Exploration of using graphene oxide for strength enhancement of 3D-printed cementitious mortar
Junli Liu, Phuong Tran, Thusitha Ginigaddara, Priyan Mendis
Abstract
Graphene oxide (GO) sheet as a nanomaterial has recently been incorporated into cement-based composites to improve mechanical properties. This study investigates the effectiveness of GO sheets in enhancing the compressive strength of 3D-printed cementitious mortar. Two dosages of GO are investigated, including the GO-to-binder weight ratio of 0.015% (GO-0.015) and 0.03% (GO-0.03). Experiment results show that adding GO at both dosages improves the compressive strengths of printed specimens in different loading directions. However, the strength improvement in GO-0.015 (∼10%) is more significant than GO-0.03 (∼5%). Although the scanning electron microscopy analysis demonstrates the cement matrix shares similar levels of microstructure densification in GO-0.015 and GO-0.03, the material underfill in 3D-printed GO-0.03 specimen due to its lower flowability generates large voids between filaments. Consequently, large voids acting as additional weakness offset the positive effects of GO on strength improvement in the 3D-printed specimen of GO-0.03.