Economy & Market
Benefits of gypsum capping
Published
4 years agoon
By
admin
Taiwan Capstone, the sole promoter of the new gypsum capping method, demonstrates to ICR how the technology works and why is it better than conventional methods.
The most important property of concrete for an engineer is its compressive strength. But are you testing for it in the right way? Several factors influence the measurement process. The flatness of the surface, its horizontal level does have a huge impact on the measurement outcome. To ensure that such anomalies are ruled out, conventionally the concrete specimen block is ground to get a flat surface. This method however, has several shortcomings and which can be overcome with the new gypsum capping method.
Capping is the process of leveling the ends of cylindrical concrete specimens to ensure that the test cylinder or core has smooth, parallel, uniform bearing surfaces that are perpendicular to the applied axial load during compressive strength testing. This is done to ensure that the specific criteria for flatness and perpendicularity of the ends are in accordance with the applicable standards specified.
Importance of capping
ASTM C39 requires that the ends of compressive test specimens be plane to within 0.002 inch (0.05 mm) and that the deviation of end faces from being perpendicular to the specimen axis is less than 0.5° (0.12 inch in 12 inches or 1 mm in 100 mm). Similar requirements are stated in ASTM C42 for testing cores. Irregular end surfaces or when the specimen axis is not perpendicular to the end-faces will cause stress concentrations within the test specimen and reduce the measured strength. Since the end-faces of most test specimens will not meet these requirements, procedures in ASTM C617 or C1231 for capping hardened concrete cylinders are used. This ensures that the compressive load is applied evenly and consistently for every strength test.
Capping process
ASTM C617 is the standard practice for capping cylindrical concrete specimen. Cores should be cut or ground to meet the end condition requirements or they may be capped in accordance with ASTM C617. Unbonded caps are currently not permitted when testing cores but may be permitted in the future. ASTM C617 permits a bonded cap to be applied to freshly molded cylinders using high strength gypsum plaster or sulfur mortar are permitted as bonded capping materials for hardened concrete cylinders.
Comparison
There are two ways to get the ends of the concrete specimen flat and horizontal. One is grinding the concrete surface and other is using capping material. Let’s review each one.
Grinding
Grinding is a very common and standard surface treatment method but the user must spend huge capital for the machine and also has to do periodic maintenance to ensure that ground surface remains evenly flat.
Capping material
There are three capping materials, which are qualified for this as per the IS 516 standard.
- Neat cement.
- Sulphur.
- Hard plaster.
Those are also qualified in the ASTM C617 standard.
Neat cement capping
Mix the cement with water in the desired water-cement ratio. A two to four hour additional waiting time is required before it can be pasted on the concrete surface. The waiting period is important as the mixed pastes tend to bleed, shrink and make unacceptable caps.
Sulphur capping
Sulphur capping requires a heater for melting the capping material first. It also generates toxic gas and bad odour in the process. Sulphur capping needs two hours of hardening time before testing. For concrete strengths of 350 kg/cm2 or greater, sulphur caps must be allowed to harden for at least 16 hrs before use. Besides, sulphur caps cannot be reused.
Hard plaster capping
The strength of the plaster material is a critical property for its use as capping material. Ordinary plaster of Paris will not serve the purpose of the capping material due to its low compressive strength. Taiwan Capstone manufactures extraordinary high strength gypsum for use as capping material in concrete compression strength testing. Generally, the common gypsum hardens to with stand 1000 psi more or less. However, our products in the Capstone series can reach 5,000-9,000 psi (350-630 kgf/cm2), 30 minutes after mixing with water. It is fast, more efficient, highly reproducible, health friendly to the user, easy to stock, no costly apparatus needed and follows IS 516 Indian Standard and ASTM C617 regulation. There is another material which is also used in the concrete compressive strength test. It is Neoprene pad capping. The major advantage is the convenience. But often the test results are not completely reliable. The users have to prepare different types of caps for variety of concrete specimen.
Gypsum capping vs grinding
The two methods can be compared on the basis of following characteristics:
- Surface flatness.
- Pressure uniformity.
- Sample applicability.
Surface flatness Gypsum
Gypsum shows better flatness after capping. The complete smooth surface is an outcome of the flowing gypsum slurry and the thick glass plate placed on it while the gypsum sets. After covered by the glass, the gypsum surface will become flat just like the glass surface on top of it.
Grinding
Grinding merely reveals the surface beneath the top with all its imperfections. In this process the concrete surface is treated by the grinding knife. It is difficult to get a completely smooth surface. Without the periodic maintenance, the knife frequently gets damaged and eventually leads to uneven concrete surface.
Pressure uniformity
Here, a pressure-sensitive paper is used to check the surface smoothness. As you can see from the diagram, there is a significant difference between the flatness of gypsum capped and ground surface.
Comparison of capping materials
If we compare gypsum capping, sulphur capping and the neoprene pad, it becomes obvious that gypsum has several advantages over the other two. It provides the best pressure uniformity and data accuracy. That is clear from the comparison chart below.
As the data shows, gypsum capping renders the surface extremely smooth and also makes it perfectly horizontal. Therefore, it can reach the highest compressive strength value and retain stable data at any time. From the operational point of view, gypsum only needs water for the reaction. It provides a safe working process and also increases the efficiency of the sample preparation. Sulfur has characteristics similar to those of gypsum for capping applications, but it takes a very long time to harden, with very bad odours and toxic gases let out during the process.
Neoprene pads have lower compressive strength and a higher SD value since they are often not perfectly horizontal. Furthermore, neoprene pads show higher and higher variation as the pads get reused. It is a convenient but inaccurate capping material.
Capstone compressive test data
Established in 1981, Taiwan Capstone is based in Taiwan and is the sole supplier of high strength gypsum for capping in the country. Sulfur capping is prohibited for safety reasons and rubber is banned by the market for the unstable performance.
They started their international business in April 2013 and since then, have expanded the market with competent local agent partners in India, Thailand, Singapore, Indonesia, USA, Mexico, Columbia, Canada and Israel. Now they are looking for more partners worldwide, to grow further. High-strength gypsum is absolutely the revolutionary capping material, especially considering its environment friendliness.
For more information, contact: Shailesh Chauhan Tel: 00-91-9377458606, E-mail: shailesh@itlneels.com Website: www.twcapstone.com
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SEEPEX introduces BN pumps with Smart Joint Access (SJA) to improve efficiency, reliability, and inspection speed in demanding rock blasting operations.
Designed for abrasive and chemical media, the solution supports precise dosing, reduced downtime, and enhanced operational safety.
SEEPEX has introduced BN pumps with Smart Joint Access (SJA), engineered for the reliable and precise transfer of abrasive, corrosive, and chemical media in mining and construction. Designed for rock blasting, the pump features a large inspection opening for quick joint checks, a compact footprint for mobile or skid-mounted installations, and flexible drive and material options for consistent performance and uptime.

“Operators can inspect joints quickly and rely on precise pumping of shear-sensitive and abrasive emulsions,” said Magalie Levray, Global Business Development Manager Mining at SEEPEX. “This is particularly critical in rock blasting, where every borehole counts for productivity.” Industry Context
Rock blasting is essential for extracting hard rock and shaping safe excavation profiles in mining and construction. Accurate and consistent loading of explosive emulsions ensures controlled fragmentation, protects personnel, and maximizes productivity. Even minor deviations in pumping can cause delays or reduce product quality. BN pumps with SJA support routine maintenance and pre-operation checks by allowing fast verification of joint integrity, enabling more efficient operations.
Always Inspection Ready
Smart Joint Access is designed for inspection-friendly operations. The large inspection opening in the suction housing provides direct access to both joints, enabling rapid pre-operation checks while maintaining high operational reliability. Technicians can assess joint condition quickly, supporting continuous, reliable operation.
Key Features
- Compact Footprint: Fits truck-mounted mobile units, skid-mounted systems, and factory installations.
- Flexible Drive Options: Compact hydraulic drive or electric drive configurations.
- Hydraulic Efficiency: Low-displacement design reduces oil requirements and supports low total cost of ownership.
- Equal Wall Stator Design: Ensures high-pressure performance in a compact footprint.
- Material Flexibility: Stainless steel or steel housings, chrome-plated rotors, and stators in NBR, EPDM, or FKM.
Operators benefit from shorter inspection cycles, reliable dosing, seamless integration, and fast delivery through framework agreements, helping to maintain uptime in critical rock blasting processes.
Applications – Optimized for Rock Blasting
BN pumps with SJA are designed for mining, tunneling, quarrying, civil works, dam construction, and other sectors requiring precise handling of abrasive or chemical media. They provide robust performance while enabling fast, reliable inspection and maintenance.With SJA, operators can quickly access both joints without disassembly, ensuring emulsions are transferred accurately and consistently. This reduces downtime, preserves product integrity, and supports uniform dosing across multiple bore holes.
With the Smart Joint Access inspection opening, operators can quickly access and assess the condition of both joints without disassembly, enabling immediate verification of pump readiness prior to blast hole loading. This allows operators to confirm that emulsions are transferred accurately and consistently, protecting personnel, minimizing product degradation, and maintaining uniform dosing across multiple bore holes.
The combination of equal wall stator design, compact integration, flexible drives, and progressive cavity pump technology ensures continuous, reliable operation even in space-limited, high-pressure environments.
From Inspection to Operation
A leading explosives provider implemented BN pumps with SJA in open pit and underground operations. By replacing legacy pumps, inspection cycles were significantly shortened, allowing crews to complete pre-operation checks and return mobile units to productive work faster. Direct joint access through SJA enabled immediate verification, consistent emulsion dosing, and reduced downtime caused by joint-related deviations.
“The inspection opening gives immediate confidence that each joint is secure before proceeding to bore holes,” said a site technician. “It allows us to act quickly, keeping blasting schedules on track.”
Framework agreements ensured rapid pump supply and minimal downtime, supporting multi-site operations across continents
Concrete
Digital process control is transforming grinding
Published
3 weeks agoon
February 20, 2026By
admin
Satish Maheshwari, Chief Manufacturing Officer, Shree Cement, delves into how digital intelligence is transforming cement grinding into a predictive, stable, and energy-efficient operation.
Grinding sits at the heart of cement manufacturing, accounting for the largest share of electrical energy consumption. In this interview, Satish Maheshwari, Chief Manufacturing Officer, Shree Cement, explains how advanced grinding technologies, data-driven optimisation and process intelligence are transforming mill performance, reducing power consumption and supporting the industry’s decarbonisation goals.
How has the grinding process evolved in Indian cement plants to meet rising efficiency and sustainability expectations?
Over the past decade, Indian cement plants have seen a clear evolution in grinding technology, moving from conventional open-circuit ball mills to high-efficiency closed-circuit systems, Roller Press–Ball Mill combinations and Vertical Roller Mills (VRMs). This shift has been supported by advances in separator design, improved wear-resistant materials, and the growing use of digital process automation. As a result, grinding units today operate as highly controlled manufacturing systems where real-time data, process intelligence and efficient separation work together to deliver stable and predictable performance.
From a sustainability perspective, these developments directly reduce specific power consumption, improve equipment reliability and lower the carbon footprint per tonne of cement produced.
How critical is grinding optimisation in reducing specific power consumption across ball mills and VRMs?
Grinding is the largest consumer of electrical energy in a cement plant, which makes optimisation one of the most effective levers for improving energy efficiency. In ball mill systems, optimisation through correct media selection, charge design, diaphragm configuration, ventilation management and separator tuning can typically deliver power savings of 5 per cent to 8 per cent. In VRMs, fine-tuning airflow balance, grinding pressure, nozzle ring settings, and circulating load can unlock energy reductions in the range of 8 per cent to 12 per cent. Across both systems, sustained operation under stable conditions is critical. Consistency in mill loading and operating parameters improves quality control, reduces wear, and enables long-term energy efficiency, making stability a key operational KPI.
What challenges arise in maintaining consistent cement quality when using alternative raw materials and blended compositions?
The increased use of alternative raw materials and supplementary cementitious materials (SCM) introduces variability in chemistry, moisture, hardness, and loss on ignition. This variability makes it more challenging to maintain consistent fineness, particle size distribution, throughput and downstream performance parameters such as setting time, strength development and workability.
As clinker substitution levels rise, grinding precision becomes increasingly important. Even small improvements in consistency enable higher SCM utilisation without compromising cement performance.
Addressing these challenges requires stronger feed homogenisation, real-time quality monitoring and dynamic adjustment of grinding parameters so that output quality remains stable despite changing input characteristics.
How is digital process control changing the way grinding performance is optimised?
Digital process control is transforming grinding from an operator-dependent activity into a predictive, model-driven operation. Technologies such as online particle size and residue analysers, AI-based optimisation platforms, digital twins for VRMs and Roller Press systems, and advanced process control solutions are redefining how performance is managed.
At the same time, workforce roles are evolving. Operators are increasingly focused on interpreting data trends through digital dashboards and responding proactively rather than relying on manual interventions. Together, these tools improve mill stability, enable faster response to disturbances, maintain consistent fineness, and reduce specific energy consumption while minimising manual effort.
How do you see grinding technologies supporting the industry’s low-clinker and decarbonisation goals?
Modern grinding technologies are central to the industry’s decarbonisation efforts. They enable higher incorporation of SCMs such as fly ash, slag, and limestone, improve particle fineness and reactivity, and reduce overall power consumption. Efficient grinding makes it possible to maintain consistent cement quality at lower clinker factors. Every improvement in energy intensity and particle engineering directly contributes to lower CO2 emissions.
As India moves toward low-carbon construction, precision grinding will remain a foundational capability for delivering sustainable, high-performance cement aligned with national and global climate objectives.
How much potential does grinding optimisation hold for immediate energy
and cost savings?
The potential for near-term savings is substantial. Without major capital investment, most plants can achieve 5 per cent to 15 per cent power reduction through measures such as improving separator efficiency, optimising ventilation, refining media grading, and fine-tuning operating parameters.
With continued capacity expansion across India, advanced optimisation tools will help ensure that productivity gains are not matched by proportional increases in energy demand. Given current power costs, this translates into direct and measurable financial benefits, making grinding optimisation one of the fastest-payback operational initiatives available to cement manufacturers today.
Concrete
Refractory demands in our kiln have changed
Published
3 weeks agoon
February 20, 2026By
admin
Radha Singh, Senior Manager (P&Q), Shree Digvijay Cement, points out why performance, predictability and life-cycle value now matter more than routine replacement in cement kilns.
As Indian cement plants push for higher throughput, increased alternative fuel usage and tighter shutdown cycles, refractory performance in kilns and pyro-processing systems is under growing pressure. In this interview, Radha Singh, Senior Manager (P&Q), Shree Digvijay Cement, shares how refractory demands have evolved on the ground and how smarter digital monitoring is improving kiln stability, uptime and clinker quality.
How have refractory demands changed in your kiln and pyro-processing line over the last five years?
Over the last five years, refractory demands in our kiln and pyro line have changed. Earlier, the focus was mostly on standard grades and routine shutdown-based replacement. But now, because of higher production loads, more alternative fuels and raw materials (AFR) usage and greater temperature variation, the expectation from refractory has increased.
In our own case, the current kiln refractory has already completed around 1.5 years, which itself shows how much more we now rely on materials that can handle thermal shock, alkali attack and coating fluctuations. We have moved towards more stable, high-performance linings so that we don’t have to enter the kiln frequently for repairs.
Overall, the shift has been from just ‘installation and run’ to selecting refractories that give longer life, better coating behaviour and more predictable performance under tougher operating conditions.
What are the biggest refractory challenges in the preheater, calciner and cooler zones?
• Preheater: Coating instability, chloride/sulphur cycles and brick erosion.
• Calciner: AFR firing, thermal shock and alkali infiltration.
• Cooler: Severe abrasion, red-river formation and mechanical stress on linings.
Overall, the biggest challenge is maintaining lining stability under highly variable operating conditions.
How do you evaluate and select refractory partners for long-term performance?
In real plant conditions, we don’t select a refractory partner just by looking at price. First, we see their past performance in similar kilns and whether their material has actually survived our operating conditions. We also check how strong their technical support is during shutdowns, because installation quality matters as much as the material itself.
Another key point is how quickly they respond during breakdowns or hot spots. A good partner should be available on short notice. We also look at their failure analysis capability, whether they can explain why a lining failed and suggest improvements.
On top of this, we review the life they delivered in the last few campaigns, their supply reliability and their willingness to offer plant-specific custom solutions instead of generic grades. Only a partner who supports us throughout the life cycle, which includes selection, installation, monitoring and post-failure analysis, fits our long-term requirement.
Can you share a recent example where better refractory selection improved uptime or clinker quality?
Recently, we upgraded to a high-abrasion basic brick at the kiln outlet. Earlier we had frequent chipping and coating loss. With the new lining, thermal stability improved and the coating became much more stable. As a result, our shutdown interval increased and clinker quality remained more consistent. It had a direct impact on our uptime.
How is increased AFR use affecting refractory behaviour?
Increased AFR use is definitely putting more stress on the refractory. The biggest issue we see daily is the rise in chlorine, alkalis and volatiles, which directly attack the lining, especially in the calciner and kiln inlet. AFR firing is also not as stable as conventional fuel, so we face frequent temperature fluctuations, which cause more thermal shock and small cracks in the lining.
Another real problem is coating instability. Some days the coating builds too fast, other days it suddenly drops, and both conditions impact refractory life. We also notice more dust circulation and buildup inside the calciner whenever the AFR mix changes, which again increases erosion.
Because of these practical issues, we have started relying more on alkali-resistant, low-porosity and better thermal shock–resistant materials to handle the additional stress coming from AFR.
What role does digital monitoring or thermal profiling play in your refractory strategy?
Digital tools like kiln shell scanners, IR imaging and thermal profiling help us detect weakening areas much earlier. This reduces unplanned shutdowns, helps identify hotspots accurately and allows us to replace only the critical sections. Overall, our maintenance has shifted from reactive to predictive, improving lining life significantly.
How do you balance cost, durability and installation speed during refractory shutdowns?
We focus on three points:
• Material quality that suits our thermal profile and chemistry.
• Installation speed, in fast turnarounds, we prefer monolithic.
• Life-cycle cost—the cheapest material is not the most economical. We look at durability, future downtime and total cost of ownership.
This balance ensures reliable performance without unnecessary expenditure.
What refractory or pyro-processing innovations could transform Indian cement operations?
Some promising developments include:
• High-performance, low-porosity and nano-bonded refractories
• Precast modular linings to drastically reduce shutdown time
• AI-driven kiln thermal analytics
• Advanced coating management solutions
• More AFR-compatible refractory mixes
These innovations can significantly improve kiln stability, efficiency and maintenance planning across the industry.
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