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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


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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

30-Day Traffic Diversion In Place For CC Road Works In Madhapur

Diversions in place from May 16 for cement concrete road works

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The Cyberabad Traffic Police issued a traffic advisory as road works begin for the laying of a cement concrete (CC) road from Jaya Shankar Statue to RRR Restaurant at Parvathnagar in Madhapur limits. The advisory indicated that traffic diversions will be in place for 30 days from May 16 to ensure the smooth flow of vehicles and to minimise congestion on the affected stretch. The measure aims to balance uninterrupted construction activity with the movement needs of commuters.

Traffic moving from Toddy Compound towards Parvathnagar village will be diverted at Parvathnagar junction towards Sunnam Cheruvu and the 100 feet road. Local motorists and public transport operators have been advised to follow the diversionary route as directed by traffic personnel on duty. Alternate routes and signage have been planned to mitigate delays and to manage peak hour congestion.

Police officials said the diversion had been planned to facilitate uninterrupted road works while maintaining traffic movement in the area. Commuters were urged to plan their travel accordingly and to cooperate with traffic staff managing the stretch. Authorities indicated that enforcement of diversions would be active and that violations could attract penalties.

The 30 day schedule is intended to allow contractors to complete the laying and curing phases with minimal interruption to vehicular flow. Residents and businesses in adjacent localities have been advised to factor the diversion into deliveries and travel plans. The traffic police promised continuous monitoring of the works and the operational diversions and emphasised that temporary inconvenience was necessary for longer term improvement of the road network. Traffic personnel will be stationed at key junctions and additional signage and temporary markings will be displayed to guide motorists and pedestrians through the revised alignments while public transport services will follow the diversion where feasible and operators have been asked to adjust timetables to minimise disruption.

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Concrete

HeidelbergCement India Receives Consent For Khandwa Grinding Unit

Consent granted by Madhya Pradesh Pollution Control Board

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HeidelbergCement India (HeidelbergCement India) has received regulatory consent to establish a cement blending and grinding unit at Village Dongaliya, Tehsil Punasa, District Khandwa in Madhya Pradesh. The consent was granted by the Madhya Pradesh Pollution Control Board under the Water (Prevention & Control of Pollution) Act, 1974 and the Air (Prevention & Control of Pollution) Act, 1981 and is dated 17 May 2026. The company disclosed the development in a filing made under Regulation 30 of the SEBI (Listing Obligations and Disclosure Requirements) Regulations, 2015.

The project plan envisages procurement of long term availability of fly ash and the allotment of land on lease for setting up the unit. The proposed facility is described as a blending and grinding installation which will process cementitious materials sourced from nearby operations and suppliers. Company filings state the measures required to secure raw material logistics and statutory compliance before commencing construction.

The addition of a grinding unit in Khandwa is intended to strengthen regional supply and improve logistical efficiency by reducing haulage distances for finished product. The unit is expected to complement existing capacities in central India and to offer flexibility in product mix through blending operations. The reliance on fly ash as a supplementary cementitious material will necessitate long term supply agreements with thermal power producers and coordination with waste utilisation policies.

The disclosure to the regulator and to the stock exchanges follows standard corporate governance practice and aims to keep investors apprised of capital expenditure initiatives. The company indicated that subsequent permits and clearances would be sought in accordance with applicable environmental and land use rules. The project is presented as part of HeidelbergCement India’s broader strategy to optimise capacity distribution and to respond to regional demand dynamics.

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Concrete

PROMECON introduces infrared-based tertiary air measurement system for cement kilns

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The new solution promisescontinuous, real-time tertiary air flow measurement in cement plant operations.

PROMECON GmbH has launched the McON IR Compact, an infrared-based measuring system designed to deliver continuous, real-time tertiary air flow measurement in cement plant operations. The system addresses the longstanding process control challenge of accurate tertiary air monitoring under extreme kiln conditions. It uses patented infrared time-of-flight measurement technology that operates without calibration or maintenance intervention.

Precise tertiary air measurement is a critical requirement for stable rotary kiln operation. The McON IR Compact is engineered to function reliably at temperatures up to 1,200°C and in the presence of abrasive clinker dust. Its vector-based digital measurement architecture ensures that readings remain unaffected by swirl, dust deposits or drift. Due to these conditions conventional measurement systems in pyroprocess environments are often compromised.

The system is fully non-intrusive and requires no K-factors, recalibration or periodic readjustment, enabling years of uninterrupted operation. This design directly supports plant availability and reduces the maintenance overhead typically associated with process instrumentation in high-temperature zones.

PROMECON has deployed the McON IR Compact at multiple cement facilities, including Warta Cement in Poland. Plant operators report that the system has aided in identifying blockages, optimising purging cycles for gas burners, and supplying accurate flow data for AI-based process optimisation programmes. The practical outcomes include more stable kiln operation, improved process control, and earlier detection of process disturbances.

On the energy side, real-time tertiary air data enables reduction in induced draft fan load and helps flatten process oscillations across the pyroprocess. This translates to lower fuel and energy consumption, fewer unplanned shutdowns, and a measurable reduction in NOx peaks. This directly reflects on the downstream cost implications for plants operating SCR or SNCR systems for emissions compliance.

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