Dataset Information

Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites.

ABSTRACT: Calcium leaching is a degradation progress inside hardened cement composites, where Ca²⁺ ions in cement pore solution can migrate into the aggressive solution. In this work, calcium leaching of graphene oxide (GO) reinforced cement composites was effectively characterized by combined techniques of electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). Inhibiting mechanism of GO on calcium leaching of the composites was also examined. The obtained results show that the diameter of the semi-circle of the Nyquist curves of leached samples with GO addition decreased less than that of controlled samples. After leaching for 35 days, loss rate of model impedance R_CCP of leached samples with 0, 0.05, 0.1, 0.15, and 0.2 wt.% GO addition was 94.85%, 84.07%, 79.66%, 75.34%, and 68.75%, respectively. Therefore, GO addition can significantly mitigate calcium leaching of cement composites, since it can absorb Ca²⁺ ions in cement pore solution, as well as improve the microstructure of the composites. In addition, coupling leaching depth and compressive strength loss were accurately predicted by using the impedance R_CCP.

SUBMITTER: Long WJ

PROVIDER: S-EPMC6409634 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites.

Long Wu-Jian WJ Ye Tao-Hua TH Li Li-Xiao LX Feng Gan-Lin GL

Nanomaterials (Basel, Switzerland) 20190219 2

Calcium leaching is a degradation progress inside hardened cement composites, where Ca<sup>2+</sup> ions in cement pore solution can migrate into the aggressive solution. In this work, calcium leaching of graphene oxide (GO) reinforced cement composites was effectively characterized by combined techniques of electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). Inhibiting mechanism of GO on calcium leaching of the composites was also examined. The obtained results ...[more]

PMID: 30791393

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Project description:A very low dosage of graphene oxide (GO) can enhance the mechanical durability of cement composites, but the reinforcing enhancement is highly dependent on the uniform dispersion of graphene in the matrix. Carboxylic groups at GO nanosheets have a decisive effect on GO aggregation in an alkaline cement solution because they have a strong complexation ability with aqueous Ca2+ released by cement hydration and subsequently crosslinks the adjacent graphene sheets, causing the immediate coagulation of GO. The available methods of homogeneously dispersing GO in a cement slurry cannot completely eliminate this carboxylic-crosslinking-induced GO coagulation. In this study, many hydroxyl groups were introduced onto the edge and planar nanosheets to prepare water-soluble hydroxylated graphene (HO-G) by facile ball milling. The structure of HO-G was thoroughly characterized in detail, and its dispersion behavior in pure water and Ca(OH)2 was extensively investigated. These results showed that the prepared HO-G exhibited good hydrophilicity and excellent colloidal dispersion ability against high pH and Ca2+ ions compared to GO. The effect of HO-G on the workability, mechanical strength, and chloride penetrability of a cement mortar was further studied. At a content of 0.03% by cement mass, HO-G provided 28.62 and 21.19% enhancements of compressive strength and 3.85 and 7.89% enhancements of flexural strength at 3 and 28 days, respectively, while the non-steady-state migration coefficient decreased by 31.51% compared to the reference mortar. Compared to GO, a lower dosage of HO-G exhibited a similar reinforcing effect to cement composites with little adverse impact on the fluidity of the fresh cement slurry. Moreover, the addition of HO-G could refine the pore structure, accelerate the hydration process of cement to some degree, and generate more hydration products so that the structure of the cement mortar was densified. Considering its environmentally friendly preparation, HO-G, as a promising reinforcing nanofiller, could provide a new solution to develop nanoengineered cement composites.

Dataset Information

Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites.

Publications

Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites.

Similar Datasets

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