from On the Move, Winter (December) Quarter 1998, Volume 11, Number 4
Sixty-plus key representatives of contractors, equipment manufacturers, and materials suppliers
from the hot-mix asphalt paving industry met December 1, 1998 in Salt Lake City to discuss
construction techniques, paving equipment needs, and Quality Control/Quality Assurance
(QC/QA) procedures relating to the construction of Superpave asphalt pavements. The meeting
was hosted by Cate Equipment and Ingersoll-Rand/Blaw Knox. Doug Hubbard, District Product
Support Manager of the Ingersoll-Rand company led the discussions with interactive
presentations covering paving equipment design, operating procedures and paving techniques.
UDOT Construction and Materials representatives Tom Smith, Wade Betenson, Hugh Kirkham,
Larry Buss and Cameron Peterson provided valuable input to the discussions since Utah is a lead
state in the implementation of Superpave technology.
Discussion was very candid regarding Superpave constructability issues, essential quality control
measures, materials handling problems, and proper surface preparation prior to paving. The
necessity of achieving required density in the pavement was cited as being the most critical to
good pavement performance. Full consensus was registered with regard to the fact that
Superpave mixes do require closer adherence to compaction temperature constraints and that
additional compactive effort is required to achieve specified density. In addition, the factors of
proper materials handling throughout the hot-mix production process, paver speed, rolling
patterns, and selection of proper paving equipment that is well maintained were considered to be
critical as well. The materials characteristics of Superpave mixes regarding percentage of coarse
and fine particles and crushed faces must be fully recognized and accommodated in the
construction process, along with the performance graded (PG) asphalt that is used.
Consensus was also noted regarding Superpave being the preferred choice for new or total
reconstruction. The potential of the Superpave mix design system in reducing thermal cracking,
eliminating premature rutting, and increasing the fatigue resistance of asphalt pavements was
considered worth the cost of the extra effort in construction. Mr. Hubbard emphasized
throughout his presentation that adherence to the following fundamental hot-mix asphalt paving
practice is essential:
Discussion also surrounded several fundamental issues that must be addressed from the design
side. These issues included providing an asphalt mix design that meets all volumetric criteria,
adequate lift thicknesses (i.e. 3 to 4 times the maximum nominal size of coarse aggregate),
assuring that adequate surface preparation and support is provided prior to placement, and that
adequate structural section is provided to accommodate the projected axle loads. In summary,
thorough and proper engineering must be accomplished up-front along with good fundamental
paving practices if the full potential of the Superpave mix design system is to be realized.
The hot-mix asphalt industry attendees, the UDOT representatives, and the equipment
manufacturers are commended for the proactive, constructive comments and steps taken within
this special workshop. Proper implementation and use of the Superpave mix design system
requires a team approach to achieve the significant benefits it offers.
The T² Center is committed to assisting in the early implementation of Superpave technology through technical assistance, training, workshops, information and particularly through the special experimental project addressing Superpave Implementation at the Local Level. The latest information may be obtained by calling 1-800-822-8878 or from this website.