Friedrich-Karl Ewert was born 1934 in Usedom (East Germany). From 1954 till 1956 he studied Geography at Humboldt-University, East Berlin, and then Geology at the University in Münster (Westphalia).For his fieldwork in the Pyrenees he obtained in 1964 a Doctorate in Geology. Until 1972 he worked as engineering geologist for hydro projects. In 1972 he became Professor of Geotechnics at the University of Paderborn from where he retired in 1997. From 1976 to 2002 he served as lecturer on dam foundation at the University of Technology, Delft, Netherlands.  While supervising permeability testing and grouting for dam sites he learned that the common rules disregarded essential rock properties. This initiated a lifelong yearning to better understand the permeability of rock and the development of optimal grouting procedures. He has been a strong promoter of investigating the properties of the rock at given sites, determining the geologically ruled individual  groutability and designing an appropriate grouting program.  In 1985 he published “Rock Grouting, with Emphasis in Dam Sites”, the first comprehensive monograph on this subject. Later on his numerous papers completed our knowledge on testing and grouting.  In 2011 the US Deep Foundation Institute  (DFI) and International Conference Organization for Grouting (ICOG) he was honored as "A Grouting Great” during the awards ceremony at the Fourth International Conference on Grouting and Deep Mixing held 2012 in New Orleans. Ulrich Hungsberg was born 1934 in Leipzig, Germany. From 1952 he studied Engineering Geology at the Mexican National University where he graduated as a Geological Engineer in 1958. From 1959 till 1960 he studied specialty courses in Engineering Geology at the University of Bonn, Germany. In 1960 he started working for the Mexican Government as a geological engineer at the Consulting Department of the Ministry ofHydraulic Resources and in 1969 he became Consulting Engineer in Geology and Hydrogeology of the same Consulting Department. From 2003 till 2013 he was Head of the Consulting Department at the Mexican National Water Commission and after that he retired. At present he is working in the same Consulting Department as Consulting Engineer. During his stay of 53 years at the Mexican Government he participated in the investigation, project-development, construction and maintenance of most of the dams built in Mexico in relation to their geological investigations and foundation treatments and was a member of the International Boundary and Water Commission between Mexico and the USA. Since 1986 he met Prof. Friedrich-Karl Ewert at a consulting job in Mexico, where they discovered that they had the same interests in foundation treatment through grouting. They collaborated in several dam projects and he invited Ing. Hungsberg as coauthor in the present book, joining their many years of experience in the field of Rock Grouting for Dams.