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Editors : Prof. S.V. RAMASWAMY & Er. I.V. ANIRUDHAN |
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From the Editor’s Desk.. Flyash as AdmixtureBased on the inputs from Prof. S Chandrakaran, NIT, Calicut Effective use of soil - flyash mixtures in which flyash is used as an admixture is yet to be done in large scale. There are still apprehensions about using the material as the base material because of its lightweight and relatively low shear strength characteristics. However specification for constructing embankments using flyash as a base material published elsewhere in this newsletter will be of help in increasing the use of soil-fly ash mixtures in such constructions. Studies by Virendra Singh, and others, presented at Baroda during IGC-97 indicated that there was a significant improvement in CBR and unconfined compression strength of fine alluvial silty soil by the addition of 10 to 15% fly ash. The resulting mixture can be used as sub-base material in road construction. However a greater percentage of flyash resulted in a considerable reduction in these properties. Hence fly ash consumption in these constructions is likely to be marginal compared to the production. Studies by Chandrakaran using fly as an admixture to lateritic soil presents a different picture. Generally lateritic soil is considered a good construction material, except for pure lateritic clays or silts. Chandrakaran reports that there is progressive ‘degradation’ of the base material, lateritic soil, with the addition of more and more fly ash. There is an increase in plasticity of the lateritic soil due to addition of fly ash and flocculation is cited as the cause of this phenomenon. Increase in plasticity characteristics and flocculation will improve the quality of laterite as a lining material. On the other hand the coefficient of permeability marginally increases with the addition of fly ash, thus reducing the effectiveness of laterite - fly ash mixture as a liner. There is also a notable reduction in shear strength with the addition of fly ash. Similar behaviour is reported with respect to the CBR values. All these findings on lateritic soil - fly ash mixture in different proportion point to very limited utility of fly ash where lateritic soil is available as base material. When we approach the results in the other direction in which the lateritic soil is acting as an admixture, 50 to 60% (by total weight) addition of laterite into the fly ash can improve the quality of fly ash as a construction material where shear strength requirements are not very critical. The major field where replacement of 50 to 60% laterite with fly ash can prove advantageous is in the lining of canals and ponds. Use of lateritic clay in the construction of lining with fly ash as a one to one admixture can be successful. ¤ Prof. S. Chandrakaran, NIT Calicut,’Ground improvement by Lime and Flyash Column Method’, Short Term Course on Gorund Improvement, IIT Madras, December 2003. Felicitation of Founders & Past Chairmen of IGSCC IGS, Chennai Chapter organized a pleasant function on October 15, 2003 to felicitate the eminent geotechnical engineers who had successfully started the chapter and diligently nurtured its growth. The persons honoured were felicitated and presented with a memento. The persons honoured and the felicitators were, Dr.V.V.S.Rao (Er.V.Balakumar), Prof. A.Sargunan (Er.M.Elangovan), Prof. S.V.Ramaswamy (Dr.K.Premalatha), Dr. Varghese Chummar, (Er. K. Rajamani), Er. Shankar Guha (Prof. S.R. Gandhi), Dr. B.Ramanathan (Er.V.Balakumar) and Prof. M.R.Pranesh (Prof.K.Ilamparuthi). The mementoes were presented by Er. G.Sivaprakasam, Team Constructions. Prof. K.Ilamparuthi presided over the function and Er. I.V.Anirudhan proposed a vote of thanks. ¤
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809 Murugesan V. 810 Rajkumar R. 811 Dodgoudar 812 Baddam Shyamala 813 Ramana Chandaka 814 Vijaya Lakshmi Rayapati 815 Darga Kumar N 816 Sangeetha M 817 Sudhakar Sunkura 819 Muthiah C
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Geotechnical Calendar GEOSUPPORT – 2004, Geo-Institute of ASCE and ADSC: The International Association of Foundation Drilling, Orlando, Florida, USA, January 28 – 31, 2004 First CUSST Conference on Recent Advances in Civil Engineering, Civil Engineering Division, School of Engineering, Cochin University of Science and Technology, Cochin, March 25 – 27, 2004. Asian Regional Conference on Geosynthetics (GEOASIA 2004), South Korea, June 21 – 23, 2004. National Symposium on Advances in Geotechnical Engineering (NSAGE 2004), Karnataka Geotechnical Centre, Department of Civil Engineering, Indian Institute of Science, Bangalore, July 22 - 23, 2004 Joint Speciality Conference on Probabilistic Mechanics and Structural Reliability, Sandia National Laboratories, Albuquerque, New Mexico, July 26 – 28, 2004. The Seventh International Conference on the Application of Stresswave Theory to Piles –Malaysia – August 8-10, 2004 sec@iem.po.my International Conference on Site Characterisation, Lisbon, Portugal, Sept. 20 – 22, 2004 Indian Geotechnical Conference – 2004, Ground Engineering – Emerging Techniques, Indian Geotechnical Societies, Warangal and Kakinada Chapters, Dec. 17 – 19, 2004. Indian Geotechnical Conference – 2005, Indian Geotechnical Society, Ahmedabad Chapter, Ahmedabad, December 2005. |
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