Microstructure Development and Mechanism of Hardened Cement Paste Incorporating Graphene Oxide during Carbonation

Abstract

In this work, the carbonation mechanism of cement paste containing graphene oxide (GO) was examined by evaluating its electrochemical, kinetic, and microstructural characteristics under accelerated carbonation, corresponding to a 20% concentration of CO2, a temperature of (30 ± 1) °C, and a relative humidity of 65%–70%. Transport properties of the composites were studied using a non-destructive electrochemical impedance spectroscopy (EIS) technique, while their carbonation kinetics was investigated via thermogravimetric analysis (TGA). The obtained EIS results indicated that the ion diffusion and transport resistance increased after the incorporation of GO, while TGA results revealed that the carbonation of portlandite (CH) and calcium-silicate-hydrate (C-S-H) was significantly inhibited during early ages of carbonation due to the increased degree of hydration. In addition, the hybrid GO/hydration products from the carbonation process were characterized, and the formation of a hydrated phase coated with a carbonated layer was observed via scanning electron microscopy and energy dispersive spectroscopy. Porosity variations of the studied materials during carbonation were also evaluated using a mercury intrusion porosimetry method. The porosity of the OPC decreased more significantly during the initial carbonation period as compared to the effect observed for the GO cement-based material.

Department(s)

Civil, Architectural and Environmental Engineering

Comments

The authors gratefully acknowledge the financial support provided by the National Natural Science Foundations of China (No.51578341, No. 51778368).

Keywords and Phrases

Calcium silicate; Cements; Electrochemical impedance spectroscopy; Electrochemistry; Energy dispersive spectroscopy; Graphene; Hydrated lime; Hydration; Microstructure; Porosity; Scanning electron microscopy; Silicate minerals; Thermogravimetric analysis; Accelerated carbonation; Calcium silicate hydrate; Carbonation of portlandite; Cement based material; Hardened cement paste; Mercury intrusion porosimetry methods; Micro-structural characteristics; Microstructure development; Carbonation; Graphene oxide (GO)

International Standard Serial Number (ISSN)

0958-9465

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Elsevier, All rights reserved.

Publication Date

01 Nov 2018

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