A significant problem associated with asphalt concrete mixtures is the lack of durability resulting from an inadequate asphalt cement content. Additional asphalt cement added to increase durability results in flushing, bleeding and a significant loss In stability. Fibers have been used in stone matrix asphalt and open-graded friction course pavements successfully throughout Europe to allow high...

Organisms of the genera Pseudomonas, Chromobacterium, and Bacillus capable of degrading asphalt were isolated by enrichment cultures. The asphalt degradation by these organisms varied from 3 to 25% after incubation for 1 week. The effects of temperature, pH, and atmosphere of incubation on asphalt degradation were investigated and were shown to vary with different organisms on the same substrate.

Asphalt pavement recycling has grown dramatically over the last few years as the preferred way to rehabilitate existing asphalt pavements. Rehabilitation of existing asphalt pavements has employed different techniques; one of them, cold in-place recycling with foamed asphalt (CIR-foam), has been effectively applied in Iowa. However, Iowa’s current cold in-place recycling (CIR) practice utilizes...

rutting of hot mix asphalt pavements due to increased number of heavy vehicles, especially in tropical regions, causes several performance problems. large stone asphalt mixtures have more stiffness and shear resistance and so more rutting resistance compared to conventional mixtures. hence, using these mixtures in thick layers of hot mix asphalt pavements at tropical regions could be an appropr...

Asphalt paving is a specific type of construction work: the machines and materials constantly move while the asphalt mixture constantly cools down. The machine operators do have a clear goal – to provide an equally distributed and uniformly compacted asphalt layer in time-restricted conditions. But what does it mean in particular? In reality, the asphalt should be compacted to a certain degree ...

US transportation agencies have been increasingly using recycled asphalt shingles (RAS) in hot mix asphalt (HMA) applications over the last 25 years. Initial use of RAS started with recycled postmanufacturers shingles, but now agencies are showing a growing interest in using post-consumer (tear-off) RAS in asphalt applications. Post-consumer asphalt shingles typically have 20 to 30 percent asph...

US transportation agencies have been increasingly using recycled asphalt shingles (RAS) in hot mix asphalt (HMA) applications over the last 25 years. Initial use of RAS started with recycled postmanufacturers shingles, but now agencies are showing a growing interest in using post-consumer (tear-off) RAS in asphalt applications. Post-consumer asphalt shingles typically have 20 to 30 percent asph...

Recent research shows that macro-scale cracking in asphalt binder may originate from its intrinsic defects at the nano-scale. In this paper, a molecular dynamics (MD) simulation was conducted to evaluate the nucleation of natural defects in asphalt. The asphalt microstructure was modeled using an ensemble of three different types of molecules to represent a constituent species: asphaltenes, nap...

To evaluate the condition of asphalt pavement road, two GPR systems with different frequency band were mounted in the trailer type vehicle. The GPR system with higher frequency band was used to measure the thickness of the asphalt layers and the other system with lower frequency band was used to detect the air cavity located beneath the asphalt pavement.

This paper presents parts of the results from a research project sponsored by Taiwan Environmental Protection Administration (TEPA), investigating both the physical and environmental properties of asphalt mixtures using different amount of incinerator bottom ash (IBA) as fine aggregate substitution. The Marshall mix design method was used to determine the design asphalt content and evaluate the...