Issue 47

M. Fallah Tafti et alii, Frattura ed Integrità Strutturale, 47 (2019) 169-185; DOI: 10.3221/IGF-ESIS.47.14 174 Sasobit is similar to the Paraffin Wax which is one of the derivations of crude oil but its molecular weight is higher than Paraffin Wax. It can easily be dissolved in the bitumen at temperatures above 120°C and there would be no segregation afterward. This material has a melting temperature between 70°C and 110°C and creates a homogeneous solution with bitumen. Sasobit is supplied in two physical forms namely, tablets form (4mm diameter) and granule form (1mm diameter). In this research, Sasobit was initially dissolved in the bitumen at 120°C. It was then used at three different proportions namely, 2, 2.5, and 3 wt% of bitumen to produce HMA samples. These proportions are in the range of proportions recommended by its manufacture and are generally used in previous researches as well [1, 8, 5, 18, 19, 20] . The properties of the Sasobit used in this research is presented in Tab. 5 . Description Characteristics Tablets form (4mm diameter) or granules form (1mm diameter) Form 622 kg/m 3 Density of tablet shape (4 mm diameter) 590 kg/m 3 Density of granules (1 mm diameter) Clear white Color Homogeneously dissolved in bitumen Solubility Decreases bitumen viscosity Viscosity 70°C to 110°C Melting point Coal derivatives- Hydrocarbon Aliphatic Chemical structure Table 5 : Properties of applied Sasobit. Parafibers Parafibers are comprised of fibers and white powders. The ratio of the powder to the fiber is pre-determined by the manufacture. It is similarly added to the asphalt mixture as the PACSF. The only difference is the percentage in which they are added to the asphalt mixture. In this research, Parafibers were used in three different proportions namely, 0.1, 0.15 and 0.2 wt% of the asphalt mixture to produce their corresponding samples. These proportions were selected to cover the recommended range by its manufacture. The properties of Prafiber used in this research is presented in Tab. 6 . Description Characteristics Compound Fibers and powders Form 18.1 gr/cm 3 Density White fiber and white powder Color 100 °C to 110 °C Powder melting point 230 °C Fibers melting point 12-18 mm Fibers length 1.3 mm Fibers diameter 6 GPa Modulus of elasticity Table 6 : Properties of applied Parafibers. S AMPLES PREPARATION ggregates were kept overnight in an oven with its temperature set at 110°C and then heated for 4 hours at 160°C before mixing with the bitumen. Each modifier was added to asphalt mixture in accordance with the procedure described in the previous section. An asphalt mixer was used to produce a homogeneous asphalt mixture. For each A