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

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false
false
false

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X-NONE

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

Concrete

Meghalaya Cabinet Approves MCCL Closure, Writes Off Rs. 244.3 mn

Cabinet approves winding up of state-owned cement company

Published

3 days ago

on

October 19, 2026

By

admin

The Meghalaya Cabinet has approved the closure and winding up of Meghalaya Cherra Cement (MCCL), a state-owned cement company, with pending liabilities of approximately Rs. 244.3 mn to be written off as part of the process. The decision was announced by Chief Minister Conrad K Sangma on October 13, 2026.

The approved write-off comprises about Rs. 89 mn in sales tax dues and Rs. 155.3 mn in royalty dues. The Cabinet’s decision addresses the liabilities that remained after the company’s operations and enables the government to proceed with its formal closure.

Sangma said employee dues owed by MCCL had been settled in line with the state government’s commitment. The settlement of employee-related liabilities is a key part of the winding-up process and removes outstanding obligations to the company’s workforce.

The Chief Minister explained that MCCL is owned by the government, meaning the pending liabilities would otherwise involve transfers between the state government and its departments. Writing off the dues is intended to simplify the accounting and administrative steps required to complete the closure.

The decision is also intended to ensure that the winding-up does not create an additional financial burden for the state government. With employee payments settled and the sales tax and royalty liabilities addressed through the approved write-off, the Cabinet’s approval marks a further step towards completing the formal closure of MCCL.

The action follows the state government’s decision to discontinue the company and resolve its outstanding obligations through an orderly winding-up process. The approved measures cover the principal liabilities identified for settlement and allow the government to advance the remaining formal procedures associated with closing the state-owned enterprise.

Concrete

Fornnax Wins AIRIA’s Special Export Award for Rubber Machinery in 2025-26

Published

3 days ago

on

October 19, 2026

By

admin

Fornnax Technology Pvt. Ltd. has been honoured with the Special Export Award – Rubber Machinery for 2025–26 by the All-India Rubber Industries Association (AIRIA), in recognition of its highest exports of tyre recycling plants to the European region.

With more than a decade of experience in India’s tyre recycling industry, Fornnax has contributed to the development of advanced recycling technologies and infrastructure. The company currently holds a 90% market share in India’s domestic tyre recycling sector, while exports account for 30% of its business, spanning markets such as Europe, Australia and the GCC.

The award marks another milestone for Fornnax, whose tyre recycling lines and advanced shredding technologies are supporting the growth of the circular economy in India and international markets.

Commenting on the recognition, Mr. Jignesh Kundaria, Founder and Director of Fornnax, said:

“This honour from AIRIA is a reflection of an incredible journey we have undertaken over the years. When we started Fornnax, there was no established recycling industry in India to follow. We chose to build for the future instead. Today, when you see India’s tyre recycling sector, it has already transformed into a dynamic, high-growth industry and we are extremely proud to have played our part in building it.”

Unlike standalone equipment suppliers, Fornnax focuses on developing complete, high-capacity recycling infrastructure. Its integrated systems combine multiple stages of shredding and size reduction to enable efficient, continuous operations. This system-level engineering approach helps recycling operators improve throughput, equipment reliability and operational consistency.

The recognition reinforces Fornnax’s commitment to developing engineering technologies that contribute to a more efficient and circular recycling ecosystem.

Looking ahead, the company aims to expand its international presence while continuing to develop advanced shredding and recycling solutions to address the growing volumes and evolving requirements of the global recycling industry.

For more information, visit: www.fornnax.com

Concrete

Cement Prices Likely to Rise Rs. 10-15 per Bag from Mid-October

Input costs and steady demand may drive cement price increases

Published

1 week ago

on

October 14, 2026

By

admin

Cement manufacturers in India are likely to raise prices by Rs. 10-15 per bag from mid-October, as they seek to offset persistent increases in power and fuel costs. Emkay Research said its channel checks indicated a high probability of an increase from October 12, supported by the start of the busy construction season and favourable demand-supply conditions.

The sector had implemented similar rate adjustments of Rs. 10-15 per bag during the first quarter, but the increases were insufficient to cover higher operating costs. Prices also softened during July and August because of the monsoon, widening the gap between realisations and input expenses. Delayed plant expansion programmes have pushed clinker utilisation rates towards 79 per cent by FY28, helping to balance market fundamentals.

Emkay Research said steady volume offtake was supporting cement consumption, with non-trade demand driving activity across regional markets. Industry volumes are expected to grow by 7-8 per cent year on year during the first half of FY27, while demand momentum is projected to remain firm over the following 18 months. The outlook includes the busy construction season in the second half of FY27 and infrastructure activity linked to general elections in the first half of calendar year 2029.

The brokerage expects overall cement demand to record a compound annual growth rate of about 7 per cent between FY26 and FY28. However, elevated operating expenses are likely to continue weighing on profitability. Input costs have risen by Rs. 300-400 per t over the past six to seven months, with the full impact expected to become visible in second-quarter earnings and remain persistent through the second half of FY27.

Spot prices for petcoke and imported coal are approximately 20 per cent and 16 per cent above their second-quarter averages, at USD 175 per t and USD 150 per t, respectively. Packing costs have also increased, with polypropylene granule prices rising above Rs. 135 per kg. Emkay Research estimated that second-quarter earnings could decline by Rs. 200-250 per t sequentially because of higher fuel bills and negative operating leverage, and said the sector requires sustained price increases of about Rs. 10 per bag to offset cost inflation.