Our company will be repairing a concrete spillway for a dam. We'll be repairing slab-on-grade work and walls. We're investigating several repair methods including wet- and dry-process shotcreting. What are the relative advantages and disadvantages of these methods?
According to Rusty Morgan of Hardy BBT Ltd., economics usually dictates the method used. Wet shotcreting requires continuous shooting and is well suited for high-production jobs. To use this method economically for repair you have to do much of the repair surface preparation ahead of time. But on spillway repairs, this may require lots of scaffolding and drive up costs. Dry-mix methods are more commonly used because they work better when there's frequent starting and stopping. You can use less scaffolding because each area to be repaired can be done from surface preparation to shooting before moving on to the next area. Some contractors use a high-reach crane instead of scaffolding, but the dry process works well with this approach too.