Water-Based Graphene Nanofluid Additives: Advancements in Sustainable, Low-Carbon, High-Performance Nanocarbon-Modified Cementitious Materials

Keywords:
Graphene nanofluid cement additives; orthogonal experiments; microstructure analysis; modification mechanism

Source:
Publication Year: 2024
Source: Cement and Concrete Research
Lead Author: Assistant Professor Pei Chun, Shenzhen University School of Civil and Transportation Engineering
Corresponding Author: Professor Zhu Jihua, Shenzhen University School of Civil and Transportation Engineering

Background:
In building materials, the cement industry ranks as the second-largest carbon emitter after steel. Achieving carbon neutrality requires prioritizing energy-saving and emission reduction in cement production. Due to cement’s significant carbon footprint, developing low-carbon, high-performance cementitious materials is essential. Carbon nanomaterials have recently gained attention for enhancing cement-based composites, improving mechanical strength, impermeability, freeze resistance, and enabling applications in smart infrastructure such as heated roads. However, practical application of carbon nanomaterials faces challenges such as high production costs and difficulty achieving uniform dispersion in concrete. Customizing nanocarbon materials for cement-based applications is thus critical.

Since the discovery of graphene, various scalable production methods have emerged, including chemical vapor deposition, chemical exfoliation, and liquid-phase exfoliation. High-concentration water-based graphene nanofluid additives (GNA), produced by high-shear and ultrasonic exfoliation, have demonstrated stability, high yield, cost-efficiency, and suitability for large-scale civil engineering applications. Compared to traditional materials, nanofluid-modified cement composites show outstanding mechanical performance and multifunctionality. Studies indicate that GNA reduces cement binder demand by 20.6%, meeting structural load requirements while significantly lowering carbon emissions per ton of cement by 184 kg.

Objective:
Given the extensive demand for cementitious composites, it is crucial to focus on the development of high-performance carbon nanomaterials that also consider material supply and production simplicity to prevent excessive engineering costs.

Research Overview:
This study validates the effectiveness of liquid-phase graphene exfoliation in water to create nanocarbon-enhanced concrete. Utilizing industrial-grade graphene nanoplatelets with polyvinyl alcohol (PVA), a polymer commonly used in civil engineering, the method replaces concrete water with a water-based graphene nanofluid additive (GNA) produced via high-shear and ultrasonic processes. Techniques like scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) reveal the additive’s synergistic modification mechanism. Graphene dispersion concentration is measured via spectrophotometry, while transmission electron microscopy (TEM) and atomic force microscopy (AFM) assess the nanoplatelet morphology, structure, and layer count.

Main Findings:
This study developed a concentrated water-based graphene nanofluid additive (GNA) with 13 g/L of high-quality few-layer graphene using industrial-grade graphene sheets and PVA via high-shear and ultrasonic exfoliation. As a long-term stable, high-yield, cost-effective additive, GNA is well-suited for large-scale civil applications. The synergy of graphene and PVA enhances cement paste mechanical properties, setting a new benchmark in advanced construction materials. Optimal proportions determined through orthogonal experiments—water-to-cement ratio (W/C) of 0.45, PVA content (P/C) of 0.5 wt%, and graphene content (G/C) of 0.1 wt%—improve compressive and flexural strength significantly at both 7 and 28 days. The GNA-modified cement paste exhibits higher hydration rates, increased calcium hydroxide content, and enhanced interfacial properties, contributing to its superior mechanical performance.

Comparison and Implications:
This research demonstrates the feasibility of synthesizing graphene-based additives with industrial-grade materials, achieving results comparable to commercial products. The study offers an eco-conscious approach by non-covalently functionalizing graphene dispersions with polymers, opening new possibilities for nanomaterials in civil engineering applications. The findings expand the application scope of civil engineering materials and provide a path for future research exploration.

Reference Link:
https://doi.org/10.1016/j.cemconres.2024.107505