Printability Characterization of Graphene-Reinforced Cementitious Composites (2021-03)¶

The cement-based additive manufacturing, commonly known as 3D concrete printing, facilitates the use of advanced cementitious materials in construction as this construction technique minimizes waste and enables the optimal placement of the material. 3D printable cementitious mixtures should have specific consistency for successful manufacturing. In particular, they should be extruded smoothly during the printing process while maintain their shape after deposition, both of which are closely related to the rheological properties of cementitious mixture. The use of graphene in cementitious composites has been widely explored in recent years and it was shown that graphene can improve the mechanical properties and durability of cementitious composites. However, the rheological properties and printability characteristics of graphene-reinforced cementitious materials still remain underexplored. This study investigates the effects of graphene nanoplatelets (GNPs) on rheological and printability characteristics of GNPreinforced cementitious composites. GNPs are added into cementitious mixtures, designed for 3D concrete printing applications, at concentration of 0%, 0.05%, 0.10%, 0.15%, 0.20%, and 0.25% by weight of cement. GNPs are first dispersed into water through the help of ultrasonic treatment and a polycarboxylate-based superplasticizer. The dispersion quality of GNPs is assessed through UV-vis absorption spectroscopy, optical microscopy, and Raman spectroscopy. Then, the rheological properties of GNP-reinforced mortar composites are studied using a shear rheometer via stress-growth tests, shear rate ramp up-down tests, and structural recovery tests.