable supply. This reduces the risk of supply chain disruptions caused by factors such as natural disasters, market changes, or geopolitical risks.

The strategies and innovations adopted to ensure a consistent and reliable supply of SCMs include establishing long-term partnerships with suppliers, investing in advanced processing techniques, exploring alternative SCM sources, implementing strict quality control measures, and diversifying supply chains. By implementing these approaches, we ensure that use of SCMs in cement production is an effective and viable solution for reducing the environmental impact of operations

How does the use of SCMs align with your company’s broader goals around circular economy and resource efficiency?
Here are some ways in which the use of SCMs supports these goals:

• Reducing waste: The use of SCMs, such as fly ash and slag, diverts significant quantities of industrial waste from landfills, turning it into a valuable resource that can be used in construction. This helps to reduce waste and conserve natural resources.
• Reducing carbon emissions: Cement production is a significant contributor to greenhouse gas emissions, and the use of SCMs can significantly reduce the amount of cement required in concrete mixtures. This helps to reduce the carbon footprint of construction activities and move towards a low-carbon economy.
• Enhancing resource efficiency: The use of SCMs can reduce the demand for raw materials, energy, and water in the production of concrete. This not only conserves natural resources but also reduces the costs associated with the extraction, transportation and processing of these materials.
• Closing the loop: SCMs encourage closed-loop systems in the construction sector, where waste materials from one process become input materials for another. This can improve the efficiency and sustainability of the construction industry.
• Supporting sustainable design practices: The use of SCMs can support sustainable design practices by improving the durability and performance of structures while also reducing their environmental impact. This supports a circular approach to design, construction and operation of buildings and infrastructure
  that improves their social, economic and environmental sustainability.

What future trends or developments do you foresee in the use of SCMs within the cement industry?
Future trends in the use of SCMs within the cement industry are likely to focus on: increased utilisation of diverse waste-derived SCMs, development of new SCM sources to address potential shortages, advanced characterisation techniques to optimise SCM blends and data-driven approaches to predict and optimise SCM usage for reduced carbon footprint and improved concrete performance; all driven by the growing need for sustainable cement production and stricter environmental regulations.
Key aspects of this trend include:

• Expanding SCM sources: Exploring a wider range of industrial byproducts and waste materials like recycled concrete aggregate, activated clays and certain types of industrial minerals as potential SCMs to reduce reliance on traditional sources like fly ash, which may become increasingly limited.
• Advanced material characterisation: Utilising sophisticated techniques to better understand the chemical and physical properties of SCMs, allowing for more precise blending and optimisation of their use in cement mixtures.
• Data-driven decision making: Implementing machine learning and big data analysis to predict the performance of different SCM combinations, allowing for real-time adjustments in cement production based on available SCM sources and desired concrete properties.
• Focus on local sourcing: Prioritising the use of locally available SCMs to reduce transportation costs and environmental impact.
• Development of new SCM processing techniques: Research into methods to enhance the reactivity and performance of less readily usable SCMs through processes like activation or modification.
• Life cycle analysis (LCA) integration: Using LCA to assess the full environmental impact of different SCMs and optimise their use to minimise carbon emissions throughout the cement production process.
• Regulatory frameworks and standards:Increased adoption of building codes and industry standards that promote the use of SCMs and set targets for reduced carbon emissions in cement production.

– Kanika Mathur

Rajesh Kumar Nayma, Assistant General Manager – Environment, Wonder Cement, shares the company’s ambitious commitment to reducing emissions through advanced technology and alternative fuel use, thereby driving significant change in the cement industry.

How does your company address the environmental impact of cement production, particularly in terms of reducing emissions?
Wonder Cement Limited (WCL) has played a vital role in Indian infrastructure development and focuses towards a more sustainable future, including environment protection, clean energy and water positivity. The organisation is a firm believer in putting a positive impact on the environment. Environment and sustainability is a core value that drives our operations. We are committed to minimising the environmental impact from cement production, particularly when it comes to emissions. We do the impact analysis due to operation of the units being carried out at design stage level to ensure minimum impact on the environment i.e. air, water and land. Equipment selection is done accordingly taking various measures to ensure no fugitive emission, stack emission, water pollution and soil degradation such as installation of best-in-class air pollution control equipment (ESP’s Reverse Air Baghouse); bag filters at all the material transfer points; provided covered storage facilities/storage silos to maintain ambient air quality; fugitive emission and stack emission well within the prescribed emission Norms, Selective Non Catalytic Reactor (SNCR) for control of NOx Emission; and preventive routine maintenance of air pollution control equipment are carried out. By taking these measures, WCL ensures emissions are well below the stipulated norms for particulate matter, SO2 and NOx.

We are focusing on reducing the GreenHouse Gases (GHG) emissions, too. Due to our operations, we have done GHG Invertisation, which aims to achieve Net Zero by 2060, in line with the nation’s commitment in COP-26.
We have Zero Liquid Discharges facilities across all our units. Being dry process cement manufacturing units, the wastewater generation in our units is very low in quantum and the implemented closed-loop systems help to reuse process water and minimise fresh water consumption. WCL is reusing 100 per cent STP/ETP water in its process, greenbelt development and dust suppression at its integrated cement plant and split grinding units.

What measures have been implemented to monitor and control emissions of CO2, NOx, and particulate matter during the cement manufacturing process?
We have installed an Online Continuous Stack Monitoring System (OCEMS) in all the process stacks along with PTZ cameras and Continuous Ambient Air Quality Monitoring Systems (CAAQMS) in all our operating units. Real time data of OCEMS/CAAQMS is transmitted to SPCB/CPCB servers, and also to our control systems, which enables us to take corrective action on priority.
The major pollutants through air are particulate matter and gaseous emissions. The emissions of particulate matters from all the stacks are maintained within the prescribed norms by installing bag house, bag filters and electorstatic precipitator (ESP) at all major sources of air pollution i.e. raw mill, kiln, clinker cooler and coal mill cement mills and captive power plant (CPP).
We have also installed SNCR technology along with a low NOx burner to reduce NOx emissions effectively to keep the same in the prescribed norms and lime dosing systems have been installed in the power plants to ensure SO2 emission within the prescribed norms.
We use alternative fuels and raw materials (AFR) in order to increase our green energy portfolio, to reduce the clinker factor and to reduce the power/energy consumption per tonne of clinker/cement. The installation of WHRB in all the operating kilns has further helped in cutting down the CO2 emissions.

Can you elaborate on the role of alternative fuels and raw materials in reducing the environmental footprint of cement production?
The use of AFR plays a critical role in our strategy to reduce the environmental footprint of cement production. By substituting traditional fossil fuels with waste-derived alternatives like biomass, refuse-derived fuel (RDF) and industrial by-products, we significantly lower CO2 emissions and reduce the demand for natural resources.
The utilisation of supplementary cementitious materials (SCMs), such as fly ash, helps in reducing clinker consumption, which is a major source of carbon emissions in cement production. This not only decreases our reliance on energy-intensive processes but also promotes waste recycling and resource efficiency. AFR adoption is an integral part of our commitment to the circular economy, ensuring that we minimise waste and optimise the use of materials throughout the production cycle, ultimately contributing to a more sustainable and eco-friendly cement industry.
WCL is exploring transitioning from fossil fuels to cleaner alternatives like biofuels or hydrogen or RDF/plastic waste/other hazardous waste. Till date, 5 per cent TSR has been achieved, while the intent is to achieve more than 20 per cent TSR. WCL is utilising the hazardous and other waste as an alternative fuel or raw material. We have used more than 3 lakh metric tonne of hydrogen waste and other waste in FY-2023-24.

How does your company approach waste management and recycling to minimise environmental harm?

WCL is focusing on the 3 R’s – Reduce, Reuse and Recycle. We focus on optimum utilisation of natural resources and reuse of said resource as well as recycling of the waste material generated from our operations.
We are contributing to reduce the legacy waste generated in our municipalities and we have co-processed more than 50000 tonnes of RDF/plastic waste. Additionally, we are sending other waste generated at our facilities such as used oil / used lead acid batteries / e-waste to authorised recyclers. We are focused on targeted reduction in waste generation.
We are also utilising alternative raw materials. which are the waste from other industries such as red mud, chemical gypsum, iron sludge and ETP sludge to substitute natural resources.
WCL is also increasing the use of recycled content of plastic in PP bags.
We have met our EPR target for plastic waste introduced in the market for FY 23-24 through co-processing of plastic waste in its kiln. Additional EPR credit will be traded for this in the market.

What are the biggest challenges your company faces in achieving compliance with environmental regulations, both locally and globally?
WCL is committed toward 100 per cent compliances to applicable rules and regulations and having dedicated resources to do so, when we talk about the challenges WCL faces in complying with environmental regulations is the constantly evolving nature of both local and global environmental rules and regulation which further leads to strength. While we are committed to adhering to stringent regulations, keeping up with the rapid changes in environmental laws requires continuous upgradation in technology and processes. Another challenge is the high capital investment needed for adopting cleaner technologies, such as De_Sox System / SNCR / Up-gradation of ESP /bag house and carbon capture systems.
Additionally, the availability of AFR can be inconsistent, making it difficult to achieve consistent reductions in GHG emissions. Despite these challenges, WCL remains committed to sustainability and continuously collaborates with regulatory bodies and industry experts to stay ahead of compliance requirements. We also invest in research and development to innovate our production processes, ensuring that we not only meet but exceed environmental compliances.

What technological innovations or process optimisations has your company adopted to lower greenhouse gas emissions?
WCL has adopted several technological innovations and process optimisations to lower greenhouse gas emissions. One of the key initiatives is the installation of 45 MW waste heat recovery systems, which capture excess heat from the production process and convert it into energy, reducing the overall carbon footprint. We have also introduced advanced burner technology with lower NOx emissions and optimised energy consumption and presently we are less than 47 KWh/tonne of clinker, which is one of the best in the cement industry.
The deployment of energy-efficient vertical roller mills (VRM) for clinker grinding also contributes to reducing energy consumption and emissions. These innovations are part of our broader commitment to sustainability and are continuously enhanced to meet global environmental standards.
WCL is focusing on investing in renewable energy sources like solar or wind power to meet the electricity needs. We have installed a solar power plant at our Nimbahera plant and Jhajjar grinding unit as well as 15 MW windmills at Pratapgarh, for our grinding units located at Aligarh, Uttar Pradesh and Dhule Maharashtra. We have renewable power purchase agreements to source renewable energy, which will replace approximately 50 to 60 per cent of energy demand from the grid, further leading to reducing the GHG emissions.
WCL is taking various operational/capex measures to reduce the energy requirement like installation of VFD, optimisation of differential pressures across bag filters and optimisation of kiln operation to get maximum output.

How does your company engage with stakeholders, including local communities and environmental agencies, to ensure transparency and sustainability in your operations?
WCL has a well-defined approach for identification of stakeholders, which is done after considering the material influence each group has on the company’s ability to create value (and vice-versa). The objective of stakeholder engagement is to foster connections, build trust and confidence and buy-in for your company’s key initiatives. This can also help us mitigate potential risks and conflicts with stakeholders.
Stakeholder engagement is done is to understand the needs and expectation of anyone who has a stake in our company, based on which we can develop our strategy and identify our focus areas such as:

• What long-term goals has the company set in terms of reducing emissions
• What steps are being taken to achieve them
• What are the key focus areas to take society along with us

WCL places great emphasis on engaging with stakeholders, including local communities, environmental agencies and industry experts, to ensure transparency and sustainability. We conduct regular environmental audits and share our findings with relevant regulatory bodies to ensure compliance. Our CSR initiatives are closely aligned with community needs, particularly in areas like water conservation, afforestation and waste management, health, education and women empowerment, which directly impact the local environment.
We maintain an open dialogue with local residents to address their concerns about air quality, emissions and resource use and carry out need based assessment and accordingly design our CER/CSR programme and further implement the same.
Additionally, WCL participates in various industry forums and collaborates with environmental agencies to stay ahead of regulatory changes and adopt best practices. Transparency is key to building trust, and we ensure that all stakeholders are kept informed about our sustainability initiatives through periodic reports and community outreach programs. This collaborative approach ensures that we maintain a positive environmental and social impact.

What long-term goals has your company set in terms of reducing emissions, and what steps are being taken to achieve them?
WCL has set ambitious long-term goals to significantly reduce emissions in line with global climate targets. One of our primary objectives is to achieve net-zero carbon emissions by 2060, with interim goals to reduce CO2 intensity by 25 per cent by 2040 through increasing Green Energy Portfolio from present 41 per cent to 70 per cent, AFR and green hydrogen 3 per cent to 40 per cent, reduction in clinker factor from 79 to 60 per cent and CCUS and electrification of the kiln, introduction of LC3 and PLC cements based on techno-economic feasibility.
To achieve these targets, we are investing to develop facilities to feed more AFR, which helps to reduce dependence on fossil fuels and natural resources and lower carbon emissions. We are also exploring carbon capture and storage (CCS) technologies to capture CO2 emissions at their source. WE are committed to achieving its long-term sustainability goals and contributing to the global effort to combat climate change.

– Kanika Mathur

Raju Ramchandran, SVP Manufacturing (Cluster Head – Central), Nuvoco Vistas, sheds light on the company’s robust commitment to sustainable cement production, achieving low emissions through innovative energy solutions, alternative fuels and circular economy practices.

How does your company address the environmental impact of cement production, particularly in terms of reducing emissions?
As a cement manufacturing company, managing energy consumption and emissions is crucial to achieving sustainable operations. At Nuvoco, we have taken significant measures to address this material issue and use it as a competitive advantage for the company. We are consistently enhancing the integration of green power and alternative fuels within our operations. This ongoing commitment is pivotal to our strategy for reducing Greenhouse Gas (GHG) emissions, highlighting our dedication to sustainable practices.
Nuvoco maintains one of the lowest carbon footprints in the industry, with carbon emissions standing at just 457 kg of CO2 per tonne of cementitious materials. Our solar energy capacity has also grown significantly, increasing from 1.5 MW to 5.3 MW for FY 23-24.

What measures have been implemented to monitor and control emissions of CO2, NOx and particulate matter during the cement manufacturing process?
We consistently track air emissions from fuel combustion in our cement manufacturing and power generation operations. The burning of fossil fuels releases pollutants such as Oxides of Sulphur (SOx), Oxides of Nitrogen (NOx), and Particulate Matter (PM), which require stringent monitoring.
We ensure compliance with regulatory standards by using the Continuous Emission Monitoring System (CEMS) to monitor these emissions. For the FY 23-24, both our stack and fugitive emissions have stayed within the permissible limits set by Pollution Control Boards. Moreover, our ongoing monitoring of fugitive emissions ensures that we meet the prerequisite air quality standards.

Can you elaborate on the role of alternative fuels and raw materials in reducing the environmental footprint of cement production?
The use of alternative fuels and raw materials plays a critical role in reducing the environmental footprint of cement production. At Nuvoco, we are actively embracing this approach to promote sustainability and lower our dependence on traditional fossil fuels and virgin raw materials.
Our manufacturing processes enable the use of waste materials from industries like steel and thermal power generation as alternative fuels. Our mix of alternative fuels includes solid waste, liquid solvent, biomass, refuse derived fuels (RDF) from municipal solid waste, and other substances, with a focus on biomass. By incorporating alternative fuels we not only reduce carbon emissions but also contribute to waste management by diverting materials from landfills. Additionally, in line with our sustainability objectives, we plan to considerably expand our use of alternative fuels in the coming years.
During FY 23-24, the utilisation of Alternative Raw Materials (ARM) in our processes increased to 33.9 per cent in cement production, up from 27.7 per cent in the previous year. Incorporating materials such as chemical gypsum, fly ash and slag into our cement formulations significantly reduced our reliance on virgin raw materials and further promoted circularity in our operations.

How does your company approach waste management and recycling to minimise environmental harm?
The principles of a circular economy are integral to our sustainability initiatives. We engage in a variety of efforts to minimise waste generation, promote resource efficiency, and reduce our environmental footprint. We collaborate with other industries to incorporate their waste into our operations, using it as alternative raw materials. By introducing substitute materials into our cement production, such as blended cement with reduced clinker content, we are able to lower waste disposal volumes and significantly reduce carbon emissions.
In our Ready-Mix Concrete (RMX) plants, we actively integrate recycled aggregates from Construction and Demolition (C&D) waste into our manufacturing process. This practice not only boosts the sustainability of our concrete products but also prevents valuable materials from ending up in landfills, contributing to better resource efficiency.
A notable innovation is the ‘Nu Aqua Zero Debris Recycler System,’ which addresses the challenges of solid concrete waste and slurry disposal at RMX plants. This system significantly reduces debris generation and recycles wastewater for reuse, cutting down on freshwater consumption and solid waste. This initiative underscores Nuvoco’s dedication to promoting sustainability and fostering a circular economy in the building material industry.

What long-term goals has your company set in terms of reducing emissions, and what steps are being taken to achieve them?
Nuvoco has set a long-term vision for reducing emissions, anchored in its ‘Protect Our Planet’ agenda. This agenda aligns with the growing focus on Environmental, Social and Governance (ESG) principles, which have become increasingly important to stakeholders, including customers, employees, partners, investors, regulators and local communities. Sustainability is a core component of our business strategy, driving its commitment to responsible and environmentally conscious operations.
The company’s approach is structured around five key themes: Decarbonisation, Water Management, Circular Economy, Biodiversity and Waste Reduction. As part of its decarbonisation strategy, Nuvoco is committed to reducing carbon emissions by 2 per cent annually. This effort includes a focus on maximising the use of alternative fuels, harnessing waste heat for green energy generation, and incorporating innovative green products such as the ECODURE range.

What technological innovations or process optimisations has your company adopted to lower greenhouse gas emissions?
The company has dedicatedly installed a system that is capable of utilising agricultural waste, refuse derived fuel (RDF), plastic waste, municipal waste, biomass, tyre chips and other hazardous waste sources. We have introduced AFR feeding into the pyro process system for enabling uniform feeding and incorporating all necessary safety interlocks throughout. This system allows us to consume alternate fuels in an efficient and effective way without impacting the environmental standards prescribed and approved by the Pollution Control Board of India. Although this project is primarily focused on environmental sustainability, it also has several other benefits for clinker production and can offer significant cost savings through its alternative fuels program.
The company has also made significant modifications across its plants to improve energy efficiency, specifically targeting SHC (Specific Heat Consumption) and SPC (Specific Power Consumption) during clinker and cement production. Our waste heat recovery systems currently have a combined capacity of 44.7 MW, with plans for further optimisation to increase power generation.

– Kanika Mathur