Effect of foaming technique and mixing temperature on the rheological characteristics of fine RAP-foamed bitumen mixtures

Abstract

This paper evaluates and compares the differences in the rheological characteristics of the fine aggregate matrix (FAM) portion of plant produced Foamed Bitumen Mixtures (FBMs) by means of a mechanical foaming process, and by the incorporation of zeolites in combination with Reclaimed Asphalt Pavement (RAP) material. This evaluation explores, for the first time, the impact of plant production variations for half-warm, warm and hot processes (i.e. mixing temperatures around 90°C, 120°C and 160°C, respectively) on their rheological response. A fine Virgin-HMA, a fine HMA-RAP – no foaming technique -, and a 100% fine RAP mixture were also produced for comparison purposes. Dynamic Mechanical Analysis (DMA) tests were conducted on all evaluated FAM mixtures to determine their linear viscoelastic properties. Results indicate that the rheological response of the fine RAP-FBMs is influenced primarily by the contribution of the RAP binder in the total bitumen blend, and ageing of the fine RAP material, which were a function of the foaming technology and the production temperature of the materials.

Keywords:

• reclaimed asphalt pavement
• foaming technologies
• fine aggregate matrix
• dynamic mechanic analysis
• viscoelastic properties

Additional information

Funding

The first author would like to acknowledge COLCIENCIAS for the funding provided through the program no. 617-2013 for doctoral studies abroad, and the partial funding provided by the Nottingham Transportation Engineering Centre (NTEC) at The University of Nottingham.