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2017SpringShotcreteEMag

East Side Access Project By Frank E. Townsend III In May 2014, Superior Gunite was issued a subcontract by the Michels Corporation to shoot approximately 2000 yd3 (1500 m3) of shotcrete for overbreak build back on the arches of the East Side Access Project—CM005 Manhattan South Structures. This initial subcontract for the build back of the over-excavation of rock was required to achieve a 1:10 smoothness ratio for the application of the polyvinyl chloride (PVC) waterproofing membrane. As the project continued into 2015, the Michels Corporation and New York Metropolitan Transportation Authority (MTA) management further recognized the advantage that Superior Gunite provided to the scope of the CM005 Project and added 5000 yd3 (3800 m3) of structural shotcrete in the arch sections. The use of shotcrete in additional structural concrete portions of the project not only aided the overall production schedule but also added flexibility to place concrete in areas where expensive individual custom forms would be required for each placement. BUILD BACK AND SMOOTHENING As construction continued in the early stages, it was realized that several areas of the project not only required a smoothening course to bring the substrate to a 1:10 smoothness ratio but also were found to have overbreak of up to 18 in. (450 mm) beyond A-line in the arch sections and beyond 18 in. (450 mm) in areas with intersecting geometries. In some of these areas of heavy overbreak, reinforcement dowels in conjunction with steelreinforced fiber shotcrete (SRFS) was needed to support the depth of material being applied on the substrate. Fig. 1: Upper-level arch section of three-level structure TT#1. Overbreak reinforcement dowels and grade control wires Fig. 2: Waterproofing membrane installed after build back and smoothing has been completed in the upper-level arch of TT#1 structure Fig. 3: Tunnel section arch reinforcing bar upper-level arch of TT#1 structure Fig. 4: Tunnel and cross-passage intersection arch reinforcing bar upper-level arch of TT#1 structure 12 Shotcrete | Spring 2017 www.shotcrete.org


2017SpringShotcreteEMag
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