Evaluation of Recycled Base Aggregates

Project Details
STATE

WI

START DATE

10/17/16

END DATE

10/17/18

RESEARCHERS

Andrew Zimmer

SPONSORS

WI DOT

KEYWORDS

Asphalt pavements; Blending; Concrete aggregates; Deformation; Economic benefits; Environmental impacts; Pavement distress; Pavement performance; Recycled materials

Project description

While Wisconsin Department of Transportation (WisDOT) has been using Recycled Asphalt Pavement (RAP) and Recycled Concrete Aggregate (RCA) for their economic and environmental benefits for over thirty years, there has been great interest in using them in recent years due to expected economic and environmental benefits. However, studies to support these benefits are inconclusive. Some laboratory studies indicate that, under certain conditions, RAP and RCA are more resilient, with higher durability than typical natural aggregates; but, RAP also showed temperature sensitivity and larger permanent deformations, and RCA exhibits tufa (type of limestone) formation, with a potentially lower ability to drain. Another long term (2009-2013) study found recycled and natural aggregates performed similarly; however, there are now reports of rutting and cracking. The general impression of roads constructed with recycled materials is that they are performing adequately. But we need a quantitative review of Wisconsin roads - using recycled materials compared with roads constructed with natural materials. This study needs to include a collection and comparison of pavement distress surveys for us to make wise decisions in the future. This study will conduct surveys to collect and analyze pavement distress for roadways constructed using recycled versus natural materials. If the research shows recycled materials have negative attributes, alternative techniques, such as blending aggregates, will be examined to determine if they can produce satisfactory results.
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