Measured Shear Strength and Hardness of Asphalt Mixtures Using Shear Devices Designed and Built

From examining the pavement failures and itscauses، these results are obtained، improving and increasing resistance of asphalt mixtures against incoming stresses (vertical، shear and torsion stresses)، causing delay and reduce failures created on pavement and thus their productivity and life will be increased. Costs that each year spent in the country to improve and repair of pavements withfailures، illustrate theImportance of improving the resistance of pavements against the incoming stresses. This study introduced two types of shear device has been developed in order to measure shear strength and shear stiffness of asphalt mixtures. Shear strength and shear stiffness of asphalt mixtures has a close relationship with the adhesion (c) and friction angle between the materials of asphalt aggregate mixtures. Increasing each of these parameters، the shear strength of asphalt mixtures will be increased. Identifying and evaluating effective parameters that increased asphalt mixtures resistance، including gradated aggregate materials used or the effect of compaction، type and amount of binder، asphalt mixtures with the appropriate shear resistance can be produced. This requires the evaluating of effective factors in shear strength of the constructed samples. The failure or destruction in asphalt mixtures in states of pure shear، pure tension، shear with pressure، and shear with traction can occur. In this study، to evaluate the shear resistance of asphalt mixtures made with two different penetration grade bitumen، two types of shear device was designed and built and Marshall samples made with two types of bitumen، under force of pressure - shear and pure shear were disjointed and the maximum shear strength and shear stiffness of them were calculated. Using any one of these two units، different parameters in the effective shear strength and hardness of the samples can be investigated and asphalt more shear resistance against shear forces produced. Testing and evaluation، this result is achieved that Because the effect of consumption of bitumen type on asphalt mixtures properties (increasing adhesion coefficient)، shear strength and shear stiffness of asphalt mixtures containing bitumen 60/70 in comparison with asphalt mixtures containing bitumen 85/100 is more