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cracking, use a fiber addition rate of approximately 1.5 lb/yd3 (0.89 kg/m3). b. In less-favorable ambient environmental conditions with higher evaporation rates (warm temperatures, lower relative humidity, and higher wind speeds), with a higher potential for early-age plastic and drying shrinkage cracking, use a fiber addition rate of approximately 3.0 lb/yd3 (1.78 kg/m3). c. In severe ambient environmental conditions (high temperatures and wind speeds and very low humidity) with a consequent high potential for early-age plastic shrinkage and drying-shrinkage-induced cracking, use a fiber addition rate of approximately 3.4 lb/yd3 (2.0 kg/m3), or even higher if necessary. For each of environmental conditions (a), (b), and (c), good shotcrete protection and curing practices, as detailed in ACI 506R-16, “Guide to Shotcrete,” should still be implemented. Acknowledgments The laboratory study and field evaluation of wet-mix shotcrete presented in this paper were sponsored by Canadian Greenfield Technologies Corporation of Calgary, AB, Canada. The processed natural hemp-based fiber used is manufactured by them and sold under the trade name NForce-Fiber. The shotcrete used in the laboratory study was batched and dry-bagged by Basalite Concrete Products Vancouver ULC and the wet-mix shotcrete production and testing was carried out at their Surrey, BC, Canada, plant. Shotcrete equipment and application was provided by Structural Shotcrete Ltd., Surrey, BC, Canada. The ACI Certified Shotcrete Nozzleman used to apply the shotcrete in the laboratory study was S. Ellis of Structural Shotcrete Ltd. The field and laboratory testing was conducted by LZhang Consulting & Testing Ltd., Vancouver, BC, Canada. The field evaluation of the NForce-Fiber in wet-mix shotcrete was carried out in the Jos. J. Albanese plant in Santa Clara, CA. Wet-mix shotcrete mixture designs and supply were by Central Concrete Supply Company, a division of U.S. Concrete Company. Shotcrete equipment and structural shotcrete walls construction were provided by Jos. J. Albanese. Laboratory testing was carried out by LZhang Consulting & Testing, Vancouver, BC, Canada. Overall project initiation and management was provided by D. R. Morgan of Victoria, BC, Canada. The support of the following individuals for this laboratory study and field evaluation project is gratefully acknowledged: M. Pildysh, Canadian Greenfield Technologies Corporation, Calgary, AB, Canada; D. Ceolin, Basalite Concrete Products Vancouver ULC, Surrey, BC, Canada; L. Rutt and S. Ellis, Structural Shotcrete Ltd., Surrey, BC, Canada; L. Zhang, LZhang Consulting & Testing Ltd., Vancouver, BC, Canada; C. Zynda, Jos. J. Albanese, Santa Clara, CA; and P. Frawley, Central Concrete Supply Company, San Jose, CA. Dudley R. (Rusty) Morgan, PhD, PEng, FACI, is a Civil Engineer with over 50 years of experience in the concrete and shotcrete industries. He was a member and Secretary of ACI Committee 506, Shotcreting, for over 25 years. He is a past member of ACI Committees 365, Service Life Prediction, and 544, Fiber-Reinforced Concrete. Morgan is a founding member and Past President of ASA. He is an ACI C660-approved Shotcrete Nozzleman Examiner and presenter for the ASA Shotcrete Nozzleman Education course. Morgan is a past member of the Canadian Standards Association Concrete Steering Committee and was Canadian Representative on the International Tunneling Association Committee: Shotcrete Use. He has worked on over a thousand concrete and shotcrete projects around the world during his consulting career and has edited five books and published over 150 papers on various aspects of concrete and shotcrete technology. In 2001, Morgan was elected as a Fellow of the Canadian Academy of Engineering. Lihe (John) Zhang, PhD, PEng, is an Engineer and Owner of LZhang Consulting & Testing Ltd. He received his PhD in civil engineering from the University of British Columbia, where he conducted research on fiber-reinforced concrete. He has over 15 years of experience in concrete and shotcrete technology and the evaluation and rehabilitation of infrastructure. Zhang is a member of the American Concrete Institute. He is Chair of ACI Subcommittee 506-F, Shotcreting-Underground, and a member of ACI Committees 130, Sustainability of Concrete; 506, Shotcreting; and 544, Fiber-Reinforced Concrete. He is an ACI C660-approved Shotcrete Nozzleman Examiner and presenter for the ASA Shotcrete Nozzleman Education course. Zhang is a member of ASTM Committee C09, Concrete and Concrete Aggregates, is an ASA Officer and Board Member, and chairs the ASA Technical Committee. Mike Pildysh, MEng, PEng, is President of Canadian Greenfield Technologies Corporation. He is a civil engineer with over 35 years of experience in the building materials industry. He was, for a time, Head Civil Engineer for Monenco Engineering, which was then the second largest engineering company in Canada. He subsequently founded and operated a group of companies, including the very successful Cementec Industries Inc., which supplies specialty construction materials to the civil engineering and oil industries. Pildysh is a licensed professional engineer in Alberta, British Columbia, and Ontario. He has authored 12 patents and has over 20 publications. He is a former member of the United States Research Technology Board. Pildysh is a member of ASA, the American Concrete Institute, the American Chemical Society, and the Chemical Institute of Canada. www.shotcrete.org Spring 2017 | Shotcrete 45


2017SpringShotcreteEMag
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