The author would like to thank the Virtual Cement and Concrete Testing Laboratory (VCCTL) consortium for partially funding this research, OMYA Inc. for supplying the limestone powder, Dr. Josephine Cheung of W.R. Grace & Co.- Conn. for assistance with the powder classification and for supplying the water-reducing admixture, Dr. Claus-Jochen Haecker of the Wilhelm Dyckerhoff Institut for obtaining the measured PSDs presented in this study, Mr. John Winpigler of BFRL for assistance with the mortar specimens, and Dr. Paul Tennis for a careful review of the manuscript.