Factors Affecting Compaction of Asphalt Pavements
Optimizing HMA Construction Temperatures
It has been known for some time that polymer-modified asphalts have high kinematic viscosities, yet can be mixed and compacted at temperatures well below those predicted by standard HMA guidelines. This session focused on research and good-practices which could enable the contractor to lower construction temperatures, thus achieving concurrent economic and environmental benefits.
Recent Advances in Compaction Equipment, Including “Intelligent Compaction.”
New technologies offer significant advantages for achieving targeted HMA density. Compactor add-ons such as Global Positioning Satellite (GPS) systems, IR measurement of surface temperature, and continuous density tools provide equipment operators with critical data for enhanced efficiency. New technologies such as vibratory pneumatic and oscillatory rollers offer unique alternatives for applying vibration to maximize benefits. There are proven techniques to identify and adequately compact problem mixes.
Longitudinal Joint Density
Construction of quality longitudinal joints continues to be one of the most problematic areas for HMA pavement performance. Agencies are now setting stricter compliance standards for joint density, requiring best-practice construction and effective quality control to earn full pay.
Incentives–Disincentives for Construction Quality
Over the past decade,construction specifications have evolved to include financial incentive–disincentive clauses for key elements thought to impact pavement performance, particularly smoothness and density. More recently, many of these financial adjustments have been based upon statistical criteria as defined in PWL (percent-within-limits) specifications.