Page 144 - Demo

PRECAST CONCRETE ELEMENTS144 CPI %u2013 Concrete Plant International %u2013 2 | 2026 www.cpi-worldwide.comInventorying using simple phone picturesDesign with reused material implies to know the material to work with in the first place. Due to the flat property of the large pieces of rubble considered for upcycling, their geometry is approximated as 2D elements, which ease not only design, but most importantly, scanning. Working with 2D elements allows digital acquisition with affordable cameras, through edge detection and image segmentation, thus maximizing market scalability. Thus, with the goal of keeping construction methods accessible, the author developed an accessible scanning process using a QR code (Aruco marker) and a smartphone photo (Fig. 7) [11]. The photo is then straightened based on the marker, and the 2D geometry is obtained undistorted and to scale using image segmentation based on the SAM2 model. Thus, to scan the entire stock and design from it, each rubble piece is extracted from a delivered pile or bin using any lifting equipment and slings and placed on its flat side. Placing each rubble unit on a pallet eases stock logistics. The rubble pieces are sourced from the nearest recycling centre or demolition site (Fig. 8), usually free of charge as it is still considered a waste.Large concrete rubble as an opportunityThe demolition concrete used in this research consist specifically in large flat concrete rubble of irregular bounding geometry which cannot be conveniently placed by hand (i.e., the mass of a piece is typically greater than 25 kg). Those rubble pieces offer significant benefits, they are:Fig. 6: Phone pictures of rubble pieces provide their 2D geometries through the implementation of a custom script (Re:bble 2D Scanner). Research and implementation by Maxence Grangeot, EPFL Fig. 8: Rubble from demolition is sourced in recycling centres or demolition sites. Research and implementation by Maxence Grangeot, EPFL Fig. 7: The 2D outlines of rubble pieces are digital arranged into masonry layout to maximise compression resistance. Research and implementation by Maxence Grangeot, EPFL