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Microscale insight into the influence of humidity on the mechanical behavior of mudstones
Author(s) -
Wang Linlin,
Bornert Michel,
Héripré Eva,
Chanchole Serge,
Pouya Ahmad,
Halphen Bernard
Publication year - 2015
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2015jb011953
Subject(s) - microscale chemistry , wetting , materials science , humidity , composite material , relative humidity , capillary action , micromechanics , moisture , digital image correlation , modulus , shear (geology) , geotechnical engineering , geology , composite number , thermodynamics , mathematics education , mathematics , physics
Abstract The mechanical behavior of mudstones strongly depends on humidity. In this paper, we present some microstructural insights into this phenomenon gained from a microscale investigation using a novel experimental method. The experimental method consists of combined hydric and mechanical loading tests in environmental scanning electron microscopy, as well as full‐field strain measurement by digital image correlation techniques. The sample is subjected to a stepwise wetting (21%, 80%, and 99% relative humidity); for each equilibrium moisture state, a uniaxial compression test is performed. The microscale observation reveals that humidity‐induced changes in the mechanical behavior of mudstones are controlled by the deformation and microcracking upon wetting. With increasing relative humidity, expansion of pores causes the clay matrix to be softer. In addition, because of the reduction in shear modulus and the lessening of capillary effect, shear bands are prone to appear at a high humidity state. The microcracking upon wetting, which results in predamage of the material, also affects the mechanical behavior. Finally, the sample with more moisture exhibits a more ductile behavior that involves more pronounced microcracking at failure.