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8.4.2 After a blend of polymer in unmodified asphalt binder has been prepared and is<br />
still at elevated temperature, pour enough of the blend into a clean 177 mL penetration tin to<br />
fill it to the formed roll on the cup (approximately 6 mm _ 0.25 mm from the top). Place<br />
the sample in a controlled temperature oven at 163 + 5°C for 15 to 18 hours. Remove the<br />
sample carefuIly from the oven without disturbing the surface and observe the sampIe. After<br />
the initial observation, a spatula may be used to gently probe the sample. While the sample is<br />
stii1 hot and within 5 minutes after removal from the oven, check the consistency of any<br />
surface layer and inspect for sludge on the bottom.<br />
8.4.3 Depending on the physical characteristics of the polymer and the compatibility<br />
of the particular asphalt cement/polymer modifier system, varying conditions will be noted.<br />
Report the condition of the modifier observed using the guidance provided in table 4.<br />
8.4.4 If these descriptions do not match the particular sample, note the exact<br />
phenomena encountered and retain the sample.<br />
8.5 Safety--Safety aspects of the modified asphalt binders are addressed in MP1 by a<br />
minimum Cleveland Open Cup flash point (T48) of 230°C. The modifier producer shall<br />
provide all other relevant safety _,:formation and requirements in the form of a Materials<br />
Safety Data Sheet and supporting documents.<br />
8.6 Purity--The base asphalt cement used in modified asphalt binders shaI1 meet a<br />
minimum requirement for solubility of 99 % by T44. This helps ensure that the polymermodified<br />
asphalt binder is not contaminated with unwanted mineral fines or fillers. The<br />
requirement is not placed on the blended, modified asphalt binder because many modifiers do<br />
not dissolve readily in the solvents presently used in the paving industry.<br />
8.7 Workability--Ideally, construction of asphalt concrete pavements with modified<br />
asphalt binder should not require unusual procedures in any part of the construction process.<br />
Because the formulation of modified asphalt binders has the potential to produce extremely<br />
high stiffness values, however, a high-temperature viscosity limit of 3 Pa.s at 135°C has<br />
been placed in MP1 to assure adequate pumpability of the modified binder at the HMA plant.<br />
This requirement may be waived if the modifier producer or HMA supplier warrants that the<br />
modified asphalt binder can be adequately pumped and mixed at temperatures that meet all<br />
applicable safety standards.<br />
8.8 Performance Testing of Modified Asphalt Binders--This section provides a<br />
method for determining the performance characteristics and performance grade of a modified<br />
asphalt binder according to the properties and Iimits contained in MPI. Comparison of these<br />
characteristics with those of conventional asphalt cements or of other modified asphalt<br />
binders commonly employed by a specifying agency permits an objective decision on the<br />
benefits of using a new modifier in a particular situation.<br />
8.8.1 Specimen Preparation--At least 400 g of the modified binder are required for<br />
evaluation. All test specimens should be prepared and blended (if required) in accordance<br />
with the producer's instructions. Select the initial concentration of modifier in the modified<br />
asphalt binder after consultation with the producer.<br />
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