Jeff Groom, PE, is the Senior Principal Engineer for CTL Thompson, Inc. Formerly Jeff was Mariana Islands Regional Office Manager for GHD Inc., an international consulting engineering firm based in Guam. He has managed the design portion of design-build contracts for federal projects for San Juan Construction. With over 25 years of experience, Jeff specializes in concrete consulting and quality control testing of construction materials including concrete, aggregates, mortar, grout, and masonry units. His experiences include concrete mix proportioning (normal weight, lightweight, heavy weight and roller compacted concrete) for horizontal and vertical construction applications. Frequent speaker, published author, and expert witness, Jeff has consulted around the world on projects involving concrete damage and construction defects. He is an active member of American Concrete institute, American Society of Civil Engineers and ASTM Committee C9 on Concrete Aggregates. Jeff received B.S. and M.S. degrees in Civil Engineering from the University of Wyoming and is a registered Professional Engineer in Colorado, Wyoming and Guam.