Fly Ash Improves Workability - Technical Bulletin

Blemishes in Concrete, Typically Called Rock Pockets, are indicative of concrete without suitable workability, even though the slump may be judged to be acceptable. Rock pockets indicate a separation of the paste from the coarse aggregate in the concrete mix. Concrete must be cohesive even at high slumps to maintain its homogeneous character and avoid segregation and costly rock pockets. Fly ash offers this feature without extra cost.