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Changing normal concrete into durable concrete for tunnelling application

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In this second part of the two-part series paper, the author EugenKleen of Mc-Bauchemie Mueller GmbH and Co.KG looks at the materials required to change normal concrete to durable media resistant concrete for use in tunnelling application.The main materials, which can help change normal concrete to durable aggressive media resistant concrete, are:??New generation PCE based admixtures??Condensed silica fume or microsilica slurry or??Latest generation aluminosilicatePCE based admixturesMost of the new generation superplasticizers are from the Acrylic Polymer (AP) family. Polycarboxylate is a common term for the substances that are specifically used as Polyacrylate or Polycarboxylate ether (PCE). The PCE based Super Plasticizers are by far superior to the conventional once with respect to initial slumping as well as slump retention with time. The efficient working of these plasticizers is due to the new type of molecule designs. PCE based superplasticizers produce excellent properties when used with cementitious materials. The disadvantages associated with longer setting times of conventional superplasticizers is offset by PCE based super plasticizer and therefore its use in concrete can also attain high early strengths. The development of highly effective superplasticizers with long and consistent duration of action is therefore an important precondition for the production durable concrete, due to low water contents and high early strength requirements.Concrete additives based on PCE offer advantages like:Significant reduction of the water demand of the mix??Little loss of consistency??Short setting times??High early strengths??Low tendency to segregationThe advantages of these new generation polymers are very clear, not only in terms of performance but also in terms of the dosages used for similar conditions and this factor balances the disadvantages in economy, as new generation superplasticizers are relatively expensive per unit price.Condensed Silica Fume/Microsilica:The term ‘microsilica’ is adopted to characterise the silica fume, which is used for the production of concrete. Microsilica or Condensed Silica Fume (CSF) is a by-product resulting from reduction of high purity quartz with coal in the electric arc furnaces used in manufacture of silicon, ferrosilicon and other alloys of silicon.There are three main reasons for the incorporation of silica fume as an additive for HPC. Microsilica has a filter effect i.e. very fine particle distributed itself in the space between the materials in the concrete in a homogenous way to give rise to more dense concrete. Silica fume improves the strength of the transition zone between cement paste and aggregates. CSF is highly pozzolanic in combination with Portland cement.During cement hydration there is surplus of calcium hydroxide. The added condensed silica fume’s SiO2 reacts with surplus of calcium hydroxide, which are greater amounts of calcium silicate hydrate, which are denser and stronger than calcium hydroxide. The pozzolanic reaction and the filler-effect lead to a compaction of the cement paste and the conversion of CH crystals into CSH gel leads to homogenous paste. The phenomenon of dense packing in the interface zone of aggregates also contributes to increase the strength of the concrete on account of aggregates fully contributing their strength of concrete with silica fume is greater than those of the matrix, indicating the contribution of the aggregate of microsilica (50:50 with water) have all the benefits in transportation, dispensing methods, mixing times and dispersions to get the desired effect in durable concrete for tunnelling segments.New Generation Aluminosilicates:New generation aluminosilicates based on special nano-crystalizers have been developed. These new materials improve the properties that are crucial for the durability of high performance concrete. In addition to reducing chloride migration, an exceptional chemical and resistance to aggressive media of the concrete can be achieved with aluminosilicates. The concrete structure is simultaneously reinforced right down to nanoscale, density is improved and compressive and flexure strength as well as abrasion resistance of the high-performance concrete is increased. There is also a significant reduction of micro-crack formation, which makes it particularly suitable for the production of tunnelling concrete. Aluminosilicate reduce the proportion of portlandite by way of a pozzolanic reaction that changes it into the aluminosilicate crystals into calcium silicate hydrate. In addition to the unique resistance against acids a crystalline micro-reinforcement within the concrete structure is achieved. This reduces the risk of micro-crack formation, rendering concrete impermeable.Due to high homogeneity and reduced tackiness compared with microsilica based concrete, workability is improved significantly. In many instances this enables the production of high-performance concrete that can be pumped. In addition, a distinct improvement of the building structure’s aesthetics is gained due to the fair appearance of the concrete surface. Aluminosilicates perform over some of the disadvantages of microsilica:??Graded for dispersion in concrete??Graded particle size??Optimises mixing time within concrete??Good dispersion reduces unreacted material in the mix and increases passivation by C-S-H gel on aggregate surface??Material if agglomerated improve strength of the mix??Reduces risk of alkali silica reaction by agglomeration of aluminosilicate particles.All in all, the use of PCE admixtures and microsilica or aluminosilicate slurries in addition to the standard ingredients in concrete, plus excellent mix-design practices can facilitate the production of high performance concretes resistant to aggressive media, suitable for use in tunnelling applications.

Key difference between Microsilica and Aluminosilica


Normal
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false
false
false

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Microsilica

Aluminosilica

1

By-product of
ferrosilicium and silicium production, not specifically produced for concrete

1

Manufactured product. It
is only produced for use as concrete additive

2

Quantities are depending
on the metal industry and the economic development

2

Quantities are not
depending on other industries and are unlimited, therefore reliable
availability

3

Quality of the product
has a higher deviation because it is only a by-product

3

High quality standards
for end product because every step in production is controlled




























































































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Concrete

India’s Steel Imports Drop 34 Per Cent, Exports Rise 25 Per Cent In April–October

Consumption grows despite weak prices and subdued demand

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India’s finished steel imports fell 34.1 per cent year-on-year to 2.5 million tonnes in the first seven months of the financial year, according to government data. Despite the decline, the world’s second-largest crude steel producer remained a net importer of finished steel during the April–October period. The fall in imports came alongside a 7.4 per cent rise in domestic consumption, which reached 92.2 million tonnes.

South Korea emerged as India’s largest source of finished steel imports, supplying 1.4 million tonnes. It was followed by China, Japan and Russia. Although total imports declined sharply, the figures show a continued inflow of foreign steel into the Indian market.

Domestic production remained strong. Finished steel output stood at 91.6 million tonnes for April–October, while crude steel production reached 95.7 million tonnes, underscoring the scale and resilience of India’s steel industry despite external competition.

In contrast to the fall in imports, India’s finished steel exports jumped 25.3 per cent year-on-year to 3.5 million tonnes. Europe was a major destination, with Italy and Belgium leading as top importers of Indian steel, followed by Spain. This highlights the growing global competitiveness of Indian steel in select markets.

The government noted that domestic steel prices have come under pressure due to weak demand and high supply. Trading activity also remained subdued during the festival season. This challenging environment has been particularly difficult for smaller steel producers, as previously reported.

Overall, the combination of declining imports, rising exports and increasing domestic consumption reflects the complex landscape of the Indian steel sector as it navigates muted internal demand and evolving international trade dynamics.

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JK Lakshmi Cement Plans Rs 18.16 Billion Expansion

Firm to boost clinker and grinding capacity in Chhattisgarh

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JK Lakshmi Cement announced on Tuesday that it will invest Rs 18.16 billion to expand its manufacturing operations in Chhattisgarh. The company intends to raise its clinker production capacity by 2.31 million tonnes per annum (MTPA) and its cement grinding capacity by 1.2 MTPA, supported by this proposed investment.

The Memorandum of Understanding for the expansion was signed during the Chhattisgarh Investor Connect event in New Delhi, in the presence of Chief Minister Vishnu Deo Sai. The added capacity will enhance the company’s ability to serve the rapidly growing markets of Eastern and Central India, where demand for building materials remains robust.

The move supports JK Lakshmi Cement’s broader goal of increasing its total capacity to around 30 MTPA in the coming years. Deputy Managing Director Shrivats Singhania said the expansion marks a significant step in the company’s next phase of growth, adding that Chhattisgarh has long been central to its manufacturing strategy.

Over the past decade, JK Lakshmi Cement has contributed to strengthening Chhattisgarh’s industrial landscape since establishing its integrated plant in Durg in 2015. The company has implemented multiple initiatives, including a manufacturing facility with 1.8 MTPA of clinker capacity and 2.7 MTPA of cement capacity, operational upgrades with energy-efficient technology and automation, and logistics improvements through enhanced rail connectivity.

Chhattisgarh continues to show strong economic momentum, making it one of the most promising markets for cement demand, said Arun Shukla, President and Director at JK Lakshmi Cement. The company’s shares closed 0.28 per cent higher at Rs 782.10 on the BSE.

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Balancing Rapid Economic Growth and Climate Action

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Dr Yogendra Kanitkar, VP R&D, and Dr Shirish Kumar Sharma, Assistant Manager R&D, Pi Green Innovations, look at India’s cement industry as it stands at the crossroads of infrastructure expansion and urgent decarbonisation.

The cement industry plays an indispensable role in India’s infrastructure development and economic growth. As the world’s second-largest cement producer after China, India accounts for more than 8 per cent of global cement production, with an output of around 418 million tonnes in 2023–24. It contributes roughly 11 per cent to the input costs of the construction sector, sustains over one million direct jobs, and generates an estimated 20,000 additional downstream jobs for every million tonnes produced. This scale makes cement a critical backbone of the nation’s development. Yet, this vitality comes with a steep environmental price, as cement production contributes nearly 7 per cent of India’s total carbon dioxide (CO2) emissions.
On a global scale, the sector accounts for 8 per cent of anthropogenic CO2 emissions, a figure that underscores the urgency of balancing rapid growth with climate responsibility. A unique challenge lies in the dual nature of cement-related emissions: about 60 per cent stem from calcination of limestone in kilns, while the remaining 40 per cent arise from the combustion of fossil fuels to generate the extreme heat of 1,450°C required for clinker production (TERI 2023; GCCA).
This dilemma is compounded by India’s relatively low per capita consumption of cement at about 300kg per year, compared to the global average of 540kg. The data reveals substantial growth potential as India continues to urbanise and industrialise, yet this projected rise in consumption will inevitably add to greenhouse gas emissions unless urgent measures are taken. The sector is also uniquely constrained by being a high-volume, low-margin business with high capital intensity, leaving limited room to absorb additional costs for decarbonisation technologies.
India has nonetheless made notable progress in improving the carbon efficiency of its cement industry. Between 1996 and 2010, the sector reduced its emissions intensity from 1.12 tonnes of CO2 per ton of cement to 0.719 tonnes—making it one of the most energy-efficient globally. Today, Indian cement plants reach thermal efficiency levels of around 725 kcal/kg of clinker and electrical consumption near 75 kWh per tonne of cement, broadly in line with best global practice (World Cement 2025). However, absolute emissions continue to rise with increasing demand, with the sector emitting around 177 MtCO2 in 2023, about 6 per cent of India’s total fossil fuel and industrial emissions. Without decisive interventions, projections suggest that cement manufacturing emissions in India could rise by 250–500 per cent by mid-century, depending on demand growth (Statista; CEEW).
Recognising this threat, the Government of India has brought the sector under compliance obligations of the Carbon Credit Trading Scheme (CCTS). Cement is one of the designated obligated entities, tasked with meeting aggressive reduction targets over the next two financial years, effectively binding companies to measurable progress toward decarbonisation and creating compliance-driven demand for carbon reduction and trading credits (NITI 2025).
The industry has responded by deploying incremental decarbonisation measures focused on energy efficiency, alternative fuels, and material substitutions. Process optimisation using AI-driven controls and waste heat recovery systems has made many plants among the most efficient worldwide, typically reducing fuel use by 3–8 per cent and cutting emissions by up to 9 per cent. Trials are exploring kiln firing with greener fuels such as hydrogen and natural gas. Limited blends of hydrogen up to 20 per cent are technically feasible, though economics remain unfavourable at present.
Efforts to electrify kilns are gaining international attention. For instance, proprietary technologies have demonstrated the potential of electrified kilns that can reach 1,700°C using renewable electricity, a transformative technology still at the pilot stage. Meanwhile, given that cement manufacturing is also a highly power-intensive industry, several firms are shifting electric grinding operations to renewable energy.
Material substitution represents another key decarbonisation pathway. Blended cements using industrial by-products like fly ash and ground granulated blast furnace slag (GGBS) can significantly reduce the clinker factor, which currently constitutes about 65 per cent in India. GGBS can replace up to 85 per cent of clinker in specific cement grades, though its future availability may fall as steel plants decarbonise and reduce slag generation. Fly ash from coal-fired power stations remains widely used as a low-carbon substitute, but its supply too will shrink as India expands renewable power. Alternative fuels—ranging from biomass to solid waste—further allow reductions in fossil energy dependency, abating up to 24 per cent of emissions according to pilot projects (TERI; CEEW).
Beyond these, Carbon Capture, Utilisation, and Storage (CCUS) technologies are emerging as a critical lever for achieving deep emission cuts, particularly since process emissions are chemically unavoidable. Post-combustion amine scrubbing using solvents like monoethanolamine (MEA) remains the most mature option, with capture efficiencies between 90–99 per cent demonstrated at pilot scale. However, drawbacks include energy penalties that require 15–30 per cent of plant output for solvent regeneration, as well as costs for retrofitting and long-term corrosion management (Heidelberg Materials 2025). Oxyfuel combustion has been tested internationally, producing concentrated CO2-laden flue gas, though the high cost of pure oxygen production impedes deployment in India.
Calcium looping offers another promising pathway, where calcium oxide sorbents absorb CO2 and can be regenerated, but challenges of sorbent degradation and high calcination energy requirements remain barriers (DNV 2024). Experimental approaches like membrane separation and mineral carbonation are advancing in India, with startups piloting systems to mineralise flue gas streams at captive power plants. Besides point-source capture, innovations such as CO2 curing of concrete blocks already show promise, enhancing strength and reducing lifecycle emissions.
Despite progress, several systemic obstacles hinder the mass deployment of CCUS in India’s cement industry. Technology readiness remains a fundamental issue: apart from MEA-based capture, most technologies are not commercially mature in high-volume cement plants. Furthermore, CCUS is costly. Studies by CEEW estimate that achieving net-zero cement in India would require around US$ 334 billion in capital investments and US$ 3 billion annually in operating costs by 2050, potentially raising cement prices between 19–107 per cent. This is particularly problematic for an industry where companies frequently operate at capacity utilisations of only 65–70 per cent and remain locked in fierce price competition (SOIC; CEEW).
Building out transport and storage infrastructure compounds the difficulty, since many cement plants lie far from suitable geological CO2 storage sites. Moreover, retrofitting capture plants onto operational cement production lines adds technical integration struggles, as capture systems must function reliably under the high-particulate and high-temperature environment of cement kilns.
Overcoming these hurdles requires a multi-pronged approach rooted in policy, finance, and global cooperation. Policy support is vital to bridge the cost gap through instruments like production-linked incentives, preferential green cement procurement, tax credits, and carbon pricing mechanisms. Strategic planning to develop shared CO2 transport and storage infrastructure, ideally in industrial clusters, would significantly lower costs and risks. International coordination can also accelerate adoption.
The Global Cement and Concrete Association’s net-zero roadmap provides a collaborative template, while North–South technology transfer offers developing countries access to proven technologies. Financing mechanisms such as blended finance, green bonds tailored for cement decarbonisation and multilateral risk guarantees will reduce capital barriers.
An integrated value-chain approach will be critical. Coordinated development of industrial clusters allows multiple emitters—cement, steel, and chemicals—to share common CO2 infrastructure, enabling economies of scale and lowering unit capture costs. Public–private partnerships can further pool resources to build this ecosystem. Ultimately, decarbonisation is neither optional nor niche for Indian cement. It is an imperative driven by India’s growth trajectory, environmental sustainability commitments, and changing global markets where carbon intensity will define trade competitiveness.
With compliance obligations already mandated under CCTS, the cement industry must accelerate decarbonisation rapidly over the next two years to meet binding reduction targets. The challenge is to balance industrial development with ambitious climate goals, securing both economic resilience and ecological sustainability. The pathway forward depends on decisive governmental support, cross-sectoral innovation, global solidarity, and forward-looking corporate action. The industry’s future lies in reframing decarbonisation not as a burden but as an investment in competitiveness, climate alignment and social responsibility.

References

  • Infomerics, “Indian Cement Industry Outlook 2024,” Nov 2024.
  • TERI & GCCA India, “Decarbonisation Roadmap for the Indian Cement Industry,” 2023.
  • UN Press Release, GA/EF/3516, “Global Resource Efficiency and Cement.”
  • World Cement, “India in Focus: Energy Efficiency Gains,” 2025.
  • Statista, “CO2 Emissions from Cement Manufacturing 2023.”
  • Heidelberg Materials, Press Release, June 18, 2025.
  • CaptureMap, “Cement Carbon Capture Technologies,” 2024.
  • DNV, “Emerging Carbon Capture Techniques in Cement Plants,” 2024.
  • LEILAC Project, News Releases, 2024–25.
  • PMC (NCBI), “Membrane-Based CO2 Capture in Cement Plants,” 2024.
  • Nature, “Carbon Capture Utilization in Cement and Concrete,” 2024.
  • ACS Industrial Engineering & Chemistry Research, “CCUS Integration in Cement Plants,” 2024.
  • CEEW, “How Can India Decarbonise for a Net-Zero Cement Industry?” (2025).
  • SOIC, “India’s Cement Industry Growth Story,” 2025.
  • MDPI, “Processes: Challenges for CCUS Deployment in Cement,” 2024.
  • NITI Aayog, “CCUS in Indian Cement Sector: Policy Gaps & Way Forward,” 2025.

ABOUT THE AUTHOR:
Dr Yogendra Kanitkar, Vice President R&D, Pi Green Innovations, drives sustainable change through advanced CCUS technologies and its pioneering NetZero Machine, delivering real decarbonisation solutions for hard-to-abate sectors.

Dr Shirish Kumar Sharma, Assitant Manager R&D, Pi Green Innovations, specialises in carbon capture, clean energy, and sustainable technologies to advance impactful CO2 reduction solutions.

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