The non-uniform spatial dispersion of graphene oxide: A step forward to understand the inconsistent properties of cement composites

Graphene oxide (GO) has been extensively employed to improve the mechanical strength, hydration and durability of cement composites. Recently, an interesting phenomenon can be found that the variation of cement performances is inconsistent with identical GO dosage. However, the related mechanisms remain unclear. Herein, we elucidate the relationship between the spatial dispersion of GO and inconsistent properties of cement composites. Firstly, X-ray computed tomography is developed to observe the distribution of GO. Moreover, the morphology and pore structure of hardened cement paste are studied. Finally, the scattered degree of mechanical strength is evaluated. Obtained results show GO forms many agglomerations with irregular flat shape. Polycarboxylate-ether could reduce the amount of GO aggregations, but not completely eliminate the agglomerations. Aggregated GO induces uncertain pores and sequentially increases the total porosity. The spatial distribution of GO aggregations is non-uniform. These factors lead to the larger scattered strength of specimens with GO. The discrepancies in dispersion degree of GO are mainly responsible for the inconsistent properties of cement composites. This study could provide a deeper understanding of the conflicting properties of GO reinforced cement-based materials.