Use of decorative concrete overlay for transportation infrastructure design

The novel concept of applying decorative concrete overlay (DCO) during the infrastructure design process supports the nationwide initiative for increased implementation of context-sensitive solutions. The DCO is a polymer-acrylic cementitious microtopping, a few millimeters thick, colored to look like stone, brick, or wood, for example, and skimmed or sprayed onto existing or new structural concrete. This research aimed to evaluate the potential of DCO to serve as a long-lasting aesthetic treatment for transportation infrastructure. A brief case study of typical decorative treatments and their associated costs indicated that DCO would be competitive in certain infrastructure applications. The DCO durability characteristics were examined by incorporating environmental conditions such as submersion in saltwater, exposure to ultraviolet light and moisture cycling, and intrusion of deicing salts (salt ponding). Fracture and pull-off adhesion testing were also conducted to evaluate the bonding of DCO to structural concrete. Flexural fracture testing showed that the bond between the DCO and concrete sample was unbroken, and failure was observed in the structural concrete. Adhesion testing indicated that the spray-on application method produces significantly stronger bond strengths than the alternative sponge technique. However, DCO must be sprayed on within a specific thickness range in order to achieve optimum strength. Chloride-ponding test results indicated that an additional benefit of DCO is that it acts as a protective coating against salt penetration. Overall, the research indicated that there may be significant potential for implementing DCO as a lasting and durable decorative contribution to the transportation design process.