Asphalt Material Characterization in Support of Mechanistic–Empirical Pavement Design Guide Implementation in Virginia

Abstract

The procedure proposed in the Guide for Mechanistic–Empirical Design of New and Rehabilitated Pavement Structures (referred to as MEPDG) heavily depends on the characterization of the fundamental engineering properties of paving materials. This paper presents the results of a project aimed at the characterization of hot-mix asphalt (HMA) in accordance with the procedure established by MEPDG to support its implementation in Virginia. The project examined the dynamic modulus, the main HMA material property required by MEPDG, as well as creep compliance and tensile strength, which are needed to predict thermal cracking. Loose samples of 11 mixes (four base, four intermediate, and three surface mixes) produced with PG 64-22 binder were collected from different plants across Virginia. Representative samples underwent testing for maximum theoretical specific gravity, asphalt content by the ignition oven method, and gradation of the reclaimed aggregate. Specimens for the various tests were then prepared by use of the Superpave® gyratory compactor. The test results showed that the dynamic modulus is sensitive to the mix constituent properties (aggregate type, asphalt content, percentage of recycled asphalt pavement, etc.) and that even mixes of the same type (SM-9.5A, IM-19.0A, and BM-25.0) had different measured dynamic modulus values. The Level 2 dynamic modulus prediction equation reasonably estimated the dynamic modulus measured; however, it did not capture some of the differences between the mixes found in the measured data.

Sensitivity analysis of dynamic response and fatigue behaviour of various asphalt concrete mixtures

“…However, this seems to be deemed fit until temperature reaches 37.8 °C, as the phase angle tends to behave oppositely and tends to decrease with increase in temperature and decrease with decrease in frequency. This is in agreement with the findings of past researches that concluded that the elastic behaviour of the aggregate dictates the response of the HMA at high temperatures and low frequencies …”

“…This is in agreement with the findings of past researches that concluded that the elastic behaviour of the aggregate dictates the response of the HMA at high temperatures and low frequencies. 7,22…”

“…A research was carried out in Virginia state to examine dynamic modulus of HMA mixtures to predict creep amenability and tensile strength of asphalt concrete mixtures. This research study concluded that better characterisation can be obtained by dynamic modulus, which is sensitive to mix constituents (aggregate type, asphalt content, percentage of recycled asphalt pavement) . Apeagyei investigated the various asphalt mixtures and performed flow number tests and correlated with dynamic modulus at 38 °C test temperature for various gradations.…”

“…This research study concluded that better characterisation can be obtained by dynamic modulus, which is sensitive to mix constituents (aggregate type, asphalt content, percentage of recycled asphalt pavement). 7 Apeagyei 8 investigated the various asphalt mixtures and performed flow number tests and correlated with dynamic modulus at 38°C test temperature for various gradations. The dynamic modulus test is costly and difficult to perform in laboratory.…”

Evaluation of reflective cracking in pavements using a new procedure that combine loads with different frequencies

“…As a reference, in the existing literature, the modulus which is usually assumed in numerical models to apply traffic loads is approximately 6000 MPa, while in the case of low frequency loads this value decreases to 1000 MPa or less [25]. In this case, the variation range of moduli has been estimated from the master-curve of a wearing course mixture obtained by Flintsch et al [26] in their study. For this purpose, temperatures from 0°C to 20°C and frequencies from 10 Hz to 0.001 Hz have been considered reasonable [27].…”