High Friction Surface Treatment Deterioration Analysis and Characteristics Study

Abstract

High friction surface treatment (HFST) is used to improve friction on curved roadways, especially on curves that have a history of wet pavement crashes. Observations on the long-term performance monitoring of HFST sections at the National Center for Asphalt Technology (NCAT) Test Track showed friction (skid number, SN) dropped significantly at the end of service life of HFST, creating unsafe driving conditions. There is no clear, observed friction deterioration trend to predict the friction drop when using friction performance measures like SN. Therefore, there is an urgent need to explore and develop supplementary HFST safety performance measures (such as aggregate loss) that can correlate to friction deterioration and provide predictable, cost-effective, and easily measurable results. The objectives of this paper are to (i) analyze the correlation between HFST aggregate loss percentage area and friction value using a dynamic friction tester (DFT), and (ii) study the characteristics of HFST deterioration associated with aggregate loss, at the NCAT Test Track and at selected HFST curve sites in Georgia (using 2D imaging and high-resolution 3D laser scanning). Results show a strong correlation between HFST aggregate loss percentage area and DFT friction coefficient. Where friction measurement is used as the primary safety performance measure, it is recommended that HFST aggregate loss be used as a supplementary performance measure for monitoring the HFST safety performance deterioration. Aggregate loss can be easily identified by characteristics such as color and texture change. Preliminary texture analyses of 3D HFST surface profiles show lower mean profile depth (MPD) and ridge-to-valley depth (RVD) texture indicators can also identify loss of aggregate spots on HFST surface.

Comprehensive Framework and Roadmap for Life-Cycle Management of High-Friction Surface Treatments

“…The subjectivity challenge can be addressed using 3D pavement-scanning technologies that can be used objectively to assess aggregate loss and other distresses based on texture characteristics. The observed relationship between highlighted texture parameters and DFT friction shows that texture parameters (including traditional mean profile depth, ridge to valley depth, and HFST topography-based parameters, such as average height, angularity, and density) are promising for detecting poor (low) HFST friction performance and can potentially predict low friction concerns on HFST sites (3,11). Thus, state transportation agencies can leverage their 3D pavement-scanning technologies (that state DOTs have already used to collect 3D pavement data) to cost-effectively and regularly monitor HFST friction deterioration.…”

“…The authors have performed studies at the NCAT test track to study the characteristics of HFST aggregate loss and its relationship with friction. The authors (a) identified HFST aggregate loss characteristics (based on appearance and surface texture), including the color contrast between HFST surfaces and their background pavement colors and changes in 3D macrotexture ( 3 ), (b) characterized HFST aggregate loss using quantitative parameters, such as aggregate loss areas derived from color contrast and 3D surface macrotexture parameters derived from topographical properties (such as aggregate height, shape, and density [ 11 ]), and (c) revealed a strong correlation between DFT friction and aggregate loss areas, and, also, a strong correlation between friction (DFT60) and 3D macrotexture parameters. The authors’ study provides sufficient evidence to conclude that HFST friction deterioration is largely controlled by HFST aggregate loss and change in macrotexture.…”

“…Based on the friction performance monitoring at the HFST site at NCAT, it is observed that there were no clear deterioration trends (based on skid number readings measured with locked-wheel skid testers) before the HFST deteriorated substantially ( 3 ). Consequently, historical friction values (measured with DFT or locked-wheel skid testers) alone may not be sufficient to provide advance warning of potential HFST deterioration to the transportation agencies for taking timely corrective actions.…”

“…HFST can maintain good long-term friction performance. However, the friction performance can deteriorate rapidly toward the end of its life ( 3 ). This deterioration can be caused by end-of-life aggregate loss (caused by age-related reduction in the resin binder’s binding capacity in addition to vehicle shear forces acting on the HFST surface).…”

“…Substantial aggregate loss on wheel paths exposes the smooth epoxy/resin binder layer, resulting in large friction reduction. It is noted that friction compromising aggregate loss can also occur shortly after construction because of poor surface preparation, incorrect binder formulation, insufficient binder thickness, or insufficient aggregate embedment depth ( 3 ).…”