Automating the construction of bus bays with reinforced concrete

When renovating intensively used bus bays, roads and squares, the need for their periodical closure to traffic during the period of works is inconvenient. In the case of concrete surface repairs, this timeline is additionally elongated due to the standard requirement of a 28-day curing period. The Department of Geomechanics, Civil Engineering and Geotechnics of the AGH University of Science and Technology has investigated the prototype RoadTronic robot to make slabs reinforced with a mesh of glass fibre rods. Process automation permits the application of rapid-setting CSA-based (calcium sulphoaluminate-based) cements, which achieve a compressive strength of over 20 MPa after just 1.5 h. The good properties of such cement have been confirmed by several years of use on the runway at Seattle-Tacoma Airport. Preliminary tests of the early compressive strength of Rapid Set® CSA-based concrete performed at the department, as well as calculations of guaranteed strength, indicate that young concrete can transmit operational load after just 4 h from mixing with water. The investigated solution assures a complete slab following one passage of the robot. This would permit the removal of the existing layer during reduced vehicle traffic, e.g., between 06:00 and 22:00, and the execution of a new abrasive concrete layer by 02:00, so as to restore regular traffic at 06:00.