An investigation of the existence of predominant frequency, fp (or frequencies), and the ability to predict critical pavement responses in asphalt layers using those predominant frequencies has been presented. The study used an extensive database of computed pavement response histories of four different asphalt pavement structures (thin and thick) at two temperatures (21 and 40°C) subjected to a tandem axle load at three speeds (16, 65, and 97 km/h) using the pavement response analysis program 3D-Move Analysis. The conversion of load duration to frequency and the validity of using one response component (σzz) alone in the estimation of the pulse time (tp) were explored. Instead of focusing on only σzz, attention is given to all pavement response components (stresses and strains). In addition, verification of whether the use of a consistent set of fp value(s) can in fact adequately capture all components of pavement response has also been undertaken. The viscoelastic properties that are representa...

The overall objective of this study was to assess the performance of warm mix asphalt (WMA) mixtures in South Dakota based on laboratory and field evaluations. The study included three WMA technologies (Advera, Evotherm, and foaming) and three aggregate types (limestone, quartzite, and natural gravel). A comprehensive laboratory programme was conducted to assess the impact of WMA in terms of stiffness and mixtures’ resistance to moisture damage, rutting, fatigue cracking, and thermal cracking. Overall, the WMA mixtures performed comparatively similar to the hot mix asphalt (HMA) mixtures. The impact of the WMA technology was found to be aggregate dependent. WMA test sections were constructed on four Highways in South Dakota to validate the laboratory findings. During construction, percent compaction, roughness measurements were collected. Field observations indicated that WMA mixtures can be successfully produced and constructed using South Dakota's materials.

This paper summarizes the literature review as well as the documented use and performance of airfield pavements that used reclaimed asphalt pavement (RAP) in hot-mix asphalt (HMA). A review of in-service airfield pavements with RAP-containing HMA mixes was conducted as part of this study. Two civilian airports and one military airport were identified as currently using RAP in the HMA surface course. The three airports are Logan International Airport (BOS), Griffin-Spalding County Airport (6A2), and Oceana Naval Air Station (NTU). Furthermore, the impact of RAP on the performance life of HMA airfield pavements on a large hub, small hub, and general aviation was evaluated using actual airport traffic mixes. The performance life analysis used the characteristics and mechanical properties of HMA mixes in the linear elastic airfield pavement design software (LEDFAA1.3) to compare the estimated performance life of HMA pavements with and without RAP materials. The documented research effort has recently been con...

A comprehensive study was conducted to evaluate the impact of liquid and lime additives on the pavement performance of asphalt mixtures from five different sources around the USA. Three types of mixtures were evaluated from each source: untreated, liquid-treated and lime-treated. The measured properties of the 15 mixtures included the dynamic modulus master curves and their resistances to rutting and fatigue at the undamaged and moisture-damaged conditions. The moisture-damaged state consisted of subjecting the mixtures’ specimens to six freeze-thaw cycles. First the mixtures from each source were ranked based on their individual properties, i.e. dynamic modulus, permanent deformation and fatigue characteristics. Next, the measured properties of the mixtures were used in a mechanistic analysis to predict the rutting and fatigue lives of flexible pavements constructed with the evaluated mixtures. The estimated rutting and fatigue lives of the flexible pavements were ranked within each source. The analysis of the data showed that ranking of the mixtures within each source based on their individual properties significantly differs from the mixtures based on their rutting and fatigue lives estimated by the mechanistic analysis. This observation led to the conclusion that ranking hot mixed asphalt mixtures solely based on their independent properties provides unreliable recommendations concerning the relative performance of the mixtures. Finally, the performance of the mixtures was compared within each source and showed that lime-treated mixtures out-performed the liquid-treated mixtures for all sources regardless if the source required anti-strip additive or not.

Since the mid-1980s, polymer-modified asphalt concrete mixtures have been widely used to minimize rutting failures of flexible pavements. This research investigates the permanent deformation behavior of unmodified asphalt concrete mixtures as compared to the behavior of asphalt concrete mixtures modified with polyethylene. The rutting resistances of the mixtures at 40°C and 60°C are evaluated in the laboratory using the repeated-load permanent-deformation test. The data from the repeated-load permanent-deformation tests are used in the VESYS model to predict the rutting development of typical pavement structures built with both modified and unmodified mixtures. The analysis of the VESYS results indicate that the polyethylene-modified mixtures exhibit higher resistance to rutting than the unmodified ones. In addition, the layer coefficients of the polyethylene-modified mixtures were 75–85% higher than the layer coefficients of the unmodified ones.