Effect of RAP content on flexural behavior and fracture toughness of flexible pavement

Muhammad Mubaraki,S.A Osman,H.E.M Sallam

doi:10.1590/1679-78255516

Muhammad Mubaraki, S.A Osman + Show 1 more

Open Access

https://doi.org/10.1590/1679-78255516

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Abstract

Abstract The use of recycled Reclaimed Asphalt Pavement (RAP) material into flexible pavement contributes to sustainable development with environmental and economic benefits. In the present work, Semi-Circular Bending (SCB) specimen has been adopted to study the flexural strength and mode-I fracture toughness of flexible pavement with and without RAP. Two different resources of RAP, namely KS and KF, with two different percentages (20% and 40%) have been examined. Smooth and cracked specimens have been cast to measure the flexural strength and mode-I fracture of flexible pavement containing RAP, respectively. Smooth and cracked specimens for flexible pavement without RAP, as control beams, have been cast for the sake of comparisons. The experimental results showed that, the flexural strength and mode-I fracture toughness of flexible pavement containing 40% RAP are higher than those of flexible pavement without RAP, for the two types of RAP. Comparison between the of work of fracture calculated based on AASHTO TP 105-13 and AASHTO TP 124-16 showed that, the calculation based on AASHTO TP 105-13 is more accurate than that based on AASHTO TP 124-16. Furthermore, the suggested quad-linear relation to work of fracture predictions is easier and more reasonable for presenting the experimental results especially for the descending part of P-LLD curve than that suggested as exponential curve by AASHTO TP 124-16. For all groups, the type of failure is intergranular-mode fracture.

Highlights

Repeated traffic loading usually induces daily damages of pavement
One of the main objectives of the current study is to experimentally study the flexural strength and mode-I fracture toughness of flexible pavement with different reclaimed asphalt pavement (RAP) percentages
The second objective of the present work is to apply the concept of dmax to evaluate the fracture toughness of flexible pavement containing RAP measured from the Semi-Circular Bending (SCB) specimen suggested by different specifications AASHTO TP105-13 (2015), AASHTO TP 124-16 (2016) and EN 12697-44 (2010)

Summary

Introduction

Repeated traffic loading usually induces daily damages of pavement. Many attempts were made to enhance the properties of asphalt pavements by adding fibers, nanofibers, and Polymers (Yoo et al, 2018, Naqi et al, 2018, Abtahi et al, 2010). The use of reclaimed asphalt pavement (RAP) as recycling flexible pavement material becomes more widespread in last three decades (Ulsen et al, 2018, Mubaraki and Sallam, 2018, Al-Qadi et al, 2014). RAP is defined as recycling flexible pavement material to produce reusable asphalt. The RAP binder is aged, making it substantially harder than the normal or virgin bitumen used in hot mix asphalt (HMA) mixes. This may, be beneficial with respect to controlling rutting because a higher stiffness contributes to improved resistance against rutting.

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