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2015WinterShotcreteEMag

Shotcrete FAQs company that wants to hand-finish the 6 in. (152 mm) wide Answer: This seems to be two questions: trough; another wants to shoot up to foam. Can you tell me 1. The repairs should be accomplished as recommended in which is best and why? ICRI Technical Guidelines: the area to be repaired should be chipped out to sound concrete, sandblasted or waterblasted Answer: This is a classic performance-versus-prescription to remove any bruised material, dampened to a saturated situation. The owner or customer should specify the desired surface-dry condition, and patched with a reputable and end product and the contractor should choose the means and known repair mortar. methods. Although they may both provide a great product, what works for one con- tractor or what he/she is comfortable doing may be completely different than another contractor. Question: Would epoxy-coated rein- forcing bar be required for a shotcrete site retaining wall that does not have water- proofing behind it? Answer: Shotcrete is a method of placing concrete and the properties of properly placed shotcrete are equal to those of cast concrete. We have seldom seen the use of epoxy-coated reinforcing bar in retaining walls with or without waterproofing. (The California Department of Transportation builds many retaining walls with cast concrete and with shotcrete and seldom uses epoxy-coated reinforcing bar or waterproofing.) It is important that you use a contractor qualified and experienced in this type of work and who uses ACI Certified Noz- zlemen and a qualified crew. Question: I am involved with an above- grade canal replacement project that used shotcrete. The forms were recently pulled from one of the vertical walls, and exten- sive defects were visible throughout the wall length. Reinforcing bar shadowing occurred at nearly every vertical bar as well as numerous void pockets of various depths (some even up to 3 in. 76 mm). Demolishing and replacing the wall is not a viable option. I am responsible for developing repair recommendations to the client and would like to know if there are any standards for shotcrete tolerances, specifically in regards to defects. I am going to specify that a repair mortar be used for repairing the defects and would appreciate any insight into this, as well as any wisdom that could be offered in dealing with rein- forcing bar shadowing. Shotcrete • Winter 2015 61


2015WinterShotcreteEMag
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