Effects of Milling and Other Repairs on Smoothness of Overlays on Asphalt Pavements

Abstract

The application of asphalt overlays on existing pavements comprises a significant percentage of the maintenance activities undertaken to restore asphalt pavement condition. The improvement of surface smoothness from overlay construction is gaining increasing attention because smoother overlays are likely to have longer lives as a result of decreased dynamic loading and to provide fuel economy benefits and greater comfort to road users. This paper presents a study in which the California Department of Transportation (Caltrans) Pavement Condition Survey (PCS) data were used to investigate the effects of repairs, preoverlay condition, and surface and binder type on initial overlay (postoverlay) smoothness. Linear mixed-effect models were used in the analysis to take into account the variation across random-effect variables. The smoothness of overlays was measured in terms of the international roughness index (IRI). The analysis indicated that the pavement preoverlay condition (IRI) was the most important variable to affect overlay smoothness: pavements with lower preoverlay IRIs were smoother than those with higher preoverlay IRIs. An increase in overlay thickness also was found to have a significant effect on the smoothness when the preoverlay condition was poor. In terms of preoverlay repairs, analysis of the Caltrans PCS data showed that pavements with digouts (milling and patching in the wheelpaths) performed better than did pavements whose entire surface was milled before the overlay. The effects of surface type (dense- or gap-graded versus open-graded) and binder type (rubberized or not rubberized) depended on the preexisting pavement condition, other factors, or both. Possible reasons for differences between this study and previous ones are offered.

The Application of Tribological Tests to Study the Wear Behavior of Asphalt Cutter Teeth: An Experimental Investigation Using Baroid Tribometer

“…Studies in the field have analyzed the interaction between milling drum teeth and asphalt layers. The research papers [6][7][8][9][10][11][12][13] provide information and results focused, mainly, on the aspects related to how the dislocation of asphalt concrete components (mixture of aggregates and filler/bitumen in solid state) occurs under the action of the cutter teeth, while the specialized literature [14][15][16][17][18][19][20][21] investigates the effect of the milling process on the milling teeth. The experimental research [14] evaluated, through statistical analysis, the wear process of teeth from two different manufacturers.…”

Factors Affecting Maintenance Probability and Resurfacing Thickness Based on the Pavement Management System

“…us, this paper mainly focusses on the latter. Research studies have demonstrated that thicker overlay lead to lower roughness after rehabilitation and delayed the propagation of reflective cracking significantly but increased the rutting depth sometimes [16][17][18]. However, engineers often get stuck in choosing an appropriate milling and resurfacing thickness if field core tests were not performed.…”

Effect of Mill and Thin Overlays on Roughness for Pavements in Cold Climate Locations

“…Several studies have investigated the effect of milling and overlays on pavement roughness, although not specifically for thin overlays. Hung et al analyzed pavement condition survey data from the California Department of Transportation (Caltrans) and found that the IRI before overlay was the most significant predictor of overlay smoothness, as pavements with lower preoverlay IRIs were smoother than those with higher preoverlay IRIs ( 14 ). In addition, the effects of milling and digouts varied depending on the level of preoverlay IRI, with better results being obtained when the preoverlay IRI was greater than 120 in./mi.…”