Augmenting BIM with 3D Imaging Data to Control Drilling for Embeds into Reinforced Concrete Bridge Decks

Placing embeds into reinforced concrete structures, after concrete is poured, without damaging reinforcement bars (rebar) is an industry-wide challenge encountered across the construction industry. In concrete structures such as containment vessels, bridge decks and post-tensioned concrete floors damaging rebar may compromise structural integrity and result in considerable rework. Although negative impressions for embeds can be made by placing various objects such as wooden dowels or steel rods into the rebar cage prior to pouring the concrete (and removing them once the concrete has partially or fully set), this practice is labor intensive and time consuming. A method of mapping the locations of the rebar free spaces before pouring and controlling the drilling process in real-time could have significant benefits. This paper presents research that investigated and implemented conceptual solutions for processing and incorporating point cloud data obtained from various 3D-imaging technologies into the drilling process. The 3D imaging technologies were used to map the locations of rebar within a replica of a section of a railway bridge deck. Once the point clouds were processed, zones that are safe for drilling are automatically detected and saved as a Building Information Model (BIM) that is then used to provide real-time feedback to the drill operator about whether it is safe to continue drilling based on the position and orientation of the drill. A conceptual method for providing visual feedback about the rebar-free zones to the drill operator using a laser projector was also developed. Finally, a visualization method for comparing the data obtained from the various 3D imaging technologies using the BIM is discussed.