Connect with us

Concrete

Using Slag as Fine Aggregate in Concrete

Published

on

Shares

Disposal of waste slag is a major concern and is perceived as an environmental hazard across the steel industry. Nagesh Veeturi, Executive Director – Civil, and Sumanta Sahu, DGM – Quality, KEC International, investigate the possibility of utilising slag as a fine aggregate and its effect on the strength and workability parameters of concrete.

Concrete is one of the major construction materials in civil construction. It is a composite material with cement, aggregate, sand, admixture and water as ingredients. River sand and Manufactured Sand are mostly used as fine aggregate in concrete. River sand is formed by the natural weathering of rocks over many years and is preferred to be used as fine aggregate. Manufactured Sand is produced by crushing hard rocks into smaller sizes using a crusher followed by washing to use in concrete. The growth of infrastructure and building projects demand the use of huge quantities of sand in concrete.
The mining of sand from riverbeds is posing a serious threat to the environment causing the erosion of riverbeds and banks, triggering landslides, inducing loss of vegetation on the riverbanks, lowering the underground water table, etc. Hence, sand mining from riverbeds and rock is being restricted or banned by the authorities nowadays. To nullify the above concerns, concrete mix trials were conducted in our quality laboratory by using LD slag and blast furnace slag as fine aggregate.

LD Slag
LD slag is a byproduct of the steel industry. It is produced from impurities during the steel-making process. LD Slag consists of calcium, magnesium, iron, silicon and aluminium oxides minerals. During the production of steel, the slag is separated from steel in the furnace, and steel slag fine aggregate is formed after quenching the molten slag with water. There are many grades of steel produced and properties of steel slag vary depending on raw materials used for steel production. LD slag is typically granulated and used as a fine aggregate. Normally it is heavier than sand and its specific gravity is observed to be 3.2 to 3.6 with water absorption around 3 per cent.

Production process of LD Slag.
Due to its high density, segregation is observed as a fine aggregate in concrete. Materials can be used as partial replacement of fine aggregate.

Blast furnace slag
Blast furnace slag is a byproduct produced during the iron making process in blast furnaces. During the smelting process, iron ores are fed into the furnace at high temperature. The process leads to the production of molten iron and waste materials. Slag, which is a waste material, is separated and quenched with water. This rapid cooling process solidifies the slag into granular particles. Blast furnace slag is observed to be lighter than sand, specific gravity of sand is found to be 2.01.

Concrete mixes with slag as fine aggregate
Concrete mix trials were conducted with LD slag, BF slag as fine aggregate. Due to the high density of LD slag, segregation was noticed on concrete mixes. The same segregation is observed in concrete mix by using BF slag due to its lightweight. Further concrete mix trials were conducted by mixing LD slag and BF slag with different proportions – this is done to study the initial properties of concrete such as cohesiveness and workability retention.
The concrete mix is observed to be cohesive
with good workability retention by using LD slag and BF slag as fine aggregate with the same
proportions. Other properties of concrete such as setting, and strength were observed complying to specification requirements.

Benefits of using LD slag and BF slag as fine aggregate
Durability:
Calcium oxide and silicon oxide are prime chemicals used in the composition of LD slag and BF slag, and both possess pozzolanic properties. calcium oxide and silicon oxide react with calcium hydroxide produced during hydration of cement and increases strength and permeability properties
of concrete.
Sustainable approach: LD slag and BF slag are the by-products from the iron industry which makes it an industrial waste product. Using materials as fine aggregate helps to conserve natural resources. Storage of this material is a major concern in industry. Utilisation of LD slag and BF slag as fine aggregate minimise storage area, air pollution.
Reduction in carbon footprint and heat of hydration: The use of LD slag and BF slag as a fine aggregate leads to reduction in cement content in concrete mixes. Cement is a major source of rise in temperature in concrete mixes that leads to increase in carbon emission during its production process. Reduction in cement content minimises the heat of hydration and prevents thermal cracks in concrete.
Enhance workability in concrete mixes: Workability in concrete is increased due to the even surface of LD slag and BF slag. This makes the concrete easier to place during the construction process.
Cost optimisation: LD slag and BF slag are industrial waste products and are cheaper than manufactured sand and river sand. Also due to the pozzolanic properties of slag, cement content in concrete can be minimised. Overall concrete cost is reduced with improved performance.
Due to the vast growth of construction sectors, the demand for concrete has increased as a fine aggregate. Thus, it is essential to find suitable alternatives to sand such as slag materials.
It is observed that the combined use of LD slag and BF slag as fine aggregates leads to cohesive mix with desired workability and strength. The PC base chemical admixture was added to reduce the water content and maintain workability of the mix. Finally, it is concluded that slag can be used as an alternative of sand in concrete. As both types of slags are by-products from the steel industry, their long-term performance is vital, and further studies in this direction are still in progress.

ABOUT THE AUTHOR:
Nagesh Veeturi, Executive Director – Civil, KEC International
is a seasoned professional having entrepreneurial and leadership skills with key focus on strategy and business transformation.

Sumata Sahu, DGM – Quality, KEC International has 32 years of rich experience in the construction industry mainly as QA/QC and project management professional.

Concrete

India Sets Up First Carbon Capture Testbeds for Cement Industry

Five CCU testbeds launched to decarbonise cement production

Published

on

By

Shares



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.

Continue Reading

Concrete

JK Lakshmi Adopts EVs to Cut Emissions in Logistics

Electric vehicles deployed between JK Puram and Kalol units

Published

on

By

Shares



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.

Continue Reading

Concrete

Holcim UK drives sustainable construction

Published

on

By

Shares



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

Continue Reading

Trending News

SUBSCRIBE TO THE NEWSLETTER

 

Don't miss out on valuable insights and opportunities to connect with like minded professionals.

 


    This will close in 0 seconds