Material characteristics of rapid prototyping concrete and member behavior

In this study, concrete rapid prototyping (CRP) system was developed, and the rheology properties of fresh concrete suitable for CRP were defined by conducting literature review and computational fluid dynamic (CFD) analysis. In addition, mix proportion of concrete with proper viscosity and yield stress for concrete printing was proposed through trial mixing tests. The ratio of printing head speed to concrete extrusion speed (VR) and height of extruder nozzle suitable for CRP were derived from extrudability tests, and a proper printing time gap (PTG) was identified from buildability tests. Then, flexural tests of CRP and reinforced concrete (RC) members were conducted, and their flexural performance were compared and analyzed in detail. The test results showed that the ductility of the CRP member was smaller than that of the RC member, but their flexural strengths were very similar.