Microstructure and mechanical properties of fibre reinforced asphalt mixtures

• Published in: Construction & building materials 2020-04, Vol.240, p.117932, Article 117932
• Main Authors: Mohammed, Monketh, Parry, Tony, Thom, Nick, Grenfell, James
• Format: Article
• Language: English
• Subjects: Fatigue; Fibre; Fibre distribution; Fracture toughness; Microstructure; Moisture damage; Stiffness
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.117932

•The fibres increased the stiffness of the asphalt mixtures.•Steel fibres showed the highest improvement in the indirect tensile strength.•All asphalt mixtures exhibited high resistance to moisture damage.•Specimens after RLAT testing were more susceptible to moisture damage.•Adding fibres showed an improvement in the low temperature cracking resistance.•Adding 2.0% glass and steel fibre to the asphalt mixture results in lower fatigue life. Conventional asphalt mixtures can perform satisfactorily in most flexible pavement and airfield applications. However, during recent years the trend has been towards traffic growth, severe climate conditions, and heavier loads. This allied to durability and cost effectiveness issues, has raised the demand to improve the mechanical properties of conventional asphalt materials by means of modification. Fibres may have the potential to achieve such modification and, thereby, enhance the mechanical properties of asphalt mixtures. This paper examines the relative performance of asphalt mixture modified with different fibre types and contents against the main distress types experienced by flexible pavements. Also, fibre distribution and orientation in the asphalt mixture are explored in this paper. The scanning electronic microscope images show the difference in the microstructure among fibre types. X-ray computed tomography investigation results indicate that steel fibres are present throughout the asphalt mixture specimen. The test results show that fibres have a notable impact on the stiffness modulus and fracture toughness of asphalt mixtures at 20 °C test temperature. In addition, fibres provide slightly improved fatigue life of fibre reinforced asphalt mixtures, mainly at low strain values. Furthermore, results indicate that there is no detrimental impact of fibres on either the tensile strength or the moisture damage resistance of such mixtures.