Evaluation of Circular Texture Meter for Measuring Surface Texture of Pavements (05-1981) - MP-57**
Brian D. Prowell, Advanced Materials Services, LLC
Doug I. Hanson, No Organization

The CT Meter is a laser based device for measuring the mean profile depth (MPD) of a pavement at a static location. Both MPD measurements from the CT Meter and mean texture depth (MTD) measurements from the sand patch test were obtained in five random locations in each of 45 section 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 (SMA) and Novachip. Testing indicated that CT Meter produced comparable results to the ASTM E965 Sand Patch Test. When open-graded mixtures were excluded, this study indicated that the offset was non-significant 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 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 percent. The between lab coefficient of variation for the CT Meter is estimated to be 4.2 percent. Both estimates are based on the average of two tests being reported as a single measurement. This indicates that the CT Meter is more variable than the sand patch test. However, less technician skill is required to operate the CT Meter.