Q.: We do a lot of parking deck repair that involves removing delaminated concrete and concrete damaged by freezing and thawing. We remove concrete from beneath the rebars to make sure there's room for repair concrete to bond to the bars. But during the abrasive blasting operation that precedes concrete placement it's hard to clean the underside of the bars. Any suggestions for how to do this efficiently?
A.: Robert Kennerly of Sutton-Kennerly & Associates in Greensboro, North Carolina, has a method that seems to work pretty well. He suggests putting a thin steel plate beneath the rebars before abrasive blasting them. The abrasive bounces off the plate and hits the underside of the bars, thus cleaning both top and bottom of the bars.