In this work, an aged asphalt was mixed with a new modified based on styrene–butadiene–styrene (SBS) in different proportions, and the warm mixing agent added to simulate fusion behaviour recycled fertilizer (reclaimed pavement, RAP) content. Low field nuclear magnetic resonance (LF-NMR), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) were used as analytical techn...

The use of polymer in hot mix asphalt production has remarkably in recent decades. Destruction due to moisture in hot mix asphalt is of basic matters about flexible pavement durability. In recent decades different ways have been used to evaluate moisture Sensitivity of HMA which some of them are simple with low cost and some are complicated with more reliable results. In this research the effec...

Putting Research Into Practice Page 10 The National Center for Asphalt Technology (NCAT) has just completed a National Cooperative Highway Research Program (NCHRP) Project: NCHRP 9-11, “Segregation in Hot Mix Asphalt Pavements.” Dr. Mary Stroup-Gardiner was the principal investigator on this project. Segregation has historically been defined to mean localized areas of coarse materials in some a...

This report evaluates the effectiveness of rubber-asphalt and ebonite-asphalt mixes based on a review of published literature and unpublished reports. It discusses in detail various aspects of these mixes, including: diffe ent applications, physical properties, experiences of state highway agencies, and claimed advantages and problems associated with their use. The addition of ground tire rubbe...

From the perspective of sustainability and environmental concerns, use cold-mix asphalt (CMA) recycled pavement (RAP) is more advantageous than hot mix (HMA) warm (WMA). Some researchers used a mixture CMA RAP to improve mechanical properties made it economical. However, only few studies have focused on using high content RAP—particularly 100% RAP—as virgin aggregate. Therefore, this study aims...

Hot-mix asphalt (HMA) surfaces comprise about 90% of the highways and roads in the U.S. Highways and are typically engineered to last 15 years or more, but many have been failing early due to potholes, cracks, raveling, and other problems. This premature road failure unnecessarily wastes millions of taxpayer dollars every year. This paper describes a series of research studies that were conduct...

BACKGROUND Asphalt workers are exposed to polyaromatic hydrocarbons (PAHs) from hot mix asphalt via both inhalation and dermal absorption. The use of crumb rubber modified (CRM) asphalt may result in higher exposure to PAHs and more adverse effects. Our aim is to assess occupational exposure to PAHs from conventional and CRM asphalt paving by measuring PAH metabolites in urine, and to investiga...

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 ...