Quality assessment of Norwegian field trials with Warm Mix Asphalt

Resumé

Eleven test sections with Warm Mix Asphalt (WMA) were constructed in four Norwegian regions in 2011. WMA is produced and laid at lower temperature than traditional asphalt concrete due to a modified mix technique or use of a temperature reducing additive. The aim of the project was to document that WMA’s are of same level of quality as ordinary hot mix asphalt.
The test roads sections were 1020 m in average. The trial WMA and the corresponding reference asphalt were laid in parallel lanes. Average daily traffic (ADT) of the test sections were 650 to 9000.
Six WMA techniques were applied and surveyed:
- WAM-foam
- LMK-foam
- Green asphalt (foaming and adding recycled asphalt)
- Rediset WMX (chemical additive)
- Cecabase RT (chemical additive)
- Sasobit (organic additive).
Same aggregates and gradation was used in the WMA and in the reference asphalt. The WMA-trial mixes were documented by binder testing, Marshall density, adhesion and wheel-track rutting.
In the field trials, temperature reductions of 20 to 39 °C were achieved with the WMA techniques. The WMA quality was assessed by measuring void content and wheel-tracking rutting on drilled cores from the newly laid pavement. The initial rutting and IRI-evenness of the test sections were measured with a mobile laser pavement profile scanner. The development of rutting and IRI-evenness will be measured annually. Due to differences between asphalt mixes, traffic volumes and local climates, emphasis was laid on the relative performance of the WMA and reference on each test section. There were no significant difference in quality between the new-laid WMA’s and the reference asphalts. The long term performance of the test sections will be followed up.