Automation and Robotics of Underwater Concreting in Huge Scale Steel Caisson, The Main Tower Foundation of the Akashi Kaikyo Bridge

Antiwashout underwater concrete totalling about 500,000 meter cube in volume was placed for the two under water foundations of the Akashi Kaikyo bridge, to be the world’s longest suspension bridge when completed. Placing took a year under severe marine conditions with a maximum 8- knot tidal current and a maximum depth of 60 m. Because the concrete had to be placed in layers over the wide area of a steel caisson, which acts as the formwork, and under great depth, a cleaning robot to clean the undersea bedrock surface was used, production and placing of concrete was automated, and a construction joint treatment robot was used to obtain good quality concrete.