Rheological Characterization of Three-Dimensional-Printed Polymer Concrete

Conventional cement-based concrete is widely used as a construction material due to its ability to flow before hardening and to adopt the shape of the formwork as it is placed. Contrarily, in layered extrusion additive manufacturing, commonly known as three-dimensional (3D) printing, concrete is shaped without formwork. This imposes stringent time-dependent rheological requirements of materials used for 3D printing. Polymer concrete (PC) is a material extensively used in the precast industry. This paper reports on the potential use of PC for 3D printing applications. The influence of mixture design parameters-specifically rheology modifier content, filler-polymer ratio, and aggregate-polymer ratio-on the rheological properties of a 3D-printable PC are investigated. The rheological properties of seven PC mixtures are tested and characterized. PC can be described as a Bingham pseudoplastic material, and a Herschel-Bulkley model can accurately describe its rheological behavior (dynamic shear stress) over time. The evolution of static yield stress over time was found to follow an exponential trend. The use of these models to predict the dynamic and static yield stress of PC shall enable the design of efficient and stable 3D printing. Finally, 3D-printed PC shows good mechanical performance with compressive strength above 30 MPa (4351 psi) at 7 days of age. Automation of the PC precast industry using 3D printing will create new opportunities for the use of PC in civil infrastructure.