State Study 111 - Polymer Modified Hot Mix Asphalt Field Trial.pdf

TRAFFIC VOLUMES
Traffic for this segment of I-55 for 1994 is 14,000 ADT and year 2014 design traffic is
projected to be 25,000 ADT with 28 percent trucks. Cumulative 18,000 lb. equivalent single
axle loads (ESALs) for the design period is 18.95 million. A deflection survey (Dynaflect)
resulted in a recommended additional structure of 3 in for the first 5.3 mi. and 4.5 in for the
remaining 9.3 mi. These recommended thicknesses represent confidence levels between 85%
and 98%.
DETAILS OF PROJECT
The typical sections for this project called for milling 3.5 in deep, 3 in of HMA base course,
either 2 in or 3.5 in of HMA binder course, and 1.5 in of HMA surface course. The roadway
south of 708+68 was to receive 2 in HMA binder course and the roadway north of station
708+68 was to receive 3.5 in of HMA binder course. Paved shoulder grades were to be
adjusted with HMA. The cross-slope of the traffic lanes was to be increased from the existing
1.56% to 2%.
The items in the project specifications addressing the polymer modified HMA are described as
follows:
1. Each modifier will be used in an approximate 0.5 mi. section in the top two pavement
lifts for both northbound lanes (24 ft wide roadway) for a total thickness of modified
HMA of 3.5 in (later changed to 3 in). Transition sections of approximate 0.5 mi.
lengths will separate the various modifier sections. Polymer modified HMA will be
permitted in the transition sections to the extent necessary to use any remaining
modified binder prepared for the 0.5 mi. test section. All HMA in the transition sections
will, however, be paid for at the price for non-modified HMA.
2. HMA aggregate gradation will be held constant for all modified HMA sections as well
as the control section (remainder of the northbound lanes) for each pavement lift.
3. Modified binder content must be within 0.3 percent of the binder content of the nonmodified
HMA for the particular layer.
4. The base asphalt for the modified binders must be an AC-20. The base asphalt must
be from the same source for all modified HMA sections as well as the control section,
i.e., for all the northbound lanes for the top two pavement lifts.
5. Each modifier manufacturer will be required to have a technical representative on site
throughout the production of modified HMA with their modifier.
6. The polymer loading to be used for each modifier must be approved by MDOT. Each
manufacturer shall submit to the MDOT Research Engineer copies of at least three
different HMA mix designs used previously which incorporated their modifier into HMA
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