Levich Institute Seminar Announcement, 02/24/2015
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Shiho Kawashima
Department of Civil Engineering and Engineering Mechanics
"Characterizing the Thixotropy of Cement-Based Systems"
Over its lifetime, cement-based materials transition from behaving as a near-Newtonian fluid to a viscoelastic fluid/solid to eventually a rock-like solid. And although the first two phases are fleeting compared to the third phase, this earlier life period is intimately tied to materials processing. Therefore the corresponding properties are critical in determining the efficiency of the placement process during construction, as well as the eventual performance of the structure in place. This requires that the rheological properties of the material be well characterized and controlled. During placement the material undergoes a wide range of deformations – very large during processes such as pouring and pumping, but then diminishingly small after placement when it is essentially at rest. And the flow behavior of cement-based materials is significantly affected by aging (due to the continuous progression of cement hydration) and shear history (due to particle rearrangement within the suspension). This talk will cover studies that investigate the specific rheological aspect of thixotropy in cement paste and mortar systems that incorporate highly-purified attapulgite clay through static shear and dynamic rheological protocols that span wide timescales and magnitudes of deformations and rates.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
MS, PhD Structural Engineering and Materials, Northwestern University
Assistant Professor of Civil Engineering and Engineering Mechanics, Columbia University
RECENT RESEARCH INTERESTS
Cement and concrete rheology - thixotropy, mortar systems, pressure/temperature effects