Physiochemical and mechanical properties of reduced graphene oxide–cement mortar composites: Effect of reduced graphene oxide particle size

The use of graphene derivatives to improve the performance of cement mortar composites has received significant attention in recent years. However, because of diversity of graphene derivatives and their properties, which depend on their preparation, it is critical to consider their size, surface chemistry, crystallinity, surface area, and impurity. In particular, there is still lack of understanding on the influence of the graphene particle size on the performance of cement mortar composite. This paper presents the study on the size effect of reduced graphene oxide (rGO) on physiochemical and mechanical properties of cement mortar composites. A series of rGOs with different particle sizes were prepared by different sonication times of 1, 2, 4, 6, and 8 h and then added with optimum dosage of 0.1% to the composites. The mechanical test results revealed that the composite containing rGO with 0.1% dosage and particle size of 169.8 ± 5.8 nm prepared with 4 h sonication time has 53% and 91% higher tensile and compressive strengths at 28 days than the plain cement mortar composite, respectively, which are higher than those obtained by the use of rGO with particle size of 245.0 ± 29.3 nm prepared with 1 h sonication time. This is explained by the higher molecular bonding, hydration degree, and crystallinity of the composite incorporating rGO with a smaller particle size. This study provides a valuable contribution toward better understanding of the influence of rGO particle size on the properties of cementitious composites to optimize their performance.