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Bhaumik A.K.,Indian School of Mines | Gupta A.K.,Indian Institute of Technology Kharagpur | Gupta A.K.,Wadia Institute of Himalayan Geology | Clemens S.C.,Brown University | Mazumder R.,National Council for Cement and Building Materials
Current Science | Year: 2014

Morphometric study of Melonis barleeanum and Hoeglundina elegans was carried out on 15 core top samples from the Indian Ocean. Length to breadth ratios and wall and septal thicknesses of the largest tests of both the species from each sample, along with δ13C and δ18O values of Cibicides wuellerstorfi were measured. Both the species show equal growth rates of the test in their normal habitat. However, the high organic carbon preference species M. barleeanum shows more elongation of the test during food scarcity. This effect is not evident in H. elegans, which varies in its wall and septal thicknesses with bottom-water oxygen levels of the deep water mass up to 2000 m, probably to maintain the required rate of osmosis for the intake of dissolved O2. Below this depth both parameters show parallel relationship with deviation indicating that oxygenation may play some role in the variation of wall and septal thicknesses. Thinning or thickening of the wall and septa in M. barleeanum and H. elegans has no relation with the water depth, indicating no relation with either the overlying pressure effect or nutrients as each deep water mass has a different nutrient budget. Depletion in δ13C and enrichment in δ18O below 2000 m water depth suggests that up to 2000 m depth, the Indian Ocean is bathed by the welloxygenated, low-nutrient North Atlantic Deep Water (NADW), whereas below 3000 m cold, nutrient-rich Antarctic Bottom Water (AABW) is dominant. Between 2000 and 3000 m water depths, the water mass in the Indian Ocean is a mixture of NADW and AABW.


Bohra A.,National Council for Cement and Building Materials | Nema A.K.,Indian Institute of Technology Delhi | Ahluwalia P.,Tata Consultancy Services Ltd.
International Journal of Environmental Technology and Management | Year: 2012

Municipal solid waste in developing nations like India is an area of major concern. The concerns associated with waste management are not only public health and safety but also for sustainable development. Life cycle assessment (LCA) can be applied to assess the environmental sustainability of waste management systems. In the present study, global warming potential of various municipal waste management options was evaluated using LCA. The model was applied for a case study of Delhi (India). From the results of the study, it was found that the scenario of maximum diversion from sanitary landfill results in least impact to global warming. © 2012 Inderscience Enterprises Ltd.


Ali M.M.,National Council for Cement and Building Materials | Agarwal S.K.,National Council for Cement and Building Materials | Pahuja A.,National Council for Cement and Building Materials
Advances in Cement Research | Year: 2013

The addition of copper oxide in cement raw mix is known to improve its burnability, with increase in formation of the alite phase. Copper slag, a by-product of the metallurgical industry, containing copper oxide can therefore be a useful additive in the manufacture of cement, particularly for hard burning raw mixes. This paper presents a study on the effect of addition of 1.5-2.5% of a typical by-product copper slag sample to cement raw mixes prepared from two different limestone samples, with free silica content of 5.52 and 10.97% and average grain sizes of 124 and 175 μm. The clinker parameters such as limestone saturation factor, silica modulus and alumina modulus were in the ranges 0.91-0.92, 2.11-2.29 and 1.0-1.20, respectively. The fineness values of the raw mixes were 3.50-4.20 and 20.80-21.34% retained on 212 and 90 μm sieves, respectively. Burnability studies of these raw mixes were conducted at temperatures of 1300, 1350, 1400 and 14508C, with retention time of 20 min, and showed increase in the rate of lime assimilation, acceleration in the formation and growth of C3S and lowering in clinkerisation temperature by 508C. The free silica was found to be completely assimilated at 14008C in mixes containing copper slag. The mineral phase developments and microstructures of laboratory clinker samples fired at 1400 6 58C were comparable to control clinker prepared at 1450 6 58C. Physical properties of ordinary Portland cement prepared using this clinker showed performance comparable with control cement. The copper slag contains heavy elements, therefore a leaching study was also conducted by immersing hardened cement pastes in distilled water for 6 months. The leachates, such as barium, copper and chromium, were found to be 0.032, 0.005 and 0.031 ppm, indicating fixation of these elements in the clinker mineral phases.


Ali M.M.,National Council for Cement and Building Materials | Chaturvedi S.K.,National Council for Cement and Building Materials | Sharma P.S.,National Council for Cement and Building Materials
Cement International | Year: 2011

In the last decade, global needs and concerns in the areas of energy, GHG emissions, conserving natural resources and preserving the environment have resulted in application oriented developments in the field of cement, silicates and other cementing materials. In this pursuit, besides conventionally used fly ash and granulated blast furnace slags, various other industrial wastes and by products such as spent pot linings, non ferrous slags, refinery wastes, etc. have been investigated and have shown potential for beneficial use. Fly ash have been also investigated for use in sintered light weight aggregates and concrete, cement/silicate bonded fly ash/clay fly ash building bricks, precast fly ash concrete building units, cellular concrete, bricks and blocks, lime and cement fly ash concrete, structural fill for roads, construction sites, land reclamation etc., as a filler in mines, as a filler in bituminous concrete and manufacture of insulating and semi-insulating bricks, as a plastisizer and a pumping aid, as a water reducer in concrete, sulphate resisting concrete and as a filler in paints and pigments. While fly ash can find usage in many other areas as well, the use in PPC and in concrete still remain the biggest user segment of fly ash with the PPC production level reaching to ∼100 million tonnes during 2009-10 amounting to more than 62 percent of total cement production in India. Diversifications in the use of raw materials, fuel, industrial wastes and basic research findings to conserve energy in cement manufacture and generate special properties have resulted in development of jet set fluoroaluminate, expansive, oil well, alkaline, dental, nuclear and photo chromic cements. These developments were based on modifications or additions in the chemistry of Portland Cement. In the field of nuclear research, the shielding of radiation and fixation of disposal wastes need cements and development of barium aluminate and other products was quite a success. Further, the production of Portland limestone cement (PLC) is described as a fast and economical technical solution for cement industry around the world. Geo polymer cement is another area of importance as it provides the opportunity for both waste beneficiation/valorisation and immobilization, while providing an alternative to a highly polluting existing technology. The future of R&D in the area of cement and building materials will revolve around development of cost effective, consumer friendly and high performance materials based on Nano-Technology. This is one area which needs systematic and through investigations and shall generate benefits of exponential order.


Chaturvedi S.K.,National Council for Cement and Building Materials | Yadav D.,National Council for Cement and Building Materials | Chatterjee V.P.,National Council for Cement and Building Materials | Pahuja A.,National Council for Cement and Building Materials
Cement International | Year: 2015

In India, the estimated generation of fly ash was of the order of 190 million tonnes in 2010/11, expected to reach 450 million tonnes by 2020/21, and 900 million tonnes by 2031/32, thus posing serious disposal and ecological problems in addition to occupying large tracts of scarce valuable land. Despite the development of a large number of technologies for utilization of fly ash, its estimated use remains around 100 million tonnes only. Major problems in the utilization of fly ash relate to its availability in the wet state, quality variation and high capital and operational cost of storage, handling and transportation systems. The paper highlights the availability and physical, chemical and mineralogical characteristics of fly ash, its activation and research and the development work carried out worldwide for promoting its use. Further, improvement in fly ash quality through processing by mechanical chemical and thermal routes will play an important role in enhancing the fly ash utilization potential, engineering properties of fly ash-based cement, concrete and building materials besides mitigation of global warming. The results of mechanical activation by grinding of storage mix non-conforming fly ash indicated improvement in its quality in terms of lime reactivity, fineness, glass content, etc.


Agarwal S.K.,National Council for Cement and Building Materials | Pahuja A.,National Council for Cement and Building Materials | Ali M.M.,National Council for Cement and Building Materials | Singh B.K.,ZINC Inc | Duggal S.,ZINC Inc
Advances in Cement Research | Year: 2015

The presence of mineral phases bearing iron, sulfur, sodium, potassium and zinc in jarosite, a residual by-product of the zinc industry, showed its suitability for use as a mineraliser in the development of clinker mineral phases. Different cement raw mixes RM-1 to RM-5, prepared by incorporating 0.5-1.75 wt% jarosite, maintaining clinker parameters LSF: 0.92, SM: 2.14-2.22, AM: 1.09-1.13, potential phases C3S: 57.73-58.84, C2S: 17.37-17.97, C3A: 5.57-6.00 and C4AF: 14.06-14.42 and fired at temperatures of 1300, 1350, 1400 and 1450°C showed the mineralising effect of jarosite in terms of rapid lime assimilation and improved clinker mineral phase formation as compared to a control mix prepared without using jarosite. The optimum clinkerisation temperature was reduced by, 50°C. The physical characteristics of the cement sample (OPC-4) prepared with 1.5 wt% optimised dose of jarosite showed a 18-25% increase in compressive strength development at early ages as compared to the control cement. As jarosite contains heavy elements such as barium, cobalt, copper, lead, manganese, strontium, zinc and so on, a leaching study was taken up by immersing 28-d hardened neat cement cubes in aggressive mediums such as sulfate, chloride and alkaline solutions along with lean water over a period of 24 months. The leachates contents were found to be in negligible amounts, indicating fixation of heavy elements in clinker mineral phases.


Gupta R.S.,National Council for Cement and Building Materials | Vanguri S.,National Council for Cement and Building Materials | Liju V.,National Council for Cement and Building Materials | Ali M.M.,National Council for Cement and Building Materials | Pahuja A.,National Council for Cement and Building Materials
Cement International | Year: 2014

The article reports on the properties of geopolymeric cements prepared by alkali activation of low lime fly ash at two different Blaine fineness levels using a concentrated solution of sodium hydroxide as an activating agent and subjected to different initial thermal curing conditions. The Na2O concentration was kept the same in all the samples. However, the H2O content varied to maintain the workability in the same range in all the mixes. In the case of unprocessed fly ash based samples, the initial temperature curing was carried out at 90 °C and 60 °C for different retention periods by introducing the samples into the oven at ambient temperature and then raising the temperature to the targetted level of thermal curing. It was observed that the gain in compressive strength was rapid in specimens thermally cured at 90 °C. The time given to achieve the 90° C curing temperature was also found to influence the compressive strength development. The slow heating condition ie. relatively longer time to achieve the temperature resulted in better strength gain in the specimens. However, the specimens cured at 90 °C were found to be cracked in drying shrinkage and showed dimensional stability when the curing temperature was kept at 60 °C up to the certain retention time. Keeping in view this behavior, investigations were carried out on samples of processed fly ash having relatively higher fineness by alkali activation and curing at 60 °C for different retention periods. The study showed that the fineness of fly ash and curing conditions affected the formation of geopolymers, microstructure and morphology developments to achieve strength development and dimensional stability.


Ali M.M.,National Council for Cement and Building Materials | Singh B.K.,National Council for Cement and Building Materials | Agarwal S.K.,National Council for Cement and Building Materials | Duggal S.,National Council for Cement and Building Materials | Pahuja A.,National Council for Cement and Building Materials
Advances in Cement Research | Year: 2014

Jarosite, a residual by-product generated by the zinc industry during the hydrometallurgical process, contains predominantly Fe2O3, SO3 and alkalis with a small amount of ZnO. These constituents are known to contribute significantly in the formation of clinker mineral phases and, therefore, the jarosite could be an effective mineraliser and activator in the manufacture of ordinary Portland cement (OPC) clinker. This paper highlights the effect of the addition of 0.5-2.0% of typical jarosite in cement raw mixes prepared with different grade limestone samples along with other conventional raw materials. The clinker parameters such as LSF, SM and AM were maintained in the range of 0.92, 2.07-2.18 and 1.01-1.14 respectively. Burnability studies conducted at temperatures of 1300, 1350, 1400 and 14508C with a retention time of 20 min showed an increase in the rate of lime assimilation and rapid formation of clinker mineral phases. The mineral phase developments and microstructures of laboratory clinkers fired at 1400 6 58C were found to be adequate in the presence of the optimum dose of 1.5% jarosite and were comparable to the control clinker (without jarosite addition) prepared at 1450 6 58C. The physical performance of the OPC sample thus prepared from the above mineralised clinker showed performance comparable to the control cement. As the jarosite contained heavy elements, a leaching study was carried out by immersing 28 d hardened neat cement cubes in 500 ml distilled water over a period of 24 months in air-tight containers. Leachates such as barium, cadmium, cobalt, chromium, copper, manganese, zinc, lead and strontium were found to be in negligible amounts.


Harsh S.,National Council for Cement and Building Materials | Arora A.K.,National Council for Cement and Building Materials | Thomas V.,National Council for Cement and Building Materials | Ali M.M.,National Council for Cement and Building Materials
Cement International | Year: 2014

The effect of nanosilica on OPC hydration was investigated using differential thermal analysis, thermogravimetry and Fourier-transform infrared spectroscopy. Pastes of OPC and OPC blends containing 3 and 5 mass % nanosilica, were prepared using a w/c ratio of 0.4. Nanosilica of average particle size of 15 nm was used in these investigations. The pastes were hydrated for 1, 3, 7 and 28 d in sealed plastic vials. Hydration was stopped at the required age by opening the vial and washing the ground paste with acetone. The dried hydrated powdered samples were investigated for their mineralogy and hydration products using the above-mentioned instrumental methods. The DTA and TG curves of the samples were recorded from ambient to 950 to 1 000. The total weight loss as well as the weight loss corresponding to Ca(OH)2 decomposition were computed from these curves. The results indicated that the total weight loss of the hydrated samples containing nanosilica, especially at early ages, was higher compared to the total weight loss of corresponding hydrated OPC samples. The DTA/TG studies thus indicated the acceleratory effect of nanosilica on early cement hydration reactions. The results further indicated that though the total weight loss of hydrated OPC-nanosilica samples was higher, the weight loss corresponding to Ca(OH)2 decomposition was lower in these samples compared to the weight loss from Ca(OH)2 decomposition in hydrated OPC samples. These results indicated pozzolanic reaction of nanosilica even at early age of 1 d as well as at later ages. FTIR investigations supported the conclusions drawn from the DTA/TG investigations. OPC and OPC nanosilica blends were also tested for setting time and compressive strength. Samples containing nanosilica exhibited significantly shorter initial setting times. The initial setting time of blends containing 3 and 5 mass % nanosilica was reduced by 50 and 83 % respectively, compared to initial setting time of the control OPC. The reduction in the final setting time of these blends was in the range of 7 to 44 %. Use of 3 to 5 mass % nanosilica in the OPC blends resulted in an increase of 10 to 49 % in compressive strength at ages of 1 to 28 d.


Pahuja A.,National Council for Cement and Building Materials | Ali M.M.,National Council for Cement and Building Materials
Cement International | Year: 2013

In recent decades the global needs and concerns in the areas of energy, GHG emissions, conservation of natural resources and preservation of the environment have resulted in application-oriented developments in the fields of cement, concrete and other cementitious materials. The National Council for Cement and Building Materials (NCB), which guides the affairs of the Indian Cement and Construction industries, is uniquely positioned to provide technological improvement and technical support services, sustainable development and growth for the industries. Some of the noteworthy research work where the NCB has made great progress includes clinker formation under the influence of fluxes, modifiers and mineralizers, increased utilization of fly ash in PPC by mechanical, chemical and thermal activation, exploration of the potential for utilization of low grade limestone and non-conventional slags from zinc, copper and other industries in cement, increased use of alternative and waste-derived fuels, increased energy efficiency by de-bottlenecking process lines, life cycle studies, etc. The other important services rendered are development of standard reference materials, test methods and building codes along with pioneering technologies such as geopolymers, composite cements, the application of nano technology in cement and concrete, and high performance concrete. The advances achieved in the cement and concrete sectors would not have been possible without the improvement in the quality of human resources carried out by the NCB through its dedicated and tailor-made training modules. These have been made possible through the availability of multi-disciplinary expertise at the NCB, coupled with world class testing and evaluation facilities at its Ballabgarh, Hyderabad and Ahmedabad units. The achievements of the various NCB centres are described below.

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