Study of Bituminous Surface Treatments in Virginia: Analysis of Factors That Significantly Influence the Quality of Bituminous Surface Treatments

About the report:

It is obvious that many variables may influence the quality of a surface treatment, but the relative importance of the many variables involved is a matter of conjecture. The purpose of this study was to define those variables which do significantly influence the quality of surface treatments in Virginia and to determine the acceptable limits for them. The range in conditions and materials encountered were limited to those normally found in Virginia. Also, since the data were obtained from surface treatment projects included in the regular work schedule, there was very little opportunity to establish any experimental design. Because of this limitation it was impossible to evaluate all the variables it was hoped could be included in the study. Of the many variables included air temperature, surface temperature, average vehicles daily, and age at the time of evaluation seem to most significantly affect the performance of a surface treatment. Three of these variables, air temperature, surface temperature, and AVD, are controllable and one, age, is not controllable. Based on the information obtained in this study it appears that the lower limit for air temperature should be 70°F and the upper limit for AVD should be approximately 400, assuming procedures for surface treatment work remain the same as encountered in this project. It was found that air and surface temperatures correlate well, and it is only necessary to control one. Air temperature was chosen as the one to control since it is easier to measure. The percentage distribution of the surface treatment jobs evaluated in this study was 40% good, 32% fair, 16% poor, and 12% very poor. Adoption of the guidelines suggested above for air temperature and AVD would have changed the percentage distribution to 47% good, 39% fair, 10% poor, and 4% very poor; but under these guidelines 49% of the jobs would not have been placed.

Authors