The Effect of Diffraction in the Degree of Bitumen Penetration on Asphalt Mixture Used for Surface Layer

Objectives: This research discuss the simulation of the bad bitumen which gives a penetration out of the specification limit and Study the effect of crumb rubber on the performance of asphalt mixture in case of low penetration grade and waste cooking oil in case of high penetration grade.

Presentation of Case: Determination of the permissible limits of the diffraction in the degree of penetration for Suez Bitumen and Alexandria bitumen.

Methodology: 14 asphalt mixtures are designed by using two types of bitumen (Alexandria bitumen and Suez bitumen). By using crumb rubber powder (C.R.P) with contents (6%, 8% and 10%) to decrease penetration for Alex bitumen by (59, 56 and 53) respectively. Then (-C.R.P-) was added with ratios (5%, 6.5% and 8%) to decrease penetration for Suez bitumen by (59, 56 and 53) respectively. after that waste cooking oil was added with different percentages (0.3%, 0.5% and 1%) for each bitumen type to increase penetration by (71, 74 and 77) respectively. Marshall Test was implemented for all asphalt mixtures to determine stability value and flow. The ITS Test was performed for all mixtures to determine tensile properties for mixtures.

Results: The results were showed important conclusions for using bitumen with penetration grades (60/70) with increase or decrease in penetration by 7.

Conclusion: This study recommends using (C.R.P) with ratios (10% and 5%) from bitumen weight for Alex and Suez bitumen respectively for achieving 53, 59 penetration to obtain 29% increase of stability value and 23.64% for Alex and Suez bitumen mixture respectively.