Polymer-Modified Bitumen Production Based on Performance Grade for Application in Different Zones of Iran

Due to performance grade (PG) zonation of different parts in Iran and poor properties of 60/70 penetration grade bitumens for pavement applications, suitable polymer modified bitumen was produced. To fulfill this purpose, different PMBs samples were produced using 60/70 penetration grade bitumen and various percentages of VB (20 and 25%), with different percentages of SBS Calprene C501 (4, 4.5, 5 and 5.5%), in a high shear homogenizer in 1 h mixing time at 160°C temperature. To determine the performance grade, aging effect, low temperature performance and rheological properties such as evaluation of rutting and fatigue factors some SHRPs measurements (DSR, RV, RTFOT, PAV and BBR) were conducted. The results showed that the sample with 5.5% SBS with 20 and 25% VB, at high temperatures presented good properties such as: the best performance grade (76°C), the highest resistance and elastic behavior in comparison with the other samples. These samples were subjected to rutting and fatigue tests for both aged bitumen in RTFOT and unaged bitumen. The results indicated that adding SBS to bitumen could not improve the performance at low temperatures, compared to 60/70 grade bitumen, but it did improve the properties of polymer-modified bitumen at similar low temperature (-18°C). So, samples with 4, 4.5 and 5% SBS with 20 and 25% VB, are suitable to be applied in provinces which 60/70 grade bitumens are not suitable. In some provinces such as Khoozestan, with a PG of 76, the compositions with 5.5% SBS with 20 and 25% VB, are found to be suitable.