Assessment of Workability and Compactability of Warm-Mix Asphalt

Abstract

One of the main benefits advertised about the use of warm-mix asphalt is the increased workability at conventional and lower compaction temperatures. From a field perspective, “workability” is commonly defined as the asphalt mixture property that describes the ease with which the asphalt mixture can be placed, worked by hand, and compacted to the desired mat density. Unfortunately, a laboratory property and test condition have yet to be developed to quantify these field characteristics. A research effort to evaluate the workability and compactability of different warm-mix additives preblended in a polymer-modified asphalt binder at varying percentages is summarized. Different test procedures, both asphalt binder related and asphalt mixture related, were evaluated and compared. Test results indicated that conventional mixing and compaction temperature asphalt binder tests were insensitive to the different warm-mix additives and dosage rates. Compaction data obtained with the gyratory compactor also indicated the device was generally insensitive to workability and compactability. Meanwhile, the University of Massachusetts workability device and the Marshall compaction hammer were found to rank the general workability and compactability of the mixtures in a rational order and compared favorably with one another. Not only was a promising new asphalt binder test, the lubricity test, sensitive to dosage rate and warm-mix additive, but the ranking compared favorably with mixture tests. The hope is that the information in this research effort can help in the selection and validation of warm-mix additives as a compaction aid.

Evaluation of Rediset for use in warm-mix asphalt: a review of the literatures

“…Bhargav (2013) found that minimum air voids of mixtures with 1.5%, 2% and 2.5% Rediset occurred at 1208C as a compaction temperature. In other studies, it was observed that air voids of Marshal samples decreased as Rediset content increased (Bennert et al 2010). Lee and Kim (2009) found that the bulk specific gravity of mixtures containing Rediset (prepared for indirect tensile strength test) were higher than those mixtures containing Sasobit w , Advera, Asphamin, Cecabase and Evotherm.…”

“…Bennert et al (2010) reported that that addition of 1% Rediset in a PG76-22 has no effect on the recovery percentage and nonrecoverable creep compliance (J nr ), while 2% Rediest content increased the J nr and decreased the percentage of recovery in the multiple stress creep and recovery test (MSCR) at 648C. It implies that Rediset content may have an effect on the high temperature properties of an asphalt binder.…”

“…According to Bennert et al (2010), workability is defined as the ease of placing the asphalt mixtures on the road surface of road, ease of working by hand and compaction of asphalt mixtures to the desired mat density. When asphalt binder viscosity cannot provide useful information on mixing and compaction properties of asphalt mixtures, other tests and indicators can be used for evaluation of asphalt mix properties at temperatures near the production and compaction conditions.…”

“…Because surfactant-based WMA additives are using other types of mechanisms for reducing mix and compaction temperatures, other laboratory tests such as lubricity tests were considered for evaluation of asphalt binder properties at very high temperatures (Hanz et al 2010b). Generally, the concepts of thin-film rheology are used in lubricity tests (Bennert et al 2010). Bennert et al (2010) showed that the shear rate of asphalt binder with various amounts of Rediset is higher than a neat binder at the peak point of torque on DSR plates in lubricity test.…”

“…Generally, the concepts of thin-film rheology are used in lubricity tests (Bennert et al 2010). Bennert et al (2010) showed that the shear rate of asphalt binder with various amounts of Rediset is higher than a neat binder at the peak point of torque on DSR plates in lubricity test. It implies that internal friction in the particles of asphalt mixture containing Rediset can be lower than asphalt mixture without warm additive.…”