Better Roads

July 2014

Better Roads Digital Magazine

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RoadScience 8 July 2014 Better Roads provides a long-lasting, noise-reducing surface texture for concrete pavement. "[NGCS] is a diamond saw-cut surface designed to provide a consistent profile absent of positive or upward texture, resulting in a uniform land profile design with a predomi- nantly negative texture," IGGA says in its tech brief, Next Gen- eration Concrete Surface. "Conventional diamond-ground surfaces produce a positive or upward texture, although they are still quieter than most other concrete pavement surface textures." Thus the NGCS is predominantly a level (land) surface with grooves, in different configurations for different end re- sults, rather than a surface with closely spaced parallel ridges featuring irregular "fins." "The texture is most easily constructed in a two-pass opera- tion using diamond-tipped saw blades mounted on conven- tional diamond grinding and grooving equipment," IGGA says. "Testing has shown that these textures can be used for both new construction and rehabilitation of existing surfaces." Refinement of the NGCS continues. At the January 2014 Transportation Research Board (TRB) meeting in Washing- ton, D.C., researchers described an automated groove iden- tification and measurement methodology that can reliably judge surface/groove conditions as the NGCS ages. "Since the grooved texture may deteriorate over time, the measurement of groove dimensions becomes an indispensable tool for NGCS's long term performance evaluation," say Kelvin C. P. Wang, Lin Li, Qiang Joshua Li, and Paul Tikalsky, P.E., Oklahoma State University-Stillwater, and Larry Scofield, P.E., IGGA, in their peer-reviewed paper, Automated Groove Identification and Measurement for Next Generation Concrete Surface (NGCS) Using 3D Pavement Data at 1mm Resolution. "The NGCS surface is the new non-porous concrete tex- ture introduced in the last 20 to 30 years, which is a hybrid texture that resembles a combination of diamond grind- ing and longitudinal grooving for concrete pavement," the authors say. "Since October of 2007, there are 17 surfaces in 10 states in which evaluation of its performance is ongoing. Some of the NGCS sections are monitored to evaluate their effectiveness in noise reduction and safety improvement over time. The presence of the downward or negative texture can decrease tire-pavement noise by 6 dBA, which is equivalent to 75 percent of noise reduction." Traditional point laser-based profiling system is used to measure pavement transverse grooves, the authors write. "However, this technique is incapable of evaluating longitu- dinal grooves that are used in NGCS," they say. Alternatively, they propose an automated groove identification and mea- surement methodology for NGCS using 1mm resolution 3D pavement surface data collected from the recently developed PaveVision3D Ultra System. "A template-matched groove identification algorithm is proposed to detect and identify the longitudinal grooves for NGCS," they say. "Subsequently, the groove dimensions are estimated based on an established procedure. Comparing the constructed NGCS groove dimensions with the esti- mated dimensions derived from this research, it is demon- strated that the proposed algorithm is robust in detecting longitudinal NGCS grooves and estimating their dimensions. Further research is anticipated to investigate the groove dimensions on NGCS's noise level and safety performance over time." Read about shot blast texturing at I-440 concrete pavement preservation project near Nashville included 350,000 square yards of diamond grinding and grooving. Photo courtesy of International Grooving and Grinding Association Ames Engineering of Ames, Iowa, conducted profile testing of three lanes in both directions of Chicago's I-290, the Eisenhower Expressway, between Austin Avenue and Sacramento Boulevard after diamond grinding (as shown here) was done in 2010. The profile testing was conducted to compare the stone matrix asphalt ride qualities with those of the conventional diamond-ground pavement. Photo courtesy of International Grooving and Grinding Association

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