This thesis discusses and documents the validation efforts related to Ontario’s LS-299 and LS-308 test methods which are two new test methods developed for the performance-based specification grading of asphalt cement. In addition, this report presents the field validation of a simple performance indicator, loss tangent, for specification grading of asphalt cement for thermal cracking. Furthermore, another objective of this study is to investigate and compare the low temperature fracture and rheological behavior of engineered asphalt materials from field and laboratory-aged test sections on Highway 655 in northern Ontario. Extracted asphalt cements from 20 contract sites in eastern and northeastern Ontario were tested according to Ontario’s LS-299 and LS-308 test methods. It was found that all good performing contracts that showed little or no distress showed low grade losses in LS-308 and retained high strain tolerances as measured in LS-299 compared to the poor performing contracts. Asphalt cements recovered from these 20 contract sites in eastern and northeastern Ontario were also tested in torsion bar geometry to determine their viscoelastic properties. It was decided to focus on the phase angle, as a more direct measure for low temperature performance. Phase angle is a very sensitive parameter to small changes in rheology as the phase angle is approximately equal to the derivative of the logarithm of the stiffness with respect to frequency. It was found that tan() was able to distinguish good from poor performers with 95% accuracy after only a short period of conditioning prior to testing. This is a considerable improvement over the current low temperature bending beam rheometer protocol. Black space diagrams, frequency sweeps, Cole-Cole plots, and master curves were generated for comparison of field and laboratory aged materials from the Highway 655 trial in northern Ontario. The findings show that chemical hardening occurs much faster in the field than through laboratory ageing methods. Also, reversible ageing of binders may occur at low temperatures and could be linked to field performance. Furthermore, a high low temperature phase angle appears to be a reasonable indicator for thermal cracking resistance. / Thesis (Master, Chemistry) -- Queen's University, 2009-08-28 15:12:29.845

Asphalt mixtures are complex composites that comprise aggregate, asphalt binder, and air. Several research studies have shown that the mechanical behavior of the asphalt mixture is strongly influenced by the matrix, i.e. the asphalt binder. Therefore, accurate constitutive models for the asphalt binders are critical to ensure accurate performance predictions at a material and structural level. However, researchers who use computational methods to model the micromechanics of asphalt mixtures typically assume that (i) asphalt binders behave linearly in shear, and (ii) either bulk modulus or Poisson’s ratio of asphalt binders is not time dependent. This research develops an approach to measure and model the shear and bulk behavior of asphalt binders at intermediate temperatures. First, this research presents the findings from a systematic investigation into the nature of the linear and nonlinear response of asphalt binders subjected to shear using a Dynamic Shear Rheometer (DSR). The DSR test results showed that under certain conditions a compressive normal force was generated in an axially constrained specimen subjected to cyclic torque histories. This normal force could not be solely attributed to the Poynting effect and was also related to the tendency of the asphalt binder to dilate when subjected to shear loads. The generated normal force changed the state of stress and interacted with the shear behavior of asphalt binder. This effect was considered to be an “interaction nonlinearity” or “three dimensional effect”. A constitutive model was identified to accommodate this effect. The model was successfully validated for several different loading histories. Finally, this study investigated the time-dependence of the bulk modulus of asphalt binders. To this end, poker-chip geometries with high aspect ratios were used. The boundary value problem for the poker-chip geometry under step displacement loading was solved to determine the bulk modulus and Poisson’s ratio of asphalt binders as a function of time. The findings from this research not only improve the understanding of asphaltic materials behavior, but also provide tools required to accurately predict pavement performance. / text

The main objectives of this research were twofold: 1). to develop advanced material characterization techniques for bitumen, mastic and mortar aiming to improve the knowledge of the behavior of asphalt concrete at micro and meso scales, and 2). to develop an efficient macro-mechanical numerical model capable of determining flexible pavement responses to traffic and environmental loads.

The Diploma thesis is focus on polymer modified bitumen for warm mix asphalt. The theoretical part of the thesis describes additives which influence the properties of bitumen for their use and reduction of production and service temperatures. Further, the theoretical part describes the conclusions from the researches. This part also describes empirical and functional tests of bituminous binders. The practical part presents the results of individual tests. Tests were performed on samples of non-aged, aged by RTFOT and RTFOT + PAV methods. The results of the work and the assessment of the suitability of bituminous binders are summarized at the end of the thesis.

The diploma thesis is focused on polymer modified binders with different polymer doses. The theoretical part describes the history of the use of bitumen, the extraction of bitumen from oil and behavious of the polymer type SBS/SB, which is used in the diploma thesis on modified binders. Further, the theoretical part describes the empirical and functional tests of bitumen binders. In the practical part the results of indidual tests are presented and compared with the standard ČSN 65 7222-1. At the end of the diploma thesis are summarized results of work and evaluation of binders with the best achieved properties.

The thesis describes the relaxation properties of bituminous binders determined in dynamic shear rheometer (DSR). Paving bitumen, polymer modified bitumen (PMB) and crumb rubber modified bitumen (CRmB) were chosen for comparison. In order to describe the effects of ageing on asphalt binders relaxation properties, the laboratory simulation of ageing using RTFOT and 3xRTFOT method was performed. For each binder were simultaneously conducted tests of needle penetration, softening point and elastic recovery. Selected bitumens were used for the production of asphalt mixtures. The low-temperature properties tests (TSRST) were performed for these mixtures, when the results were compared to the relaxation properties of binders determined in the DSR.

The theoretical part of this thesis describes the rheology of bituminous binders, aging of asphalt binders and laboratory methods simulating short and long term aging. The following describes an empirical tests (needle penetration, softening point ring ball method) and functional tests (complex shear modulus and phase angle, dynamic viscosity), which are performed in the dynamic shear rheometer. At the end of this section, laboratory aging of bituminous binders using method RTFOT and method RTFOT + PAV is described in more detail. In the practical part of this thesis, the results of all tests performed on the binders aged using RTFOT + PAV are introduced and compared with results of properties of non-aged binders and binders aged by 3xRTFOT.

Dissertation thesis is focused on rheological properties of asphalt binders and on changes of their performance during the lifetime in road structures. Aging processes of asphalt binders and methods of laboratory aging are described in the theoretical part of the thesis. Furthermore, basic rheological models and related test methods for the evaluation of asphalt binders are described. In the practical part, properties of asphalt binders are investigated after aging process and their performance is evaluated by empirical and functional test methods. The various methods of aging are compared with each other and a relationship between real conditions and laboratory aging is researched. In the next section, vacuum flashed cracked residue (VFCR) is added to the selected asphalt binders and their influence on rheological properties during description of aging of asphalt binders is investigated. The results were used in publication of two certified methodology under the title „The methodology for the evaluation of paving bitumen in terms of susceptibility to thermal oxidative aging“ and „The methodology describes laboratory aging of asphalt mixtures“. The results of the thesis are listed in the conclusion.

Subject of this diploma thesis is to describe the effect of adding different amount of aged binder recovered from RAP on the change of properties of polymer modified bitumen. The RAP containing unmodified bitumen and the RAP where we can expect bitumen modification are used to recover binder. The binder obtained from RAP is dosed into the virgin binder in amount of 15 %, 30 % and 50 %. The methods of recycling of flexible pavements, extraction and regeneration of asphalt binders, rejuvenating of their properties and methods of empirical and functional laboratory tests are described in the theoretical part. The practical part deals with evaluating and comparison of the results mixed binders properties.