The National Center for Asphalt Technology (NCAT) has undertaken a wide range of hot mix asphalt (HMA) related research projects. These projects have been funded by various agencies such as the National Cooperative Highway Research Program (NCHRP) of the Transportation Research Board, the Federal Highway Administration (FHWA), the Alabama Department of Transportation, the South Carolina Departm...

The National Center f’or Asphalt Trchnolofiy (NCAT) has just complctd two Nation;ll Coopwrrive HicThw:tv Rr<e:lrch Pq!ram (NtHR6) Projects: NCHRP 9-X. “Designing Stone Matrix Asphalt (SMA) Mixtures.” and NCHRP 9-9. “Reilnement of Superpave Gyratory Compaction Procedure.” Dr. Ray Brown. NCAT director. was the p r i n c i p a l invcsti:etor on both pmjects. The fint project on SMA represented ;I ...

Lignin fibers typically influence the mixture performance of stone matrix asphalt (SMA), such as strength, stability, durability, noise level, rutting resistance, fatigue life, and water sensitivity. However, limited studies were conducted to analyze the influence of fibers on the percent voids in mineral aggregate in bituminous mixture (VMA) during the mixture design. This study analyzed the e...

During the process of compaction in Hot-Mix Asphalt (HMA) mixtures, the distance between aggregate particles decreases as they come together and eliminate air-voids. By measuring the inter-particle distances in a cut-section of a HMA sample the degree of compaction can be estimated. For this, a calibration curve is generated by computer simulation technique when the gradation and asphalt conten...

A micromechanical finite element (FE) framework was developed to predict the viscoelastic properties (complex modulus and creep stiffness) of the asphalt mixtures. The two-dimensional (2D) microstructure of an asphalt mixture was obtained from the scanned image. In the mixture microstructure, irregular aggregates and sand mastic were divided into different subdomains. The FE mesh was generated ...

pavement permanent deformations due to lack of shear strength in mixture are a major reason of rutting. any simple test to determine mixtures resistance to permanent deformation isn’t distinguished in the 1st level of superpave mix design method and prevalent methods for evaluating mixture rut resistance are expensive and time-consuming. two aggregate types, gradations, asphalt cements and fill...

Title of dissertation: Effect of Aggregate Inhomogeneity on Mechanical Properties of Asphalt Mixtures Haleh Azari, Doctor of Philosophy, 2005 Dissertation directed by: Professor Richard McCuen Department of Civil and Environmental Engineering Vertical and radial inhomogeneity of asphalt mixture components in laboratoryfabricated specimens have been of concern in asphalt mixture testing because ...

The use of recycled materials in pavement construction has seen, over the years, a significant increase closely associated with substantial economic and environmental benefits. During the past decades, many transportation agencies have evaluated the effect of adding Reclaimed Asphalt Pavement (RAP), and, more recently, Recycled Asphalt Shingles (RAS) on the performance of asphalt pavement, whil...

Bio-oil is a dark brown, mobile liquid derived from the thermo-chemical processing of bio-mass. Bio-oils generally contain water and lignin. Lignins are highly-available, well-studied carbohydrate derivative known for their antioxidant properties. For asphalt pavements, oxidation can cause deterioration, a longterm aging process, and eventually result in cracking. Therefore, bio-oil could poten...

Since the 1960s, Stone Mastic Asphalt (SMA) pavement surfaces have been used successfully in Germany on heavily trafficked roads. Because of its excellent performance characteristics, road authorities in Germany as well as major European Countries quickly adopted SMA as a standard wearing course. As a consequence of an asphalt study tour in Europe of an American delegation in 1990, SMA test sec...