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Making self consolidating concrete using building demolished waste

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Preservation of the environment and conservation of the rapidly diminishing natural resources is the essence of sustainable development. Recycling of concrete from the Building Demolished Waste(BDW) to produce aggregates suitable for structural and non-structural applications is fast emerging as a commercially viable and technically feasible operation.Self-Compacting Concrete (SCC) is considered as a concrete which can be placed and compacted under its self-weight with little or no vibration effort, and which is at the same time, cohesive enough to be handled without segregation or bleeding. It is used to facilitate and ensure proper filling and good structural performance of restricted areas and heavily reinforced structural members.The use of Recycled Concrete Aggregate (RCA) in construction works is a subject of high priority in building industry throughout the world and it is a good solution to the problem of an excess of waste material, provided that the desired final product quality is reached. This reduces the consumption of the natural resources as well as the consumption of the landfills required for waste concrete. The technology today has advanced so far that it is forcing us to think in terms of ‘sustainability’. Ductility of concrete is provided with fiber reinforced cementitious composites, because fibers bridge crack surfaces and delay the onset of the extension of localised crack.Research significanceAn attempt has been made in the present investigation to develop a standard grade Self Compacting Concrete without and with polypropylene and glass fibers and without and with recycled aggregate. The present work provides very useful information for the practical use of fibrous self compacting concretes in the field, employing recycled aggregate form Building Demolished Waste (BDW).Properties of SCC in fresh stateA concrete mix is called Self Compacting Concrete if it fulfills the requirement of filling ability, passing ability and resistance to segregation. The filling ability is the ability of the SCC to flow into all spaces within the formwork under its own weight.Passing ability is required to guarantee a homogenous distribution of the components of SCC in the vicinity of obstacles. The resistance to segregation is the resistance of the com-ponents of SCC to migration or separation and remains uniform throughout the process of transport and placing. To satisfy these conditions EFNARC has formulated certain test procedures.IngredientsOrdinary Portland cement of 53 grade (compressive strength not less than 53 Mpa) was used in the study. The cement was selected as per IS-12269. Fine aggregate was standard river sand procured locally and was confirming to zone-II as per IS-2386. Crushed granite was used as coarse aggregate. The aggregate was passed through standard sieves of 16mm and retained on 4.75mm sieve. Recycled aggregate from building demolished waste was crushed and classified before use. For qualifying the utility of recycled aggregate in concrete, the important parameters like bulk density, voids ratio, specific gravity, water absorption, crushing and impact value, angularity and IAPST were determined based on IS Codal provisions. There properties were determined for different replacement of Recycled Concrete Aggregate (RCA) in Natural Aggregate (NA). The properties are shown in Table 1.Tests on FRSCRACThe slump flow equipment is currently used widely in concrete practice, and the method is very simple and straight forward. Thus the H-flow combined with T50 was selected as the first priority test method for estimating the filling ability of FRSCRAC. The V-funnel or Orimet tests are recommended as second priority alternatives to the T50 measurement. The passing ability of fresh SCC can be tested by U-box or J-ring. The basic properties of SCC without and with fiber and/or recycled aggregate are shown in Table 2. The fresh properties of SCC and FRSCC are suggestive of confirmation with the EFNARC Specifications.The source of fly ash used in the experiments was from a local coal fired thermal power station, where flyash is evolving out as a bye-product. The specific gravity was 2.05 with silicon dioxide content above 92 per cent. The fly ash was used as a partial replacement for cement. Conplast SP 337 superplasticizer and Viscosity Modifying Agent (VMA) were added in optimum dosages for improving the strength and workability properties of SCC. The Nansu mix design procedure is adopted to develop M40 Grade Concrete for different replacements of recycled aggregate in natural agg-regate and without or with fiber additions. The ingredients are shown in Table 3. The Glass Fiber (GF) is Cem-Fil Anti Crack and its specific gravity is 2.6 and the specific surface area is 105 m2 /kg. Poly Propylene Fiber (PF) with a diameter of 20-200 ?m, modulus of elasti-city 5-10 Gpa and tensile strength of over 500-750 mpa was used.Experimental programAn experimental program was designed to compare the strength properties of self- compacting concrete using recycled aggregate and without or with fiber addition. Cubes, cylinders and prisms of standard dimensions were cast and tested to determine the compressive strength, split tensile strength, flexural strength and modulus of elasticity of Fiber Reinforced Self- Compacting Concrete (FRSCC) using Recycled Aggregate (RA) from Building Demolished Waste (BDW).Casting and Testing of specimensThe influence of recycled aggregate and fiber on the behavior in compression, split tension and flexure is being investigated. 150×150 mm cubes for compressive strength, 150 mm diameter and 300 mm height cylinders for split tensile strength and 100x100x400 mm prism specimens for studying the modulus of rupture were employed. The program consisted of casting and testing a total number of 54 cubes, 54 cylinders and 54 prisms cast in 9 batches. Of these 54 cubes, 18 cubes corresponding to each Natural Aggregate (NA), 50 per cent Natural & Recycled (NARA) and 100per cent Recycled Aggregate (RA). Of these 18 cubes, six cubes correspond to each no fiber (WF), with PF and with GF additions. Similarly additional 54 cylinders (18 with NA, 18 with NARA, and 18 with RA) were cast for examining the stress-strain behavior of M40 grade for different fibers. The mix was designed as per modified Nansu method of mix design. All the specimens were demoulded after 24 hrs and kept in water for curing for 28days.The specimens were capped using plaster of paris to ensure plane-testing surface. Tinius Olsen Testing Machine (TOTM) of capacity 2000 KN was used for testing the specimens under standard load rate control. While testing, precautions were taken to ensure axial loading. For flexural strength standard three point loading was adopted. The modulus of elasticity of concrete was determined using compressometer setup and tested under TOTM.Discussion of test resultsThe results obtained from the detailed experimental program conducted on SCC without and with fiber are discussed. Table 4 shows the details of various mechanical properties viz., compressive strength, split strength and flexural strength for self-compacting concretes. The optimum fiber content was utilized through out the experimentation and this was based on initial strength and flow studies.Compressive strength of FRSCRAC

The mechanical properties of NA, NARA, and RA concrete cast without and with fiber additions are shown in Table 4.Addition of fibers has definitely increased the com-pressive strength, though marginally. The percentage increase in strength with fiber addition is plotted in Fig 5. It can be noted that the percentage increase is marginal. It is 1.90 per cent, 2.01 per cent in case of NA, 1.03 per cent, 1.62 per cent in 50 per cent Natural-Recycled Aggregate(NARA) and 0.94 per cent, 1.22 per cent in Recycled Aggregate(RA) with Polypropylene Fiber Reinforced Self-Compacting Concrete and Glass Fiber Reinforced Self-Compacting Concrete respectively. It can hence be concluded at this stage that fiber additions do not increase the compressive strength much.
Influence of fibers on split tensile strength
The tensile strength of SCC is relatively much lower than its compressive strength because, it can be developed more quickly with crack propagation. Hence, it is important to improve the tensile strength of such a concrete. The variation of split tensile strength with fiber addi-tions is shown in Table 4. The increase is 14.19 per cent, 17.74 per cent in Natural Aggregate (NA), 9.97 per cent, 14.09 per cent in 50 per cent Natural-Recycled Aggregate (NARA) and 6.25 per cent, 11.72 per cent in Recycled Aggregate (RA) with GFRSCC and PFRSCC respectively (Fig 6). It can hence be inferred from the above that the fiber additions has a pronounced increase in the split tensile strength of self compacting concrete.Influence of fibers on flexural strength

Table 4 & Fig 7 show the details of the percentage increase in flexural strength for fiber additions. There is an increase in flexural strength of fibrous concretes as compared to no fiber concretes. The values are close to 0.7 as given by IS code for the relationship between flexural strength sqrt (fck) for normal concrete. The value of flexural strength to is more with polypropylene and glass fibrous concretes compared to no fiber concretes. From Fig 7, it is clear that there is an increase of 3.15 per cent, 13.32 per cent in Natural Aggregate(NA), 2.93 per cent, 9.57 per cent in 50 per cent Natural-Recycled (NARA) and 2.31 per cent, 8.96 per cent in Recycled Aggregate(RA) with GFRSCC and PFRSCC respectively. At this stage it may be concluded that the bending behaviour is greatly improved with glass fiber additions in self com-pacting concrete.Influence of fibers on modulus of elasticityThe brittle behavior of SCC is known. The fiber addition in such concretes modified the stress-strain behaviour of plain concrete. Using a compressometer setup and under compression the stress-strain values are evaluated and curves were drawn for the initial elastic portions. The Modulus of Elasticity (E) was calculated, following the specifications as laid by IS Code 516-1999. Table 4 shows the details of the values of modulus of elasticity for self-compacting concrete for Natural(NA), 50per cent Natural-Recycled (NARA) and Recycled Aggregate(RA) and without & with fiber respectively. It may be concluded that the addition of fiber in general increased the value of Modulus of Elasticity (E) of self-compacting recycled aggregate concrete. These values were close to 5000*vfck in case of no fiber concrete and higher in case of fibrous concretes.ConclusionsBased on experimental study on Fiber Reinforced Self Compacting Concrete (FRSCC) using recycled aggregate the following conclusions can be drawn.??From the properties of RCA it can be concluded that the coarse aggregate obtained from crushing BDW can be used for structural concrete works. This confirms the fact that RCA is in no way inferior to NA.??Self Compacting Concretes could be developed with recycled aggregate using high powder content, lesser quantity of coarse aggregate, high range super plasticizer and VMA to provide stability and fluidity to the concrete mixes.??There is a marginal increase in compressive strength, very good increase in the split tensile strength and a good increase in the flexural strength of FRSCRAC. The increase in split tensile and flexural strength is more in the case of glass fiber as compared to polypropylene fiber.??The relationship between compressive and split tensile strength and flexural and characteristic compressive strength for without and with fiber is suggested.??The fibrous specimens failed only by splitting of the fiber and there was no deboning of fibers noticed in any of the specimens.

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Concrete

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

Rs 273 crore purchase broadens the developer’s Pune presence

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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.

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Adani Cement and Naredco Partner to Promote Sustainable Construction

Collaboration to focus on skills, technology and greener practices

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Adani Cement has entered a strategic partnership with the National Real Estate Development Council (Naredco) to support India’s construction needs with a focus on sustainability, workforce capability and modern building technologies. The collaboration brings together Adani Cement’s building materials portfolio, research and development strengths and technical expertise with Naredco’s nationwide network of more than 15,000 member organisations. The agreement aims to address evolving demand across housing, commercial and infrastructure sectors.

Under the partnership, the organisations will roll out skill development and certification programmes for masons, contractors and site supervisors, with training to emphasise contemporary construction techniques, safety practices and quality standards. The programmes are intended to improve project execution and on-site efficiency and to raise labour productivity through standardised competencies. Emphasis will be placed on practical training and certification pathways that can be scaled across regions.

The alliance will function as a platform for knowledge sharing and technology exchange, facilitating access to advanced concrete solutions, innovative construction practices and modern materials. The effort is intended to enhance structural durability, execution quality and environmental responsibility across developments while promoting adoption of low-carbon technologies and green cement alternatives. Companies expect these measures to contribute to longer term resilience of built assets.

Senior executives conveyed that the partnership reflects a shared commitment to strengthening quality and sustainability in construction and that closer engagement with developers will help integrate advanced materials and technical support throughout the project lifecycle. Leadership noted the need for responsible construction practices as urbanisation accelerates and indicated that the association should encourage wider adoption of green building norms and collaboration within the real estate and construction ecosystem.

The organisations said they will also explore integrated building solutions, including ready-mix concrete offerings, while supporting initiatives aligned with affordable and inclusive housing. The partnership will progress through engagements, conferences and joint training programmes targeting rapidly urbanising cities and growth centres where demand for efficient and environmentally responsible construction grows. Naredco, established under the aegis of the Ministry of Housing and Urban Affairs, will leverage its policy and advocacy role to support implementation.

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Operational Excellence Redefined!

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Operational excellence in cement is no longer about producing more—it is about producing smarter, cleaner and more reliably, where cost per tonne meets carbon per tonne.

Operational excellence in cement has moved far beyond the old pursuit of ‘more tonne’. The new benchmark is smarter, cleaner, more reliable production—delivered with discipline across process, people and data. In an industry where energy can account for nearly 30 per cent of manufacturing cost, even marginal gains translate into meaningful value. As Dr SB Hegde, Professor, Jain College of Engineering & Technology, Hubli and Visiting Professor, Pennsylvania State University, USA, puts it, “Operational excellence… is no longer about producing more. It is about producing smarter, cleaner, more reliably, and more sustainably.” The shift is structural: carbon per tonne will increasingly matter as much as cost per tonne, and competitiveness will be defined by the ability to stabilise operations while steadily lowering emissions.

From control rooms to command centres

The modern cement plant is no longer a handful of loops watched by a few operators. Control rooms have evolved from a few hundred signals to thousands—today, up to 25,000 signals can compete for attention. Dr Rizwan Sabjan, Head – Global Sales and Proposals, Process Control and Optimization, Fuller Technologies, frames the core problem plainly: plants have added WHRS circuits, alternative fuels, higher line capacities and tighter quality expectations, but human attention remains finite. “It is very impossible for an operator to operate the plant with so many things being added,” he says. “We need somebody who can operate 24×7… without any tiredness, without any distraction… The software can do that for us better.”

This is where advanced process control shifts from ‘automation spend’ to a financial lever. Dr Hegde underlines the logic: “Automation is not a technology expense. It is a financial strategy.” In large kilns, a one per cent improvement is not incremental—it is compounding.

Stability is the new productivity

At the heart of operational excellence lies stability. Not because stability is comfortable, but because it is profitable—and increasingly, low-carbon. When setpoints drift and operators chase variability, costs hide in refractory damage, thermal shocks, stop-start losses and quality swings. Dr Sabjan argues that algorithmic control can absorb process disturbances faster than any operator, acting as ‘a co-pilot or an autopilot’, making changes ‘as quick as possible’ rather than waiting for manual intervention. The result is not just fuel saving—it is steadier operation that extends refractory life and reduces avoidable downtime.

The pay-off can be seen through the lens of variability: manual operation often amplifies swings, while closed-loop optimisation tightens control. As Dr Sabjan notes, “It’s not only about savings… there are many indirect benefits, like increasing the refractory life, because we are avoiding the thermal shocks.”

Quality control

If stability is the base, quality is the multiplier. A high-capacity plant can dispatch enormous volumes daily, and quality cannot be a periodic check—it must be continuous. Yet, as Dr Sabjan points out, the biggest error is not in analysis equipment but upstream: “80 per cent of the error is happening at the sampling level.” If sampling is inconsistent, even the best XRF and XRD become expensive spectators.

Automation closes the loop by standardising sample collection, transport, preparation, analysis and corrective action. “We do invest a lot of money on analytical equipment like XRD and XRF, but if it is not put on the closed loop then there’s no use of it,” he says, because results become person-dependent and slow.

Raju Ramachandran, Chief Manufacturing Officer (East), Nuvoco Vistas Corp, reinforces the operational impact from the plant floor: “There’s a stark difference in what a RoboLab does… ensuring that the consistent quality is there… starts right from the sample collection.” For him, automation is not about removing people; it is about making outcomes repeatable.

Human-centric automation

One of the biggest barriers to performance is not hardware—it is fear. Dr Sabjan describes a persistent concern that digital tools exist to replace operators. “That’s not the way,” he says. “The technology is here to help operator… not to replace them… but to complement them.” The plants that realise this early tend to sustain performance because adoption becomes collaborative rather than forced.

Dr Hegde adds an important caveat: tools can mislead without competence. “If you don’t have the knowledge about the data… this will mislead you… it is like… using ChatGPT… it may tell the garbage.” His point is not anti-technology; it is pro-capability. Operational excellence now requires multidisciplinary teams—process, chemistry, physics, automation and reliability—working as one.

GS Daga, Managing Director, SecMec Consultants, takes the argument further, warning that the technology curve can outpace human readiness: “Our technology movement AI will move fast, and our people will be lagging behind.” For him, the industry’s most urgent intervention is systematic skilling—paired with the environment to apply those skills. Without that, even high-end systems remain underutilised.

Digital energy management

Digital optimisation is no longer confined to pilots; its impact is increasingly quantifiable. Raghu Vokuda, Chief Digital Officer, JSW Cement, describes the outcomes in practical terms: reductions in specific power consumption ‘close to 3 per cent to 7 per cent’, improvements in process stability ‘10 per cent to 20 per cent’, and thermal energy reductions ‘2–5 per cent’. He also highlights value beyond the process line—demand optimisation through forecasting models can reduce peak charges, and optimisation of WHRS can deliver ‘1 per cent to 3 per cent’ efficiency gains.

What matters is the operating approach. Rather than patchwork point solutions, he advocates blueprinting a model digital plant across pillars—maintenance, quality, energy, process, people, safety and sustainability—and then scaling. The difference is governance: defined ownership of data, harmonised OT–IT integration, and dashboards designed for each decision layer—from shopfloor to plant head to network leadership.

Predictive maintenance

Reliability has become a boardroom priority because the cost of failure is blunt and immediate. Dr Hegde captures it crisply: “One day of kiln stoppage can cost several crores.” Predictive maintenance and condition monitoring change reliability from reaction to anticipation—provided plants invest in the right sensors and a holistic architecture.

Dr Sabjan stresses the need for ‘extra investment’ where existing instrumentation is insufficient—kiln shell monitoring, refractory monitoring and other critical measurements. The goal is early warning: “How to have those pre-warnings… where the failures are going to come… and then ensure that the plant availability is high, the downtime is low.”

Ramachandran adds that IoT sensors are increasingly enabling early intervention—temperature rise in bearings, vibration patterns, motor and gearbox signals—moving from prediction to prescription. The operational advantage is not only fewer failures, but planned shutdowns: “Once the shutdown is planned in advance… you have lesser… unpredictable downtimes… and overall… you gain on the productivity.”

Alternative fuels and raw materials

As decarbonisation tightens, AFR becomes central—but scaling it is not simply a procurement decision. Vimal Kumar Jain, Technical Director, Heidelberg Cement, frames AFR as a structured programme built on three foundations: strong pre-processing infrastructure, consistent AFR quality, and a stable pyro process. “Only with the fundamentals in place can AFR be scaled safely—without compromising clinker quality or production stability.”

He also flags a ground reality: India’s AFR streams are often seasonal and variable. “In one season to another season, there is major change… high variation in the quality,” he says, making preprocessing capacity and quality discipline mandatory.

Ramachandran argues the sector also needs ecosystem support: a framework for AFR preprocessing ‘hand-in-hand’ between government and private players, so fuels arrive in forms that can be used efficiently and consistently.

Design and execution discipline

Operational excellence is increasingly determined upstream—by the choices made in concept, layout, technology selection, operability and maintainability. Jain puts it unambiguously: “Long term performance is largely decided before the plant is commissioned.” A disciplined design avoids bottlenecks that are expensive to fix later; disciplined execution ensures safe, smooth start-up with fewer issues.

He highlights an often-missed factor: continuity between project and operations teams. “When knowledge transfer is strong and ownership carries beyond commissioning, the plant stabilises much faster… and lifecycle costs reduce significantly.”

What will define the next decade

Across the value chain, the future benchmark is clear: carbon intensity. “Carbon per ton will matter as much as cost per ton,” says Dr Hegde. Vokuda echoes it: the industry will shift from optimising cost per tonne to carbon per ton.

The pathway, however, is practical rather than idealistic—low-clinker and blended cements, higher thermal substitution, renewable power integration, WHRS scaling and tighter energy efficiency. Jain argues for policy realism: if blended cement can meet quality, why it shall not be allowed more widely, particularly in government projects, and why supplementary materials cannot be used more ambitiously where performance is proven.

At the same time, the sector must prepare for CCUS without waiting for it. Jain calls for CCUS readiness—designing plants so capture can be added later without disruptive retrofits—while acknowledging that large-scale rollout may take time as costs remain high.

Ultimately, operational excellence will belong to plants that integrate—not isolate—the levers: process stability, quality automation, structured AFR, predictive reliability, disciplined execution, secure digitalisation and continuous learning. As Dr Sabjan notes, success will not come from one department owning the change: “Everybody has to own it… then only… the results could be wonderful.”

And as Daga reminds the industry, the future will reward those who keep their feet on the ground while adopting the new: “I don’t buy technology for the sake of technology. It has to make a commercial sense.” In the next decade, that commercial sense will be written in two numbers—cost per tonne and carbon per tonne—delivered through stable, skilled and digitally disciplined operations.

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