Effect of Concrete Mix Design Factors on Static Yield Stress Changes due to Vibration

Digital fabrication of concrete structures has gained substantial research traction over the last decade, enabling efficient material use and adding more architectural freedom. Current research focuses on chemical and mineral admixtures, as well as manipulating the cement hydration reaction to control the yield stress evolution with time in the cement paste. Instead of providing yield stress through the concrete fluid properties, a high yield stress can be provided by interparticle friction from the use of high aggregate volumes and large nominal maximum aggregate size, with flow enhanced for material extrusion by vibration. Granular physics was applied to concrete mixture design to develop concrete mixtures with excellent edge retention abilities that flow easily under vibration. A linear regression analysis of concrete yield stress after vibration revealed that water content is most important, followed by fineness modulus of the aggregate combination and density after vibration. A decrease in water content, increase in fineness modulus and increase in density after vibration were found to increase the static yield stress after vibration.