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Gypsum, the speed breaker

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Gypsum is the most essential ingredient of the finished cement. Though useful, handling of gypsum in a cement plant is not so easy since it is a hygroscopic material and very sticky in nature.

The terms cement and concrete are used interchangeably, although cement is actually an ingredient of concrete; gypsum is often added to cement to slow down the setting (hardens) time. Cement sets quickly and retarding that process allows workers to pour the mixture into the various forms or frames needed.

The majority of cement plants in Greece mainly use natural gypsum to prevent rapid cement setting. The partial or total replacement of gypsum by materials, which contain calcium sulphate, has been instigated by two facts. Firstly, the increasing availability of low-cost by-products containing calcium sulphate and secondly, the prospect of the gypsum quarries to mine, in the near future, a rock that is a mixture of gypsum and anhydrite.

FGD gypsum, a waste material of the desulphurisation process in coal burning power plants, to convert SO3 content of flue gases into gypsum, is an important alternative source of chemical gypsum. The experiments done with only FGD gypsum shows that the setting time was influenced by the percentages of FGD gypsum addition in the mortars tested. The initial and final setting time increased with increasing FGD gypsum ratio. The compressive strength also was affected by increase of FGD gypsum in the mortars. At all ages the compressive strength of the mortar with addition of FGD gypsum in combination with natural gypsum was higher that to other mixtures. The performances of cements prepared with mixtures FGD gypsum/natural gypsum were better compared with that prepared only with natural gypsum. At the same time, a hydration study of cements with FGD is presented. The addition of FGD gypsum increases setting time without affecting the compressive strength profile. The degree of dehydration of the dehydrated calcium sulphate regulates setting and strength performance of the cement partially replaced with either anhydrite or FGD gypsum.

In addition, gypsum will react with the tricalcium aluminate mineral (C3A), which is the compound mainly responsible for the early setting time of cement. The reaction of gypsum with (C3A) will retard the setting time of cement (i.e. prolong the setting time), which is necessary for concreting operations to be completed perfectly, if the amount of gypsum is small the setting time will be short, however, addition large amount of gypsum to the clinker during its grinding will delay the harden of the cement paste and producing a large amount of heat during the reaction and solidification of concrete. Therefore the amount of gypsum should be controlled to achieve the proper setting time and decreasing the percentage of SO3 in the concrete, and to avoid steel corrosion and concrete structure deformation.

While producing 53 grade of cement, generally cement plant prefers to use mineral gypsum. Today industry faces shortage of mineral gypsum, which is the purer form of gypsum and the gap is bridged by synthetic gypsum mainly coming from fertiliser industry. This gypsum is commonly known as chemical gypsum. Shreesh Khadilkar in his article has covered in details about various options available on sourcing gypsum. As stated by Shreesh, FGD gypsum from thermal plants can become alternate source in place of fertiliser gypsum but it is still at an experimental stage.

Handling of gypsum in a cement plant is not so easy since it is a hygroscopic material and very sticky in nature. The readers now will appreciate that though gypsum is essential ingredient of cement but proving to be a speed breaker.

VIKAS DAMLE

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Concrete

15th Cement EXPO to be held in March 2025 in Hyderabad

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Cement EXPO 2025, which will be held along with the 10th Indian Cement Review Conference and the 8th Indian Cement Review Awards, promises to be bigger, drawing in greater participation, fostering more profound discussions and showcasing the continued evolution of the cement industry.

Mumbai

After the arousing success of the 14th Cement EXPO, which was held on December 14-15, 2023 at Manekshaw Centre along the 9th Indian Cement Review Conference and the 7th Indian Cement Review Awards, the next edition of Cement EXPO will be hosted in March 2025 in Hyderabad. The 15th Cement EXPO promises to be bigger and even more impactful than 2023 edition with more participating companies and larger exhibition area. The 3-in-1 event is organised by FIRST Construction Council (an infrastructure think tank) and Indian Cement Review (ICR).

The 14th Cement EXPO received big thumps up from the industry with over 1,500 senior managers/decision makers visiting the expo. The EXPO was inaugurated by Dr Vibha Dhawan, Director General, TERI; and Ali Emir Adiguzel, Founder and Director, World Cement Association, along with Pratap Padode, Founder, FIRST Construction Council (FCC). Top notch companies from the Indian cement industry’s supply chain presented their latest innovations and offerings in the sprawling two-tiered exhibition space.

The 14th Cement EXPO garnered significant support from the Ministry of Road Transport and Highways, Government e-Marketplace (GeM), and the Department for Promotion of Industry and Internal Trade (DPIIT), Ministry of Commerce and Industry, Government of India (GoI).

The 7th Indian Cement Review Awards presented awards to 11 companies in different categories recognising their contribution to growth and innovation in the industry. While Parth Jindal (Managing Director of JSW Cement) was conferred with the Indian Cement Review – Person of the Year Award 2023, Vinita Singhania (Vice Chairman and Managing Director at JK Lakshmi Cement Ltd) was presented with the prestigious Lifetime Achievement Award.

With a theme centred on ‘Driving Sustainability Through Technology’, the 9th Indian Cement Review Conference hosted thought provoking discussions, panel sessions, and presentations, showcasing the industry’s commitment to embracing cutting-edge solutions.

The success and resonance of the 2023 edition has laid the groundwork for the 15th Cement EXPO 2025, which is bound to be bigger, drawing in greater participation, fostering more profound discussions and showcasing the continued evolution of the cement industry.

The EXPO, along with the 10th Indian Cement Review Conference and the 8th Indian Cement Review Awards, will contribute significantly to the ongoing transformation of the cement industry.

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Concrete

JK Lakshmi Cement records hike in profits

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JK Lakshmi Cement announced a significant increase in standalone net profit, which jumped by 69 per cent to Rs.124.06 Crores in the Oct-Dec 2023 quarter. The company achieved a 7 per cent increase in standalone net sales and reported a clinker capacity utilisation of 105 per cent and cement capacity utilisation of 79 per cent in the same quarter. The company attributed its improved profitability to higher volume, better product and sales mix, and a reduction in fuel costs.
In terms of sustainability initiatives, the company is implementing projects to enhance its TSR and WHR capacity, as well as sourcing solar power to increase the share of renewable energy at its Durg Cement Plant. Additionally, the company’s subsidiary, Udaipur Cement Works Ltd (UCWL), successfully commissioned its second clinker line and is expected to commission its cement grinding capacity expansion soon.
The company is also undertaking expansion projects, including increasing clinker capacity and establishing cement grinding units at various locations, with a proposed investment of Rs.2,500 crores. Funding for this project is proposed to be through term loans from banks and internal accruals. The company also announced an interim dividend of 40 per cent.

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Concrete

Rajasthan gets a water harvesting project

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Prince Pipes and Fittings Limited, in partnership with Ambuja Foundation, has launched a comprehensive water harvesting project in Chomu district of Rajasthan as part of its CSR initiative. The project aims to address water scarcity and enhance community resilience against water-related challenges. Ambuja Foundation will focus on setting up over 50 rooftop rain rainwater harvesting systems to provide a reliable source of water for 250 people. Additionally, efforts will be made to revive 2 village ponds, creating 10,000 cubic meters of water storage capacity, and to rejuvenate groundwater by implementing check dams, farm ponds and farm bunding. The project also includes educating the local community on water conservation techniques and promoting conscious water usage. This initiative seeks to support farmers through the government’s subsidies to install sprinkle irrigation systems at a minimal cost, while also contributing to livestock strengthening and promoting community ownership.

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