RUPESH KUMAR explains why it is important to control concrete temperature and how it can be done.
With mega structures coming up every?where using high-grade concrete, the control of concrete temperature is become a matter of frequent discu?ssion among civil engineers.
The concern
Green concrete, the nascent stage of concrete hardening, requires a lot of care to mature as good concrete. Concrete is weak in tension bearing; more so, in the initial stage of hardening. Its vulnerability becomes more critical when there are tensile forces induced owing to the hardening process. Being an exothermic reaction, heat is generated during the process; this causes thermal differential and stress that act as a tensile force and cause cracks.
In many cases, cracks developed at the initial stages do not heal and remain or widen further as the concrete shrinks during further hardening. This leads to a situation where structural stability, integrity and durability begin to get compromised. The following observations can be made in the early days of concrete, primarily in the first week:
Concrete matures with time and temperature.
Strength comes with maturity.
In seven days, almost 2/3 of 28 days strength gain for OPC cement-based concrete is expected, though this can vary according to the design mix.
The exothermic chemical reaction is most active during this period.
Thermal gain is achieved to its maximum during this period; concrete core temperature starts declining after reaching its peak in most cases.
Core temperature rise causes thermal differential and stress in concrete.
The higher the temperature, faster the maturity. But early higher temperature leads to a greater tendency to crack internally, owing to higher thermal stress. Increasing temperature in the early days has shown more strength on the seventh day and less on day 28 compared to standard maturity of concrete on day seven and 28 respectively, owing to thermal micro-cracking.
Concrete plastic shrinkage and initial shrinkage are more dominant during this period and slow down with time. Late shrinkage can continue for many months but the effect is not so significant as the concrete strength is able to counteract the stress of late shrinkage in most cases.
Cracks developed during the initial stage owing to plastic shrinkage may not heal automatically in further maturity. On the contrary, at times the crack increases in width, depth or both with time, owing to shrinkage stress acting as a localised tensile force.
Cracks develop when the tensile stress increases more than the tensile bearing capacity of the concrete.
If the concrete does not gain sufficient strength during the peak concrete temperature, and specifically during higher thermal differential, there is higher likelihood of cracking.
The peak temperature of concrete and the thermal differential depends on the green concrete temperature as well as the ambient temperature along with shuttering (temporary formwork) condition.
The heat gain in the concrete for a given design mix is the same; thus, the green concrete has a direct effect on the heat gain and rise in concrete core temperature. The higher the green concrete temperature, higher the core peak temperature, and vice versa.
The thermal differential causes the stress in the concrete and core to the surface temperature of the concrete must be kept in controlled condition to control the differential. However, the peak temperature of the core beyond a limit may cause other long-term effects like DEF (delayed ettringite formation; a matter yet to be ascertained codally) and needs to be addressed. In Indian tropical conditions, DEF is not expected to be of serious concern if the temperature is taken care of to limit peak temperature below 70?and pozzolanic material is used in the mix. However, thermal differential of concrete must be an area of focus for durable concrete.
Green concrete temperature
The temperature control limits of green concrete are specified in various codes and they all vary. There are references for RCC green concrete temperature for below 40?, up to 38? up to 32?, up to 30? and up to 25? in various codes, including BIS, BS and ASTM.
With higher grades of concrete, the maximum allowable core temperature restrictions are of higher consideration, which restrict the green concrete temperature less than what is allowed in the codes.
To restrict the peak temperature, the green concrete temperature is asked to be reduced. In such a specific scenario, a holistic approach should be taken to define the green concrete temperature as lowering the temperature is a costly affair – although it is not intended to compromise the strength and durability of the concrete. Care should be taken as green concrete temperature control requires a broader approach than simply lowering the temperature during production; it should first be ascertained whether it is really required. It is more prudent to have higher temperature rather than more thermal differential. Also, the lower temperature should be sustained – not less at any one stage of the concrete production, transportation, placement and construction. Further, thermal consideration of concrete is more important for mass concrete than smaller sections.
Way to set concrete temperature limit
To understand the thermal consideration for a given concrete in a project, a preliminary test should be done to arrive at the initial data. Except generally established limits, at present, the codes have not established the procedure for review and analysis of concrete temperature acceptance for a given scenario. A procedure with the action points mentioned below can be used to logically arrive at a calculation analysis and mock-up review to arrive at the concrete temperature acceptance for the given scenario. Some important questions to ask during calculation analysis and mock-up testing are:
How does the concrete temperature rise with time and when the peak temperature is reached for a given mix? For this, a thermal probe can be inserted before placing the concrete and recoding can be done using a thermal data logger. Alternatively, manual set-up and reading can be done, but manual recoding is tedious. The data can be recorded or plotted and analysed.
What is the design calculation with consideration of thermal stress and the crack width allowed as per the design? The data can be obtained from the design calculation sheet or designer.
How is the reinforcement as per the design of the structure and is it able to take the stress developed in the concrete owing to thermal stress? The designer can confirm this and reinforcement adequacy for taking additional thermal stress can be checked considering the crack width limitation as per the design calculation.
How is the maturity of concrete and subsequently the strength of concrete with respect to time? The data can be obtained by taking additional sufficient concrete samples and keeping them under standard testing condition. Curing tank temperature can be taken if the temperature is not being maintained in the curing tank. Testing of concrete sampling shall be done as per testing the procedure at various durations.
Is there any crack observed in the mock up and is there is any crack owing to thermal stress and not plastic shrinkage? To avoid plastic shrinkage, the mock shall preferably be for an adiabatic condition for unreinforced, 1 cu m of mass or miniature replica of the actual structure.
Close observation is required to check crack development; if required, a core can be taken to check the inside of the concrete mass. Normally, thermal stress if developed and causing a crack inside, will reflect up to the surface as the surface to core thermal differential is expected to be more than the thermal differential of the core to the other inner part of concrete. Based on a visual examination, the cracks can be checked.
Now, based on the data mentioned above, one can calculate the estimated concrete temperature and acceptable thermal differential. It can also be analysed whether the concrete is expected to crack beyond the design calculation for the given reinforcement design and estimated concrete peak temperature in the project ambient temperature, and more so for the thermal differential. Then, verification can be done by examining the mock-up concrete.
Thus, one can ascertain whether concrete can sustain the expected peak temperature and thermal differential for a given design mix with reinforcement as per design and ambient condition during construction. In case of non-reinforced concrete (PCC-based structure), reinforcement stress bearing will not be present and the concrete would be able to sustain only as much stress as the maturity of concrete will allow.
About the author
Rupesh Kumar is a Quality Manager and Concrete Technologist with 18 years of experience working in mega projects in India and abroad. He has dealt with more than 2.5 million cu m of concrete in projects of RMC, hospital, factories, stadium, metros, airports and statue.
This artical was first published in Construction World magazine
Indian Cement Review (ICR) and Fuller Technologies brought industry, policy and technology leaders together to discuss how cement innovation can drive green construction at scale, writes Rakesh Rao.
India is building at a pace few countries can match. Highways, airports, housing, logistics parks, industrial corridors and urban infrastructure are reshaping the country’s economic geography. But beneath this growth story lies a difficult question: can India continue to build at scale without locking itself into a high-carbon future?
That question formed the core of an online panel discussion titled “Driving Green Construction Through Cement Innovation”, organised by Indian Cement Review (ICR) in association with Fuller Technologies as the Presenting Partner on June 25, 2026. The webinar brought together experts from cement technology, R&D, global industry platforms, building performance policy and international development cooperation to examine how low-carbon cement and material innovation can accelerate India’s green construction transition.
The discussion came at a crucial time. India has committed to achieving net-zero emissions by 2070 and reducing the carbon intensity of its economy by 45 per cent by 2030. At the same time, the country’s construction sector is expanding rapidly, driven by urbanisation, infrastructure development, housing demand and industrial growth. Cement, as one of the most widely used construction materials, sits at the heart of this transition. It is indispensable to development, but also central to the challenge of reducing embodied carbon in buildings and infrastructure.
Moderated by Nitika Krishan, Senior Urban Infrastructure and Sustainable Policy Consultant, the panel featured:
Dr Hemantkumar Aiyer, VP and Head R&D, Nuvoco Vistas Corp Ltd;
Devika Wattal, Innovation Lead, Global Cement and Concrete Association (GCCA);
Dr Sunita Purushottam, MD, GBPN India (Global Buildings Performance Network); and
Vaibhav Rathi, Senior Technical Advisor, GIZ (the German Agency for International Cooperation)
Setting the tone for the discussion, Nitika Krishan underlined the scale of the challenge before the sector. “The question before us is no longer whether we build, but how we build sustainably,” she said. She pointed out that construction accounts for nearly 40 per cent of global energy-related carbon emissions when both operational and embodied carbon are considered. Cement production, she added, remains one of the hardest industrial processes to decarbonise.
For India, this is not merely an environmental issue. It is a development issue, a competitiveness issue and increasingly, a market issue. As one of the world’s largest cement producers and among the fastest-growing construction markets, India’s material choices will influence the carbon trajectory of its built environment for decades. As Krishan observed, sustainability solutions in economies such as India must not remain limited to laboratory success. They must be scalable, commercially viable and practical at national level.
The innovation gap: From technology to market
Experts believe that there is a need to bridge the innovation gaps for making decarbonisation in cement and concrete scalable. Devika Wattal of GCCA, explained, “The starting point must be the core cement manufacturing process itself. The first and foremost is the heart of our process, the heart of cement manufacturing. How do we reduce clinker? That is always a topic where industry is working very intrinsically.”
Clinker reduction remains one of the most important pathways for lowering emissions in cement. Since clinker production is energy-intensive and chemically emits carbon dioxide, reducing the clinker factor through supplementary cementitious materials (SCMs), blended cements and new chemistries can have a significant impact. Wattal also noted that carbon capture, utilisation and storage (CCUS) will have a role, though it may not be the first lever for all markets.
However, she stressed that innovation cannot stop at technology development. A solution that works in the lab must also be adaptable to industry, scalable in production and acceptable in construction practice. “It is important for that innovation to be adaptable, to be scalable, and so that it can be executed in real time,” she said.
Wattal also called for stronger enabling systems around innovation. These include performance-based standards, product-level embodied carbon databases and clearer frameworks for evaluating green materials. Without these, low-carbon cement products may struggle to compete with conventional materials in procurement and design.
R&D must balance carbon, cost and performance
Bringing in the R&D perspective into the discussion, Dr Hemantkumar Aiyer of Nuvoco Vistas emphasised that low-carbon cement development cannot be treated as a single-variable exercise. Cement must perform in real construction conditions. It must deliver strength, durability, consistency and cost competitiveness, while also reducing carbon.
“The root of understanding and balancing all these aspects lies in materials, and knowing the materials,” he said.
According to Dr Aiyer, R&D teams must understand the variability of raw materials such as fly ash, slag and clinker. Different sources produce different material behaviours. This makes mix optimisation, material characterisation and processing-property relationships critical. When performance is affected, cement manufacturers must understand how strength enhancers, admixtures and other performance chemicals interact with the material system.
He also linked material science with process efficiency. Clinkerisation takes place at extremely high temperatures, around 1,400 to 1,450 degrees Celsius. Any improvement in raw mix design, process control or energy optimisation can, therefore, help reduce emissions and cost. Dr Aiyer pointed to artificial intelligence-based optimisation, Cement 4.0 tools and advanced software as important enablers for real-time process and material control.
“The more you understand the materials, the more you can control it,” he said.
LC3: The promise is proven, the sequencing is not
Limestone calcined clay cement, commonly referred to as LC3, has attracted global attention because it can reduce clinker content significantly by using calcined clay and limestone while maintaining performance in many applications. Kiranmai Sanagavarapu of Fuller Technologies said the technology itself has already moved beyond proof of concept. Fuller Technologies has worked with calcined clay technology for nearly two decades and has seen plants running in France and Ghana. These plants, she said, are meeting local and national specifications, while the economics are beginning to make sense.
“The calciner is performing, the economics is stacking up, it is making business sense to produce,” she said.
But if the technology is viable, why has adoption not scaled faster? For Sanagavarapu, the answer lies in project sequencing. Too often, clay characterisation happens after equipment is specified. This, she warned, is a backward approach because calciner design depends on clay mineralogy, kaolinite content, iron levels, reactivity, moisture and other variables.
“If you don’t know what your deposit looks like before you commit for the equipment, you are, in a way, going blind into designing,” she said.
She also identified permitting and plant integration as major bottlenecks. Environmental clearances, mining permissions and local regulatory approvals must begin early. Similarly, calcined clay must be integrated into existing grinding, blending and logistics systems from the design stage, not treated as an afterthought during commissioning.
India already has IS 18189:2023 standard for LC3, but Sanagavarapu pointed out that the standard is not yet visible enough in procurement documents. “The gap between what is technically being permitted and what the procurement is asking is the single biggest bottleneck,” she said.
In her view, successful scale-up depends on getting the sequence right: clay characterisation first, permitting in parallel, standards aligned with construction, and integration built into plant design.
India’s LC3 journey: Progress, but demand remains thin
Providing details of India’s LC3 commercialisation experience, Vaibhav Rathi of GIZ noted that JK Cement carried out the first commercial production of LC3 at its Rajasthan plant, followed by JK Lakshmi Cement three months later. These initiatives were supported by the International Climate Initiative of the Government of Germany, with IIT Delhi contributing deep institutional knowledge on LC3 research and BIS certification.
Rathi said India’s early experience has produced clear lessons. One of the biggest was the need to build capacity among regulators. While BIS certification existed, State Pollution Control Boards were unfamiliar with the technology and unsure about the approval pathway.
“The capacity building is not just needed amongst the producer and the users of the cement, but also the regulators who are working with this technology for the first time,” he said.
He also highlighted the need for better information on China clay deposits. Since China clay is currently classified as a minor mineral, centralised data on availability, quality and location is limited. If cement manufacturers are to adopt LC3 at scale, stronger mineral intelligence will be important.
The third issue is demand. LC3 has already been used in projects such as Palava City in Mumbai and Noida International Airport, but these remain limited examples. “It is in a chicken and egg situation,” Rathi said. “Cement companies are saying we need more demand, and users are saying there is not enough cement available.”
Public procurement, he suggested, could help break this cycle. If agencies such as CPWD and other public bodies begin testing, accepting and specifying LC3, it could create the market confidence needed for cement companies to invest in production and storage.
Building codes must catch up with innovation
Dr Sunita Purushottam of GBPN India argued that material choices will determine built environment emissions over the long term, but India’s current policy signals remain fragmented. Although LC3 has received BIS recognition, she pointed out that building codes, municipal bylaws, schedules of rates and sustainability codes do not yet provide uniform guidance on low-carbon cement.
“The current cement regulations are largely prescriptive and favouring traditional materials,” she said. This limits the ability of alternative materials to compete on performance, durability and emissions.
Dr Purushottam also raised the issue of taxation. Cement, including LC3, currently falls under the same GST bracket as conventional cement. A differentiated tax structure, she argued, could help accelerate market adoption. “In order for the market to demand LC3, that differentiation in the GST could go a long way,” she said.
She noted that green building certifications such as IGBC and GRIHA are already creating demand for low-carbon materials by assigning points for embodied carbon and sustainable material use. However, she said large-scale adoption will require regulatory mandates, particularly through building codes and state-level notifications.
She also cautioned that low-carbon cement alone does not solve the entire building performance problem. A material may reduce embodied carbon, but the operational carbon of a building depends on thermal performance, design, insulation and energy use. “The energy part has two elements,” she said. “One is the embodied carbon of the material itself, and the other is the operational carbon.”
Collaboration is the bridge between invention and impact
Wattal said GCCA sees innovation as a strategic priority and works through platforms that connect industry with academia and start-ups. “There is no way we will decarbonise our sector without innovation,” she said.
However, she stressed that research must be connected to actual industry challenges. Innovations developed in isolation may fail when they encounter real-world barriers such as raw material variability, plant integration, cost, standards and finance. Start-ups, too, need industry mentorship and scale-up pathways.
Wattal also flagged the importance of finance. Even strong technologies may struggle to attract investment if there is no common understanding of bankability. “We have always put projects into, is this a bankable project? But the definition of a bankable project has never been defined,” she said.
For India, she saw strong potential in its academic and start-up ecosystem, but said the challenge lies in alignment and prioritisation. The country has the research base, industrial capacity and market size. What it now needs is a coordinated route from innovation to deployment.
There is a practical concern for cement manufacturers: how can existing plants be adapted for lower emissions without compromising reliability or commercial viability?
Kiranmai Sanagavarapu addressed, “The reliability risk in calcined clay retrofit is definitely real, but it is almost always self-inflicted. The risk arises when a new process is added to an existing circuit without properly redesigning grinding and blending configurations.”
Existing cement plants, she explained, can take two broad routes. The first is external sourcing of calcined clay combined with mill optimisation. This requires lower capital investment and can potentially move in 12 to 18 months if other conditions are in place. It may reduce emissions by around 20 to 30 per cent. The second route is integrated calcination on site, which requires higher capital expenditure and longer lead times, but provides greater control over quality, supply and emissions reduction potential.
For Sanagavarapu, the principle is simple: low-carbon retrofits must be designed with intent. “Design it with an intent properly from the start. Start in the market conditions where the economics are already working,” she said.
Circularity: The overlooked advantage
According to Vaibhav Rathi, fly ash and slag are already well established in cement and construction (C&D), but construction and demolition waste remains underutilised. “C&D waste is a growing business opportunity which not many have taken up,” he said. India’s continuous construction and demolition activity creates huge volumes of waste, much of which contributes to air pollution, land degradation and material inefficiency. With the right processing and standards, this waste can be converted into useful construction products.
Rathi also pointed out that LC3 has a circular economy dimension that is often overlooked. It can use low-grade kaolin-rich clay left behind after high-grade clay is extracted for other applications. “LC3 is not only a low-carbon solution, but also a circular economy solution,” he said.
At the same time, he cautioned that LC3 in India is not yet cheap because it has not reached scale. Site-specific techno-commercial feasibility studies, supported jointly by development agencies and industry, could help companies assess whether LC3 production makes technical and financial sense at a given location.
Dr Purushottam added that India must address both low-carbon cement and construction waste together. “Both low-carbon cement and C&D waste go hand in hand. India does not have an option but to work on both,” she said.
Dr Aiyer called for policy shifts from both government and industry, including preferential purchasing of sustainable materials, minimum supplementary cementitious material requirements in public and public-private projects, and faster regulatory implementation. “If we can fast-track the regulatory standards and their implementation on the ground, that is the way to go,” he said.
From green ambition to green construction
Cement innovation is no longer only about chemistry. It is about systems. Low-carbon cement will scale only when technology, standards, procurement, finance, regulation, education and construction practice move together.
LC3 and other low-carbon technologies have shown promise. India has early commercial examples, strong research capability and growing market interest. But mainstream adoption will depend on whether demand can be created, regulators can be capacitated, standards can be embedded in procurement, and manufacturers can see a clear business case.
For a country building at India’s scale, the opportunity is enormous. Cement will continue to be central to infrastructure and urban development. The challenge now is to ensure that the cement used in India’s growth story carries a lower carbon burden.
Rakesh Rao
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JK Cement gained after being declared preferred bidder for the Gilund Limestone Block in Chittorgarh, Rajasthan, a lease area of 370.96 hectares. The firm saw its shares trade at Rs. 5550.05, up by 28.45 points or 0.52 per cent from the previous close of Rs. 5521.60 on the BSE. The scrip opened at Rs. 5569.15 and touched a high of Rs. 5625.00 and a low of Rs. 5531.00.
The stock recorded turnover of 1742 shares on the counter and the BSE group A stock with face value Rs. 10 has a 52 week high of Rs. 7565.00 on 20-Aug-2025 and a 52 week low of Rs. 4670.05 on 12-Jun-2026. Last one week high and low stood at Rs. 5625.00 and Rs. 5329.00 respectively. The promoters holding in the company stood at 45.66 per cent, while institutions and non-institutions held 40.61 per cent and 13.73 per cent respectively.
The e-auction conducted by the Government of Rajasthan resulted in the company being declared preferred bidder for the mining lease, and the allocation will enable the company to plan phased development of the deposit, subject to regulatory approvals. The Gilund block spans 370.96 hectares and its allocation is intended to support raw material security for the company’s cement operations in the region. The designation follows the government auction process and will allow the company to plan development and integration of the deposit into its supply chain.
The current market capitalisation stands at Rs. 430.38 billion (bn), reflecting market response to the mining news and prevailing valuation levels for the sector. Investors and analysts will watch for formal allotment and related disclosures that can clarify timelines, capital expenditure and expected production profiles. The report is intended for informational purposes and does not constitute investment advice, and market participants are advised to consult advisers before making decisions.
Star Cement has been declared the preferred bidder for the mining lease for Boro Lakhindong West Block following e-auctions conducted by the Government of Assam. The block is located in Boro Lakhindong Village, Umrangso Tehsil, Dima Hasao District, Assam, and extends over an area of 123 hectares. The estimated limestone resource is 207.822 million (mn) tonnes (t), a quantity that will supply raw material for cement production and support the company’s manufacturing operations in the region.
The company is engaged in the manufacturing and selling of cement clinker and cement and distributes products across the north-eastern and eastern states of India. Star Cement operates plants and logistics networks that procure and process limestone to produce clinker for cement, and the addition of Boro Lakhindong is presented as a strategic enhancement of feedstock availability. The preferred bidder status secures rights to the specified lease area under the terms of the auction process.
Financial results for the company in the fourth quarter of fiscal year 2026 showed a consolidated net profit rise of 20.24 per cent to Rs 1,481.0 mn on an 11.54 per cent increase in revenue to Rs 11,735.5 mn compared with the corresponding quarter of the previous year. Those results reflected higher sales volumes and revenue growth in the company’s primary markets and are cited in company disclosures accompanying the lease announcement. The reported performance provides context to the company’s ability to pursue and finance new mining lease opportunities.
Market reaction to the declaration was modest, with the scrip rising zero point thirty six per cent to trade at Rs 212 on the BSE. The award of the Boro Lakhindong lease concludes the e-auction process for the west block and assigns operational rights to Star Cement as the preferred bidder, subject to completion of statutory and contractual formalities.
