Gap Graded Asphalt Mixture with Macrofibres to Enhance Its Behaviour

Abstract

The addition of fibres to enhance asphalt mixture performance is an established subject of study in pavement research. However, the study of structural macrofibres, long fibres with high strength, is a relatively new field. Asphalt mixtures submitted to low and medium temperatures tend to fail due to fatigue or thermal cracking. The incorporation of these kind of fibres in high-performance mixture like gap graded asphalt concretes, Beton Bituminex Tres Mince (BBTM as normally is called in Europe) and Stone Mastic Asphalt (SMA), could enhance their performance, mainly in cold climate conditions. In this work, the low-temperature performance of three gap graded mixtures, BBTMA, BBTM B, and SMA, with the incorporation of glass and synthetic macrofibres was studied. The resistance to cracking at low temperatures (− 15 and 5 °C) was analysed by means of flexural fracture tests in notched beams. Additionally, other tests like the indirect tensile stress test at 5 and 15 °C, rutting test at 60 °C, abrasion test, and draining down test were assessed to complement the analysis. It was found that the addition of macrofibres to these high-performance mixtures greatly improved their fracture resistance, and the addition of glass and synthetic macrofibres enhanced the fracture performance at low temperature of the gap graded mixtures studied, mainly at − 15 °C giving the potential for better durability in cold climate conditions. In the case of SMA, the traditional cellulose fibres used in this kind of gap graded mixture were replaced by the macrofibres studied maintained the function of limiting the draindown of asphalt binder in SMA. The rutting performance of BBTMA and SMA with macrofibres was similar to the control mixtures, whereas in the case of one of BBTMB, an improvement was observed in the rutting slope with the addition of macrofibres.