Carbon Nanomaterials Applied in Cementitious Composites- A focus on mechanical properties and dispersion techniques

Yaghobian, Masoud

Abstract

Cementitious composites are integral to civil engineering applications, yet they are subject to limitations such as nanoscale cracking. To address these challenges, this doctoral research investigates the use of Graphene Nanoplatelets (GNPs), a cost-effective nanomaterial with a large surface area that has shown promise in improving hydration, reducing porosity, and mitigating cracking in cementitious systems. The effective dispersion of GNPs, often hindered by strong internal forces, was achieved through a unique dual-method approach involving both mechanical (sonication) and chemical (Superplasticizer, SP) means.

To rigorously evaluate the optimal conditions for GNP dispersion and subsequent impact on mechanical properties, an exhaustive testing regimen was implemented. GNPs were initially dispersed in water through sonication and the use of Superplasticizer (SP), with the quality of dispersion subsequently assessed via UV-Visible spectrometry. Various concentrations of GNPs and SP were then incorporated into cementitious composites. Mechanical tests were conducted to assess the composite's performance, followed by advanced characterization techniques, such as Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS), to examine the dispersion quality within the cementitious matrix.

This research has identified an optimal GNP concentration of 0.046 wt%, rigorously verified through a suite of experimental tests to significantly enhance the mechanical properties of cementitious composites. Concurrently, an optimal SP concentration of 0.5 wt% was found to synergistically improve these properties. Uniquely, this study also delves into the often-overlooked aspect of the shelf life of GNPs in cementitious composites, providing a novel industry-relevant metric to evaluate the quality of dispersion over time. Poor dispersion quality has been shown to negate the beneficial effects of GNPs, underlining the importance of this component of the study.

In summary, this doctoral research makes substantive contributions to the fields of materials science and civil engineering by offering rigorously-tested, practical solutions to age-old challenges in cementitious composites. Its findings have far-reaching implications for both academic research and industrial applications, serving as a cornerstone for future work in nano-enhanced construction materials.

• Thesis Type: Thesis
• Deposit Date: Jan 13, 2025
• Publicly Available Date: Jan 24, 2027
• Award Date: Jan 23, 2025