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2013SumShotcreteEMag

Pool & Recreational Shotcrete Corner Formwork does not have to be designed for high concrete strengths. Not only is the high-strength shotcrete durable but it is also watertight with good impact resistance, internal pressures which enables it to withstand accidental loadings that could As mentioned previously, fresh shotcrete is self-supporting compromise the structure. Shotcrete inherently has superior and does not flow like cast-in-place concrete. Thus, the shot- bonding of the concrete to a properly prepared substrate. The crete process has little to no lateral pressure on the form from high velocity at which the material is placed ensures that the fluid pressure. This is true regardless of shooting a pool wall, open pores or crevices of the receiving substrate will have spa, bench, or radius connection between the floor and vertical cement paste driven into and covering the surface area. Addi- wall. The only pressure on the exterior form during the shooting tionally, shotcrete’s impact velocity on the receiving surface process is the momentary impact pressure from the shotcrete acts as a natural surface roughener that further enhances placed at high velocity by air volume. bond. Combined, these effects ensure proper bond and makes Complex shapes require very little— if any—formwork The pool industry—particularly, when using the shotcrete process—epitomizes this statement. Free-form shapes, van- ishing-edge perimeters, raised spa elevations, skateboard parks, and any monolithic nonplanar concrete structure envisioned by the designer eliminates the need for complex forming through using shotcrete (refer to Fig. 3 and 4). Labor savings of at least 50% in repair applications Typically, while repairing an older pool with deteriorated or spalled concrete, the poor material is removed to expose a reusable, hard, quality concrete surface where renovation materials can be placed (otherwise, the whole pool is removed). In this type of renovation, the expediency and rapidity of placing the repair material through the shotcrete process is much more cost-effective than forming and pouring a cast-in- place repair. Using shotcrete, there are labor savings in elimi- Fig. 3: Overview of a pool with extensive curves typifying nating form placement and stripping, the need for a bonding shotcrete’s flexibility agent, and placing and consolidating cast concrete. New construction speed savings of 33 to 50% The overall time of installation and implicit costs associated with the speed of installing a concrete pool shell using the shotcrete process versus using cast-in-place methods is sig- nificant. Quite simply, it takes 33 to 50% less time to build the same size pool structure with shotcrete compared to cast-in- place methods. Excavation, forming, reinforcing steel work, and concrete placement need less time to complete because of the one-sided forming aspect and use of the surrounding earth as part of the support structure, as well as requiring less labor force to complete each phase. Better bonding to the substrate enhances durability Concrete placement through the shotcrete process is the Fig. 4: Using shotcrete makes curved concrete pool ideal way to place concrete, and when done properly, will yield surfaces easy Shotcrete • Summer 2013 57


2013SumShotcreteEMag
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