01476604

Component

Transportation agencies are increasingly using recycled asphalt shingles (RAS) in asphalt pavements for economic and environmental benefits. The primary components of RAS are asphalt, mineral filler, aggregate granules, and either organic or fiberglass fibers. The effect of these components on the dynamic modulus of an asphalt mixture, which is a key input in the Mechanistic-Empirical Pavement Design Guide (MEPDG) and a critical property of asphalt mixtures related to its performance, are still uncertain. As part of National Pooled Fund Study TPF-5(213), a series of experimental plans was conducted utilizing demonstration based paving projects to investigate various factors related to RAS utilization. Thirteen mix designs with RAS contents ranging from zero to six percent were developed and constructed in Indiana, Iowa, Minnesota, and Missouri. Field produced mixtures were procured and sent to Iowa State University’s Asphalt Lab for laboratory dynamic modulus testing. The test results are used in this study to evaluate two commonly used dynamic modulus predictive models, the Witczak and Hirsch models. Two versions of the Witczak models, which were developed in 1999 and 2006, are evaluated in this research. It was found that the Witczak models were not very effective in estimating the modulus values of RAS mixtures. This study concludes that commonly used dosages of RAS in asphalt mixtures affects the prediction accuracies of the Witczak and Hirsch models due to biases of the E* predictive models in terms of input parameters, inaccuracies of input parameter measurements, effects of blend efficiency, and influences of the RAS fibers.

This paper was sponsored by TRB committee AFK30 Characteristics of Nonasphalt Components of Asphalt Paving Mixtures.

01470560

13-4489

English

16p

2013

Transportation Research Board 92nd Annual Meeting

Digital/other

Figures; References; Tables

Dynamic modulus of elasticity; Mathematical prediction; Pavement design; Recycled materials; Shingles

Hirsch model; Predictive models; Witczak model

Design; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I31: Bituminous Binders and Materials; I33: Other Materials used in Pavement Layers

Transportation Research Board Annual Meeting 2013 Paper #13-4489

TRIS, TRB, ATRI

Feb 5 2013 12:52PM