Effects of Asphalt Mixture Constituents on the Recycled Binder Contribution

Abstract

Reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) are incorporated into some asphalt mixtures produced today. The use of recycled asphalt materials (RAM) in asphalt mixtures encompasses engineering challenges pertaining to uncertainty in the proportion of the recycled binder that is in contact with and blends with the virgin binder in the asphalt mixture, termed recycled binder contribution (RBC) here. Recent research shows that agglomerations of RAM particles are the main cause of partial RBC. These agglomerations prevent recycled binder from interacting with the virgin binder. However, current practices generally assume complete RBC and a detailed understanding of the role of asphalt mixture constituents on RBC does not at present exist. The use of softer binders, extenders, and recycling agents has been proposed in high-RAM-content mixtures to restore recycled binder stiffness and embrittlement. However, the effects of asphalt binder variables as well as RAM type, source, and content on RBC is at present poorly understood. This paper aims to investigate the effects of asphalt mixture constituents on the RBC in asphalt mixtures using energy-dispersive x-ray spectroscopy (EDS) tracer-based microscopy analysis. It is found that the virgin binder, RAM type, and source significantly influence RBC in asphalt mixtures. However, RAP age level and content as well as additives are found to have only marginal impacts on RBC.

Keywords

Infrastructure Materials Asphalt Materials Selection and Mix Design Reclaimed Asphalt Pavements

Get full access to this article

View all access options for this article.

References

Hand

A. J.

Aschenbrener

Resource Responsible Use of Reclaimed Asphalt Pavement in Asphalt Mixtures [Tech Brief]. FHWA-HIF-22-003. FHWA, Washington, D.C., 2021.

Federal Highway Administration. Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage 2020 Information Series 138 11th Annual Survey. Report No. IS 138(12e), FHWA, Washington, DC, 2020.

Martin

A. E.

Fawaz

Arámbula-Mercado

Akash

Garcia Cucalon

Yin

Chowdhury

, et al. Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios. Transportation Research Board, Washington, D.C., 2020.

Castorena

Pape

Mooney

Blending Measurements in Mixtures with Reclaimed Asphalt Use of Scanning Electron Microscopy with X-Ray Analysis. Transportation Research Record: Journal of the Transportation Research, 2016. 2574: 57–63. https://doi.org/10.3141/2574-06

Martin

A. E.

Mercado

E. A.

Abdelaziz

Binder Availability in Recycled Materials: Review of Literature on Available Quantification Methods. Report FHWA/TX-21/0-7062-R1B. Texas Department of Transportation, Austin, TX, 2021.

Nguyen

V. H

. Effects of Laboratory Mixing Methods and RAP Materials on Performance of Hot Recycled Asphalt Mixtures. PhD thesis. University of Nottingham, Notthingham, England, 2009.

Navaro

Bruneau

Drouadaine

Colin

Dony

Cournet

Observation and Evaluation of the Degree of Blending of Reclaimed Asphalt Concretes Using Microscopy Image Analysis. Construction and Building Materials, Vol. 37, 2012, pp. 135–143. https://doi.org/10.1016/J.CONBUILDMAT.2012.07.048

Jiang

Zhou

Dong

Laboratory Observation and Evaluation of Asphalt Blends of Reclaimed Asphalt Pavement Binder with Virgin Binder Using SEM/EDS. Transportation Research Record: Journal of the Transportation Research Board, 2018. 2672: 69–78. https://doi.org/10.1177/0361198118782023

Abdalfattah

I. A.

Mogawer

W. S.

Stuart

Quantification of the Degree of Blending in Hot-Mix Asphalt (HMA) with Reclaimed Asphalt Pavement (RAP) Using Energy Dispersive X-Ray Spectroscopy (EDX) Analysis. Journal of Cleaner Production, Vol. 294, 2021, p. 126261. https://doi.org/10.1016/J.JCLEPRO.2021.126261

10.

Pape

Castorena

Analysis of the Role of Recycled Material Agglomerations on the Location of Fracture in Asphalt Mixtures. Journal of Transportation Engineering, Part B: Pavements, Vol. 148, No. 2, 2022, p. 04022031. https://doi.org/10.1061/JPEODX.0000382

11.

Bressi

Cavalli

M. C.

Partl

M. N.

Tebaldi

Dumont

A. G.

Poulikakos

L. D.

Particle Clustering Phenomena in Hot Asphalt Mixtures with High Content of Reclaimed Asphalt Pavements. Construction and Building Materials, Vol. 100, 2015, pp. 207–217. https://doi.org/10.1016/J.CONBUILDMAT.2015.09.052

12.

Pape

S. E.

Castorena

C. A.

Assessment of the Impacts of Sample Preparation on the Use of EDS for Analysing Recycled Asphalt Blending. Journal of Microscopy, Vol. 283, No. 3, 2021, pp. 232–242. https://doi.org/10.1111/JMI.13036

13.

Mocelin

D. M.

Castorena

Impacts of Recycled Binder Availability on Volumetric Mixture Design and Performance. International Journal of Pavement Engineering, 2022. https://doi.org/10.1080/10298436.2022.2046276

14.

Lakens

Equivalence Tests: A Practical Primer for t Tests, Correlations, and Meta-Analyses. Social Psychological and Personality Science, Vol. 8, No. 4, 2017, pp. 355–362.

15.

Pape

Castorena

Application of Sieve Analysis to Estimate Recycled Binder Availability. Transportation Research Record: Journal of the Transportation Research Board, 2022. 2676: 170–181. https://doi.org/10.1177/03611981211073324