Sulfur is one of those chemical materials that is used in the different industries frequently, but considerable volume of it is produced because of industrial and volcanic processes all over the world and this amount is excessive. On the other hand, reserving this volume of sulfur in a usual place is dangerous because of being flammable and toxicity. So, finding a good application of this material is a vital problem for factories. One of the best places to use that, is in making the road pavements better and modifying bitumen specifications. Although that using sulfur in bitumen makes its features better totally, in this situation, beside of the probability of pollution and causing fire, produced asphalt concrete, will be harder and more brittle. So, nowadays using some materials in asphalt concrete to solve this problem is usual. In this study, the application of usual sulfur that is modified by a specific procedure (and is named Modified or Odorless Sulfur) is assessed in the in the combination with the bitumen (by Dynamic Shear Rheometer Test) and in the asphalt concrete (by Marshal Test). For this, beside of the replacement of the bitumen by 5, 10, 15 and 20 percent of sulfur (by the weight of the bitumen), Polypropylene (PP) fibers is used to prevent the asphalt concrete from hardening and being brittle. The bitumen that is used to making asphalt concrete samples is replaced by 10, 20, 25, 30, 35 and 45 percent of sulfur (by total weight of samples). The percentage of PP fibers is 0.15, 0.3, 0.5 and 1 percent of sample's total weight. The used fiber's length is 12 and 18 mm. Results show that using 10% - 15% sulfur in the bitumen, improves the properties of the combination considerably. Beside of this, using 20% - 30% sulfur in the bitumen that is used in making asphalt concrete samples and the application of 0.3% - 0.5% of 12 mm PP fibers, improves strengthening properties of samples and makes produced asphalt concrete more economical. Keywords: Modified Sulfur, PP Fibers, Modified Bitumen, Sulfur Asphalt Concrete, Asphalt Concrete Reinforcing
