Concrete pavement recycling is a relatively simple process that involves breaking, removing and crushing hardened concrete from an acceptable source to produce recycled concrete aggregate (RCA). The formal process of RCA production typically involves an initial evaluation of the existing source concrete; pavement preparation, which may include removal of an asphalt overlay; pavement breaking, r...

The Heavy Weight Deflectometer (HWD) test is one of the most widely used tests for assessing the structural integrity of airport pavements in a non-destructive manner. The elastic moduli of the individual pavement layers predicted from the HWD deflection measurements through inverse engineering analysis are effective indicators of pavement layer condition. The primary objective of this study wa...

The finite element (FE) method has been widely used in predicting the structural responses of asphalt pavements. However, the three-dimensional (3D) modeling in general-purpose FE software systems such as ABAQUS requires extensive computations and is relatively time-consuming. To address this issue, a specific computational code EasyFEM was developed based on the finite layer method (FLM) for a...

are collaborating to evaluate the performances of three flexible pavement designs, including two perpetual/long-life (with and without the rich bottom mix (RBM) layer) and one conventional pavement designs. The three flexible pavement designs are being monitored by strain, pressure, temperature and moisture sensors, which are installed in the asphalt, granular and sub-base layers. Two types of ...

The principles underlying current mechanistic–empirical pavement design methods for fully flexible pavements have changed little in the past 30 years. They generally use linear elastic theory to determine the permissible strain at critical locations in the pavement structure to safeguard the road against excessive fatigue and structural deformation. These criteria are calibrated using performan...

The AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) pavement performance models and the associated AASHTOWare® Pavement ME Design software are nationally calibrated using design inputs and distress data largely from the national Long-Term Pavement Performance (LTPP). Further calibration and validation studies are necessary for local highway agencies’ implementation by taking into acc...

in petrochemical industry, the production of polyvinyl chloride (pvc) is accompanied by formation of heavy end wastes which consist of a mixture of di and multichloro compounds as kind of materials which are generated in ethylene dichloride (edc) purifcation. a high quantity of chloro compounds found in the heavy end waste allows it to be polymerized with alkaline polysulfdes to form polysulfde...

The National Airport Pavement Test Facility (NAPTF) was constructed to generate full-scale testing data to investigate the performance of airport pavements subjected to complex gear loading configurations of new generation aircraft. During the first test program, the NAPTF test sections were simultaneously subjected to Boeing 777 trafficking in one lane and Boeing 747 trafficking in another lan...

the available methods for predicting mechanical characteristics of pavement layers are categorized into two general groups, destructive and non-destructive. in destructive method, using coring and pavement subgrade and performing necessary experiments on them, the quantities of layers properties will be identified. in non-destructive method, the attained deflection is measured by applying the l...