Effects of cellulose fibers on the properties of asphalt mixtures

Abstract

• Mechanical properties were more sensitive to CF addition methods than volumetric. • CF orientation and distribution may affect the variation in measured properties. • No unique CF-asphalt mixture met all the required properties. • The determination of optimum CF content was inconclusive. Various types of additives have been used in asphalt pavement industry to improve the performance. Among these additives, fibers have received increasing attention to achieve the desired improvement. This investigation aims to evaluate the effect of applying dry and wet methods separately to introduce the cellulose fibers (CF) into the local hot mix asphalt (HMA). The evaluation was carried out by measuring the volumetric and mechanical proprieties of conventional (control) and CF-asphalt mixtures. This study also aims to examine the possibility of using the cellulose fiber as a sustainable material in the local asphalt pavement industry. The effect of variations in cellulose fibers content; 2.5%, 5.0%, 7.5%, and 10.0% by the weight of asphalt cement, aggregate source (Al-Nibaay and Al-Suddor aggregates), and two methods (wet and dry) for adding cellulose fibers to asphalt mixtures are evaluated. Marshall methodology and indirect tensile strength test (ITS) were applied to investigate the effects of these variables. The results of this study showed that the difference in mechanical properties of the fiber-reinforced asphalt mixtures was more sensitive to CF application methods in these mixtures than the difference in volumetric properties. In addition, the wet method improved most properties of Al-Nibaay aggregate asphalt mixtures while the dry method improved most properties of Al-Suddor aggregate asphalt mixtures. Determination of optimum CF content was found inconclusive due to the wide variation in the measured properties. CF can be recommended as a promising sustainable additive to improve the properties of local asphalt pavement. However, further investigation remains necessary to precisely determine the optimum CF content in parallel with the optimum asphalt content and it is also important to assess the resistance of CF-asphalt mixtures to moisture damage and aging.