01552167

Component

In an attempt to conserve natural resources such as materials and energy there is a trend to increase the amount of recycled asphalt pavement (RAP) in asphalt pavement construction. Currently in Iowa, the amount of RAP materials allowed for the surface layer is limited to 15% by weight. The objective of this paper is to develop quality standards for inclusion of RAP content higher than 15% in asphalt mixtures. To determine if the higher percentage of RAP materials greater than 15% can be used in Iowa’s state highways, three test sections with target amounts of RAP materials of 30%, 35% and 40% were constructed on Highway 6 in Iowa City. To meet Superpave mix design requirements for mixtures with high RAP contents, it was necessary to fractionate the RAP materials. Based on an extensive sieve-by-sieve analysis of RAP materials, the optimum sieve size to fractionate RAP materials was then identified. Three test sections with actual RAP contents of 30.0%, 35.5% and 39.2% were constructed and the average field densities measured from the cores were 95.3%, 94.0%, and 94.3%, respectively. Field mixtures were compacted in the laboratory to evaluate moisture sensitivity using a Hamburg Wheel Tracking Device and rut depths after 20,000 passes were less than 3 mm for all three test sections. The binder was extracted from the field mixtures from each test section and tested to identify the effects of RAP materials on the performance grade of the virgin binder. Based on Dynamic Shear Rheometer and Bending Beam Rheometer tests, the virgin binders (PG 64-28) from test sections with 30.0%, 35.5% and 39.2% RAP materials were stiffened to PG 76-22, PG 76-16, and PG 82-22, respectively. Finally, a condition survey of the test sections was conducted to evaluate their short-term pavement performance.

This paper was sponsored by TRB committee AFD00 Section - Pavement Management.

01550057

15-5175

English

16p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Asphalt pavements; Condition surveys; Hot mix asphalt; Laboratory tests; Mix design; Pavement performance; Reclaimed asphalt pavements; Recycled materials; Superpave; Test sections

RAP content

Iowa; Iowa City (Iowa)

Design; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I31: Bituminous Binders and Materials

Transportation Research Board Annual Meeting 2015 Paper #15-5175

TRIS, TRB, ATRI

Dec 30 2014 1:44PM