TY - JOUR
T1 - X-ray microtomography shows pore structure and tortuosity in alkali-activated binders
AU - Provis, John L.
AU - Myers, Rupert J.
AU - White, Claire Emily
AU - Rose, Volker
AU - Van Deventer, Jannie S.J.
N1 - Funding Information:
This work was funded by the Australian Research Council (ARC) , including some funding through the Particulate Fluids Processing Centre , a Special Research Centre of the ARC , and also via a Linkage Project grant co-sponsored by the ARC and Zeobond Research . Travel funding for J.L. Provis to conduct experimental work at Argonne National Laboratory was provided by the Banksia Environmental Foundation through the award of the Brian Robinson Fellowship. We also thank Adam Kilcullen for his assistance in conducting the sample synthesis, and Dr Xianghui Xiao and Dr Francesco de Carlo for assistance in the data collection and processing on the 2BM instrument. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. Special thanks are also due to Dr Y. Nakashima and Dr S. Kayima, the authors of reference [34] , as their freely available Mathematica 5.2 scripts Clabel.nb , Pre_Rwalk_image.nb and Rwalk.nb were instrumental in enabling the tortuosity calculations presented in this study, and to an anonymous reviewer for insightful comments which have helped to improve the manuscript.
PY - 2012/6
Y1 - 2012/6
N2 - Durability of alkali-activated binders is of vital importance in their commercial application, and depends strongly on microstructure and pore network characteristics. X-ray microtomography (μCT) offers, for the first time, direct insight into microstructural and pore structure characteristics in three dimensions. Here, μCT is performed on a set of sodium metasilicate-activated fly ash/slag blends, using a synchrotron beamline instrument. Segmentation of the samples into pore and solid regions is then conducted, and pore tortuosity is calculated by a random walker method. Segmented porosity and diffusion tortuosity are correlated, and vary as a function of slag content (slag addition reduces porosity and increases tortuosity), and sample age (extended curing gives lower porosity and higher tortuosity). This is particularly notable for samples with ≥ 50% slag content, where a space-filling calcium (alumino)silicate hydrate gel provides porosity reductions which are not observed for the sodium aluminosilicate ('geopolymer') gels which do not chemically bind water of hydration.
AB - Durability of alkali-activated binders is of vital importance in their commercial application, and depends strongly on microstructure and pore network characteristics. X-ray microtomography (μCT) offers, for the first time, direct insight into microstructural and pore structure characteristics in three dimensions. Here, μCT is performed on a set of sodium metasilicate-activated fly ash/slag blends, using a synchrotron beamline instrument. Segmentation of the samples into pore and solid regions is then conducted, and pore tortuosity is calculated by a random walker method. Segmented porosity and diffusion tortuosity are correlated, and vary as a function of slag content (slag addition reduces porosity and increases tortuosity), and sample age (extended curing gives lower porosity and higher tortuosity). This is particularly notable for samples with ≥ 50% slag content, where a space-filling calcium (alumino)silicate hydrate gel provides porosity reductions which are not observed for the sodium aluminosilicate ('geopolymer') gels which do not chemically bind water of hydration.
KW - Alkali activated cement (D)
KW - Microstructure (B)
KW - Transport properties (C)
KW - X-ray microtomography
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U2 - 10.1016/j.cemconres.2012.03.004
DO - 10.1016/j.cemconres.2012.03.004
M3 - Article
AN - SCOPUS:84861190560
SN - 0008-8846
VL - 42
SP - 855
EP - 864
JO - Cement and Concrete Research
JF - Cement and Concrete Research
IS - 6
ER -