Rheological enhancement of fresh polymer-modified cement composites via surface-modified graphene oxide

Abstract

Polymer-modified cement (PMC) composites are extensively utilized in modern construction, especially in tunneling and structural applications, but their excessive flowability and reduced thixotropy continue to present fundamental rheological challenges. We present a novel approach to improving the rheological performance of PMC via surface-modified graphene oxide (GO), i.e., GOPMC composites. Specifically, the flow behavior of GOPMCs in relation to shear stress–shear strain response and apparent viscosity were investigated. The rheological parameters were analyzed by using Herschel–Bulkley's model. Additionally, zeta potential and dispersion analysis were conducted to investigate interparticle interaction forces. Flow measurement confirmed ∼20 % lower flowability of the GOPMC than the reference PMC. GOPMC composites further displayed higher yield stress of ∼82 % and ∼33 % reduced viscosity with inherent decreased shear-thickening compared to reference PMC composites. The yield stress of the GOPMC composite increased over time, disclosing distinct structural evolution linked to enhanced hydration kinetics by GO. Additionally, GO nanosheets in the GOPMC altered the rheopectic behavior of the redispersible polymer and enhanced the degree of thixotropy by ∼80 %, attributable to the promotion of bridged flocculated structures which produces a rigid system, facilitated by particle interaction forces comprising of van der Waals and steric forces. This latter observation provides a mechanistic framework for the enhanced rheological performance of GOPMC composites aiming at broader civil engineering and construction sector applications beyond tunneling.