Manufacturing Additively, With Fresh Concrete

This research explores mega-scale additive manufacturing, using fresh concrete. In traditional concreting, rigid forms mold and protect young concrete, like an exoskeleton. Typically, these forms are not removed until the maturing material has developed considerable load-bearing strength. Conversely, Contour Crafting, an automated construction technology under development at the University of Southern California, proposes to rapidly fabricate civil structures additively — layering continuous ribbons of fresh unconfined concrete. The process, which is akin to 3-D printing, leverages a special polymer-modified concrete which is both highly workable and shape–stable. However, without exoskeleton, the freshly layered concrete must be load-bearing immediately upon placement. This is an unprecedented structural requirement, and little has been done to substantiate uncured concrete as a load-bearing member. This research establishes the build rates and material health monitoring necessary to erect these structures safely, and demonstrates the Contour Crafting process is viable.