Microstructure and Chloride Diffusion Properties of Hardened Fly Ash Cement Paste with Three-dimensional Graphene

Jingwei Ying,Xiaoying Xi

doi:10.1186/s40069-021-00494-5

Jingwei Ying, Xiaoying Xi

Open Access

https://doi.org/10.1186/s40069-021-00494-5

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Abstract

In this paper, the influence of three-dimensional graphene (3DG) on the microstructure and chloride diffusion properties of fly ash cement paste was investigated. 3DG accounting for 0.0–0.2% of cement mass was evenly dispersed in hardened cement paste containing fly ash by using ultrasonic and polycarboxylate superplasticizer. The microstructure of the cement paste was characterized by mercury intrusion test (MIP), X-ray diffraction (XRD), and scanning electron microscope (SEM). The results indicate that an appropriate amount of 3DG accelerates the secondary hydration of fly ash and provides a platform for the growth of cement hydration crystals. Moreover, the hydrated crystal fills the pores, reduces the harmful porosity, and refines the pore structure. The enhanced microstructure significantly improved mechanical properties and chloride diffusion resistance of hardened fly ash cement. With the addition of 0.1% 3DG, the compressive strength increased by 31.33%, and the chloride diffusion coefficient was reduced by 49.44%. The findings are beneficial to promote the generalized application of 3DG in cement in the marine environment.

Highlights

As an important building material in ocean structural engineering, the corrosion of sulfate and chloride ions seriously endangers the safety and durability of concrete structures (Ariyachandra et al, 2021; Li et al, 2020; Park & Choi, 2012)
3.1 Microstructural Characterization 3.1.1 Pore Structure The pore characteristics of the 3DG fly ash cement system of 28d were characterized by mercury intrusion porosimeter (MIP)
4 Conclusions The innovation of this research is that three-dimensional graphene (3DG) with different blending amounts was used in fly ash cement-based materials

Summary

Introduction

As an important building material in ocean structural engineering, the corrosion of sulfate and chloride ions seriously endangers the safety and durability of concrete structures (Ariyachandra et al, 2021; Li et al, 2020; Park & Choi, 2012). Fly ash has contributed to the improvement of the pore structure and microstructure of cement in active effect and micro-aggregate effect (Shen & Zhang, 1981), which further provide enhanced mechanical strength (Hefni et al, 2018) and durability (Yamato et al, 2020). The emergence of nanomaterials provides a new direction for improving the early mechanical properties Nanomaterials, such as nano-SiO2, nano-Fe2O3, and carbon nanotubes, have been proven to effectively enhance the performance of cement-based materials (Konstantopoulos et al, 2020; Mittal et al, 2015; Zhang et al, 2019b). Previous studies have shown that two-dimensional graphene shows a good reinforcement effect in fly ash cement-based materials. Techniques, including mercury intrusion porosimeter (MIP), X-ray diffraction (XRD), and scanning electron microscopy (SEM), were employed to characterize the influence of 3DG on the microstructure of fly ash cement paste

Experimental

Results and Discussion

Conclusions