With reference to ‘fly ash’ produced by the power plants using coal as fuel, which of the following statements is/are correct?
- Fly ash can be used in the production of bricks for building construction.
- Fly ash can be used as a replacement for some of the Portland cement contents of concrete.
- Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements.
Select the correct answer using the code given below.
[UPSC Civil Services Exam – 2015 Prelims]
(a) 1 and 2
(b) 2 only
(c) 1 and 3
(d) 3 only
Answer: (a)
Explanation:
- Fly ash is the residual substance that results from the combustion of pulverized coal and is carried away from the combustion chamber by exhaust gases.
- This by-product is generated primarily by coal-fired electric and steam generating plants.
- Furthermore, fly ash finds numerous uses each year in a wide range of engineering applications, such as soil and road base stabilization, grouts, structural fill, and asphalt filler.
- Additionally, fly ash is utilized in the production of Portland cement, embankments, flowable fills, geopolymers, roller compacted concrete, bricks, metal matrix composites, waste treatment and stabilization, and catalysts.
- Fly ash consists primarily of oxides of silicon, aluminum iron and calcium. Magnesium, potassium, sodium, titanium, and sulfur are also present to a lesser degree.
- Environmental benefits
- Incorporating fly ash into the production of concrete can enhance its durability, thereby prolonging the lifespan of concrete roads and structures.
- Additionally, the use of fly ash in place of manufactured cement results in a net reduction of energy usage and greenhouse gas emissions, as well as other air pollutants.
