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Waste Glass as Pozzolana

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Dr SB Hegde, Professor, Jain University and Visiting Professor, Pennsylvania State University, United States of America, gives a detailed account of the use of waste glass as Pozzolana, a sustainable solution for cement production, in a two-part article.

The increasing demand for cement, coupled with growing environmental concerns, has led to a search for alternative materials that can reduce the carbon footprint of cement production. Waste glass, a significant environmental concern itself, has emerged as a promising alternative due to its pozzolanic properties.
This paper delves into the concept of utilising waste glass as a pozzolanic material in cement production, highlighting its benefits, challenges and potential for sustainable development based on the research and development work carried out by the author. This is part one of the study; part two will be featured in the consecutive issue of the magazine.

Generation and Availability of Waste Glass
On a global scale, this only amounts to a recycling rate of less than 35 per cent. Worldwide, around 130 million tonnes (Mta) of glass are currently produced annually.
India alone produces three million tonnes of glass waste annually, of which only 35 per cent is recovered, and the rest often ends up in landfills or down cycled into construction material aggregates. Glass is found in municipal solid waste (MSW), primarily in the form of containers such as beer and soft drink bottles; wine and liquor bottles; and bottles and jars for food, cosmetics and other products. India is one of the largest consumers of glass in the world, and as a result, it also generates a significant amount of waste glass. Waste glass, also known as cullet, can come from various sources such as bottles, jars, containers, windows and other glass products.
The availability and generation of waste glass in India depend on several factors, including population, consumption patterns, recycling infrastructure and waste management practices. Glass waste can be generated from residential households, commercial establishments and industries as well as construction and demolition activities. In recent years, there has been growing awareness about the importance of recycling glass waste in India. Recycling glass has several environmental benefits, such as reducing the consumption of raw materials, saving energy and reducing landfill waste.

Infrastructural requirement
To effectively use waste glass as a pozzolanic material in a cement plant, certain facilities and processes can be implemented. Here are some key facilities that can be created:

  1. Glass Sorting and Preprocessing: A facility for sorting and preprocessing waste glass is essential to segregate glass by colour and removing contaminants such as paper, plastics and metals. Crushing or grinding equipment can be used to reduce the glass to a suitable particle size.
  2. Glass Storage and Handling: Adequate storage facilities should be established to store the sorted and processed glass. It is important to protect the glass from moisture and other environmental factors that can affect its quality.
  3. Glass Dosing System: A dosing system should be set up to accurately measure and control the amount of waste glass being added to the cement production process. This can involve automated feeders or other equipment to ensure a consistent and controlled addition of glass.
  4. Glass Grinding or Milling Equipment: Depending on the desired fineness of the waste glass, a grinding or milling unit may be required to further reduce the particle size. This equipment can include ball mills, vertical roller mills, or specialised glass grinding mills.
  5. Blending and Mixing Facilities: Cement plants typically have blending and mixing facilities where various supplementary cementitious materials, including waste glass, can be combined with other raw materials. This ensures homogeneity and uniformity in the cement production process.
  6. Quality Control and Testing: Facilities for quality control and testing should be in place to assess the chemical and physical properties of the waste glass, as well as the performance of the cementitious mixtures incorporating the glass. This can include laboratory testing equipment and personnel trained in relevant testing methods.
    It’s important to note that the specific facilities required may vary depending on the scale of the cement plant and the volume of waste glass being processed. Detailed engineering studies and consultations in cement production and waste management can help determine the optimal design and layout of these facilities within a cement plant. Additionally, it is advisable to comply with relevant environmental regulations and obtain any necessary permits or approvals from statutory bodies in that particular country for handling and using waste glass within the cement plant.

The Fineness of Waste Glass
When waste glass is used as a supplementary cementitious material in cement production, it is important to consider the fineness or particle size distribution of the glass. The fineness of waste glass affects its reactivity and compatibility with
cement, which can impact the performance of the cementitious mixture.
The specific fineness requirements for waste glass can vary depending on the specific application, the type of cement being used, and the desired properties of the final concrete or mortar. However, in general, the waste glass particles should be finely ground to ensure effective pozzolanic or latent hydraulic reactions with the cement.
Here are some common guidelines for the fineness of waste glass used in cement:
Particle Size Distribution: The waste glass particles should have a range of sizes to ensure good packing and fill the voids between cement particles. A typical particle size distribution for waste glass in cement applications is similar to that of cement, with a majority of particles passing through a 325 mesh (45 microns) sieve.
Blaine Fineness: The Blaine fineness test is often used to measure the specific surface area of cementitious materials. The waste glass should generally have a Blaine fineness similar to or higher than that of cement. Typical values can range from 300 to 500 m²/kg or higher, depending on the application.
Grinding or Milling: Waste glass may require grinding or milling processes to achieve the desired fineness. The grinding method can vary depending on the available equipment and the specific glass composition. Ball mills, vertical roller mills or specialised glass grinding equipment can be used.
Gradation Control: It is important to control the gradation of waste glass during the grinding process. A well-controlled gradation can improve the flowability and workability of the cementitious mixture.
It is worth noting that the precise fineness requirements may vary depending on the specific standards, specifications, or guidelines established by statutory bodies of the particular country.

Attributes of Waste Glass as Pozzolana
Based on research and development investigations the following avenues are investigated for utilisation of waste glass.
Pozzolanic Properties of Waste Glass: Pozzolanic materials, when combined with calcium hydroxide in the presence of water, react to form cementitious compounds. Waste glass, rich in amorphous silica, exhibits excellent pozzolanic properties. Through a process called pozzolanic reaction, waste glass can contribute to the strength, durability, and chemical resistance of cementitious materials.
Environmental Benefits: Incorporating waste glass as a pozzolanic material in cement production offers significant environmental advantages. Firstly, it reduces the need for virgin raw materials such as limestone, thus conserving natural resources. Additionally, it mitigates the environmental impact associated with glass waste disposal, diverting it from landfills or incineration.
Improved Concrete Performance: The use of waste glass as a pozzolanic material enhances the performance of concrete. Due to its pozzolanic activity, waste glass reacts with calcium hydroxide in the cement matrix, resulting in denser and more durable concrete. This leads to improved mechanical strength, reduced permeability, and increased resistance to chemical attack.
Supplementary Cementitious Material: Waste glass can be used as a supplementary cementitious material (SCM) in cement production. When properly ground and processed, waste glass can replace a portion of cement without compromising the desired concrete properties. This substitution not only reduces cement consumption but also lowers the carbon dioxide emissions associated with cement production.
Sustainable Development and Circular Economy: Utilising waste glass as a pozzolanic material aligns with the principles of sustainable development and the circular economy. It promotes resource efficiency, reduces waste generation, and contributes to a more sustainable construction industry. The integration of waste glass into cement production presents opportunities for collaboration between cement manufacturers, waste management companies, and regulatory bodies to develop innovative and eco-friendly solutions.

References

  1. Utilisation of Waste Glass Powder in Concrete by P. Manoj Kumar,
    K. Sreenivasulu, and M. Srinivasulu Reddy, International Journal of Innovative Research in Science, Engineering and Technology, 2013.
  2. Recycling of Waste Glass as a Partial Replacement for Fine Aggregate in Concrete Mix by W. A. Rahman, M. A. S. Al-gahtani,
    and M. A. K. El-Kourd, Journal of King Saud University – Engineering Sciences, 2010.
  3. Mechanical and Durability Properties of Concrete Containing Glass Powder as Partial Replacement of Cement by A. Shayan and R. Xu, Construction and Building Materials, 2004.
  4. Properties of Glass Concrete Containing Fine and Coarse Glass Aggregates by Z. Feng, S. Xie, and Y. Zhou, Journal of Materials in Civil Engineering, 2011.

ABOUT THE AUTHOR
Dr SB Hegde, Professor, Jain University and Visiting Professor, Pennsylvania State University, United States of America.

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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