TY - JOUR
T1 - Yield stress measurements of mud sediments using different rheological methods and geometries
T2 - An evidence of two-step yielding
AU - Shakeel, Ahmad
AU - Kirichek, Alex
AU - Chassagne, Claire
PY - 2020
Y1 - 2020
N2 - Yield stress materials have a wide range of commercial applications. Yet, the suitable way of determining the yield stress values of a given material has been the subject of many studies and debates. Yield stresses are dependent on the material (shear) history and composition, which implies that robust protocols should be developed to study the yield stress dependence on a given parameter. In this study, three natural mud samples from a port having different densities were chosen for analysis. Four different geometries including concentric cylinders (Couette), cone and plate, parallel plates, and vane geometries were used. Our aim was to find the geometry and measurement protocol that best adapted to natural mud samples: the measurement should be reasonably fast and the major changes in sample structure (two-step yielding) should be recorded within the same measurement. Various rheological experiments such as stress sweep, oscillatory amplitude sweep, creep and stress growth tests were tested. Two-step yielding behavior was observed for the mud samples in stress sweep and amplitude sweep tests. The first yield point was linked with the breakage of interconnected network of aggregates/flocs while the second one was attributed to the collapse of aggregates into the smaller flocs or individual particles. Stress sweep tests proved to be practical, time efficient, and reliable tests for measuring yield stress values. Our study showed that Couette and parallel plate geometries are the most suitable geometries for analyzing the two yield stresses of the samples. Vane geometry is appropriate to study consolidated (solid-like) systems as for these samples a Couette geometry cannot be used because the bob could get stuck during the experiment.
AB - Yield stress materials have a wide range of commercial applications. Yet, the suitable way of determining the yield stress values of a given material has been the subject of many studies and debates. Yield stresses are dependent on the material (shear) history and composition, which implies that robust protocols should be developed to study the yield stress dependence on a given parameter. In this study, three natural mud samples from a port having different densities were chosen for analysis. Four different geometries including concentric cylinders (Couette), cone and plate, parallel plates, and vane geometries were used. Our aim was to find the geometry and measurement protocol that best adapted to natural mud samples: the measurement should be reasonably fast and the major changes in sample structure (two-step yielding) should be recorded within the same measurement. Various rheological experiments such as stress sweep, oscillatory amplitude sweep, creep and stress growth tests were tested. Two-step yielding behavior was observed for the mud samples in stress sweep and amplitude sweep tests. The first yield point was linked with the breakage of interconnected network of aggregates/flocs while the second one was attributed to the collapse of aggregates into the smaller flocs or individual particles. Stress sweep tests proved to be practical, time efficient, and reliable tests for measuring yield stress values. Our study showed that Couette and parallel plate geometries are the most suitable geometries for analyzing the two yield stresses of the samples. Vane geometry is appropriate to study consolidated (solid-like) systems as for these samples a Couette geometry cannot be used because the bob could get stuck during the experiment.
KW - Mud sediments
KW - Oscillatory measurements
KW - Rheology
KW - Steady measurements
KW - Two-step yielding
KW - Yield stress
UR - http://www.scopus.com/inward/record.url?scp=85085732624&partnerID=8YFLogxK
U2 - 10.1016/j.margeo.2020.106247
DO - 10.1016/j.margeo.2020.106247
M3 - Article
AN - SCOPUS:85085732624
SN - 0025-3227
VL - 427
SP - 1
EP - 12
JO - Marine Geology
JF - Marine Geology
M1 - 106247
ER -