The objectives of this research were to evaluate the rapid triaxial test method for use in quality control of hot-mix asphalt production and, if possible, determine test conditions for reliable results. The scope of this study consisted of testing different mixes at two different temperatures and frequencies and evaluating the results. The equipment was rugged and portable, and the hardware and software were easy to handle and did not require extensive technician training. The results from this study show that modulus and phase angle values obtained from testing are sensitive to key mixture components and properties. The coefficients of variation of results obtained from tests conducted at 60 deg C and 1 Hz are low. Tests with fine-graded mixes showed good correlation of dynamic stiffness parameters with rutting, and the stiffness parameters were found to be sensitive to the ratio of dust to effective binder. One significant advantage of using this test procedure as a regular quality control tool is that decisions can be made on the basis of performance-related parameters rather than on the basis of volumetric properties only. In view of its desirable qualities, this test method seems to be usable on a regular basis for quality control testing. However, before it is used, agencies must adopt a test protocol and establish target values and allowable variations.
Abstract