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2016SummerShotcreteEMag

Pool & Recreational Shotcrete Corner Shotcrete Pool Inspection— Checklist By Chris Zynda Swimming pools have been around for over 100 years, and the water-containing pool shells have been built in many different ways, including fiberglass, concrete block, vinyllined, and concrete. We must remember that a swimming pool is a large investment and, like any structure, needs a good foundation and quality construction to last for the decades intended. Shotcrete (wet- and dry-mix process) is the most common method for placing the concrete in swimming pool floors, coves, and walls. Quality shotcrete placement creates the foundation for a lifetime concrete shell. The first step in shotcrete pool construction is to understand the two processes— wet-mix and dry-mix—used in shotcrete placement. After a specific process has been selected for the project, the owner or the engineer or designer responsible for qualifying the contractor and their field performance should put together an evaluation checklist as shown below. Preconstruction 1. Pool contractor: years of experience with overall pool construction. 2. Past shotcrete pool projects of similar size and scope. 3. Shotcrete contractor experience: years of experience and projects of similar size and scope. Fig. 1: A pool wall installed with wet-mix shotcrete before the pool floor has been placed. As a result, the pool floor is now contaminated with the rebound and cuttings from the shotcrete operation. This sloppy material sitting on the floor has not been vibrated or consolidated and must be considered as waste material and removed. Leaving this material in place would weaken the pool structure and significantly reduce the long-term durability of the pool shell. Unfortunately, incorporation of rebound and cuttings in the pool shell is the cause in 95% of swimming pool failures Fig. 2: The shotcrete (wet-mix process) floor being installed first Fig. 3: Another pool floor being placed first with a concrete boom pump and the placement crew vibrating the concrete and screeding to the desired height. Installing the floor before the walls helps to guarantee no cuttings or rebound will be used in the structure. Also, note that a board is used at the edge of the floor to create a consistent joint. This allowed the joint to be prepped with water blast at 0.25 in. (6.35 mm) roughness before shotcreting the wall 26 Shotcrete • Summer 2016


2016SummerShotcreteEMag
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