TO PREPARE THIS CHAPTER, THE CONTENTS OF THE 4^th edition were drawn on. The author acknowledges the authors of the prior three editions: ASTM STP 169 (1956) by Carl E. Wuerpel, U.S. Army Corps of Engineers, and ASTM STP 169A (1966), B (1978), and C (1983) by Paul Klieger, Consultant-Concrete and Concrete Materials. The current edition will review and update the topics addressed by the previous authors, and introduce new relevant technology with corresponding up-to-date references.