Study of Void Detection Methods and Slab Stabilization Procedures

摘要

The report covers the evaluation of static deflection testing, Falling WeightDeflection (FWD) testing, and a short-pulse radar system (Penetradar Inc.) for locating and/or measuring the thickness of voids underneath a jointed reinforced concrete pavement (JRCP). All three methods were evaluated in June 1986 on a section of SR 80 in Union County. These void detection tests were conducted prior to the performance of concrete pavement restoration on the existing pavement. Analysis of the data reveals that the transverse joints were probably locked during testing. Thus, the validity of the deflection data obtained at this time appears to be in question. For 13 joints and cracks, grout takes were correlated with the area of the subsurface voids indicated in the Penetradar survey. No correlation was found to exist between void area and grout take. In 1986, Penetradar Inc. completed 146 lane miles of a short-pulse radar survey on SR 79 in Mecer and Crawford Counties. PennDOT personnel cored 25 locations where the survey had indicated the presence of subsurface voids. 23 of these cores had at least 0.125 inches in thickness. At cored void thicknesses equal to or less than 0.375 inches, the void thickness indicated by the Penetradar survey was usually within 0.150 inches of the cored void thickness. For cored void thicknesses in excess of 0.375 inches, the radar survey usually underestimated void thicknesses by at least two to one.