Question

Use of fly-ash for the production of concrete in hot weather.?

Answer 1

Basically fly ash is by-product left from burning coal which is collected in electrical generating station or baghouse. Using of fly ash in concrete has many good results and also improves concrete performance in both the fresh and hardened condition.

Use of Fly Ash for concrete in hot weather -

• Increases Workability- Fly ash provides lubricant effect in the concrete thus increasing the workability of the concrete.
• Decreases water demand- Fly ash reduces water requirements by 2 to 10 percent .
• Setting time - Concrete will set slowly when fly ash is used.
• Early-age strength- Initially fly ash affects the strength of concrete so its better reducing fly ash content.
• Long-term strength - Decrease in water use leads to to gain strength over the period of time.
• Increases Pumpability - Fly ash tends to reduction in frictional losses while pumping concrete.
• Reduces heat of hydration- Replacing of cement with fly-ash in the concrete reduce the heat of hydration of concrete .
• Improves Placeability and Finishability - Fly ash allows concrete to move more fluidly which makes it easy for placing and finishing processes.
• Reduces permeability - The reduction in water use and development of additional cementitious compounds tends to decrease pore interconnectivity of concrete, thus reducing in permeability.
• Improves durability- Fly ash use increases in cementitious compounds with reduction in permeability ultimately resulting in improved durability.
• Decreases resistance to carbonation- Fly ash use in concrete reduces its resistance to carbonation.
• Improves sulfate resistance- Sulfate resistance is increased by use of F-class fly ash in concrete.

Summary- Basically fly ash is by-product left from burning coal which is collected in electrical generating station. Fly ash allows concrete to move more fluidly which makes it easy for placing and finishing processes.