• Strain gauges are recommended, and the use of telltales is deemed helpful in test shafts and demonstration shafts, and when sufficient indicative movement at the top of production shafts might not manifest. • The contractor needs flexibility with the water/cement ratio to achieve the desired improvement from post-grouting. • Changes in water/cement ratio must be recorded during construction. • Minimum grout volume must be a net volume that considers the grout volume required to fill the grout delivery system. Acknowledgements The workshop was sponsored by the FHWA Office of Infrastructure. Deep Foundations Institute recognizes the valuable efforts of Silas C. Nichols, P.E., Benjamin S. Rivers, P.E., and Sarah Skeen from FHWA who guided the organization and execution of the workshop and provided detailed review and critique of the workshop report. We appreciate the contributions of Tom Shantz, P.E., G.E., from Caltrans who partnered with FHWA in organization and execution. ADSC provided a financial contribution to the workshop, and its support and participation in the workshop activities are valued. The conscientious input from Antonio Marinucci, Ph.D., P.E., (consultant) and Sarah Skeen who assisted in recording notes during the presentations and discussions was vital to the accuracy of the report. The presenters and attendees openly and constructively shared their broad knowledge and extensive experience in quality assurance of post- grouted drilled shafts to make this workshop successful. Their commitment of time and resources are gratefully acknowledged. References Fleming, W.G.K. (1993). “The Improvement of Pile Performance by Base Grouting”; Proceedings of Institution of Civil Engineers, London, 1993, 97, May, 88-93, paper 3078. Marinucci, A and S. Nichols (2016) “Optimized Drilled Shaft Design through Post-Grouting: Shorten That Shaft for Better Performance.” Geostrata Issue 3, Pg. 38-42. Muchard, M. (2015). “United States State of Practice for Post- Grouting Methods,” Presentation at Workshop on Quality Assurance of Post-Grouted Drilled Shafts, Deep Foundations Institute, Oakland, October 15-16. Mullins, G., Dapp, S., Fredrick, E., and Wagner, V. Post-Grouting Drilled Shaft Tips: Phase I Research Report; Florida Department of Transportation, December 2001. Mullins, G. and Winters, D. Post-Grouting Drilled Shaft Tips: Phase II Research Report; Florida Department of Transportation, June 2004. The report can be downloaded at http://www.dfi.org/ publications.asp?goto=1018#P1018 90 • DEEP FOUNDATIONS • SEPT/OCT 2016
