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2016SummerShotcreteEMag

Shotcrete Panels for Evaluation and Testing Shotcrete panels come in a variety of sizes and shapes, and with differing purposes. I will discuss the three most common types: • Preconstruction; • Mockup; and • Production. Preconstruction Test Panels Preconstruction test panels are used to qualify the shotcrete nozzleman, crew, equipment, and material. It takes a complete, experienced team for a successful concrete project using shotcrete placement. The preconstruction panel should represent the most difficult-to-shoot part of the proposed project. This will often be the sections with the most congested reinforcing, large or irregular shaped block-outs or embeds, or a complicated geometry. I suggest doing a shop drawing for all preconstruction test panels. The shop drawing would include plan size and depth of the panel along with the layout of all the reinforcing and embeds to be included (refer to Fig. 1). The test panel shown in Fig. 2 was designed for qualifying two nozzlemen, one on the left and one on the right. The reinforcement layout has By Chris Zynda three curtains of reinforcing with vertical No. 11 (No. 36M) bars with staggered couplers; the boundary elements have No. 5 (No. 16M) stirrups spaced at 6 in. (150 mm). The test panel section was 24 in. (600 mm) thick. The minimum crew to prepare this representative panel required a nozzleman, an air lance tender, a hose tender, and a concrete pump operator. Note in the picture, the nozzleman (on the right) is shooting the face of the panel with an air lance tender (on the left). With this heavily congested section and with large reinforcing bars, an experienced, qualified contractor is a must for a quality job. Note in Fig. 3, the plywood at the top of panel was placed to represent the beam that will be shot against in the structural section. You should also note there is no sag of the shotcrete below the beam. The reinforcing bars sticking out represent the dowels that will be coming out of the existing building after the epoxy-set dowels are installed. Typical preconstruction panels will have three cores taken for evaluation of encasement and consolidation, while three additional cores are taken for evaluation of compressive strength. Fig. 1: Section drawings of a heavily reinforced wall 10 Shotcrete • Summer 2016


2016SummerShotcreteEMag
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