Using Reclaimed Asphalt Pavement (RAP) in asphalt mixes has become a common practice in many countries as experience indicated that the recycling of asphalt pavements is very advantageous from different perspectives. Some of the advantages of utilizing RAP include conservation of asphalt and aggregate resources, conservation of energy, and reduction in life-cycle cost. In this study, the suitab...

Language: English The Challenge At the outset the asphalt paving process seems to be simple. Trucks deliver hot mix asphalt from plants to the construction site. There the asphalt is loaded on asphalt pavers that evenly spread the asphalt. Finally, compactors compact the asphalt to its required density. Despite this relatively structured process our research shows that there are significant dis...

Abstract—In order to use bitumen in hot mix asphalt, it must have specific characteristics. There are some methods to reach these properties. Using polymer modifiers are one of the methods to modify the bitumen properties. In this paper the effect of StyreneButadiene-Rubber that is one of the bitumen polymer modifiers on rheology properties of bitumen is studied. In this regard, the rheological...

Background The modification of asphalt binder to improve performance properties has grown significantly since the implementation of the Strategic Highway Research Program (SHRP) binder specifications. There has been increased use of polymers, crumb rubber modifier and Polyphosphoric Acid (PPA). There has been concern by many highway agencies about the performance characteristics of PPA modifica...

BACKGROUND Asphalt workers are exposed to bitumen fume and vapour, and to exhaust from engines and passing traffic. AIMS To assess the occurrence of respiratory symptoms and signs of airflow limitations in a group of asphalt workers. METHODS All 64 asphalt workers and a reference group of 195 outdoor construction workers from the same company participated in a cross-sectional study. Spirome...

We report on dry asphalt roads acting as 'mayfly traps'; that is, they lure swarming, mating and egg-laying mayflies in large numbers. To explain this surprising behaviour, we performed multiple-choice experiments with Ephemeroptera in the field, and measured and compared the reflection-polarization characteristics of an asphalt road and a mountain creek from which mayflies emerge. We show here...

Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA) concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant...

This study made comparisons of the expected noise and durability performance of asphalt surface mixes based on laboratory testing only, and recommended a set of surface mixes for field test sections with improved surface performance properties. The study included a series of experiments to investigate the effects of several important mix variables identified in studies of field test sections, i...

The National Center for Asphalt Technology (NCAT) completed a roundrobin study in March to determine the accuracy and precision of the NCAT asphalt content tester. The Center has conducted research since 1990 to develop this test method for determining asphalt content of hot mix asphalt (HMA) mixtures by ignition (See the fall, 1994, issue of Asphalt Technology News). In the ignition method, a ...