Investigation of dispersion behavior of GO in aqueous and effect of ultra-low dosage GO on structure and properties of cement-based composites

• GO nanosheets always trend to form aggregation no matter how low content. • APCs can adsorb GO to form brush dispersion and reach evenly dispersion. • Use of APCs/GO can achieve ultra-low dosage GO and improve significantly strength. • Analyze the influence degree of the factors on the performances by ANOVA. The main problem of graphene oxide (GO) used in cement-based composites is that it cannot be evenly dispersed in the cement matrix, which not only leads to high dosage and cost, but also reduces its action effects. By investigating the dispersion behavior of GO in aqueous, it is found that no matter how low the GO dosage is, the GO always gather into aggregations and resulting in uneven distribution. For uniformly dispersing GO in the cement matrix in the form of single-layer or few-layer, the amphoteric polycarboxylate superplasticizer (APCs) contained amino groups with multi-branch chain structure was prepared and found that it can evenly disperse GO by forming PACs/GO composites. The research founded that GO nanosheets were evenly adsorbed on the molecular chains of APCs with smaller clusters and presented its multi-chain existence state. Meanwhile, it is found that the cement-based composites contained ultra-low dosage GO by dolped with APCs/GO composite have significantly improved in structure and performances. The influence degree of PCs, APCs, PCs/GO, APCs/GO on cement matrix composites was analyzed by ANOVA.The dispersion mechanism of GO is proposed and it is thought that APCs first adsorbs GO nanosheets on its multi-branch molecular chains and then GO nanosheets falls off from APCs molecular chain under alkaline condition of cement slurry to form evenly dispersion in cement matrix by helping of mechanical agitation. The research result has positive significance for promoting application of GO in cement-based composites.