PREFACE: To conserve both resources and energy@ and to reduce CO2@ emissions@ the Canadian Centre for Mineral and Energy Technology (CANMET) of Natural Resources Canada@ Ottawa@ has played a significant role in Canada for over 35 years in research on fly ashes@ ferrous and nonferrous slags@ and silica fumes. In July-August 1983@ CANMET@ in association with the American Concrete Institute and the U.S. Corps of Engineers@ sponsored a five-day international conference at Montebello@ Quebec@ Canada@ on the Use of Fly Ash@ Silica Fume@ Slag and Other Mineral By-products in Concrete. The conference brought together representatives from industries@ universities@ and government agencies to present the latest information on these materials and to explore new areas of needed research. The two-volume proceedings of the conference containing 62 papers from 15 countries were published as ACI Special Publication SP-79.