Bitumen MC70 products have been used many years in the maintenance and repair of road surfaces, and isolation but road surface is used much more widely than the other usage and named liquid asphalt MC70, commonly called “asphalt medium curing
” or “tack oil” (which has carried the commercial designations: MC70)
However, tack oil bitumen MC70 has many shortcomings making it less than an effective road surface repair product.In repairing pot holes or filling cracks
in existing asphalt road surfaces, tack oil is strictly a “gluing” process or a “tacking” of new asphalt to the old. There is no homogeneous admixture of the new with the old asphalt.
Weather and climate conditions must be near “perfect” for application of tack oil, which at best allows for only a minimal time until replacement again is necessitated. Tack oil cannot be used in cold or wet weather or on wet surfaces. Also, tack oil repair of road surfaces requires a multiple highway crew to apply the asphalt and the use of expensive equipment. The bitumen MC70 must be pre-heated
to 250 degrees F for 2-3 hours before application, then applied and the overlaying asphalt rolled or tamped in place to form a smooth surface.
Alternatively, a top dressing can be applied to provide a flexible, tough, abrasion resistant surface. The resultant surface functions as a wear course in which a further increase in the compressive and tensile strengths of the base course have been increased. Colors, such as green or black, may be added to the top dressing to yield an appearance which is aesthetically pleasing or functional. After curing of bitumen MC70, the dressing forms a surface suitable for moderate airport traffic or highway traffic, or helicopter touchdown areas.
Analysis and specification of bitumen MC70
Kinemalic 1 viscosity at 60°C, eSt
Flash Point (Tag Open-Cup),°C
Distillate test 2 :
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Distillate, percent by Volume of total 360°C
Residue from distillation to 360°C:
Test on residue from distillation Penetration at
25°C,100g, 5 sec.
Ductility 3 at 25°C, cm
ASTM D402 / ASTM D113
Solubility in trichloroethylene, percent mass
ASTM D402 / ASTM D2024
Water, percent volume