Effect of different fibres on the performance properties of cold recycled mixture with asphalt emulsion

Fibre is one of the most popular additives in hot mix asphalt (HMA). However, there are few research studies about the application of fibres in cold recycled mixture with asphalt emulsion. In this study, five popular fibres are introduced to the emulsion recycled mixture, including polyester fibre, polypropylene (PP) fibre, polyacrylonitrile (PAN) fibre, lignin fibre, and basalt fibre. The optimum pre-mixing water (OPW) content, optimum emulsion content (OEC) and optimum fibre content of recycled mixtures reinforced by fibres are determined. The indirect tensile strength (ITS), moisture susceptibility, bending cracking at low temperature, rutting and fatigue life of mixtures with these fibres are investigated. The test results indicate that the OPW and OEC of recycled mixture are influenced by types and contents of fibres. Although different fibres lead to obviously different ITS values, the optimum content for each fibre is near 0.3% by weight of RAP. All five fibres improve the performance properties of the emulsion recycled mixture. The improved percentages depend on the type of fibres. Polyester fibre has higher improvement on fatigue life than the other fibres. Therefore, polyester fibre is recommended as the most effective fibre to improve the emulsion recycled mixture.