The objective of this study is to evaluate the rheological properties and chemical bonding of nano-modified asphalt binders blended with nanosilica. In this study, the nanosilica was added to the control asphalt at contents of 4% and 6% based on the weight of asphalt binders. Superpave binder and mixture tests were utilized in this study to estimate the characteristics of the nano-modifed aspha...

heat stress effects on physical and mental health of workers and decreases human function. asphalt workers are both exposed to the heat of their working process and to the sun heat. this study aimed at evaluating thermal stress and its following function fall and the effect of asphalt work on the degree of heat stress and asphalt workers’ physiological parameters. the present study was done at ...

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 ...

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...

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 ...

This work aims to improve the rutting and fatigue cracking resistance of asphalt binders using selected nanoor micro-sized materials and to shed light on the microstructure changes induced by such modification to asphalt binders. The four modifiers (Nanomer I.44P, carbon microfiber, non-modified nanoclay and polymer modified nanoclay) were added into the control asphalt binder (PG 58-34). The S...

knowledge of the warming or cooling effects induced by asphalt or grass covered areas, may improve our understanding of how thermal stress or thermal comfort is created for workers who have to work outdoors for long hours in warm seasons. for this purpose a field measurements were carried out to know the cooling and warming effects of two adjacent areas, one covered with grass and the other wit...

Significant public procurement changes are forcing road construction companies to professionalise planning and control of asphalt paving projects. In an effort to outperform competitors, companies seek better control over the paving process, over the planning and scheduling of resources and work, and over performance. For the asphalt paving companies to be able to improve product and process pe...

Disclaimer: Mention of any company or product does not constitute endorsement by NIOSH. A s part of its mandate to " provide a safe and healthful workplace for working women and men, " the National Institute for Occupational Safety and Health (NIOSH) critically evaluates the scientific data on potentially hazardous occupational exposures or work conditions and makes recommendations that address...

background:  controversy exists as to the potential of asphalt fumes to induce respiratory symptoms and lung functional impairments. objective: to examine the respiratory effects, if any, of occupational inhalation exposure to asphalt fumes. methods:  in this cross-sectional study, 74 asphalt workers and 110 unexposed employees were investigated. the prevalence of respiratory symptoms among sub...