SEDIMENT MECHANICS LAB
View of the Sediment Mechanics Laboratory
Chamber of the uniaxial load frame
Laser particle size analyzer
Student picking foraminifera
Student mixing sediment slurry for resedimentation experiment
Growing bacteria from pore fluid on petri dishes
Resedimentation is a technique to simulate the natural processes of sedimentation and burial under controlled laboratory conditions. Initially, sediment samples must be ground into a dry powder using a mortar and pestle for homogenization (a). Water is added to create a slurry (b). Peat, bacteria, microfossils, and other material may be added to the slurry to examine their influence on intrinsic mechanical properties of mudstones. The slurry is poured into a consolidometer (c) and weights are incrementally loaded onto the consolidometer to add pressures up to 100 kPa (d). Different weights represent different pressures mudstones are subjected to in nature.
UNIAXIAL COMPRESSION TESTS
A Sigma-1 load frame by GeoTac is used to perform constant-rate-of-strain (CRS) consolidation tests according to ASTM D4186-06 guidelines in order to compress samples beyond the resedimentation stress of 100 kPa. We use a 10 klb load capacity load frame, a software-controlled pump, and pressure transducers rated to 300 psi. During CRS tests we obtain a continuous data set of stress, porosity (void ratio), compressibility, and permeability up to 10s of MPa. We also have the ability to perform flow-through permeability tests.
LASER PARTICLE SIZE ANALYZER
The Malvern Mastersizer 3000 is a laser diffraction system measuring particle size between 0.01 - 3500 microns using a single lense range. Therefore, this system is good for a variety of sediments. The Hydro EV sample dispersion unit is designed for applications with larger sample volumes and works well for clays.
A Rigaku Miniflex 600 benchtop X-ray diffraction analyzer is used for mineral identification and quantification in bulk and clay-sized sediment samples. It can determine phase identification and quantification, percent (%) crystallinity, crystallite size and strain, lattice parameter refinement, Rietveld refinement, and molecular structure.
SCANNING ELECTRON MICROSCOPY
The Phenom XL Scanning Electron Microscope (SEM) focuses electron beams on samples and analyzes the resulting signature (secondary electrons emitted) to produce high-resolution images of the surface topography of samples. Resulting images can be further analyzed for chemical composition (energy dispersive X-ray spectroscopy, EDS).
The Olympus BX53M allows workers to digitally image thin sections of rock and sediment samples while using standard reflected and transmitted light microscopy techniques. Different observation methods utilize brightfield, darkfield, polarized light, fluorescence, transmitted light, and more. The microscope is equipped with a camera and connects to a computer for further analysis of digital images. The scope champions precision optics through wave front aberration control, stable color temperature, high-intensity white LED illumination, auto calibration, and image shading control.