Low temperature performance grading currently relies solely on Bending Beam Rheometer (BBR) for determining low temperature creep stiffness (S) and rate of modulus relaxation (m-value) at 60s, both determined at low stress-strain levels, in the pre-failure zones. This aspect raises questions with regard to applicability of properties derived from the linear viscoelastic range for prediction of asphalt binder thermal cracking behavior. Furthermore, many researchers have reported a discrepancy between field cracking severity and predictions based on asphalt binder properties since the asphalt binder-aggregate interaction is non-existent in asphalt binder testing. Therefore evaluation of asphalt mastics properties which could save a considerable amount of time and equipment in comparison to mixture testing should be prioritized. These challenges indicate that considering fracture properties of asphalt mastics could be a better approach for prediction of thermal cracking in asphalt pavements. It is believed that development of failure master curves for the damage characterization of asphalt mastics at different temperatures and loading rates would be beneficial for better characterization of resistance to thermal cracking. Therefore, in this dissertation a mechanistic approach on the development of such asphalt mastic failure master curves was derived using the new BBR-SENB test for damage resistance characterization. The complexity of the viscoelastic behavior of asphalt mastics in terms of time and temperature dependency is also recognized by the sensitivity of the failure properties to changes in loading time and temperature. This dissertation documents the development, calibration, and validation of a fundamental analysis framework of asphalt mixtures thermal cracking behavior using asphalt mastics as the continuous phase of these mixtures. Key conceptual components of this study include applying time temperature superposition principles to large strain failure properties, development of asphalt mastic failure master curves, and investigating relationship between mastic viscosity and aggregate structure of asphalt mixtures in the context of thermo-volumetric properties of mixtures. An analysis framework for predicting thermal cracking of asphalt mixtures was developed which include considering asphalt mastics, aggregate internal structure and temperature dependent thermo-volumetric properties. Results where compared to experimental data measured using the ATCA device, which allowed measuring strain and stress build up during cooling.

The current test methods for measuring fatigue cracking resistance of asphalt mixtures involves many steps which are time-consuming and costly. On the other hand, asphalt binder and mastic testing are less time consuming and more accessible to practitioners than mixtures testing. Therefore, if the routinely measured properties of asphalt binders, fillers, and volumetric parameters of asphalt mixtures can be used to predict cracking resistance of mixtures, the effort to perform mixtures testing of asphalt mixtures can be minimized. The objective of this study is to develop prediction models for cracking and damage behavior of asphalt mixtures using the stepwise regression method at intermediate temperatures from limited laboratory testing of binders and mixture volumetric properties routinely done in practice. In the first phase of this study, the effects of physical and chemical properties of fillers on fatigue of asphalt mastic are measured using LAS test are measured. Then prediction models of Linear Amplitude Sweep (LAS) parameters of the mastics are developed using the physical (Rigden Voids-RV and Fineness Modulus-FM), chemical properties (Calcium Oxide and Methylene Blue) of the fillers, and the LAS parameters of the binders. The results show that the fatigue cracking resistance of mastic is dependent on the interaction between base asphalt binder and filler type. The results also show that the effect of fillers on the fatigue life of mastic is dependent on the failure criterion used in the analysis of LAS test. It is also found that the fatigue cracking resistance (LAS Parameters) of mastic can be predicted reliably from Rigden Voids and LAS parameters of binders. In the second phase of the study, prediction models of cracking resistance of mixtures as measured by the Semi-Circular Bending- Illinois Flexibility Index Test (SCB-IFIT) are developed using an experimental database including 44 mixtures that are short-term-aged and 30 for long-term-aged mixtures. These mixtures are produced with varying combinations of Recycled Asphalt Pavement (RAP), binder, aggregate sources, and fillers. More specifically, models for the SCB parameters (Flexibility Index (FI), post-peak slope, and Fracture Energy (Gf) models are constructed using various independent variables such as asphalt content, asphalt film thickness, aggregate gradation, RAP content, LAS parameter of binder and mastic properties. A sensitivity analysis is performed to access the impact of these independent variables on SCB parameters. Based on the correlation and validation results, the developed models of SCB parameters are found to predict the FI, post-peak slope and Gf of asphalt mixtures with high accuracy. The developed models are recommended to use for estimating the fatigue cracking resistance of asphalt mixtures when testing is not feasible or as an initial step for selection of mixture designs and binder grades before mixture testing.

The purpose of this study was to evaluate the effect of binder type, mastic, and aggregate type on the low-temperature cracking characteristics of asphalt mixtures. Six different performance grade (PG) binders were utilized for this study: PG64-28, PG64-28 with poly phosphoric acid, PG64-34 SBS, PG76-22 SBS, a terminal blend asphalt rubber, and PG64-28 with 2 % latex. Each binder was tested to determine its low-temperature cracking resistance using the asphalt binder cracking device (ABCD) and the Superpave tests. A Superpave 9.5 mm mixture was designed using each of the six binders for this study and two sources of aggregates (crushed stone and gravel). Each mixture was then tested for low-temperature cracking resistance using the asphalt concrete cracking device (ACCD). Mastics corresponding to each mixture were tested for low-temperature cracking resistance using the ABCD. Analysis of the results showed that the AASHTO critical cracking temperature had a strong correlation with the ABCD binder and mastics results, but did not correlate well with the mixture tests. Mastic testing generally did not correlate well with the mixture test results. ABCD and ACCD tests results indicated that they were sensitive to binder type, aging time, and aggregate types.

This work presents the results of RILEM TC 237-SIB (Testing and characterization of sustainable innovative bituminous materials and systems). The papers have been selected for publication after a rigorous peer review process and will be an invaluable source to outline and clarify the main directions of present and future research and standardization for bituminous materials and pavements. The following topics are covered: - Characterization of binder-aggregate interaction - Innovative testing of bituminous binders, additives and modifiers - Durability and aging of asphalt pavements - Mixture design and compaction analysis - Environmentally sustainable materials and technologies - Advances in laboratory characterization of bituminous materials - Modeling of road materials and pavement performance prediction - Field measurement and in-situ characterization - Innovative materials for reinforcement and interlayer systems - Cracking and damage characterization of asphalt pavements - Recycling and re-use in road pavements This is the proceedings of the RILEM SIB2015 Symposium (Ancona, Italy, October 7-9, 2015).

Inspired from the legacy of the previous four 3DFEM conferences held in Delft and Athens as well as the successful 2018 AM3P conference held in Doha, the 2020 AM3P conference continues the pavement mechanics theme including pavement models, experimental methods to estimate model parameters, and their implementation in predicting pavement performance. The AM3P conference is organized by the Standing International Advisory Committee (SIAC), at the time of this publication chaired by Professors Tom Scarpas, Eyad Masad, and Amit Bhasin. Advances in Materials and Pavement Performance Prediction II includes over 111 papers presented at the 2020 AM3P Conference. The technical topics covered include: - rigid pavements - pavement geotechnics - statistical and data tools in pavement engineering - pavement structures - asphalt mixtures - asphalt binders The book will be invaluable to academics and engineers involved or interested in pavement engineering, pavement models, experimental methods to estimate model parameters, and their implementation in predicting pavement performance.

The mixture design and performance characteristics of crumb rubber modified asphalt concretes were investigated in this research project to meet the requirements of the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991, which has required each State to incorporate scrap tire rubber into its asphalt paving materials. Specifically, the objectives of this research encompass the following: (i) investigation of the rheological properties of asphalt-rubber binder to determine optimum content of crumb rubber; (ii) development of optimum mix design for various applications, including both wet and dry mix processes; (iii) characterization of mechanical properties of recommended paving mixtures, including resilient modulus, fatigue cracking behavior, low-temperature thermal cracking resistance, water sensitivity test, incremental creep test and loaded wheel track test; and (iv) comparison of performance of selected paving mixes.