CORRELATION STUDY OF CALIFORNIA PROFILOGRAPH AND K. J. LAW PROFILOMETER

The Arizona Department of Transportation (ADOT) uses the California profilograph and the K.J. Law 690 DNC profilometer for measuring pavement roughness. However, ADOT has not used the K.J. Law profilometer on portland cement concrete (PCC) pavement construction contracts because the current smoothness specifications are given in terms of the California profilograph index (PRI). This study was initiated to determine the feasibility of including the K.J. Law profilometer as one of the principal devices for testing PCC pavement surface smoothness. To accomplish that objective (a) PCC pavement sections were selected for use in the testing of the K.J. Law profilometer and the California profilograph, (b) pavement roughness data were obtained from the selected sections by both the profilometer and profilograph, and (c) correlation analysis was conducted for the two types of devices. It was found from this study that (a) between three and five replicates are required to obtain a good estimate of the PRI and (b) a good linear relationship is obtainable for the mean values of profilometer Mays index and PRI and also between the profilometer international roughness index and PRI values. On the basis of this study, it was concluded that (a) the California profilograph and the K.J. Law profilometer can be linearly correlated, (b) it is feasible to calibrate the California profilograph by the profilometer, (c) the profilometer must be calibrated first before it can be used to calibrate profilographs, and (d) it is not practical to interchangeably use the profilometer and profilographs because each device is more suited for some jobs than others.