Evaluation of Low- and Intermediate-Temperature Performance of Bio Oil-Modified Asphalt Binders

Sara A Alattieh,Waleed Zeiada,Ghazi G Al-Khateeb

doi:10.3390/su13074039

Abstract

Fatigue cracking and low-temperature cracking are two major distresses that occur in asphalt pavements. Fatigue cracking is a load-associated distress caused by the tensile stresses at the bottom/top of the asphalt concrete (AC) layer due to repeated traffic loading. On the other hand, low-temperature cracking occurs when tensile stresses built up with in the AC layer at low temperatures exceed the tensile strength of that layer. In this study, the performance of date seeds oil bio-modified asphalt binders (DSO-BMB) is evaluated against fatigue and low-temperature cracking. The DSO-BMBs are prepared using volume ratios of 1.5, 2.5, 3.5, 4.5, and 5.5% date seeds oil-to-asphalt binder. The base asphalt binder used in the study is a 60/70-penetration grade with a Superpave performance grade (PG) of PG 64–16. The dynamic shear rheometer (DSR) standard test was used to assess the fatigue performance of the bio-modified binders (BMBs), while the bending beam rheometer (BBR) test was used to test the BMBs for low-temperature performance. In addition, the DSR linear amplitude sweep (LAS) test was used to evaluate the fatigue tolerance behavior of the DSO-BMBs. The analysis and results of the study showed that the bio-oil enhanced the low-temperature performance. The low PG grade improved from −16 °C for the control asphalt binder to −28 °C for the BMB. Additionally, the fatigue resistance of the BMBs was improved as illustrated by the damage–characteristic curves of the modified asphalt binders from the visco-elastic continuum damage (VECD) analysis and the increase in the number of cycles to fatigue failure (Nf).

Highlights

Cracking is one of the major distress modes for asphalt pavements and is categorized in two main groups: (1) load-associated and it occurs when tensile stresses due to repetitive traffic loading exceed the tensile strength of the material, creating microcracks that grow and coalesce into macrocracks that lower pavement smoothness and the structural integrity [1]
The significance change in these parameters were due to the low density of the date seed oil (DSO) (0.88 g/mL) mixed with asphalt binder [18], which resulted in a reduction in the penetration and the viscosity of the date seeds oil bio-modified asphalt binders (DSO-bio-modified binders (BMBs))
The results show that the DSO-BMB that contains higher DSO content had lower α, this reduction was due to two reasons; (1) the DSO-BMB is softer than the control asphalt binder and it is expected to perform better in terms of fatigue resistance, (2) the intermediate testing temperature for the BMB was lower than the control asphalt binder

Summary

Introduction

Cracking is one of the major distress modes for asphalt pavements and is categorized in two main groups: (1) load-associated (fatigue cracking) and it occurs when tensile stresses due to repetitive traffic loading exceed the tensile strength of the material, creating microcracks that grow and coalesce into macrocracks that lower pavement smoothness and the structural integrity [1]. There are two types of fatigue cracking: top–down and bottom–up cracking. The top–down cracking is most common in thick pavements as reported by Canestrari & Ingrassia [2]. (2) Non-load-associated (thermal cracking) which is common in the cold climate regions [3], and it occurs when the thermal stress that builds up during cooling events in the pavement exceeds the tensile strength of the AC layer. Cracked pavements allow water to infiltrate underlying pavement layers, further weakening the pavement structure and leading to a rougher ride and shorter service life [4].

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