Rutting Potential of Warm Mix Asphalt and Possible Misleading Results due to Reheating

Warm mix asphalt, rutting resistance, reheating, modulus, tensile strength

Abstract

The main objective of this study is to evaluate the rutting potential of warm mixes
produced with various warm mix additives (Evotherm, Sasobit, and foamed asphalt). To achieve
this objective, an experimental matrix was developed to determine the mechanical properties of
warm mixes and the control mix. Laboratory performance testing includes evaluation of
modulus, strength, and rutting potential using dynamic modulus test, indirect tensile (IDT)
strength test, flow number (FN) test, and loaded wheel track (LWT) test. The test results show
that the warm mix could have slightly greater or less rutting potential than the control mix
depending on the type of warm mix additive and the recycled material used in the mix. In the
laboratory tests, plant-produced mixes were compacted in the laboratory without and with
reheating. It was found that the reheating process could significantly stiffen the mixture and the
stiffening ratios varied from 1.2 to 2.0 depending on the performance characteristics and the type
of mixture. In addition, the rutting test results show different levels of correlation with the
dynamic modulus and the tensile strength, depending on the stress state in the performance test.
This suggests that attention should be paid to the measured characteristics of each performance
test based on the loading conditions.