CHARACTERIZATION AND MODELING DETERIORATION OF HIGH FRICTION SURFACE TREATMENT
Author(s)
Pasupathipalayam Sivashanmugam, Cibi Pranav
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Abstract
A disproportionally high number of serious vehicle crashes occur at curves roadway sections even though curves only represent a fraction of the roadway network. High Friction Surface Treatment (HFST), composed of a thin layer of calcined bauxite aggregate on resin-binder, is used to improve friction on curved roadways, especially on curves that have a high friction demand and a history of roadway departure crashes. HFST friction deterioration, especially due to loss of aggregates and exposure of slippery epoxy, is a serious safety concern because HFST is typically used on critical locations with high friction demand. Therefore, HFST needs to be safely managed throughout its lifecycle activities including site selection, installation, operation, and maintenance to minimize potential safety risks and ameliorate its deterioration. First, this dissertation proposes a technical and managerial integrated HFST safety management framework based on a national survey, literature review, and research findings to enable transportation agencies to manage HFST systematically, safely, and cost-effectively throughout its lifecycle. Next, this dissertation provides critical research insights for the transportation agencies to implement and operationalize some of the critical modules presented in this framework by studying the real-world HFST friction deterioration behaviors, HFST aggregate loss characteristics, and the relationship between identified HFST aggregate loss characteristics and friction. To comprehensively study and understand the real-world HFST friction deterioration behavior, this research 1) developed a data analysis framework and corresponding methodologies using trend analysis, descriptive statistics, and correlation tests to analyze friction deterioration trends, spatial friction distribution, locations of low-friction sections and wheel path positions inside curves, factors affecting the spatial-temporal friction deterioration (age, traffic, curve geometry such as radius, etc.), and HFST’s end-of-life friction deterioration attributes (such as friction drop rate, etc.), and 2) presented the preliminary findings from an analysis of 30 diverse friction improvement surface treatment (FIST) curve sites in Georgia (including calcined bauxite HFST, phonolite aggregate thin polymer overlay, and lightweight aggregate chip seal) that have been periodically monitored for three years using a Dynamic Friction Tester (DFT). Results from the preliminary findings show calcined bauxite aggregates' friction performed very well, phonolite aggregates' friction dropped significantly (40%), and identified truck loading, curve radius, curve deviation angles, and traffic speeds are factors impacting long-term friction deterioration. The outcomes of this analysis will enable transportation agencies to develop an HFST friction deterioration forecasting model, plan optimal and targeted HFST friction testing, and take proactive actions (such as detailed surveys, setup of warning signs, replacement, resurfacing, etc.), especially when the HFST friction is nearing the end of the HFST’s lifecycle. To better understand HFST friction deterioration characteristics and their relationship with aggregate loss, experimental tests involving analysis of friction, 2D images and 3D surface texture were performed at HFST sections at the National Center for Asphalt Technology (NCAT) Test Track. The key aggregate loss characteristics (based on visual appearance and texture change) were identified. HFST aggregate loss was characterized using aggregate loss percentage area and topography-based 3D surface macrotexture parameters, including height, asperity shape (average slope and curvature), and density. The analysis of relationship between friction and aggregate loss parameters discovered a strong correlation between DFT friction and aggregate loss percentage area and 3D macrotexture parameters. These findings reveal that HFST friction deterioration is largely controlled by HFST aggregate loss and change in macrotexture. The findings confirm that HFST aggregate loss can be used as a supplementary HFST performance measure (supplements to friction measurements) to study, monitor, and predict friction deterioration. In addition, a calcined bauxite HFST friction prediction model was developed to predict friction capacity using macrotexture and microtexture wavelength surface data obtained from a 3D sensing system. The developed friction prediction model showed satisfactory R-squared (almost 0.8) when predicting HFST friction. This research opens new perspectives for the use of low-cost visual inspection, 2D imaging, and 3D laser scanning technologies to monitor safety sensitive HFST friction deterioration.
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Date
2021-07-16
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Dissertation