Fly ash can be an expensive replacement for Portland cement in concrete although using it improves strength, segregation, and ease of pumping concrete. The rate of substitution typically specified is 1 to 1 ½ pounds of fly ash to 1 pound of cement. Nonetheless, the amount of fine aggregate should be reduced to accommodate fly ash additional ...
tures. Currently, fly ash is used in more than 50% of all ready mixed concrete placed in the United States, yet many design professionals continue to remain overly restrictive when it comes to using fly ash in concrete. Th is article addresses some optimal ways of specifying ﬂ y ash for use in concrete while
Utilizing fly ash in concrete and other products not only eliminates the need to dispose of fly ash in landfills but also conserves our natural resources by substituting for materials that would typically be mined. In addition, the beneficial use of CCPs can meet Leadership in Energy and Environmental Design (LEED) program requirements.
Fly ash has been used in roadways and interstate highways since the early 1950s. In 1974, the Federal Highway Administration encouraged the use of fly ash in concrete pavement with Notice N 5080.4, which urged states to allow partial substitution of fly ash for cement whenever feasible. In addition, in January 1983, the
Fly ash is a byproduct from coal-fired power plants that is frequently used as an admixture in concrete to replace a portion of the Portland cement. Using fly ash in concrete is environmentally beneficial because it reduces the Portland cement (a major contributor of CO2) required in concrete.
Conserves water because fly ash uses very little compared with traditional cement. Besides concrete, fly ash is also used in composite materials, such as in aluminum metal alloys for lightweight auto parts and synthetic lumber for outdoor decks and fences.