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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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X-NONE
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MicrosoftInternetExplorer4













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, EU Resume Talks To Finalise Free Trade Agreement

High-level negotiators meet in Delhi to push balanced trade deal

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A senior delegation from the European Union (EU) is in New Delhi from 3 to 7 November 2025 to hold detailed discussions with Indian counterparts on the proposed India–EU Free Trade Agreement (FTA). The negotiations aim to resolve key pending issues and move closer to a comprehensive, balanced, and mutually beneficial trade framework.

The visit follows Union Minister of Commerce and Industry Piyush Goyal’s official trip to Brussels on 27–28 October 2025, during which he held forward-looking talks with European Commissioner for Trade and Economic Security Maroš Šef?ovi?. Both sides reaffirmed their commitment to intensify dialogue and strengthen cooperation towards finalising the FTA.

This week’s deliberations will focus on trade in goods and services, rules of origin, and technical and institutional matters, guided by the shared goal of creating a modern and future-ready trade pact that reflects the priorities and sensitivities of both India and the EU.

The discussions gained further momentum after a virtual meeting on 3 November 2025 between Minister Piyush Goyal, Commissioner Maroš Šef?ovi?, and EU Commissioner for Agriculture and Food Christophe Hansen, which helped align positions on key areas of mutual interest.

As part of the ongoing negotiations, Ms. Sabine Weyand, Director-General for Trade at the European Commission (EU DG Trade), will visit New Delhi on 5–6 November for high-level consultations with India’s Commerce Secretary Rajesh Aggarwal. The talks will address technical and policy matters critical to concluding the agreement.

The EU delegation’s visit underscores the shared determination of India and the European Union to conclude a fair, transparent, and equitable FTA, aimed at boosting trade, investment, innovation, and sustainable economic growth.

Both sides view the FTA as a strategic pillar in their partnership, capable of enhancing market access, creating new opportunities for businesses, and promoting a resilient and diversified global supply chain.

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Om Birla: World Sees India as a Key Investment Destination

Speaker says India’s democracy and growth draw global confidence

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Lok Sabha Speaker Om Birla on Thursday said that the world is increasingly looking to invest in India, drawn by its vibrant democracy, rapid economic expansion, and technological prowess. Speaking at the 125th Anniversary Celebrations of the Bharat Chamber of Commerce in Kolkata, themed “India@100: An Age of a New Dawn,” Birla said that under the visionary leadership of Prime Minister Narendra Modi, the nation is steadily advancing towards becoming a global economic powerhouse.

He emphasised the government’s commitment to building a business-friendly environment, driven by the principles of minimum government, maximum governance. The administration, he said, is focused on reducing bureaucratic hurdles, expanding industrial capacity, and encouraging innovation. Birla also urged the private sector to invest more in research and development (R&D) and strive to meet global standards, assuring that the government will complement such efforts to strengthen India’s innovation-led growth.

Praising the Bharat Chamber of Commerce, Birla called it a source of inspiration for business chambers across India. He lauded its 125-year legacy of resilience, foresight, and public service, recalling its origins as the Marwari Chamber of Commerce. The Chamber, he noted, has played a key role in India’s industrial, social, and economic transformation and in promoting corporate social responsibility.

Birla observed that India’s success as a democracy lies in its stability, inclusiveness, and deep cultural roots. “Democracy in India is not just a system of governance, but a way of life,” he said, adding that the nation’s robust institutions ensure policy continuity and investor confidence, both crucial for long-term growth.

He stressed that where democracy thrives, sound policy decisions and effective implementation follow, creating a foundation for sustainable development. Birla also highlighted India’s rise as a global innovation hub, driven by strong public–private partnerships in technology and R&D, which are propelling India into leadership positions in emerging industries.

Touching on inclusive growth, Birla noted that the increasing participation of women and youth reflects India’s social transformation. He highlighted women’s growing role across sectors and said they will remain pivotal in shaping a self-reliant and developed India. Similarly, he praised India’s youth and entrepreneurs for driving creativity, enterprise, and innovation, shaping the country’s future with energy and vision.

Reaffirming the vision of Atmanirbhar Bharat, Birla called for stronger collaboration among industry, government, and academia to build a resilient, self-sustaining economy. He also underlined India’s emerging leadership in clean and green energy, expressing confidence that the country will play a leading role in addressing climate and environmental challenges globally.

Acknowledging West Bengal’s historical contribution to India’s growth, Birla said the state has long been a cradle of intellectual, cultural, and industrial excellence. He noted that Bengal has produced eminent thinkers, reformers, poets, and industrialists, and continues to inspire the nation with its enduring spirit of innovation and enterprise.

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Mumbai Metro, Monorail Told To Submit Disaster Plans

BMC orders SOPs and drills to strengthen emergency preparedness

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The Brihanmumbai Municipal Corporation (BMC) has directed Mumbai’s monorail and metro operators to submit detailed emergency management plans and Standard Operating Procedures (SOPs) for review, as part of efforts to bolster the city’s overall disaster preparedness framework.

The directive was issued during a meeting of civic authorities responsible for disaster management, held at the BMC headquarters on Wednesday. The session was convened to assess Mumbai’s emergency response mechanisms following the monorail breakdown near Bhakti Park, Chembur, on 19 August, which left several passengers stranded for hours due to a technical malfunction.

Dr Vipin Sharma, Chairperson of the Mumbai Suburban District Disaster Management Authority and Additional Municipal Commissioner (Western Suburbs), emphasised that the city’s monorail and metro systems must be integrated comprehensively into Mumbai’s emergency management strategy. He noted that these rapidly expanding networks require independent consideration given their critical role in public mobility.

Dr Ashwini Joshi, Chairperson of the Mumbai City District Disaster Management Authority and Additional Municipal Commissioner (City), instructed that mock drills be held regularly at all metro and monorail stations to assess and enhance emergency response capabilities.

Meanwhile, Dr Amit Saini, Additional Municipal Commissioner (Eastern Suburbs), said the session was aimed at reviewing coordination and readiness among key agencies in light of Mumbai’s expanding transport infrastructure. He stressed the importance of inter-agency collaboration to ensure rapid and efficient response during emergencies.

Professor Dr Ravi Sinha from the Indian Institute of Technology (IIT) Bombay commended the coordinated handling of the August 19 monorail incident, which involved the BMC’s disaster management department, Mumbai Fire Brigade, and other civic response teams.

Officials concluded that strengthening communication channels, training exercises, and real-time coordination between agencies would be central to improving the city’s ability to respond swiftly to future incidents involving its transport systems.

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