Technology

Mechanical Activation of Fly Ash

Published

9 years ago

November 30, 2016

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Many scientists and environmentalists have been attracted towards fly ash, though it is not an attractive material. Dr Ajit Kumar Bhonsle, who has long been associated with the construction industry, narrates his experience on improving the performance of fly ash by mechanical means.

Fly ash is a finely divided residue, resulting from the combustion of ground or powdered bituminous coal or sub-bituminous coal (lignite) and is transported by the flue gases of boilers fired by pulverised coal or lignite. It comprises spherical particles, mostly amorphous, in addition to unburnt carbon, crystalline mullite, quartz and hematite. It has cementitious properties which exhibit when mixed with hydrated lime and alkalis. The mineralogical and chemical composition of n??y ash depends on the source of the coal and design engineering of fly ash collection at the power stations.

Fly ash is a very fine powder and tends to travel far in the air. When not properly disposed, it is known to pollute air and water, and causes respiratory problems when inhaled. When it settles on leaves and crops in fields around the power plant, it lowers the yield. The conventional method used to dispose of both fly ash and bottom ash is to convert them into slurry for impounding in ash ponds around the thermal plants. The construction of ash ponds requires vast tracts of land. This depletes land available for agriculture over a period of time. When one ash pond fills up, another has to be built, at high cost and with further loss of agricultural land. Huge quantity of water is required to convert ash into slurry. During rains, numerous salts and metallic content in the slurry can leach down to the groundwater and contaminate it. Of late (early 1970s), due to development of technology, collection of dry fly ash has started.

Fly ash generation in India

75 per cent of installed power generation in India – coal-based
200 million MT of fly ash is generated every year
300-500 million MT coal used every year
Ash generation likely to reach 300+ million MT by 2017-18
Average ash contents up to 35 per cent in Indian coal
Presently as per the figures from the Ministry of Environment & Forest, only 25-35 per cent of ash is being used in fillings, embank-?ments, construction/cement industry, block and tiles, etc.

Several factors have impeded fly ash utilisation in India, while it is being extensively used globally. Coal-based thermal power stations have been operational for more than 50 years, but the concept of developing environment-friendly solutions for fly ash utilisation is only about 15 years old. Overall, fly ash utilisation in India stands at a fairly low level of about 25-35 per cent of the quantity generated. Various possibilities for increasing its use are under research and development (R&D). Among numerous factors that account for the low level of utilisation, the major factors are:

Poor understanding of the chemistry of fly ash and its derivatives for proper end applications
Absence of standards and specifications for fly ash products
Lack of reliable quality assurance for fly ash products
Poor public awareness about the products and their performance
Availability of dry fly ash collection facilities is far off from consumption places.
Easy availability of land with top soil at cheap rates for manufacturing conventional bricks
Lack of proper coordination between thermal plants and ash users.

Mechanical activation of fly ash, an efforts to increase utilisation of fly ash The need of hour is to increase utilisation of fly ash through R&D activities. One such major activity that is being tried is mechanical activation of fly ash, a process that comprises exposing the particles to high energy impacts in order break or crack the particle microstructure to increase the surface area and reactivity of each particle. It is a process not only for achieving finer fly ash (up to 6,000-8,000 Blains), but also help conversion of fly ash particles from spherical shape to crystalline shape, thereby making available larger surface area for pozzolanic reaction. With mechanical activation, even the coarse fly ash and pond fly ash can be converted to finer reactive fly ash. Refer to Table 1 and 2. This would not only double the lime reactivity of normal fly ash, but would also result in giving packing effect to its final product, there by giving the final product increased density and better strength in shorter time (J Temuujin, R P Williams, A Van Riessen).

Low fly ash utilisation – technical facts
In addition to factors discussed above, there are some technical factors also, which hinder the optimum utilisation of fly ash. The prime factors are:
Coarseness: Despite having cementitiouss and pozzolanic properties, consumption of available fly ash has limitation due to its coarseness. Coarse fly ash gives a low compressive strength when used up to 30 per cent of cement replacement.
Spherical shape: Further, the large particle sizes carry the spherical form, which is inactive to pozzolanic reaction.
Inconsistency in particle size distribution (large variation in particle size in coarse fly ash), lower fineness and spherical shape result in limited availability of surface for reactivity.
Spherical particles also contribute to lower density of the mass.
Thus, lower density hinders the development of strength at early stage.
So, how mechanical activation would overcome these limitations: As discussed above, the mechanical activation is a method of obtaining very fine fly ash (up to or +8,000 Blaine). In addition, it also destroys the spherical morphology of raw fly ash and converts fly ash particles from spherical shape to crystalline shape.
Fineness and conversion result in larger surface area availability for lime reactivity, which is vital to any material having cementitious and pozzolanic properties.
Smaller particles fill voids between larger particles, thereby giving the final product increased density and strength.
Crystalline form of the particles itself leaves no room for voids as in the case of spherical particles. This results in reduction of water consumption, which otherwise gets accumulated in the voids.
Lab tests have shown increase in lime reactivity
Improved durability of concrete, even with 50 per cent replacement of OPC
Increase in tensile strength of cement product
Reduction in water consumption

Difference between superfine fly ash (SFAF) and normal fly ash: Finer particle size of SFAF and change in its morphology allow higher dissolution rate of SFAF. Thus, Geo polymer paste made with SFAF when cured at ambient temperature leads to an increase of about 80 per cent in compressive strength when compared with Geo polymer made from normal fly ash.

Some facts
Beside environmental issues discussed above, one of the major elements, which cause global warming, is emission of carbon dioxide (CO2). It is observed that production of one tonne of Portland cement releases an equal amount of CO2 into atmosphere, thus utilisation of fly ash in cement will help to contain CO2 emission. Therefore, use of fly ash will increase the cement production which in turn will slow down the rate of depletion of available natural resources.

An estimate says replacing 15 per cent cement worldwide by fly ash will reduce CO2 emission by 227 million tonne.
The target is replacing 50 per cent of cement worldwide by fly ash will reduce CO2 by 750 million tonne. Refer to Table 3. This may be equal to removing 25 per cent of all automobiles in the world.
Full utilisation of generated fly ash in India will provide employment potential for more than 3,00,000 people. This will generate a business volume of over Rs 4,000 crore.

Materials
I shall now give my experiences on improving the performance of fly ash through mechanical ways. Fly ash used for study purpose is procured from the Gandhinagar Thermal Power Station in Gujarat and Parli Thermal Power Station at Parli Vaijnath in Beed district of Maharashtra. Around 80 tonnes of samples is collected for study assessment.

Method
After mechanical activation, both the samples were analysed for the particle sizes, fineness (blains air permeability) and lime reactivity. The analysis was conducted at National Council for Cement and Building Materials (NCCBM) at Ahmedabad, Gujarat. Standard method of testing were done as per IS 3812- Part 1 and 2 (2003) as Specification for Pulverised Fuel Ash, Part 1: for use as pozzolanic additive in cement, cement mortar and concrete [CED 2: Cement and Concrete] and specification for pulverised fuel ash, Part 2: for use as admixture in cement mortar and concrete [CED 2: Cement and Concrete] and IS 1727 (1967) for methods of test for pozzolanic materials [CED 2: Civil Engineering].

Test results of parameter for fineness, lime reactivity and compressive strength are mentioned in the tables Refer to Table 1 and 2.

Conclusion
Fly Ash is a wonderful material, however need of the hour is to explore its properties scientifically and make use of the same in various spheres.
Mechanically activated fly ash has vast potential to improve upon the utilization of fly ash in no. of fields viz cement, concrete, cement products like paver blocks bricks.
Mechanically activated fine fly ash can also be used in paint industry, cement roof sheeting industry
Consistent quality of activated fly ash can be a good substitute for concrete/cement strength enhancing material viz micro silica alcofine etc.
Activation facility if set up near thermal power plant it would generate employment opportunity to the local labour force.
Activation of fly ash may a good tool to combat the problem of Fly Ash disposal which is likely to increase in the days to come.
Up to 110 per cent of strength activity index can be achieved when normal fly ash is ground to smaller size.
Strength activity index of normal fly ash can be improved by grinding and coarse fly ash is not in crystalline phase.
For a good quality of micro fine fly ash, by classifying or grinding, the important factor is its fineness. Fly ash with finer particle size increases ultimate strength as well as rate of strength gain of fly ash cement mortar.
When keeping the same work-?ability of mortal, the use of finer fly ash demands less water than the use of normal coarse one.

Excerpt from the former President, APJ Abdul Kalam?s address to the nation on the eve of the country?s 56th Republic Day
Conversion of fly ash into wealth generator: Fly ash can become a wealth generator by making use of it for producing ?green building? materials, roads, agriculture etc.
Full utilisation of the generating stock will provide employment potential for three hundred thousand people and result in a business volume of over Rs 4,000 crore.?(ENVIS newsletter vol. 2, no.6 Jan 2007)

The author is an expert with over 35 years of experience working in cement, concrete and allied fields.

Economy & Market

SEW-EURODRIVE India Opens Drive Technology Centre in Chennai

Published

2 weeks ago

March 25, 2026

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The new facility strengthens SEW-EURODRIVE India’s manufacturing, assembly and service capabilities

SEW-EURODRIVE India has inaugurated a new Drive Technology Centre (DTC) in Chennai, marking a significant expansion of its manufacturing and service infrastructure in South India. The facility is positioned to enhance the company’s responsiveness and long-term support capabilities for customers across southern and eastern regions of the country.

Built across 12.27 acres, the facility includes a 21,350-square-metre assembly and service setup designed to support future industrial growth, evolving application requirements and capacity expansion. The centre reflects the company’s long-term strategy in India, combining global engineering practices with local manufacturing and service capabilities.

The new facility has been developed in line with green building standards and incorporates sustainable features such as natural daylight utilisation, solar power generation and rainwater harvesting systems. The company has also implemented energy-efficient construction and advanced climate control systems that help reduce shopfloor temperatures by up to 3°C, improving production stability, product quality and working conditions.

A key highlight of the centre is the 15,000-square-metre assembly shop, which features digitisation-ready assembly cells based on a single-piece flow manufacturing concept. The facility also houses SEW-EURODRIVE India’s first semi-automated painting booth, aimed at ensuring uniform surface finish and improving production throughput.

With the commissioning of the Chennai Drive Technology Centre, SEW-EURODRIVE India continues to strengthen its manufacturing footprint and reinforces its long-term commitment to supporting industrial growth and automation development in India.

Economy & Market

RAHSTA Roundtable Sets Agenda for Smarter, Safer Highways

Published

4 weeks ago

March 16, 2026

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Roundtable discussions focus on innovation for safer highways.

Held on 12 March 2026 at Courtyard by Marriott, Mumbai, alongside the Infrastructure Today Airport Conclave, the RAHSTA Roundtable brought together stakeholders from across the highways and infrastructure ecosystem to shape the agenda for the 16th RAHSTA 2026, scheduled for 8–9 July 2026 at the Jio Convention Centre, Mumbai. The session focused on key industry themes including road construction, technology, safety and long-term sustainability.

Opening the discussion, Pratap Padode, Founder, FIRST Construction Council, said the roundtable marked the beginning of a broader consultative process leading up to the July event. The aim, he noted, is to bring together industry stakeholders to refine the agenda for discussions on the future of roads, bridges, tunnels and allied infrastructure.

Padode noted that while central road project awards have slowed in recent years, states are increasingly driving the next phase of infrastructure growth. Maharashtra, with its long-term road development plans and agencies such as MSRDC and MSIDC, is expected to play a significant role in this expansion.

RAHSTA Expo 2026 as a specialised platform dedicated to road infrastructure, covering highways, tunnels, bridges and flyovers along with construction technologies, safety systems and maintenance solutions. He also highlighted the growing importance of rural connectivity and said the organisers are engaging with government bodies to highlight rural road development initiatives.

Tanveer Padode, CIO, ASAPP Info Group, presented insights from IMPACCT, the group’s infrastructure intelligence platform. He pointed to a strong project pipeline despite slower highway awards earlier in the year, noting that states such as Maharashtra, Odisha and Arunachal Pradesh are emerging as key drivers of new projects. The data also revealed that only a small group of contractors participates in large-value infrastructure bids.

Lt Gen Rajeev Chaudhary, former Director General, Border Roads Organisation and Chairman of the RAHSTA Expo Committee, emphasised the need for stronger collaboration across the ecosystem, including policymakers, contractors, technology providers and financiers. He also called for addressing systemic issues within the sector and encouraged greater participation of women in infrastructure leadership.

The discussion also explored the evolving economics of road development. Phani Prasad Mandalaparthy, Associate Director, CRISIL Intelligence, noted that the slowdown in project awards reflects a shift towards higher-value logistics corridors rather than simple road widening projects. However, private participation through BOT and TOT models remains limited.

From the contractors’ perspective, Sudhir Hoshing, Whole-Time Director, Ceigall, said companies are becoming more selective in bidding, favouring projects with clearer payment mechanisms and efficient processes. While NHAI continues to offer greater operational clarity, states such as Uttar Pradesh and Bihar were cited as relatively supportive environments for project execution.

Durability and sustainability also emerged as key themes. Himanshu Agarwal, COO – Road & Infrastructure, Zydex Group India, highlighted the need to prioritise lifecycle performance and resilient pavements, while participants discussed the potential of alternative materials such as plastic waste, steel slag and industrial by-products in road construction.

Dr LR Manjunatha, Vice President, JSW Cement, emphasised that India has abundant fly ash, slag and other industrial materials that can improve durability and sustainability if integrated into specifications and policy frameworks.

Technology and equipment challenges were also discussed. Dr Lakshmana Rao Mantri, Dy General Manager, Afcons Infrastructure, highlighted the shortage of tunnel boring machines (TBMs), which is delaying several underground infrastructure projects. Participants agreed that developing domestic TBM manufacturing capabilities will be critical for future infrastructure expansion.

The future of concrete pavements was another area of discussion. Dr V Ramachandra, President, Indian Concrete Institute, stressed that the debate should focus on lifecycle performance rather than material choice alone, noting that evolving design standards are improving the feasibility of concrete roads.

Prof Dharamveer Singh of IIT Bombay added that while India has made significant progress in infrastructure development, stronger capacity building and better execution practices are essential to ensure consistent road quality.

The discussion also touched upon technology adoption in the sector. Rushabh Mamania, Partner & CBO, Roadvision, highlighted the growing role of AI in road infrastructure, noting that AI-driven monitoring systems are already being deployed across large stretches of national highways.

Overall, the roundtable underscored that the future of highway infrastructure will depend not only on the pace of construction but also on durability, safety, technology integration and sustainable materials. The discussions offered valuable insights that will help shape the agenda for RAHSTA 2026 and guide future collaboration within the industry.

Economy & Market

CTS Roundtable Charts Tech-Led Roadmap for Construction

Published

4 weeks ago

March 16, 2026

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CTS Roundtable Maps Technology Roadmap for Construction

Ahead of the Construction Technology Show (Con Tech Show) 2026, industry leaders, technology innovators and academia came together in Mumbai to deliberate on how digitalisation, automation and industrialised construction can reshape the sector. The discussion made one thing clear: construction can no longer afford to treat technology as optional.

Held on 12 March 2026 at Courtyard by Marriott, Mumbai, alongside the Infrastructure Today Airport Conclave, the CTS Roundtable served as a precursor to the Construction Technology Show 2026, scheduled for 19–20 August 2026 at NESCO, Mumbai.

A platform to move from discussion to deployment

Opening the session, Pratap Padode, Founder and Editor-in-Chief, ASAPP Info Global Group, said construction technology has long remained close to his heart, especially given the sector’s traditionally slow pace of technology adoption. He noted that over the years, the Construction Technology Summit had steadily built interest, and the next step was now to expand it into a larger, more meaningful platform that could bring together technology providers, users, startups and innovators under one roof.

Padode said the vision for CTS is not limited to software alone. The platform aims to embrace all forms of technology that can improve construction efficiency, quality and execution—from digital tools and project management systems to lean construction, off-site fabrication and startup-led innovation. He also highlighted plans to deepen startup participation and create space for young companies to showcase emerging construction solutions.

Industry at a turning point

Moderating the roundtable, Naushad Panjwani, Chairman, Mandarus Partners, set the context by pointing out that the global construction industry, despite being a multi-trillion-dollar sector, continues to lag in productivity. He noted that while manufacturing has consistently improved efficiency, construction has remained slow to modernise.

Referring to both global and Indian trends, Panjwani underlined that the industry is now at a decisive moment. India, he said, is entering a major build cycle, and delivering the next phase of infrastructure and real estate growth through traditional methods alone is no longer viable. The goal of the roundtable, therefore, was not to debate technology in isolation, but to identify the most critical conversations that would bridge the gap between innovation and implementation.

His central message was clear: CTS 2026 must be shaped around themes that make CEOs, CIOs and CTOs feel they cannot afford to miss the event.

From BIM to AI, data to governance

A major theme that emerged through the discussion was the need for better data, better visibility and better decision-making. Dr Venkata Santosh Kumar of IIT Bombay echoed this, saying that the underlying data infrastructure itself needs attention. Construction projects, particularly remote ones, often face issues around connectivity, data collection and data use. Without this foundation, more advanced technologies cannot deliver their full value.

Chandra Vasireddy, CEO & Co-founder, Inncircles, expanded the discussion to governance, arguing that technology must help connect the many moving parts of a construction business. For him, the real value of digital transformation lies in creating better governance, clearer visibility and stronger business outcomes.

Tejas Vara of Inncircles stressed the importance of timely site data for leadership teams, especially in large and remote projects where decisions on materials, machinery and manpower often get delayed because information does not reach headquarters in time.

The role of AI also featured prominently. Rushabh Mamania, Partner and CBO, Roadvision said that while AI and machine learning are now common terms, vision intelligence and language intelligence have still not deeply penetrated the construction sector. He emphasised that startups in India are building relevant AI-led solutions and are already attracting international interest, showing that innovation need not be imported—it can be built locally and scaled globally.

Industrialised construction gains ground

The roundtable also placed strong emphasis on industrialised construction methods. Kalyan Vaidyanathan, CTO – Construction & R&D, Tvasta, called for greater focus on off-site fabrication and the broader industrialisation of construction. Bhargav Jog, General Manager, Dextra, highlighted precast technology and alternative sustainable materials as areas with immediate relevance.

Several participants agreed that modular, precast and pre-engineered approaches are no longer niche ideas. They are increasingly becoming practical responses to the sector’s challenges around labour shortage, timelines, quality control and predictability.

Anup Mathew, Sr VP & Business Head, Godrej, argued that the industry needs a fully integrated approach—from design and procurement to execution and asset management. Unless these are connected, technology adoption will remain fragmented and sub-optimal. He pointed to pre-engineered and modular systems as examples of how industrial thinking can compress timelines, improve quality and reduce dependence on difficult on-site conditions.

Adoption remains the biggest hurdle

While there was broad agreement on the promise of technology, the discussion repeatedly returned to one fundamental challenge: adoption.

Abhishek Kumar, COO, LivSYT, observed that the market is crowded with solutions, but many buyers still struggle to evaluate which technology suits which use case. According to him, the industry needs clearer frameworks to help users select, compare and adopt solutions, rather than expecting a single platform to solve every problem.

Dr Tenepalli JaiSai, Associate Professor, School of Construction(SoC), NICMAR University, noted that isolated technologies will not solve the productivity problem by themselves. What is required is an integrated Construction 4.0 approach, where digital, physical and cyber-physical systems work together rather than in silos.

That concern around silos was reinforced by Subodh Dixit, former Director, Shapoorji Pallonji, who said the issue is not just that technologies are disconnected, but that stakeholders are as well. Clients, consultants, contractors and partners often operate with different priorities. Unless these silos are broken, technology will struggle to percolate across the full project value chain.

Harleen Oberoi, Project Management, Tata Realty shared a practical perspective from the client side, saying that successful BIM implementation requires investment across the ecosystem, not just within one organisation. Trade partners, vendors and other stakeholders must also be trained and aligned if the technology is to deliver its intended results.

Beyond buzzwords

A notable takeaway from the session was that the industry is moving past the phase of treating technology as a buzzword. Participants repeatedly stressed that the real question is not whether technology should be used, but where it creates measurable value and how that value can be scaled.

The conversation also expanded beyond mainstream themes to include repairs and rehabilitation, construction and demolition waste, sustainability, circular economy, green sourcing, carbon measurement, design interoperability, generative design, robotics, and the role of horticulture and greener built environments.

Setting the agenda for CTS 2026

By the close of the session, the roundtable had surfaced a strong set of themes for the upcoming show: BIM and digital twins, AI and data platforms, industrialised construction, startup innovation, governance-led technology adoption, robotics, sustainable materials, and integrated project delivery.

More importantly, the session established CTS 2026 as more than an exhibition. It is shaping up to be a serious industry platform where users, technology providers, researchers and policymakers can collectively define the future of construction.

As Padode noted in his closing remarks, the conversation will continue through further consultations and possibly webinars in the run-up to the show. If the roundtable is any indication, CTS 2026 will aim not merely to showcase technology, but to push the industry towards meaningful adoption at scale.