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
0

false
false
false

EN-US
X-NONE
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

Steel: Shielded or Strengthened?

CW explores the impact of pro-steel policies on construction and infrastructure and identifies gaps that need to be addressed.

Published

19 hours ago

on

January 31, 2026

By

admin

Going forward, domestic steel mills are targeting capacity expansion
of nearly 40 per cent through till FY31, adding 80-85 mt, translating
into an investment pipeline of $ 45-50 billion. So, Jhunjhunwala points
out that continuing the safeguard duty will be vital to prevent a surge
in imports and protect domestic prices from external shocks. While in
FY26, the industry operating profit per tonne is expected to hold at
around $ 108, similar to last year, the industry’s earnings must
meaningfully improve from hereon to sustain large-scale investments.
Else, domestic mills could experience a significant spike in industry
leverage levels over the medium term, increasing their vulnerability to
external macroeconomic shocks.(~$ 60/tonne) over the past one month,
compressing the import parity discount to ~$ 23-25/tonne from previous
highs of ~$ 70-90/tonne, adds Jhunjhunwala. With this, he says, “the
industry can expect high resistance to further steel price increases.”

Domestic HRC prices have increased by ~Rs 5,000/tonne
“Aggressive
capacity additions (~15 mt commissioned in FY25, with 5 mt more by
FY26) have created a supply overhang, temporarily outpacing demand
growth of ~11-12 mt,” he says…

To read the full article Click Here

Concrete

JK Cement Commissions 3 MTPA Buxar Plant, Crosses 31 MTPA

Company becomes India’s fifth-largest grey cement producer

Published

2 days ago

on

January 30, 2026

By

admin

JK Cement has commissioned its new 3 MTPA grey cement plant in Buxar, Bihar, taking the company’s total installed capacity to 31.26 million tonnes per annum (MTPA) and moving it past the 30 MTPA milestone. With this addition, JK Cement now ranks among the top five grey cement manufacturers in India, strengthening its national presence.

Commenting on the development, Dr Raghavpat Singhania, Managing Director, JK Cement, said, “Crossing 31 MTPA is a significant turning point in JK Cement’s expansion and demonstrates the scale, resilience, and aspirations of our company. In addition to making a significant contribution to Bihar’s development vision, the commissioning of our Buxar plant represents a strategic step towards expanding our national footprint. We are committed to developing top-notch manufacturing capabilities that boost India’s infrastructure development and generate long-term benefits for local communities.”

Spread across 100 acres, the Buxar plant is located on the Patna–Buxar highway, enabling efficient distribution across Bihar and neighbouring regions. While JK Cement entered the Bihar market last year through supplies from its Prayagraj plant, the new facility will allow local manufacturing and deliveries within 24 hours across the state.

Mr Madhavkrishna Singhania, Joint Managing Director & CEO, JK Cement, said, “JK Cement is now among India’s top five producers of grey cement after the Buxar plant commissioning. Our capacity to serve Bihar locally, more effectively, and on a larger scale is strengthened by this facility. Although we had already entered the Bihar market last year using Prayagraj supplies, local manufacturing now enables us to be nearer to our clients and significantly raise service standards throughout the state. Buxar places us at the center of this chance to promote sustainable growth for both the company and the region in Bihar, a high-growth market with strong infrastructure momentum.”

The project has involved an investment of Rs 5 billion. Commercial production began on 29 January 2026, following construction commencement in March 2025. The company said the plant is expected to generate significant direct and indirect employment and support ancillary industrial development in the region.

Concrete

JK Cement Crosses 31 MTPA Capacity with Commissioning of Buxar Plant in Bihar

Published

2 days ago

on

January 30, 2026

By

admin

JK Cement has commissioned a 3 MTPA Grey Cement plant in Buxar, Bihar, taking its total capacity to 31.26 MTPA and placing it among India’s top five grey cement producers. The ₹500 crore investment strengthens the company’s national footprint while supporting Bihar’s infrastructure growth and local economic development.

JK Cement Ltd., one of India’s leading cement manufacturers, has announced the commissioning of its new state-of-the-art Grey Cement plant in Buxar, Bihar, marking a significant milestone in the company’s growth trajectory. With the commissioning of this facility, JK Cement’s total production capacity has increased to 31.26 million tonnes per annum (MTPA), enabling the company to cross the 30 MTPA threshold.

This expansion positions JK Cement among the top five Grey Cement manufacturers in India, strengthening its national footprint and reinforcing its long-term growth strategy.

Commenting on the strategic achievement, Dr Raghavpat Singhania, Managing Director, JK Cement, said, “Crossing 31 MTPA is a significant turning point in JK Cement’s expansion and demonstrates the scale, resilience, and aspirations of our company. In addition to making a significant contribution to Bihar’s development vision, the commissioning of our Buxar plant represents a strategic step towards expanding our national footprint. We are committed to developing top-notch manufacturing capabilities that boost India’s infrastructure development and generate long-term benefits for local communities.”

The Buxar plant has a capacity of 3 MTPA and is spread across 100 acres. Strategically located on the Patna–Buxar highway, the facility enables faster and more efficient distribution across Bihar and adjoining regions. While JK Cement entered the Bihar market last year through supplies from its Prayagraj plant, the Buxar facility will now allow the company to serve the state locally, with deliveries possible within 24 hours across Bihar.

Sharing his views on the expansion, Madhavkrishna Singhania, Joint Managing Director & CEO, JK Cement, said, “JK Cement is now among India’s top five producers of grey cement after the Buxar plant commissioning. Our capacity to serve Bihar locally, more effectively, and on a larger scale is strengthened by this facility. Although we had already entered the Bihar market last year using Prayagraj supplies, local manufacturing now enables us to be nearer to our clients and significantly raise service standards throughout the state. Buxar places us at the center of this chance to promote sustainable growth for both the company and the region in Bihar, a high-growth market with strong infrastructure momentum.”

The new facility represents a strategic step in supporting Bihar’s development vision by ensuring faster access to superior quality cement for infrastructure, housing, and commercial projects. JK Cement has invested approximately ₹500 crore in the project. Construction began in March 2025, and commercial production commenced on January 29, 2026.

In addition to strengthening JK Cement’s regional presence, the Buxar plant is expected to generate significant direct and indirect employment opportunities and attract ancillary industries, thereby contributing to the local economy and the broader industrial ecosystem.

Indian Cement Review

Changing normal concrete into durable concrete for tunnelling application

Concrete

Changing normal concrete into durable concrete for tunnelling application

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