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Position Statement #4 ASA Pool and Recreational Shotcrete Committee environmental conditions, or the inadequate selection of ingredients including poorly graded aggregates, soft or deleterious aggregates, expired cement, or contaminated water. In any case, compressive strength values less than 4000 psi (28 MPa) are, in most cases, the result of intentionally or unintentionally ignoring the rules of good practice7,8 and will result in pool shell shotcrete that is not as watertight. As with any other concrete structure, shotcrete pool shells must be properly designed—both from a structural and a concrete material perspective. Good quality shotcrete properly designed, manufactured, placed, and cured will produce the desired result—a durable and essentially watertight structure. Experienced pool builders pay attention to all the details of the shotcrete process and building pool shells with watertight shotcrete. Watertightness of shotcrete should be the expectation of all parties: the client, the designer, and the contractor. References 1. ACI Committee 506, “Guide to Shotcrete (ACI 506R),” American Concrete Institute, Farmington Hills, MI, 2005, 40 pp. 2. Bolduc, L. S., and Jolin, M., “Shotcrete Boiled Water Absorption,” Shotcrete, V. 12, No. 1, Winter 2010, pp. 12-17. 3. ACI CT-13, ACI Concrete Terminology, American Concrete Institute, Fig. 1: Table 4.2.2 of ACI 350-066 Farmington Hills, MI, 2013, http://www.concrete.org/portals/0/files/pdf/ ACI_Concrete_Terminology.pdf. w/cm and higher compressive strength provide better protection 4. ASA Pool & Recreational Shotcrete Committee, “Position Statement for embedded reinforcement in water containing structures. #2, Definitions of Key Shotcrete Terminology,”Shotcrete, V. 15, No. 3, Summer 2012, p. 29. Concrete technology and common sense show that watertightness 5. Ginouse, N., and Jolin, M., “Material Velocity at the Nozzle,”Shotcrete, will be improved using a concrete with a low w/cm with V. 15, No. 4, Fall 2013, pp. 22-24. sufficient paste content—that is, well-consolidated by the 6. ACI Committee 350, “Code Requirements for Environmental Engineer- placement techniques and properly cured and protected after ing Concrete Structures (ACI 350-06) and Commentary,” American Concrete placement—thus creating a dense impermeable concrete. Institute, Farmington Hills, MI, 2006, 487 pp. There are many reasons why a shotcrete placement would V. 3, No.1, Jan. 1981, pp. 80-93. Concrete International,7. Crom, T. R., “Dry-Mix Shotcrete Nozzling,” not achieve specified minimum compressive strength. These 8. CP-60, “Craftsman Workbook for ACI Certification of Shotcrete Nozzle- include poor workmanship, defective equipment, undesirable man,” American Concrete Institute, Farmington Hills, MI, 2009, 126 pp. Position Statements ASA has produced position statements on the best practices for proper shotcrete placement. To date, four position statements from our Pool & Recreational Shotcrete Committee and one from our Board of Direction have been issued. These statements have been previously published in Shotcrete magazine. Visithttp://www.shotcrete.org/pages/products-services/shotcrete-resources.htm. 70 Shotcrete • Winter 2015


2015WinterShotcreteEMag
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