Concrete

Durable concrete for tunnelling application

Published

14 years ago

July 31, 2012

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In this first part of the two-part series, EugenKleen of Mc-Bauchemie Mueller GmbH and Co.KG spells out the properties required in concrete and the types of concrete used in tunnelling application.Over the decade the use of concrete admixtures, especially plasticizers and superplasticizers, is showing upward trend in India. The advent of concrete pumps and transit mixers has also contributed to this, as the use of superplasticizers enables trouble-free pumping operations and minimizes pipe blockages. With the advent of major metro projects across India, durability of concrete used especially for tunnelling segments is of prime importance. The earlier attitude of taking recourse to the use of admixtures only after facing problems is changing fast, and now, in most tunnelling projects, high performing admixtures are already included in the specifications and the mix is designed to achieve the necessary properties.The concrete for tunnel segments necessitates the concrete to have the following properties:??Compressive strength??Workability??Surface finish??DurabilityAs part of the durability requirements, concrete is or should be generally tested for the following properties:??Chloride migration??Sulfate resistance??Water absorption??Acid resistance??Porosity??Freeze thaw resistanceThis can be achieved using the latest technologies available for concrete. Concrete is now no longer a material consisting of cement, aggregates, water and admixtures but it is an engineered material with several new constituents like PFA, GGBSF, Microsilica, Metakaolin, Colloidal Sillica and several other binders, fillers and pozzolanic materials. The concrete today can take care of any specific requirements under most exposure conditions.The mix designs are getting relatively complex on account of interaction of several materials and mix design calls for expertise in concrete technology and materials. High performance concretes will have to be adapted for tunnelling segments, considering special properties as well as low cost maintenance strategies.What type of concrete do we use?Concrete used in tunnelling applications need the following outstanding properties viz. Compressive strength, high workability, enhanced resistances to chemical or mechanical stresses, lower permeability, durability etc. this will necessitate the use of high performance concrete. Some HPC types which will hold the key for tunnelling applications can be classified into:??Self compacting concrete / high workability concrete??Concretes resistant against aggressive mediaSelf-Compacting Concrete (SCC)Self-Compacting or Consolidating Concrete (SCC), as the name signifies should be able to compact itself by its self-weight under gravity without any additional vibrations or compaction. Self compacting concrete should be able to assume any complicated formwork shapes without cavities and entrapment of air. The reinforcement should be effectively covered and the aggregated should be fully soaked in the concrete matrix. In addition, the concrete should be self-levelling type and self-defoaming without any external compaction.The formulation of self compacting concrete has the latest concrete technology and it requires in-depth knowledge of materials and meticulous testing procedures before the concrete is designated as SCC. Self compacting concrete has the following special advantages.??Saving of cost on machinery, energy and personnel for vibrating the concrete??Considerable improvements to exposed surfaces (Fair Faced Concrete), less efflorescence??Marked improvements in durability on account of better compaction??Extremely suitable for slim and complicated moulds??Covers reinforcement effectively??Better adhesive between cement binder and aggregates??Reduction in de-moulding time??Advantage with respect to sound pollutionTherefore while calculating the costing and economics of self compacting concrete all the above mentioned advantages should be converted to cost parameters. This kind of concrete can give advantage of good compressive strength, workability and finish to the tunnel segments and may prove suitable.Durable concrete resistant against aggressive mediaOne major application of HPC is to increase the durability of concrete where aggressive underground conditions are anticipated. This can be achieved physically by resorting to very dense aggregate packing.Practically possible by selecting a very smooth sieve line from largest aggregate to the smallest grain of mineral additives like microsilica or new generation aluminosilicate slurries. Chemically, cement by itself is not acid resistant. The acid resistant binder is formed by combination of cement, microsilica / aluminosilicate and flyash. To control permeability very low water cement ratio has to be adopted. So as to provide the essential concrete properties a high-performance PCE (polycarboxylate ether) needs to be incorporated in the mix. By adjusting the particle size distribution on the micro scale the permeability of the concrete is reduced which minimizes the penetration of aggressive substances. Depending on the degree of dispersion these material particles more or less completely fill the spaces between the cement particles. During hydration the pozzolanic silica reacts with the free calcium hydroxide to form calcium silicate hydrates. This gives a denser concrete structure.(Source: Paper presented by the author at the Construction Chemicals International Conference 2012 held in Mumbai)

Concrete

NDMC Rolls Out Intensive Sanitation Drive Across Lutyens Delhi

Municipal body intensifies cleaning and monitoring across the capital

Published

13 hours ago

March 13, 2026

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The New Delhi Municipal Council has launched an intensive sanitation drive across Lutyens’ Delhi, aiming to raise cleanliness standards in the capital’s central precincts. The programme will combine enhanced manual sweeping with mechanised cleaning and systematic waste removal to cover parks, heritage precincts and prominent thoroughfares. Authorities described the initiative as a sustained effort to improve public hygiene and reduce environmental hazards while maintaining the area’s civic image.

Operational teams have been instructed to prioritise drain clearing and litter hotspots, with special attention to markets and transit nodes that attract heavy footfall. Coordination with city utilities and waste processing units will be stepped up to ensure timely collection and disposal, and supervisory rounds will monitor adherence to cleaning schedules. Officials also intend to use data-driven planning to deploy resources efficiently and to identify recurring problem areas.

The council plans to engage resident welfare associations and business stakeholders to foster community participation in maintaining cleanliness and to support behavioural change campaigns. Public communication will be amplified through notices and outreach to encourage responsible waste handling and to inform residents about collection timings and segregation norms. Enforcement measures for littering and unauthorised dumping will be reinforced as part of a broader strategy to deter violations and sustain cleanliness gains.

The move reflects a focus on urban sanitation that officials link to public health priorities and to the city administration’s commitment to maintaining civic amenities. Monitoring mechanisms will include regular reporting and inspections to review outcomes and to recalibrate operations where necessary, according to municipal sources. The council emphasised that continued community cooperation will be essential for the drive to deliver lasting improvements in the appearance and hygiene of the capital’s core areas.

Concrete

UltraTech Appoints Jayant Dua As MD-Designate For 2027

Executive named to succeed current managing director in 2027

Published

4 days ago

March 10, 2026

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UltraTech Cement has appointed Jayant Dua as managing director (MD) designate who will take charge in 2027, the company announced. The appointment signals a planned leadership transition at one of the country’s largest cement manufacturers. The board has set a clear timeline for the handover and has framed the move as part of a structured succession plan.

Jayant Dua will be referred to as MD after assuming the role and will be responsible for overseeing operations, strategy and growth initiatives across the company’s network. The company said the designation follows established governance norms and aims to ensure continuity in executive leadership. The appointment is expected to allow a phased transfer of responsibilities ahead of the formal changeover.

The decision is intended to provide strategic stability as UltraTech Cement navigates domestic infrastructure demand and evolving market dynamics. Management will continue to focus on operational efficiency, capacity utilisation and cost management while aligning investments with long term objectives. The board will monitor the transition and provide further information on leadership responsibilities closer to the effective date.

Investors and market observers will have time to assess the implications of the announcement before the change is effected, and analysts will review the company’s outlook in the context of the succession. The company indicated that it will communicate any additional executive appointments or organisational changes as they are finalised. Shareholders were advised to refer to formal filings and company releases for definitive details on governance or remuneration.

The leadership change will be managed with attention to stakeholder interests and operational continuity, and the company reiterated its commitment to delivery on ongoing projects and customer obligations. Senior management will engage with employees and partners to ensure a smooth handover while maintaining focus on safety and compliance. Further updates will be provided through official investor communications in due course.

Concrete

Merlin Prime Spaces Acquires 13,185 Sq M Land Parcel In Pune

Rs 273 crore purchase broadens the developer’s Pune presence

Published

1 week ago

March 6, 2026

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Merlin Prime Spaces (MPS) has acquired a 13,185 sq m land parcel in Pune for Rs 273 crore, marking a notable expansion of its footprint in the city.

The transaction value converts to Rs 2,730 mn or Rs 2.73 bn.

The parcel is located in a strategic area of Pune and the firm described the acquisition as aligned with its growth objectives.

The deal follows recent activity in the region and will be watched by investors and developers.

MPS said the acquisition will support its planned development pipeline and enable delivery of commercial and residential space to meet local demand.

The company expects the site to provide flexibility in product design and phased development to respond to market conditions.

The move reflects an emphasis on land ownership in key suburban markets.

The emphasis on land acquisition reflects a strategy to secure inventory ahead of demand cycles.

The purchase follows a period of sustained investor interest in Pune real estate, driven by expanding office ecosystems and residential demand from professionals.

MPS will integrate the new holding into its existing portfolio and plans to engage with local authorities and stakeholders to progress approvals and infrastructure readiness.

No financial partners were disclosed in the announcement.

The firm indicated that timelines will depend on approvals and prevailing market conditions.

Analysts note that strategic land acquisitions at scale can help developers manage costs and timelines while preserving optionality for future projects.

MPS will now hold an enlarged land bank in the region as it pursues growth, and the acquisition underlines continued corporate appetite for measured expansion in second tier cities.

The company intends to move forward with detailed planning in the coming months.

Stakeholders will assess how the site is positioned relative to existing infrastructure and connectivity.