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Research InterestsAir-coupled surface wave measurement The conventional
stress wave based NDT methods for concrete are limited by slow testing speed due
to surface coupling between the sensors and rough surface of concrete. The
air-coupled sensing technique provides a solution to this problem. In my
previous research, I successfully developed an air-coupled sensing method to
measure surface wave velocity in concrete structures, soils and asphalt
pavements. By avoiding surface contact, it significantly improves test
efficiency and consistency in surface wave velocity measurements, such as
SASW and MASW tests. Since I joined UT, I continued this research and
extended it to surface wave transmission measurement. Wave transmission
contains more information about internal defects than the velocity
measurement and is sensitive to small defects and early stage damage. One
specific problem I am working on is using the surface wave transmission
method to determine the depth of a surface-breaking crack in solids. Although
this problem has been studied since the 1980s, researchers obtained
inconsistent numerical and experimental results with no clear reasons for the
inconsistency. After extensive
experimental measurements and numerical analysis, we found that the
inconsistency is due to near-field scattering by the crack. By arranging
sensors in the far-field and using air-coupled sensors, consistent surface
wave transmission curves are obtained.
Our findings have been reported in a paper accepted for publication at
the Journal of Acoustical Society of America.
Charactering early age cementing materials
using ultrasonic waves Increasing use
of highly engineered concretes, such as self-consolidating concrete and
ultra-high performance concrete, demands more rigorous quality control and
accurate measurement techniques than conventional concrete. My research
focuses on (1) using ultrasounds to characterize early age properties of
concrete, such as setting times and rheological parameters; (2) understanding
ultrasonic wave propagation behaviors in fresh concrete (a saturated porous
solid material); (3) developing a low-cost in situ monitoring system. NDT methods for evaluation of ASR damage
in concrete Distress caused
by Alkali-Silica Reaction in concrete is a national wide problem for concrete
structures and pavements. I am
currently working on the TxDOT project 06491“Non-Destructive Evaluation of
In-Service Concrete Structures Affected by Alkali-Silica Reaction (ASR) or
Delayed Ettringite Formation (DEF),” which began in September 2009. One of
our objectives is to develop a nonlinear ultrasonic method to evaluate ASR
damage in in-service concrete structures. We are also exploring new NDT
techniques to monitor the stress level of reinforcement in concrete, in order
to predict rebar fracture caused by ASR-induced expansion.
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Department of Civil, Architectural and Environmental Engineering | School of Engineering | The University of Texas Last updated: August 22, 2010 |
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