Study of Durability of Concrete by Partial Replacement of Cement by Hypo Sludge and Fly Ash

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  • Topic: Cement, Concrete, Portland cement
  • Pages : 10 (2843 words )
  • Download(s) : 218
  • Published : December 12, 2012
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CHAPTER 01

INTRODUCTION

1.1 FLY ASH

India produces about 70 million tons of coal ash per year from burning about 200 million tons of coal per year for electric power generation. Coal-ash management posses a serious environmental problem for India and requires a mission-mode approach. Considerable research and development work have been undertaken across the country towards confidence building and developing suitable technologies for disposal and utilization of fly ash construction industries. At present about 10% ash is utilized in ash dyke construction and land filling (a technology developed and pioneered at IIT Kanpur) and only about 3% of ash is utilized in other construction industries. This is very much in contrast with 80% or more fly ash used in developed countries for the manufacture of bricks, cellular concrete blocks, road construction, land fill application, ceramics, agriculture, insulating bricks, recovery of metals and cenospheres and dam constructions. Currently, about one acre per MW of land is needed for ash disposal. Several pilot projects were undertaken in recent years to demonstrate the bulk utilization of fly ash specifically for Indian conditions. Also, it has been successfully demonstrated that fly ash can be utilized in major construction projects such as dams, ash dyke, landfills, roads and pavements, soil stabilization and for other purposes such as brick manufacture, cement industry, tiles, and paint industry. Realizing the large scale generation of fly ash, it’s very low utilization, the Government of India set up the fly ash Mission under the Department of Science & Technology at New Delhi for coordinating all such effort. A law has also been enacted in 1999 projecting 100 per cent utilization of fly ash within a stipulated period and making it mandatory to use flash for the purpose of road construction, bricks etc. within a radius of 50 km from coal based thermal power plants. In spite of an all-out effort, the fly ash utilization in the country is still very low. There are several factors responsible for this namely, lack of awareness and confidence, higher production cost, non availability of dry ash, and most important of all, easy availability of land with top soil at cheap rates. This film highlights some of the successful projects using fly ash across the country and is a humble attempt towards the confidence building exercise for fly ash utilization. Concrete is the most used material in construction. More than a tone of concrete is produced every year for each person in the planet, approximately six billion tones per year. Concrete is strong, inexpensive, versatile, and easy to make.

1.2 HYPO SLUDGE
Over 300 million tones of industrial wastes are being produced per annum by chemical and agricultural process in India. These materials pose problems of disposal and health hazards. The wastes like phosphogypsum, fluorogypsum and red mud contain obnoxious impurities which adversely affect the strength and other properties of building materials based on them. Out of several wastes being produced at present, the use of phosphogypsum, flurogypsum, lime sludge, hypo sludge, red mud, and mine tailing is of paramount significance to protect the environment. Paper making generally produces a large amount of solid waste. Paper fibers can be recycled only a limited number of times before they become too short or weak to make high quality paper.

It means that the broken, low- quality paper fibers are separated out to become waste sludge. All the inks, dyes, coatings, pigments, staples and “stickies” (tape, plastic films, etc.) are also washed off the recycled fibers to join the waste solids. The shiny finish on glossy magazine-type paper is produced using a fine kaolin clay coating, which also becomes solid waste during recycling.

This paper mill sludge consumes a large percentage of local...
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