Abstract:
The circular texture (CT) meter is a laser-based device for measuring the mean profile depth (MPD) of pavement at a static location. MPD measurements from the CT meter and mean texture depth measurements from the sand patch test were obtained in five random locations in each of 45 sections of the 2000 National Center for Asphalt Technology (NCAT) test track. The NCAT test track provides a wide range of surface types, including coarse and fine dense graded Superpave® mixes, Hveem mixes, stone mastic asphalt, and Novachip. Testing indicated that the CT meter produced results comparable with the ASTM E965 sand patch test. When open-graded mixtures were excluded, this study indicated that the offset was nonsignificant between CT meter and sand patch test results. Previously developed equations to predict macrotexture were found to be inadequate for the wide range of mix types and aggregate types found at the NCAT test track. An equation was developed to relate fineness modulus to macrotexture. This equation was validated with independent data collected by the Virginia Transportation Research Council. Testing conducted as part of a mini round robin indicated that two readings should be averaged to represent a single CT meter measurement. The within-lab coefficient of variation for the CT meter is estimated to be 2.3%. The between-lab coefficient of variation for the CT meter is estimated to be 4.2%. Both estimates are based on the average of two tests being reported as a single measurement.
