Page 43

2014WinShotcreteEMag

Fig. 8: Completed shotcrete structure undergoing 28-day wet cure to achieve high strengths of 6000 to 7000 psi (40 to 48 MPa) detail work and achievement of key tolerances matching the existing house foundation stone was throughout the installation was critical. Following used as coping and veneer material (Fig. 9). Select the 3-day shoot, the pool was water-cured and Pennsylvania bluestone made up all treads and tank-tested to ensure not only strength gain but caps. Glass tile covered the weir wall and the also water-tightness (Fig. 8). After a 28-day wet vanishing edge (Fig. 10), while Vermont slate tile cure, tests revealed strength values between 6000 was placed at the water line. Finally, a standard and 7000 psi (40 and 48 MPa). gray plaster finish was applied to the interior of For Bill Drakeley, an expert in concrete materials all three shells, allowing for maximum sharp and application who specializes in the shotcrete reflection at the water’s surface (Fig. 11). process, the significance of the use of shotcrete in The pool was filled, all systems started up, and the Donovan project cannot be overstated. With the the project was turned over to a smiling client. limited space for maneuvering at the cliff side, the flexibility of the concrete installation was para- A Final Anecdote mount. Given that all formwork, steel, and concrete Before ground was even broken, the project installations were basically out of the ground and faced significant obstacles. Given the unprec- extended outward over an edge, the shotcrete pro- edented nature of the proposed installation, the cess allowed Drakeley Pool Company to complete town building department was understandably this installation in the exact spot that the owner skeptical regarding the ultimate reliability of designated without any derivation from the original the structure. The idea that the pool could be vision. Using other concrete installation types for installed without some type of eventual flexural the shells of the spa, pool, and surge trough would movement or differential settlement was con- have greatly increased both difficulty and cost. sidered unlikely at best. It was believed that Drakeley further notes that, despite the flexibility of some type of exceptional storm may have concrete placement through the shotcrete process, adverse effects on the project, implying legal compressive values and overall structural strength repercussions for those involved in approving were not compromised in the least. “With shotcrete,” the plans. he notes, “you don’t sacrifice performance just To keep the wheels of the painstaking con- because of difficult or challenging site conditions.” struction process moving according to the client’s needs, Drakeley pressed on, hopeful that the Phase 4: Masonry and Start-Up quality of the installation would speak for itself, In homage to the natural features of the sur- resulting in ultimate approval and a new precedent rounding New England topography, native stone set for both the town and surrounding contractors. Shotcrete • Winter 2014 41


2014WinShotcreteEMag
To see the actual publication please follow the link above