To what extent can polycarboxylate superplasticizers enhance the dispersion characteristics of modified graphene oxide in cement? Insights from ultrasonication and high-shear mixing methods

Abstract

The utilization of graphene oxide (GO) as a nano-reinforcement material in cement composite has generated substantial interest. However, the aggregation of GO nanosheets in the highly alkaline environment of cement matrix, along with inadequate dispersibility, negatively impacts the performance of cement composite and limits its potential application. This study was to find efficient methods to enhance the dispersion behavior of GO in cementitious materials by understanding the effects of various superplasticizers on the dispersibility behavior of GO. Five different polycarboxylate ether superplasticizers (PCE-SPs) in dosages ranging from 5 to 20 wt% were evaluated by two different methods - ultrasonication (ULS) and high-shear mixing (NULS). Raman spectroscopy, zeta potential, dynamic light scattering, visual inspection, and optical microscopy were used to examine the dispersion characteristics. The results revealed a significant enhancement in the dispersion properties of the GO-colloidal mix when altered with PCE-SPs MG8700 and 20HE at an optimal proportion of 8–10 wt% for the NULS and 10–12 wt% for the ULS method. Moreover, the intense cavitation effect produced during the harsh treatment of ULS causes a higher degree of structural damage to the GO-nanosheets. In contrast, the NULS approach demonstrated effective dispersion of the GO-nanosheets with reduced structural damage and fragmentation. The findings of this study highlight that treating GO with suitable PCE-SPs at the appropriate dosage using the NULS method presents a promising prospect for achieving better dispersion. • High-shear mixing proves to be an efficient and scalable alternative to ultrasonication for large-scaleGO dispersion. • Optimal polycarboxylate ether superplasticizer (PCE-SP) dosages for stable GO dispersion in colloidal solutions are identified. • Certain PCE-SPs demonstrate superior performance in enhancing GO dispersion stability and reducing agglomerate size. • Long-term stability of GO-PCE-SP mixtures is confirmed from four months to one year. • These findings offer valuable insights for industrial-scale production and application of GO-based materials.