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2013SprShotcreteEMag

Committee Chair Memo ASA Pool & Recreational Shotcrete Committee By William T. Drakeley Jr. In 2011, the Pool & Recreational Shotcrete benefits owners, the foreman, and others involved with the Committee of ASA identified a “current state shotcrete process to become more proficient at recognizing of affairs” in the pool shotcrete industry. Much what makes a job successful and not so successful. effort has been put in since then to make pool 3. With approval from the ASA Board of Direction, the building using the shotcrete process more of a Pool & Recreational Shotcrete Committee has established researched and accepted practice. The ASA Pool the technical writing of Position Papers that take certain & Recreational Shotcrete Committee is currently topics or aspects of shotcrete and explain their correct merits devoting its energies to making shotcrete in the and procedures. These Position Papers are designed to be pool industry more recognized as a credible form of concrete used directly by the pool industry as a reference library. To placement with work product examples and technical writings. The date, ASA has published two Position Papers that are committee’s efforts to raise the bar in shotcrete education include: foundational for the pool industry: 1. The Committee continually restates an older and not-so-well- • Proper Compressive Values; and known compressive standard of concrete in water exposure • Terminology and Definitions. conditions. This standard and building code is represented in A third Position Paper will be released later this year on ACI 318 and a previous table in Section 4 (Table 4.2.2), which Sustainability. The committee is currently working on Position states that concrete designed to have a low permeability when Papers regarding watertightness of shotcrete, sound forming for exposed to water (yes, that indeed is a pool) shall have a minimum pool shotcrete, and the issue of control joints. We encourage all compressive value of 4000 psi (28 MPa) and maximum water- our members to participate in writing topics. This is a great way cementitious material ratio (w/cm) of 0.50. This forgotten to set records straight; throw out inaccurate procedures or knowledge has been given new life in the pool and spa industry guidelines; and get all builders, specifiers, and engineers on the and is currently replacing the substandard and incorrect lingering same page. values of anything less than this minimum benchmark. 4. Reaching out to pool industry groups or associations is 2. There has been an increased awareness at many of the critical in this next phase of contact from the ASA Pool & industry shows of shotcrete nozzleman certification. ASA Recreational Shotcrete Committee. Current discourse in the makes a concerted effort to offer the ASA education session pool industry does not necessarily support proper shotcrete (normally provided on the first day of a certification session) applications as endorsed by the American Concrete Institute to major pool shows across the country. This exposure allows (ACI) and ASA. Correcting these inaccuracies seems to be people seeking certification to receive the mandated classroom the biggest obstacle so far. Despite the committee’s efforts review and preparation for the written exam. This class also to educate and inform, minor resistance to change still exists. Table 4.2.2: Requirements for Special Exposure Conditions Maximum water-cementitious material ratio*, by weight, normal- Minimum fc′, normalweight and Exposure condition weight concrete lightweight concrete, psi* Concrete intended to have low permeability 0.50 4000 when exposed to water Concrete exposed to freezing and thawing 0.45 4500 in a moist condition or to deicing chemicals For corrosion protection of reinforcement in concrete exposed to chlorides from 0.40 5000 deicing chemicals, salt, salt water, brackish water, seawater, or spray from these sources *When Table 4.2.2 is considered, the lowest applicable maximum water-cementitious material ratio and highest applicable minimum fc′ shall be used (ACI 318). 4 Shotcrete • Spring 2013


2013SprShotcreteEMag
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