The Colorado Department of Transportation (CDOT) and the Turner-Fairbank Highway Research Center (TFHRC) will be demonstrating some European testing equipment for hot mix asphalt. The equipment includes the French mixer, French gyratory compactor, French plate compactor, French mixer, Hamburg wheel tracking device and the Georgia loaded wheel tester. The advantages, disadvantages, costs and manufacturers are discussed. The joint research project between CDOT and TFHRC to evaluate the equipment and asphalt mixes is included.
The French rutting tester has been used successfully in France to eliminate the occurrence of rutting. The Colorado Department of Transportation (CDOT) and the Turner-Fairbank Highway Research Center (TFHRC) were selected to demonstrate this equipment. Thirty-three sites across Colorado with good and poor performance and a variety of temperature and traffic conditions were selected. Test results indicated that the French rutting tester, using the French specifications, was overly severe for many of the temperature and environmental conditions encountered in Colorado. However, by adjusting the testing temperature to match the highest temperature at a site location, the French rutting tester did an excellent job of predicting pavement performance. The results from the French rutting tester also had good correlation with actual rutting depths when temperature and traffic levels were considered.
The purpose of the report is to identify differences in Colorado's aggregates and asphalt cements as measured and compared to some of the European tests and specifications. Performance-related tests for asphalt cements developed by SHRP will be the ultimate method to identify performance and should be well received in Europe. Based upon the standard empirical tests on asphalt cements from four refineries commonly used in Colorado, the asphalt cements are comparable to those used in France. The 17 most frequently used aggregate sources in Colorado were tested for the study. The angularity of fine aggregates is measured with the NAA test procedure. The quality of the P200 is measured with respect to angularity, durability, and stiffening.
