Levich Institute Seminar Announcement, 09/06/2005

Tuesday, 09/06/2005
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Kolluru V Subramaniam
City College of CUNY
Civil Engineering Department


"Ultrasonic Assessment Of State Transformation and Early Age Viscoelastic Properties Of Cementitious Materials"

ABSTRACT

Cementitous materials are transformed from a fluid to a solid state due to a chemical reaction known as hydration. These materials exhibit a continuous change in the mechanical properties with time; there a continuous change in the loss and storage moduli with time before setting and a steady increase in the elastic material properties of the hardening solid cementitous material after setting. An ultrasonic test setup and data analysis procedures, which provide for continuous monitoring of the hydrating cementitous materials from a very early age, have recently been developed. The test procedures for obtaining the ultrasonic test data and the inversion subroutines for assessing the material properties of the cementitous material at different stages of hydration are discussed. Experimental test results obtained from a mortar mixture of known composition are presented. The progressive development of the frequency dependent material properties of the mortar, particularly the shear moduli, G' and G", are shown as a function of time from a very early age.

BRIEF ACADEMIC/EMPLOYMENT HISTORY

Dr. Subramaniam is currently an Associate Professor in the Civil Engineering Department at the City College of New York (CCNY), where his principal research is in the area of Structural materials and Mechanics. Prior to joining the faculty at CCNY, Dr. Subramaniam completed his doctoral research at Northwestern University, Evanston, IL. After graduation, Dr. Subramaniam worked as a Research Associate at the Center for Advanced Cement Based Materials, Northwestern University, where he participated in studies on early-age property development of hydrating cement-based materials. Dr. Subramaniam was awarded the NSF early CAREER Grant for investigating the early-age changes in cementitious materials. He is the recipient of the James Instrument Award from the American Concrete Institute for his research on nondestructive evaluation of material property development in cement-based materials.