Material invariant properties and reconstruction of microstructure of sandstones by nanoindentation and microporoelastic analysis

The diversity of sandstones and sandstone properties that exist in nature pose a significant problem for engineers who deal with these materials, whether in oil well exploration and exploitation or art and architectural conservation. The solution proposed in this thesis takes a highly reductionist approach to the problem. Properties of the sandstone material are first reduced to material invariant properties of the material phases present in sandstone. These are universal constants which do not vary from one sample to the other. From these material invariants, it is then possible to 'nanoengineer' the properties of a specific sandstone sample based only on a few easily measured properties - the volume fractions of the material phases. To help identify material invariant phases and reconstruct microstructure, a multi-scale think model for sandstone is developed from ESEM images as well as from the results of mineralogy, grain size, and porosimetry experiments. A nanoindentation campaign is performed to characterize sandstones at multiple scales and an innovative technique is used to separate the various indentation responses that can occur on a heterogeneous composite. Material invariant phase properties are obtained for both the sand grains and the clay minerals. A new technique for estimating volume fractions of composite materials using nanoindentation is developed and verified. Clay stiffnesses are found to be highly dependent on microstructure rather than on mineralogy, and material invariant properties are proposed. A comparison of models to estimate elastic and poro-elastic properties reveal shortcomings that motivate the development of a new predictive model.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Bobko, Christopher Philip, 1981-

Advisor dc:contributor.advisor

• Franz-Josef Ulm.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/31147

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/31147