The gradual evolution of the material properties of a cement-based material, i.e. the stiffness of cement paste, is the result of the continuous change of the microstructure with the progress of the hydration process. Based on an existing micromechanical model for the simulation of the shear and elastic modulus of...
This presentation contains information on the keynote paper "Health Monitoring of Early Age Concrete". The presentation was delivered by Surendra P. Shah at CONSEC'04 in Seoul, Korea on June 30, 2004.
Experimental Time Domain Reflectometry (TDR) data obtained from the field are compared with numerical simulations using a finite-difference solution of the transmission line equations. The model simulates transmission of a voltage pulse along a lossy coaxial cable where deformities on the cable, such as crimps and shears, are represented by...
Time Domain Reflectometry (TDR) is a versatile technology amenable to a variety of measurements and nondestructive monitoring of infrastructure conditions. It can be utilized to monitor deformation of soil/rock and structures, monitor changes in fluid levels, and monitor water content of soils. Furthermore, this monitoring can be automated using systems...
Two longwall coalmine panels were mined at a depth of approximately 156 m (510 ft) beneath I-70 east of Washington, Pennsylvania such that it crossed the width of one panel at two locations. The Pennsylvania Department of Transportation (PennDoT) assumed responsibility for real time monitoring of both ground deformation and...
This paper reviews the new field of geo-measurement with metallic cable time domain reflectometry (TDR) for surveillance of transportation facilities. TDR is radar in a coaxial cable, and is especially advantageous for remote monitoring because of its inherently digital nature. Advances can be separated into those that leverage use of...
This file contains power-point slides of Application to Crossbow’s Smart Dust Challenge Contest, title "Wireless Data Acquisition System" by Mat Kotowsky and Hasan Ozer. The presentation was delivered at University of California, Berkeley on February 11, 2005.
This paper describes qualification of devices to measure sub micro-meter changes in crack width, which is the basis of autonomous crack monitoring for control of blasting vibrations. Performance of LVDT, eddy current and potentiometer sensors to monitor long-term and transient displacements will be described. Potentiometers are attractive for wireless measurement,...
Miniaturized, wireless instrumentation is now a reality and this thesis describes development of such a system to monitor crack response. Comparison of environmental (long-term) and blast-induced (dynamic) crack width changes in residential structures has lead to a new approach to monitoring and controlling construction vibrations. In wireless systems transducer power...