Medium bitumen cut back (MC-70)kinematic viscocity failure at 60 degre

[defg]

Dear all
Currently I'm supervising a double surface dressed road. The contractor has carried out tests for bitumen MC-70 as per the specification requirements basing on AASHTO M82-75(1993) and AASHTOM20-70.The tests carried out were kinematics viscosity at 60degrees,fire and flash points, solubility and distillation. According to the test results revealed that bitumen material has failed to meet the minimum kinematic viscosity requirements. Observed was 47cSt instead of 70cSt min.The rest of the tested parameters conform with the specifications.Then the Contractor has tried to make some demonstration on site a stretch of 200m by carrying out priming works.The next day the section was assessed and found to have adequate penetration into the basecourse material.So please advise if the material can be used or not!

 

[rmalinga]

If it is only the viscosity that does not meet the specification requirement, and penetration (proper) has been attained, I would think this would be acceptable. You should note that the viscosity you report is in the range for MC-30, which is also used for prime. Any temperature problems in relation to a less viscous cut-back? Keep track of the reasons for applying the prime!

 

[zakiev]

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