124,723 research outputs found
The Effect of Polymer Modification on Hot Mix Asphalt (HMA) Fracture at Tensile Loading Conditions
No full textA laboratory investigation was conducted to evaluate the effect of both cross-linked and linear
Styrene-Butadiene-Styrene (SBS) modifiers on the cracking resistance of Hot Mix Asphalt (HMA)
mixtures. Five types of asphalt mixtures composed by the same aggregate gradation but different asphalt
binders were produced in the laboratory. The cracking performances of the mixtures were evaluated using
a visco-elastic fracture mechanics-based model entitled “HMA Fracture Mechanics”. Crack localization
and crack growth were investigated performing the Indirect Tensile Test (IDT) and the Semi-Circular
Bending (SCB) test. A Digital Image Correlation (DIC) System capable of providing full field strain
maps was applied. The results show the benefit of SBS modifiers to mixture’s cracking resistance in
terms of reduced rate of damage accumulation and increased tensile limits to failure. No influence was
observed in the elastic response but rather on the time-dependent response. Finally, significant damage
and first fracture have shown to be strongly more localized in modified specimens than in the unmodified
one
Measurement and Prediction of Hot-Mix Asphalt Fracture Energy Using Micromechanical Analyses
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Influence of Mixture Properties on Fracture Mechanics in Asphalt Mixtures
No full textThis paper reports a research study aimed at providing insight into key mechanisms and mixture properties that influence fracture in asphalt concrete. The experimental analysis was based on the Hot Mix Asphalt (HMA) Fracture Mechanics visco-elastic crack growth law. HMA cracking mechanism was investigated using multiple laboratory test configurations on both unmodified and polymer modified mixtures. A Digital Image Correlation (DIC) was employed to more accurately capture localized or non-uniform stress distributions in asphalt mixtures and as a tool for detecting first fracture. Crack initiation and crack growth were predicted effectively using a Displacement Discontinuity (DD) boundary element method
Strain Localization and damage Distribution in SBS Polymer Modified Asphalt Mixtures
No full textA laboratory investigation was conducted to estimate the macroscopic cracking response of Styrene Butadiene Styrene (SBS) polymer modified asphalt mixtures by analyzing the localized strain distribution within the material microstructure. Five asphalt mixtures composed by the same aggregate gradation but different SBS modified asphalt binders were produced in the laboratory. An in-house developed Digital Image Correlation (DIC)-based system was employed to obtain 2D full-field strain maps of the specimens during tensile loading. Strain distributions were observed from three different test configurations, namely the Indirect Tensile Test (IDT), the Semi-Circular Bending (SCB) test and the Three-Point Bending (3PB) test. The cracking performances of the mixtures were evaluated using a visco-elastic fracture mechanics-based model entitled HMA Fracture Mechanics. The results clearly show the beneficial effect of SBS polymer modifier in redistributing the stress within the mastic
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Characterisation of Asphalt Mixture Cracking Behavior using the Three-Point bending Beam Test
No full textThe use of a three-point bending beam (3PB) test was investigated to characterise hot mix asphalt (HMA) cracking behaviour. Fundamental HMA fracture properties, identified as tensile strength and fracture energy density at first fracture, were determined for six different asphalt mixtures (two natural and four SBS polymer modified) applying the HMA Fracture Mechanics framework. Full-field strain maps obtained from an in-house developed digital image correlation-based method were observed to better understand the crack initiation and propagation mechanisms in the 3PB specimen. The resulting fracture behaviour was predicted using a displacement discontinuity boundary element method to model the microstructure of the six asphalt mixtures and to predict their fracture properties. Both numerical and experimental results indicate that the fracture mechanism of asphalt mixtures can be properly described from 3PB test results when appropriate interpretation models are used.</p
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