Use of an H20 meter for determination of concrete moisture content in the field

Abstract

The ability to accurately determine concrete bridge deck moisture content could increase the probability of satisfactory performance of water repellent treatment materials through choosing favorable conditions for material application. This study was undertaken to determine whether moisture content in an existing deck slab could be accurately assessed using an available measurement device (moisture meter), and to document variations in deck moisture content in the field. The moisture meter examined was a compact device which measures the dielectric properties of the tested medium (concrete). Laboratory tests were cond?cted to evaluate the accuracy of the moisture meter, and a field study was undertaken to examine the drying properties of a bridge deck through measurements obtained using the moisture meter. Results of laboratory tests indicated that the moisture meter is not well suited to providing the needed information on absolute concrete moisture content. Considerable variability in meter readings, primarily due to the meter's sensitivity to smoothness and evenness of the concrete surface, precluded accurate measurement of moisture content. Field study measurements, which were more variable than laboratory measurements, indicated that trends in relative change of deck moisture content were reflected in moisture meter readings, provided a large number of data points were used to compute the deck's global moisture content. However, absolute moisture content could not be reliably determined from the data.