EVALUATION OF PHASE ANGLE AS A PRACTICAL PARAMETER FOR LOW TEMPERATURE SPECIFICATION GRADING OF ASPHALT BINDERS
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Date
Authors
Adeyeye, Abiola
Keyword
phase angle , low temperature specification grading , BBR , specification grading , thermal cracking , Extended BBR
Abstract
The importance of road and highway systems in the development of a nation’s economy cannot be overemphasized. Over the years, concerted efforts have been made by researchers to develop and design test methods with high accuracy, repeatability, and reproducibility. The goal is to reduce pavement failures and the high cost of road construction and rehabilitation. Current low temperature performance tests such as the bending beam rheometer (BBR) and extended BBR (EBBR) tests are not without limitations. They could be time-consuming and require more sample quantity even though they are rigorous and accurate. Hence, this study aims to examine the viability of limiting phase angle measurement as a credible alternative to the laborious extended BBR (EBBR) procedure.
In this study, a total of 239 samples were tested from various agencies and are grouped into tank samples, core samples and loose mix samples. Agency A and Agency B were carefully examined to ensure climatic and traffic requirements are met. High temperature performance grade (HTPG), intermediate temperature performance grade (ITPG), regular bending beam rheometer (BBR), extended bending beam rheometer (EBBR) tests were carried out on the samples. In addition to this, the data obtained from each test were correlated with limiting phase angle temperature [T(30°), T(45°)].
From the study, Agency B largely met the climatic and traffic requirements when compared with Agency A, due to a much more effective approach adopted by the agency. Furthermore, correlation studies involving ITPG, BBR, and EBBR with limiting phase angle temperature showed that core samples have the highest correlation followed by loose mix samples and tank samples. From the large data set used in this study, it is more evident that the limiting phase angle measurement is a viable alternative to evaluate the thermal cracking performance of binders because of its higher sensitivity, easier experimental procedure, and smaller sample quantity requirement.