Use of Nano-Clays and Methylcellulose to Tailor Rheology for Three-Dimensional Concrete Printing (2021-11)¶

A concrete system is identified as highly printable if it can offer minimal resistance to handling while sustaining high load resistance and structural stability. One of the major complexities of three-dimensional (3D) concrete printing lies in its sensitivity to materials and equipment that varies the time among layers, hydration time, and shear history. While nanoclays are effective additives for enhancing structural buildup, methylcellulose is introduced as a secondary additive to significantly amplify the nanoclays’ effect on the static yield stress while prolonging the open time between layers and increasing filament cohesiveness. The compatibility of these two systems at different contents is studied by characterizing rheological properties such as static yield stress, steady-state viscosity, and storage modulus, as well as the heat of hydration through isothermal calorimetry. The hybrid system is found to increase the static yield stress by up to 900% compared to the reference paste at only 3.0 wt.% total content by mass.