Download or read book Characterization of the Bonding Fracture Properties of the Asphalt Aggregate System Using a Thin Film Interface Test written by Junyan Yi and published by . This book was released on 2015 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adhesion between asphalt-aggregate and cohesion within asphalt mastic has a significant effect on the performance of asphalt mixtures. Conventional testing methods and studies normally only focus on one of the damage modes (adhesion or cohesion), although in real asphalt mixtures (asphalt-aggregate system), these two failure modes can happen together depending on the material and loading conditions. The objective of this paper was to characterize the interface bonding characteristics of the asphalt-aggregate system using the thin-film interface test and the fracture property parameter, critical state energy density (CSED), and identify the key factors that could affect the interface bonding characteristics. The thin-film interface test simulated a more realistic bonding condition and monitored the damage between thin-film asphalt and aggregate. Experimental results showed that the effects of temperature and loading rate on the interface bonding characteristics were significant. The time-temperature superposition principle is found to work in both the linear viscoelastic range (dynamic modulus test) and the damage domain (interface bonding fracture test). Binder type, degree of aging, and types of aggregates all played an important role in the bonding performance for an asphalt-aggregate system.

Download or read book Fracture Characterization of Thin Bonded Asphalt Concrete Overlay Systems written by Sarfraz Ahmed and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Asphalt overlays provide an economical means for treating deteriorated pavements. Thin bonded overlay (TBO) systems have become popular options for pavement rehabilitation. In addition to functional improvements, these systems ensure a high degree of waterproofing benefits. Conventional asphalt concrete fracture tests were developed for pavements with homogeneous asphalt concrete mixtures, and typically their thicknesses exceed two inches. The use of spray paver technology for construction of TBO leads to continuously varying asphalt binder content, up to approximately one-third of the layer thickness. The graded properties of asphalt concrete and thickness of the TBO (typically less than 50 mm) pose challenges for the use of conventional fracture test geometries. For example, obtaining the beams for SEN[B] specimens from pavement may not practical because of insufficient layer thickness of the TBO or may lead to excessive pavement damage. Applications of the other established test geometries, the DC[T] and SC[B] tests, are limited because of the material nonhomogeneity caused by nonuniform distribution of asphalt binder and smaller as-constructed thicknesses of TBO, which are usually less than 25 mm (1 inch) for gap-graded and 50 mm (2 inch) for dense-graded hot mix asphalt (HMA) mixtures. Both the DC[T] and SC[B] tests simulate movement of the crack fronts in transverse or longitudinal directions in the pavement. Use of these tests on field-procured samples of TBO yields a crack front that encounters nonhomogeneous material through the specimen thickness. The crack moves perpendicular to the axis of material nonhomogeneity, which makes data interpretation and fundamental material fracture characterization challenging. In addition, the crack in the specimens is correlated to a crack channeling across the pavement width rather than a more anticipated bottom-up or top-down direction. New test procedures for fracture characterization of graded asphalt pavement systems that have significant material property gradients through their thicknesses have been proposed. Suitable specimen geometry and testing procedures were developed using ASTM E399 and ASTM D7313-07 as a starting point. Laboratory tests were performed using an optimized compact tension C[T] test geometry for field cores as well as laboratory-fabricated composite specimens. Laboratory testing using the proposed procedure clearly showed distinction in the fracture characteristics for specimens prepared with varying material compositions. This capability of distinguishing different materials combined with stable crack growth makes the proposed testing procedure ideal for fracture characterization of thin and graded pavement systems. Statistical analysis of test data revealed that the proposed C[T] test procedure is capable of detecting differences in fracture energy results across a wide range of pavement systems and yields a low test variability. Finite element simulations of the test procedure further indicate the suitability of the test procedure as well as demonstrate a procedure for extraction of fundamental material properties. The suitability of the proposed C[T] test in the context of warmer temperatures was also evaluated. Changes in the loading rate were suggested to minimize the creep energy dissipation during the test at different test temperatures. Composite specimen fabrication procedure has been developed to optimize the design of TBOs. The proposed procedure can also be used to prepared composite specimens for interface bond strength and rutting resistance tests with emulsion and asphalt cement as tack coat material. Suggested wet application of tack coat emulsion on textured base, compacted with heated Superpave gyratory compactor top plate closely resembles field installation of TBOs. Moreover tack coat emulsion permeation effects on mixture fracture and bulk properties were also evaluated in an experimental study. Image analysis technique was utilized to characterize the tack coat emulsion impregnation gradient through the thickness of the overlays. An integrated approach to predict cracking performance of TBOs was presented combining laboratory test results, numerical simulations and early field performance.

Download or read book Relationship Between Surface Free Energy and Total Work of Fracture of Asphalt Binder and Asphalt Binder aggregate Interfaces written by Jonathan Embrey Howson and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance of asphalt mixtures depends on the properties of its constituent materials, mixture volumetrics, and external factors such as load and environment. An important material property that influences the performance of an asphalt mixture is the surface free energy of the asphalt binder and the aggregate. Surface free energy, which is a thermodynamic material property, is directly related to the adhesive bond energy between the asphalt binder and the aggregate as well as the cohesive bond energy of the asphalt binder. This thermodynamic material property has been successfully used to select asphalt binders and aggregates that have the necessary compatibility to form strong bonds and resist fracture. Surface free energy, being based on thermodynamics, assumes the asphalt binder is a brittle elastic material. In reality, the asphalt binder is not brittle and dissipates energy during loading and unloading. The total work of fracture is the culmination of all energy inputted into the sample to create two new surfaces of unit area and is dependent on the test geometry and testing conditions (e.g., temperature, loading rate, specimen size, etc.). The magnitude of the bond energy (either adhesive or cohesive) can be much smaller in magnitude when compared to the total work of fracture measured using mechanical tests (i.e., peel test, pull-off test, etc.). Despite the large difference in magnitude, there exists evidence in the literature supporting the use of the bond energy to characterize the resistance of composite systems to cohesive and/or adhesive failures. If the bond energy is to be recognized as a useful screening tool by the paving industry, the relationship between the bond energy and total work of fracture needs to be understood and verified. The effect of different types of modifications (addition of polymers, addition of anti-strip agents, and aging) on the surface free energy components of various asphalt binders was explored in order to understand how changes in the surface free energy components are related to the performance of the asphalt mixtures. After the asphalt binder-aggregate combination was explored, the next step was to study how the surface free energy of water was affected by contact with the asphalt binder-aggregate interface. Aggregates, which have a pH of greater than seven, will cause the pH of water that contacts them to increase. A change in the pH of the contacting water could indicate a change in its overall surface free energy, which might subsequently increase or decrease the water's moisture damage potential. With surface free energy fully explored, the total work of fracture was measured using pull-off tests for asphalt binder-aggregate combinations with known surface free energy components. In order to fully explore the relationship between bond energy and total work of fracture, temperature, loading rate, specimen geometry, and moisture content were varied in the experiments. The results of this work found that modifications made to the asphalt binder can have significant positive or negative effects on its surface free energy components and bond energy. Moreover, the results from the pull-off tests demonstrated that a relationship exists between bond energy (from surface free energy) and total work of fracture (from pull-off tests), and that surface free energy can be used to estimate the performance of asphalt binder-aggregate combinations.

Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1992 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Properties and Fatigue Cracking Resistance of Asphalt Binders written by Arash Motamed and published by . This book was released on 2012 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several different types of modifiers are increasingly being used to improve the performance of asphalt binders or to achieve desired mixture production characteristics (e.g., Warm Mix Asphalt). However, current Superpave performance specifications do not accurately reflect the performance characteristics of these modified binders. The main objective of this study was to evaluate the inherent fatigue cracking resistance of asphalt binders in the form of a matrix with rigid particle inclusions. The underlying rationale for this approach was to subject the binders to a state of stress that is similar to the one in a full asphalt mixture. This was achieved by fabricating and testing composite specimens of the asphalt binders and glass beads with a specified gradation. Four asphalt binders with similar true temperature grades but different modifiers were used in this study. The viscoelastic and fatigue cracking characteristics of the binders were measured using the glass bead-binder composite specimens in a dynamic shear rheometer at an intermediate temperature. The results demonstrate that the four asphalt binders modified using different methods had different damage characteristics despite the fact that these four binders were rated to have a similar performance grade based on the Superpave specifications. Fatigue cracking characteristics of the glass bead-binder test specimens used in this study were qualitatively very similar to the fatigue cracking characteristics of full asphalt mixtures using the same binders. The rank order of fatigue cracking resistance for the four glass bead-binder mixtures compared reasonably well to the rank order of fatigue cracking resistance for the full asphalt mixtures that incorporated these asphalt binders.

Download or read book Characterization of Deformation and Fracture of Asphalt Concrete written by Yusuf Muhammad Salam and published by . This book was released on 1971 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bituminous Mixtures and Pavements VI written by A. Nikolaides and published by CRC Press. This book was released on 2015-07-28 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bituminous Mixtures and Pavements contains 113 accepted papers from the 6th International ConferenceBituminous Mixtures and Pavements (6th ICONFBMP, Thessaloniki, Greece, 10-12 June 2015). The 6th ICONFBMP is organized every four years by the Highway Engineering Laboratory of the Aristotle University of Thessaloniki, Greece, in conjunction with

Download or read book Fracture Behavior of Asphalt Materials written by Sadjad Pirmohammad and published by Springer Nature. This book was released on 2020-02-18 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the applications of fracture mechanics in the design and maintenance of asphalt concrete overlays. It provides useful information to help readers understand the effects of different material and loading type parameters on the fracture properties of asphalt concretes. It also reviews relevant numerical and experimental studies, and describes in detail design parameters such as aggregate type, air void, loading mode, and additives, based on the authors experience and that of other researchers.

Download or read book Fatigue Characterization of Asphalt Binders Using a Thin Film Poker Chip Test written by Ramez Muhammad Hajj and published by . This book was released on 2016 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asphalt binder is the adhesive that holds together aggregate particles of different sizes of an asphalt mixture. The tensile properties of an asphalt binder can greatly affect the performance of the asphalt mixture under repeated traffic loading. While the current performance grade specification has been in use for a long time to characterize the asphalt binders with regards to fatigue, it has been shown to be largely ineffective. This study was performed with the goal of investigating a strength-based measure to evaluate the fatigue cracking resistance of the asphalt binder. The poker chip geometry was used for this purpose. The test involved tensile loading of a thin film of asphalt binder between two rigid substrates. The first part of this study focused on determining failure criteria for the test. The second part was a study of the binders that have a similar grade based on the current performance grade specification but are expected to perform differently due to difference in their chemical makeup. Finally, the third part involved a study of the effects of nanomaterials as additives on the strength of the binder based on poker chip test results. The results demonstrated that failure strain criteria is promising as a material property, but still needs further study for validation. It was also observed that binders with similar performance grade had significantly different tensile strength. Finally, it was observed that nanomaterials had a significant impact on the test results of unaged binder, but had less effect on aged asphalt binders.

Download or read book Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements written by William G. Buttlar and published by Springer. This book was released on 2018-05-26 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Premature cracking in asphalt pavements and overlays continues to shorten pavement lifecycles and creates significant economic and environmental burden. In response, RILEM Technical Committee TC 241-MCD on Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements has conducted a State-of-the-Art Review (STAR), as detailed in this comprehensive book. Cutting-edge research performed by RILEM members and their international partners is presented, along with summaries of open research questions and recommendations for future research. This book is organized according to the theme areas of TC 241-MCD - i.e., fracture in the asphalt bulk material, interface debonding behaviour, and advanced measurement systems. This STAR is expected to serve as a long term reference for researchers and practitioners, as it contributes to a deeper fundamental understanding of the mechanisms behind cracking and debonding in asphalt concrete and composite pavement systems.

Download or read book Use of Semi circular Bend Test to Characterize Fracture Properties of Asphalt Concrete with Virgin and Recycled Materials written by Xuan Chen and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cracking in asphalt pavements is a challenging problem and has been the subject of numerous research studies for decades. To properly address this problem, suitable tests must be conducted to capture material behavior in cracking, such testing must be accompanied by proper mechanistic and empirical modeling of the material behavior in cracking. For mixture design and material quality control/assurance purposes, there is not a commonly accepted protocol for testing asphalt mixtures for cracking resistance characterization, due to variability of test results, non-uniformity in test specimens, and overall complexities of the tests that prevent them from being adopted for daily uses. On the other hands, for the tests that are popular for research purposes, the validity and sensitivity of such tests have not been fully witnessed and proven, due to lack of data quantity. Addressing these problems will help improve mixture design procedures and advance quality control and quality assurance of asphalt mixes, especially when complicated components, such as recycled materials and performance enhancing additives, are commonly incorporated into asphalt concrete nowadays. The overall goal of this research is to characterize the cracking resistance of various types of asphalt concrete mixes via a suitable candidate test. An additional goal is to provide guidelines for performing balanced mixture design on asphalt concrete with virgin and recycled materials when using such a test. Throughout the research, the selected fracture test, namely the semi-circular bend (SCB) fracture test, was first evaluated by investigating the sensitivity of performance indicators under various test conditions and proposing the most appropriate test conditions using a solid theoretical background. Then, the test was used to study fracture behavior of a wide range of asphalt paving materials including, but not limited to, various virgin asphalt mixes, crumb rubber modified (CRM) asphalt mixes, asphalt mixes with recycled materials such as reclaimed asphalt pavement (RAP), and recycled asphalt shingles (RAS), together with asphalt mixes with recycling agents. Not only were these mixtures prepared in a single laboratory, specimens received from different laboratories and plants were also included in the test matrix to reduce bias and to investigate the variation of the performance indicators. Additionally, a method to conduct the performance-based balanced-design using only the SCB fracture test was explored. Finally, the effect of long-term aging on fracture behavior of asphalt mixes was investigated, in order to build foundations for performance prediction commonly used in asphalt pavement design procedures. The main contributions of this study are: 1) verification of the sensitivity of the SCB test using asphalt mixtures with controlled variables under the proposed test conditions that are suitable to the commonwealth of Pennsylvania, 2) investigation of the impacts of material variables and conditioning, namely aging process, on fracture behavior of asphalt concretes, 3) exploration of possibility of performing balanced mixture design on asphalt concrete using the SCB test as a stand-alone test. The SCB fracture test procedure is found to be suitable to qualify asphalt mixes to fulfill different traffic demands and pavement structural conditions. Reliable mix design and quality assurance of asphalt pavements with complicated rehabilitation histories and sophisticated material compositions can be performed with confidence using such a test.

Download or read book Test Method to Determine Aggregate asphalt Adhesion Properties and Potential Moisture Damage written by Andrew Hanz and published by . This book was released on 2007 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Modeling of Asphalt Concrete with Heterogeneous Microstructure written by Jian Wang and published by . This book was released on 2015 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding fracture resistance of asphalt concrete is of great importance in designing pavements with long service life. This thesis focused on studying the micro and global fracture behavior of heterogeneous asphalt concrete with a numerical analysis approach. Finite element (FE) models were built with the capacity of taking heterogeneity into consideration. The asphalt concrete was modeled as a multi-phase material with coarse aggregates and fine aggregate matrix (FAM). Viscoelastic properties were assigned to the FAM. Different damage models were incorporated to study fracture at two length scales: micro-fracture within FAM and coarse aggregate-FAM interface under small displacement and global fracture resistance in the semi-circular bending (SCB) test. For micro-fracture simulation, asphalt mixture was modeled with both adhesive and cohesive failure potential. Two different fracture models, cohesive zone model (CZM) and extended finite element model (XFEM), were adopted to simulate fracture damage within the FAM (cohesive failure) and at the FAM-aggregate interface (adhesive failure), respectively. For global fracture properties, the SCB test was simulated to predict the crack propagation pattern and the load-crack mouth opening displacement (CMOD) curve of asphalt concrete. Parametric studies with different material properties of FAM and coarse aggregates-FAM interface, morphological characteristics of coarse aggregates, and testing conditions (loading rate and temperature) were carried out to study their effects on fracture behavior of asphalt concrete. The numerical models provide an effective method to study fracture mechanism of heterogeneous asphalt concrete and generates meaningful findings. The development of cracking shows that the damage in the FAM material would initiate first at a small displacement and then interconnect with the damage developed at the FAM-aggregate interface. The higher angularity and larger aggregate size induces the greater damage level; while the orientation angle along with aspect ratio has influence on the anisotropic behavior of asphalt concrete. On the other hand, the SCB test simulations show good agreements with experimental results in the literature. Increasing fracture strength and energy of FAM significantly improves fracture resistance of asphalt concrete. The spatial distribution and angularity of coarse aggregate affect crack path; while the gradation and size of coarse aggregate affect fracture strength of asphalt concrete.

Download or read book Investigation of the Fracture Resistance of Asphalt Mixtures at Low Temperatures with a Semi Circular Bend SCB Test written by Xue Li and published by . This book was released on 2005 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Resistance Characterization of Superpave Mixtures Using the Semi Circular Bending Test written by Z. Wu and published by . This book was released on 2005 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fracture resistance of asphalt mixture is an important property directly related to pavement distresses, such as cracking. This paper reports the investigation of a newly-developed semicircular bending (SCB) test as a candidate test for the fracture resistance characterization of asphalt mixtures. Thirteen Superpave mixtures, designed with four different binder types (AC-30, PAC-40, PG70-22M, and PG76-22M) and four different compaction levels (Ndesign = 75, 97, 109, and 125), were considered in this study. The SCB tests were conducted at 25°C using a three-point bending fixture in a MTS testing system. The fracture resistance was analyzed based on an elasto-plastic fracture mechanics concept of critical strain energy release rate, also called the critical value of J-integral (Jc). Preliminary results indicate that the JC values were fairly sensitive to changes in binder type and nominal maximum aggregate size (NMAS) used in Superpave mixtures. This study suggests that the SCB test could be a valuable correlative tool in the evaluation of fracture resistance of asphalt mixtures.

Download or read book Identification of Surrogates to Aggregate Plates for Adhesive Characterization of Asphalt written by Mary Lawrence Rawls and published by . This book was released on 2013 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Predicting Moisture induced Damage to Asphaltic Concrete written by and published by . This book was released on 1964 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: