Effect of mechanochemistry on graphene dispersion and its application in improving the mechanical properties of engineered cementitious composites

To improve the dispersibility of graphene in cement-based materials and achieve better mechanical properties, this study proposes a novel and practical mechanochemical grafting strategy through ball milling technique. The polycarboxylate-based superplasticizer was successfully grafted on graphene, inducing both covalent and non-covalent modifications of the graphene surface simultaneously. The mechanochemistry method under different conditions, e.g., dry milling or wet milling, was investigated. The dispersion efficiency of prefabricated graphene was compared with traditional ultrasonic dispersion methods. The graphene prepared with these dispersion methods was then applied to prepare Engineered Cementitious Composites (ECC). The results indicated that the proposed mechanochemical methods can effectively reduce particle size, increase specific surface area, and introduce abundant functional groups, thereby improving the dispersibility of graphene. Especially under wet milling conditions, smaller and more dispersed particles could be produced. The addition of well dispersed graphene at 0.1 wt% in engineered cementitious composites (ECC) showed a 24.0 % increase in compressive strength, a 32.4 % increase in tensile strength, and a 66.9 % increase in ultimate tensile strain. This improvement is attributed to the a capability of graphene sheets processed by ball milling to impede the propagation of cracks within the cement matrix.