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Sustainability the wall. Piping was also being installed into the floor area along with the floor drain pipes. This made pre-wetting the walls prior to shoot- ing and water curing the newly placed shot- crete a problem for other site work. The exposed soil in front of the wall would hold the water, leaving a muddy mess and making it impass- able for equipment and crews until it was drained or replaced. Even with all the challenges and delays faced by Coastal on this wet-mix shotcrete project, they managed to gain back most of the excess time used by the pile drilling company and the QC issues. Overall, about 4 months of schedule time were recovered along with significant cost savings by using shotcrete instead of cast-in- Fig. 8: Tight working conditions Coastal had to work in daily to allow place concrete construction. other trades to work. The wall waterproofing and reinforcing bar In conclusion, logistics, schedule time, and installation had to stop due to the dirt ramp that was in the way. Spraying costs played key roles in the selection of the wet- water on the walls made a muddy mess and had to be dug out, replaced, mix shotcrete process over conventional cast-in- and compacted before any equipment could be driven over it place construction. You may also want to check out many previous articles in Shotcrete maga- zine’s archives (http://shotcrete.org/pages/ (a) archive-search/archive-search.asp) on sustain- ability. Before selecting your contractor, make sure they are a qualified shotcrete contractor who has an experienced qualified crew with ACI Cer- tified Nozzleman. References American Shotcrete Association, 2014, “Shotcrete = Sustainability,” Shotcrete, V. 16, No. 1, Winter, pp. 56-57. Hanskat, C.S., 2010, “Sustainability of Shotcrete an Overview,” Shotcrete, V. 12, No. 2, Fall, pp. 9-12. Morgan, D.R., and Totten, L., 2008, “Guide Specifications for Structural Walls,” Shotcrete, V. 10, No. 1, Winter, pp. 18-27. Schallom, R., and Ballou, M., 2003, “What You Need to Know about Wet-Mix Shotcrete,” Shotcrete, V. 5, No. 1, Winter, pp. 22-27. U.S. Green Concrete Council, 2011, “Complex Shapes Fig. 9(a) and (b): Finished wall with the floor waterproofing being Require Very Little—If Any—Formwork,” Shotcrete, V. 13, installed, and the same wall after it was finished No. 4, Fall, pp. 48-49. U.S. Green Concrete Council, 2011, “Formwork Savings (b) of 50 to 100% over Conventional Cast-in-Place Construction,” Shotcrete, V. 13, No. 2, Spring, pp. 46-47. U.S. Green Concrete Council, 2012, “New Construction Speed Savings of 33 to 50%,” Shotcrete, V. 14, No. 3, Summer, pp. 48-50. U.S. Green Concrete Council, 2012, “Crane and Other Equipment Savings or Elimination,” Shotcrete, V. 14, No. 4, Winter, pp. 56-57. Zhang, L., 2010, “Is Shotcrete Sustainable?” Shotcrete, V. 13, No. 4, Fall, pp. 20-26. Acknowledgments The authors wish to acknowledge the contributions of Curt White to this article. Pictures by George Yoggy and Ray Schallom. 40 Shotcrete • Summer 2015


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