Influence of slag content and water-binder ratio on leaching behavior of cement pastes

•Slice specimens with slag-cement paste were designed to carry out the calcium leaching experiment.•Influences of slag content and water-binder ratio on the leaching resistance of cement pastes were investigated.•The slag-cement pastes with the optimum leaching resistance were obtained. In order to...

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Bibliographic Details
Published in:Construction & building materials 2016-12, Vol.129, p.61-69
Main Authors: Tang, Yu-Juan, Zuo, Xiao-Bao, He, Shao-Li, Ayinde, Olawale, Yin, Guang-Ji
Format: Article
Language:English
Subjects:
Analysis
Calcium leaching
Cement
Composition
Leaching
Microstructure
Porosity
SEM
Slag content
Slag-cement pastes
Water-binder ratio
XRD
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Summary:•Slice specimens with slag-cement paste were designed to carry out the calcium leaching experiment.•Influences of slag content and water-binder ratio on the leaching resistance of cement pastes were investigated.•The slag-cement pastes with the optimum leaching resistance were obtained. In order to obtain quickly the influences of blast furnace slag and water-binder ratio on the leaching behavior of cement-based material and its corrosion resistance in water environments, an accelerated calcium leaching experiment on a slice specimen with slag-cement pastes in 6M NH4 Cl solution was carried out. Using the saturation-drying weighing method, X-ray diffraction (XRD) and the scanning electron microscope (SEM/EDS) measurement, the influences of water-binder ratio and slag content on the porosity, phase composition, microstructure morphology and Calcium-Silicon ratio of slag-cement pastes in the process of calcium leaching were analyzed. Results show that, compared to cement pastes without slag, the slag-cement paste with the appropriate slag content has a low rate of microstructure deterioration and a good leaching resistance. The optimum slag contents in slag-cement pastes are respectively 40% and 50% corresponding to the low and high water-binder ratio. The porosity, Calcium-Silicon ratio and microstructure morphology of slag-cement pastes exhibit small change in the process of accelerating leaching, and this indicates that the slag-cement pastes with the optimum slag content can provide the best performance of calcium leaching resistance in the soft-water environment.
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2016.11.003