Premium
Repulsive hydration forces between calcite surfaces and their effect on the brittle strength of calcite‐bearing rocks
Author(s) -
Røyne Anja,
Dalby Kim N.,
Hassenkam Tue
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064365
Subject(s) - calcite , brittleness , mineralogy , nanometre , mineral , geology , materials science , composite material , metallurgy
The long‐term mechanical strength of calcite‐bearing rocks is highly dependent on the presence and nature of pore fluids, and it has been suggested that the observed effects are due to changes in nanometer‐scale surface forces near fracture tips and grain contacts. In this letter, we present measurements of forces between two calcite surfaces in air and water‐glycol mixtures using the atomic force microscope. We show a time‐ and load‐dependent adhesion at low water concentrations and a strong repulsion in the presence of water, which is most likely due to hydration of the strongly hydrophilic calcite surfaces. We argue that this hydration repulsion can explain the commonly observed water‐induced decrease in strength in calcitic rocks and single calcite crystals. Furthermore, this relatively simple experimental setup may serve as a useful tool for analyzing surface forces in other mineral‐fluid combinations.