QUALITY CONTROL AND QUALITY ASSURANCE OF

ASPHALT MIXTURES

 

H. I. Al-Abdul Wahhab

Professor, Department of Civil Engineering,

King Fahd University of Petroleum and Minerals

P.O. Box 1625, Dhahran 31261, Saudi Arabia

 

 

Abstract

The Gulf Countries (GC) have undergone an extremely rapid rate of development in many directions. Therefore, most of the Gulf Countries have developed more rapidly than many other industrialized countries. Due to the availability of relatively low cost asphalt binders, roadway networks in these countries are being built with flexible pavements. Over the past two decades, a massive construction program to modernize and improve the regionís highway networks has been initiated. Roads are designed to the best international standards for service life of 15 to 20 without any major maintenance. In spite of that, during the past few years some of these roads have experienced excessive failures such as rutting, raveling, depressions and fatigue cracking at early stages of pavementís life. The rate of deterioration of these pavements has been augmented by the increasing traffic volume, axle loads, tire pressure, lack of good quality materials, high water table, harsh environmental conditions, and lack or insufficient quality control and assurance practices.

††††† The quality of the asphalt concrete materials and construction methods play a significant role in the performance of the entire pavement structure. Specifications set forth by road agencies require asphalt materials to have a specified tolerance by specifying and controlling some of their important physical properties. This was done to minimize inferior performance of pavement structures in the field. Although there is similarity between many attributes of the different specifications, the specified material properties however are variable. Detailed Quality Control and Quality Assurance (QC/QA) specifications for asphalt concrete are practiced by some road agencies to control asphalt concrete materials and construction procedures variability. Some agencies have even specified some method of pay adjustment. These procedures have gained wide popularity since the historic AASHTO Road Test of 1956-1958, which has led to the development of statistically based end-result specifications.

††††† The main objective of this paper is to present statistical QC/QA methods for the control of asphalt concrete construction.