UTILIZATION OF FLY ASH IN CEMENT AND ALLIED INDUSTRIES

In the early years of thermal energy, coal fired power plants used to dispose-off entire fly ash in slurry form to ash dykes or otherwise, fly ash’s utilization avenues were not available. A few years back development of fly ash’s utilization technologies lead to strict regulations on managing coal-combustion waste to combat pollution and to maximise the applications of fly ash.

Today fly ash is used in so many industrial and commercial applications that it has become a complete industry by itself.

1. BRICK MAKING

Interestingly, a number of technologies are in vogue to manufacture good quality fly ashes bricks.  These are fly ashes-lime-gypsum, fly ash-cement, fly ash mineralization, fly ashes geopolymerization and fly ash-clay bricks, etc.  All types of fly ash bricks except fly ash-clay bricks, do away with kiln firing as well as requirement of clay. Today, India produces over 20 billion fly ash bricks per annum.

One of the best qualities of fly ashes are that it has insulation capability. Since it requires much less heat and energy to manufacture than clay bricks, fly ash bricks are energy-efficient as well as eco friendly. Fly ashes bricks come in several load-bearing grades, and to encourage and ensure consistency of quality, BIS has formulated standards and specifications for all types of fly ashes bricks. According to their official statement, “The standards lay down essential requirements of finish, dimensions, strength, water absorption, etc. in addition to quality of raw materials to be used with a view to achieve quality and uniformity in the manufacture of such bricks.”

2. CEMENT

Fly ashes are a pozzolanic material, it contains silicates & aluminates in amorphous form  and behaves like cement when combined with lime and water. Partial replacement of cement with fly ashes are not only a more viable prospect commercially, it also saves on naturals resources, reduces CO2 emissions and ensures longer durability.

3. ROADS AND EMBANKMENTS

If fly ash cement is used in construction of concrete roads, it reduces the permeability of concrete and also keeps the aggressive expansive minerals from damaging the concrete from the inside. Also, since fly ash is lighter than traditional soils, it causes lesser settlements. It is particularly relevant in stabilization projects and embankments over weak sub-soils.  Further, it exerts lesser pressure on the retaining walls.

4. MINE BACKFILLING

When areas are mined and exhausted, backfilling is required to reclaim that land, otherwise such vast tracts of land will be rendered useless. Since mines require deep or shallow excavation, they leave behind numerous hollows and shafts. If these gaps are not filled in properly, they may open large sinkholes or elongated fractures or other deformations in the future. To avoid such calamities that could possibly affect human lives, it is important to fill the mines with a material that has the ability to fill tight spaces, has a high resistance to water permeation or compression, and is eco-friendly.

Fly ashes has all these qualities and lends itself beautifully as a filler for Mine Void Filling.

5. FLY ASH COAGULANT

Water pollution is one of the biggest ecological concerns today. If on one hand we encourage rapid industrialization, which results in greater production, and therefore more effluents and pollutants, then we must also have measures to manage these wastes so that we are able to reduce our carbon footprint and protect our environment.

Fly ashes has proved useful in Wastewater Treatment, where modified or activated fly ashes traps and adsorbs various types of organic compounds. Textiles, Handmade paper, Tanning & Dyeing etc. are all industries that can benefit from using Fly ash in significantly reducing their contribution towards wastewater.

Indian economy has seen an enormous economic growth in terms of infrastructure development and manufacturing. Given the amount of natural resources that will be used in either creating this infrastructure or in the services provided by them, it is very important that environment-friendly, cost-effective options be considered very seriously. The Fly Ashes handling system industry has received a lot of impetus from the government, but if more and more people are educated about its benefits and enough attention is directed to its positive ecological impact, we are pretty sure that fly ashes will see a lot of research and technological innovation in the coming years.