Hussain U. Bahia

Computer-integrated methodologies for real-time control of asphalt paving operations

A real-time control system is needed for measuring and improving productivity and quality in asphalt pavement operations . This paper presents four computerintegrated methodologies necessary to develop a real-time control system for asphalt paving operation. These methodologies include: ( 1) simulation modeling for optimal allocation of resources, (2) automatic truck dispatching system to maximize truck productivity. (3) Global Positioning System (GPS) for realtime positional data acquisition , and (4) semi-automated path-planning and real-time guidance system for rolling operations. Interrelating these independent methodologies using a systems approach will allow for the development of a real-time control system for asphalt paving operations. Developing a real-time control system by standardizing construction practices will create a system that is amenable to strict quality and cost control.

Evaluation of rutting performance of asphalt mixtures using Extra-Large Wheel Tracking and 2-D imaging technique

The internal aggregate structure provides the load carrying skeleton of the asphalt mixtures, which plays a leading role in the rutting resistance of pavements. The main objective of this study is to investigate the application of two-dimensional (2-D) imaging and analysis technique to evaluate the role of aggregate packing in rutting performance of three different types of asphalt mixtures. The 2-D images are derived by scanning the cross sections of cylindrical samples taken from asphalt slabs which have been tested using an Extra-large wheel tracking device. Samples from loaded and unloaded areas of the slabs are analyzed to assess any difference in aggregate re-orientation and segregation effects. The mixture rutting performance is evaluated based on the total length of the contact between the aggregate particles which is derived from the image analysis. The software system called IPAS2 (Image Processing and Analysis Software) developed in previous studies is used to process the images of the asphalt mixtures with different gradations and binder contents. The results demonstrate a clear correlation between the internal structure indices and the mixture rutting performance. Such results can explain the significant role of aggregate structure in rutting of pavements.