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5. SSD means the substrate is damp, but there is no flowing water. It should feel damp to the touch, but no water is picked up on your hand when placing it against the surface. 6. Do not use bonding agents, as they can interfere and reduce the bond of the new shotcrete to the old shotcrete surface. 7. When the new shotcrete is in place, the contractor should initiate water curing as soon as possible. In warm, dry, or windy weather, fogging of the fresh surface immediately after finishing would be helpful. 8. Water curing (where the concrete is kept continuously moist) should be supplied for at least 7 days. Question: The plaster color installed in my pool was the wrong color. The plaster has been chipped out. My concern is damage to the shotcrete shell in the process. There are deep holes and gauges and there was water seepage in a few areas behind the shotcrete. There is also evidence of honeycombed areas in the shotcrete, as well as some other shotcrete concerns since reading up on the shotcrete process. Please help, as I’m being told that they will just plaster over these concerns. However, the plastering information reads that plaster thickness should not exceed 7/8 in. (22 mm) thickness (but can be a little thicker around plumbing fixtures). Answer: Shotcrete is a placement method for concrete. When the pool shotcrete contractor uses quality materials, properly sized and maintained equipment, and experienced crew members, the shotcreted pool shell should be watertight. Proper shotcrete application would also not exhibit voids, honeycomb, or major seepage through the pool shell. Before replastering, the pool shell should be evaluated and all defects (voids, cracks, porous sections, deep holes, and so on) repaired using industry-standard methods and materials. You may consider retaining a professional engineer or experienced pool consultant to evaluate the pool shell and make specific recommendations on the appropriate repair for your specific issues. You can use our Buyers Guide (www.shotcrete.org/pages/products-services/Buyers- Guide/index.asp) to locate consultants in your area. You also may want to review our pool-specific Position Statements on our website at www.shotcrete.org/pages/products-services/ shotcrete-resources.htm. The “Watertight Shotcrete for Swimming Pools” would be particularly informative for you to assist in discussions with your pool contractor. Question: I am a structural engineer and we have recently begun work with a shoring contractor. We have been designing soil nails, micropiles, soldier piles, and so on with temporary and permanent shotcrete facings. The contractor has requested that some of our future designs use chain-link mesh in lieu of welded wire mesh, particularly in temporary situations with walls under 10 ft (3 m). I understand that chain link is a cost-effective alternative and, according to the contractor, handles the shotcrete well. Do you have any experience with this type of design/installation process? Can you point me to any literature on the use of chain-link reinforcement in shotcrete walls? Answer: Some mines have used chain link mesh in shotcrete in severely deforming ground and claim that it is better in holding the ground than mesh after large deformations, in which the shotcrete sustains major cracking with deformations. Other than for such unusual applications, we do not recommend the use of chain-link reinforcement in shotcrete. It cannot be fixed “tight” and as such is susceptible to vibration and movement during shooting, resulting in shotcrete sloughing and formation of voids in the shotcrete. Also, the mesh interconnections are conducive to the formation of voids during shooting. Additionally, there don’t appear to be any consistent material standards on the strength, flexibility, or brittleness of the steel (or other materials) used in the fencing material, so a designer has no way to establish the tensile or flexural strength of the concrete sections. In brief, don’t use chain-link mesh if you want to produce quality, durable shotcrete. STRUCTURAL SHOTCRETE SYSTEMS, INC. LICENSE #579272 A www.structuralshotcrete.com JASON E. WEINSTEIN, P.E. VICE PRESIDENT 12645 CLARK STREET (562) 941-9916 SANTA FE SPRINGS, CA 90670 FAX (562) 941-8098 www.shotcrete.org Spring 2017 | Shotcrete 79


2017SpringShotcreteEMag
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