Bentonite based suspensions, which derive their particular flow properties from the characteristics of the smectite minerals (in particular montmorillonite), which are their primary components, have traditionally been the most common materials used in trenchless technology.

At the concentrations typically employed in geotechnical applications, bentonite dispersions form gels which exhibit complex rheological properties. The micrographs above obtained using cryo-scanning electron microscopy show an example of the long range order cellular structure that forms an  “attractive” gel.

SEM imaging by Debby Sherman – Purdue Life Science Microscopy Facility

Assistant Professor Marika Santagata of the Geotechnical Engineering group was awarded this month the CAREER award, the National Science Foundation's most prestigious honor for young researchers.

Professor Santagata will utilize this five year grant to conduct work on the rheological behavior and performance of Na-montmorillonite based fluids employed in trenchless technology (microtunneling, pipejacking, and horizontal directional drilling). These fluids play a critical role in the construction and rehabilitation of underground utility infrastructures, the total length of which is estimated to exceed 20 million miles in the United States alone.

The focus of the work, which is designed around rheological element tests, micro-structural observations, and laboratory scale physical model tests, will be to develop a framework for fluid selection and evaluation that links the fundamental mechanical properties of these fluids to their performance in their primary functions: lubrication, filtration control, and cutting/spoil transport.

This work builds on previous research on the rheology and microstructure of clay based dispersions conducted by Professor Santagata and two of her students thanks to another NSF grant

Professor Santagata and her research students in Summer 2004. In the front row third from the left, Wendell Solomon (MSCE 2006) and to his left David Geier (MSCE 2004) worked on the rheology of Na-montmorillonite dispersions.

The CAREER award is intended to aid the “early career-development activities of those teacher-scholars who most effectively integrate research and education”. As such, the research plan incorporates strategies to promote participation of undergraduate students in the research, integrate the research results in the undergraduate and graduate curriculum, and provide the graduate students involved with opportunities to interact with industrial partners.

Professor Santagata joined the School of Civil Engineering in 2000. She received her Laurea in Civil Engineering from the University of Ancona in Italy, and masters and Ph.D. degrees in Civil and Environmental Engineering from MIT.

For announcement on NSF web site view #0644915, "CAREER: Linking Rheology to Performance – An Integrated Approach to the Evaluation and Design of Trenchless Technology Fluids."