Question: Is there a standard or ACI reference I can use to specify that a broom finish be applied perpendicular to the slope? This is for a concrete walking surface that I was recently challenged on.
Answer: We couldn’t find anything in ACI documents that specifically says to broom perpendicular to the slope. ACI 330.1-03, Specification for Unreinforced Concrete Parking Lots, in section 3.9, says to broom perpendicular to nearest edge of pavement, implying that the brooming is perpendicular to the longer dimension which would presumably be the direction of travel. ACI’s Slabs-On-Ground Concrete Craftsman Series, CCS-1, says to run the broom crosswise (perpendicular) to the direction of pedestrian travel. Conversations I’ve had with broom manufacturers led to this statement in a recent article: Broom the surface by running a concrete broom perpendicular to the slope, if there is one. On concrete that’s intended to drain, though, broom marks should be run toward the drain.