Concrete is one of most common materials used in the construction industry. However, there is growing concern over the environmental effects of manufacturing Portland cement. Fly ash and slag have become two viable replacement options, as they benefit the concrete and decrease environmental effects. A survey was sent to prestressed manufacturers asking about their current usage of fly ash and slag as Portland cement replacements. Analysis of the type of coal burned and subsequent class of fly ash produced in relation to location of companies using specific classes showed no correlation, indicating the relative ease to acquire either class anywhere in the United States. As expected, the number of respondents claiming use of slag was lower. Every company using slag also used fly ash. Replacement percentages were reported as high as 50%, while typical release strengths were similar to fly ash at 4,000 psi (27.6 MPa), though 25% reported strengths exceeding 6,000 psi (41.4 MPa). Analysis of steel mill locations to location of users showed that the use of slag occurred only in proximity to a mill. Those not using slag reported cost and low availability as primary deterrents.
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