The Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher education institutions and industry in Indiana to facilitate innovation that results in continuous improvement in the planning, design, construction, operation, management and economic efficiency of the Indiana transportation infrastructure. https://engineering.purdue.edu/JTRP/index_html AbstractThis report concerns a feasibility study on the use of a non-destructive and non-invasive method to determine the size distribution of air voids in fresh concrete, which will be used for laying concrete pavement. A preliminary review of different techniques suggested that the measurement of the p-wave velocity of ultrasound pulses transmitted through a fresh concrete specimen offers the most straightforward approach. This report describes an experimental study to address the design of an experimental test rig, the selection of appropriate equipment, and the determination of the p-wave velocity in fresh cementitious materials. The paper starts with the ultrasound characterization of fresh cement and mortars. Then, the feasibility of using the ultrasound method to determine the air-void content in a fresh concrete specimen with a minimum thickness of 4" is examined. In addition to the discussions of the ultrasound characterization of fresh cementitious materials, this paper also reports on the development of a suite of MATLAB programs to characterize the air-void systems of hardened cementitious materials. The approach is based on image processing techniques used to analyze digital images of polished specimens collected with a flatbed scanner. The results will provide pertinent information on the airvoid systems in hardened cementititous materials. 17.

In an earlier study [K. M. Li, J. Acoust. Soc. Am. Soc. 123, 1352–1363 (2008)], an analytical expression has been derived to predict the penetration of sound into a rigid porous ground due to a monopole source. In the present study, this analytical formula has been exploited for a numerical method to characterize the acoustical properties of rigid porous materials. They can be obtained from a pair of excess attenuation spectra measured above and below a thick layer of the material. Specifically, its propagation constant and complex density ratio can be determined from the measured data by a downhill simplex method. A series of preliminary indoor measurements was conducted in an anechoic chamber for measuring the propagation of sound above and below a layer of glass beads of different sizes. Based on the measured excess attenuation spectra, the acoustical characteristics of two different sizes of glass beads were determined numerically. These acoustical parameters were compared with the predictions based on the classical impedance model.