Performance Of Warm Asphalt Mixtures Research Articles

Performance of warm asphalt mixtures containing reclaimed asphalt pavement, an anti-stripping agent, and recycling agents: A study using a balanced mix design approach

This research aims to use a balanced mix design (BMD) approach to investigate the effect of recycling agents (RAs) and an anti-stripping agent on the mechanical properties of warm-mix asphalt (WMA) containing different levels of reclaimed asphalt pavement (RAP). The BMD used three RAs (aromatic extract, triglycerides and fatty acids, and tall oil), an amidoamine WMA additive (PAWMA®), and an anti-stripping agent (Zycotherm®). The Dynamic Creep (DC), Indirect Tensile Strength (ITS), and Semi-Circular Bending (SCB) fracture tests were respectively used to evaluate the rutting, moisture susceptibility, and cracking resistance of mixtures. In addition, two-dimensional and three-dimensional (2-D and 3-D) performance interaction diagrams were developed as typical approaches for the BMD of asphalt mixtures. For mixtures with RAP, the results indicated that the aromatic extract and tall oil RAs decreased the moisture susceptibility, while triglycerides and fatty acids increased the moisture susceptibility. In addition, the RAs generally decreased the rutting resistance of mixtures while they increased the cracking resistance. This effect was more noticeable in the mixtures treated with triglycerides and fatty acids. The results also showed that introducing PAWMA® and Zycotherm® to the mixtures improved their resistance to moisture damage, cracking, and rutting.

Warm mix asphalt with synthetic zeolite: A laboratory study on mixes workability

In recent years, several warm mix asphalt technologies have been developed in order to enable significant energy savings and harmful emissions restraint by reducing mixing and compaction temperatures in hot mix asphalt production processes. This paper focuses on the evaluation of workability of WMA produced in laboratory by water-containing methodology with the addition of synthetic zeolite. Both volumetric and mechanical performance of warm asphalt mixtures compared with those of a reference hot mix were evaluated. For the Marshall specimens the variation of density with the compaction energy was also investigated. Finally, some considerations about the effect of the time of foaming (between mixing and compaction) on mixes workability are drawn.

Asphalt Production at Reduced Temperatures using Zeolites and the Impact on Asphalt Performance

ABSTRACT The potential benefits of producing and paving asphalt at lower temperatures are beyond discussion. There is already a lot of know-how on various techniques for producing warm mix asphalt, but there is insufficient data available about the impact of these techniques on the final performance characteristics of the asphalt. Nynas and BRRC are working together on a research project, to study the most important and promising warm mix techniques on laboratory and field scale. These techniques are: the use of foamed bitumen, the addition of waxes to the bitumen and the addition of zeolites to the mixture. The present paper focuses on the last technique. The performance of warm asphalt mixtures produced with different types and quantities of zeolites is compared to the performance of a reference hot mix asphalt. Several aspects have been studied: compactability, permanent deformation, water sensitivity and low temperature cracking. Small scale field trials were made to validate the findings of the laboratory research.

A Comparison of Warm Asphalt Binder Aging with Laboratory Aging Procedures

Abstract Warm asphalt has been gaining increasing popularity in recent years; however there are several characteristics about warm asphalt that are still unknown. While several studies have been conducted to study the performance of warm asphalt mixtures, aging characteristics of warm mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a limited study to evaluate the aging characteristics of two WMA binders artificially aged in the rolling thin film oven (RTFO) and the pressure aging vessel and comparing them with binder extracted from freshly prepared and artificially aged warm asphalt mixtures. RTFO aging was performed at 163°C and a lower temperature to simulate warm asphalt aging. Tests on binders aged in the laboratory and binders extracted from freshly mixed and aged mixtures indicated that the WMA binders extracted from WMA mixtures had significantly lower viscosities and G∗/sin δ compared to binders extracted from hot mix asphalt (HMA) and binders aged in the RTFO at 163°C (325°F). This indicates that the lower mixing and compaction temperatures reduce the aging of the warm asphalt binders. Also, binders extracted from WMA had significantly lower creep stiffness values and significantly higher m-values compared to warm asphalt binders aged in the RTFO at 163°C (325°F) and binders extracted from HMA. Binders containing WMA additives did not have higher G∗ sin δ values, indicating that the warm asphalt additives do not negatively affect the fatigue properties of the binders. Gel permeation chromatography analysis indicated that the addition of the warm asphalt additives did not have any significant effect on the %LMS of the binders used in this study.

Laboratory evaluation of warm asphalt binder aging characteristics

As warm asphalt has been gaining increasing popularity in recent years, there are still several characteristics of warm asphalt, which are unknown. While several studies have been conducted to analyse the performance of warm asphalt mixtures, aging characteristics of warm-mix asphalt (WMA) binders are not known in great detail. This paper presents the results of a study to evaluate the aging characteristics of WMA binders artificially aged in the rolling thin film oven (RTFO) and the pressure aging vessel. RTFO aging was performed at 163°C and a lower temperature to simulate warm asphalt aging. The results of this study indicated that reducing the aging temperature reduced the aging index and increased the m-values, but had no significant effects on G*/sin δ, G*sin δ and stiffness of the binders. Also, the addition of warm asphalt additives significantly increased the G*/sin δ values and lowered the m-values of the binders.