Compaction is the most important factor that affects the long-term performance and durability of an asphalt pavement. Achieving the proper air void content in a pavement is easy if one observes the basic factors that affect the compaction process.
Results from the past studies clearly indicate the effect of increased in-place density on the improved fatigue and rutting performance of asphalt pavements. A 1% increase in in-place density is estimated to extend the asphalt pavement service life by conservatively 10%. Thus, the cost of providing increased in-place density can be significantly less than the operation, maintenance, and road user cost savings realized due to extended service life of the pavements.
The goals of specification data mining effort were to identify how SHA’s specify mat density. This included methods of measurement (cores, gage, roller pattern), baseline measurement (maximum theoretical specific gravity, lab bulk specific gravity, control strip), sampling (lot/sublot size and how analyzed), specification type (PWL, other advanced statistics, simple average), specification limits, and incentives.
From mix design to the rolling of an asphalt pavement, a variety of factors have an effect on a contractor’s ability to achieve acceptable in-place density. Recognition of these items, and controlling of them is a means of producing a better, more consistent end product. As a higher quality product, it will not only last longer, it will require less maintenance and increase customer satisfaction while doing so.
While the double drum vibratory is the primary roller used in the US for compaction there are many more tools available for compaction. Internationally a wide spectrum of pavers and rollers are used to achieve compaction on some very stiff hard to compact mixes. This presentation will cover some of these tools and techniques to provide a perspective of what is done in other parts of the world to reach compaction on the roadway.
The asphalt mixture design and its field acceptance are related to the ability to achieve field density. The FHWA conducted a demonstration project to enhance durability through increased in-place pavement density. Several SHAs demonstrated the relationship between engineering adjustments to the asphalt mixture design and the field density achieved. The relationship of the asphalt mixture design and field density requirements from these case studies will be discussed.