The asphalt content of an asphalt mixture, as binder, is an important physical characteristics and influences the performance life of flexible pavements. Traditionally, in Iraq the asphalt content has been measured in laboratory by extraction from the mixture with chemical solvents. Recently, a new technology, known as the ignition method, has been developed to eliminate the need for these harmful solvents and to make the laboratory more safer. The main objective of this work was to evaluate and use the ignition test method to determine asphalt content and aggregate gradation in hot mix asphalt mixtures. An extensive laboratory work was conducted to meet this objective, which involving more than 300 samples of asphalt mixture, with five asphalt contents and two types of aggregate of three types of gradation, were prepared and tested using ignition and extraction methods.
Data from ten laboratories was analyzed and used to determine the accuracy and precision of this test method. The study results and statistical analysis have show that the ignition method can be used to accurately and quickly determine the asphalt content and aggregate gradation of asphalt mixtures with same, if not greater, precision than the extraction method.
Key Words: asphalt content, ignition test, hot-mix asphalt, statistical analysis