Evaluation of Mode-I Fracture Toughness of Asphalt Mixtures with Symmetric Geometry Specimen at Intermediate Temperature.

Mode I fracture (tensile type) is the common cracking mode of asphalt pavements, which is caused by thermal cyclic loading or traffic. Some studies allow the analysis of the fracture modes by means of standardized tests, some of which are limited, difficult, with little repeatability or do not generate an adequate tension state. In this paper, mode I fracture toughness of asphalt mixtures with symmetric geometry specimens at intermediate temperature is evaluated. Experimental results from direct tension test and simulations on asphalt mix specimens subjected to intermediate temperatures of 10, 20 and 30 °C, mode I load rates (0.5, 1 and 2 mm/min) and notches (2 and 3 cm) were compared to find the variables that reflect the operating conditions of the asphalt mix. Results showed that shear stresses are 8.12% lower in the simulations with respect to the tests, while the load-deformation curves show 30% and 35% variation, where the temperature of 20 °C, the notch of 2 cm and the loading speed of 1 mm/min are the conditions that best represent the stress state of the test; moreover, it manages to consider the elastic and viscous components of the material.

Rheological Evaluation of Softened Binders Blended with Aged Asphalt Selected with a High-Temperature Mixing Chart.

Reclaimed asphalt pavements (RAP) provide economic and environmental benefits. In recent decades, their use has increased, but rheological properties are affected by RAP aging, increasing stiffness, cracking, and susceptibility to water. To counteract these effects, rejuvenating agents are used, but they must be properly dosed to design quality mixtures. Therefore, different binders were analyzed, including virgin binder (VBB), binder modified by SBS polymer (MB), AC-RAP, binder softened using a rejuvenating agent, and binders softened with doses (15%, 30%, and 45%) of AC-RAP. The rheological properties were evaluated by dynamic shear rheometry (DSR) and beam-bending rheometry (BBR) tests, while the linear amplitude sweep (LAS) test was used to measure fatigue cracking and the multiple stress creep recovery (MSCR) test was used to measure rutting. A mixing chart was constructed based on a high temperature AC-RAP to satisfy the performance grade (PG 76-22). The results showed that softened binders become flexible, but when AC-RAP is added, they turn stiff and behave better than MB. Moreover, combining a rejuvenating agent and AC-RAP reduces the aging stiffness of RAP, improving its rheological properties without compromising the rutting or cracking resistance.

Natural Frequencies of seiches in Lake Chapala.

This research presents an analysis of the frequencies and vibration modes of the structure of the superficial seiches of Lake Chapala using mathematical modelling and measurements. The HAMSOM model was run with wind fields from coastal meteorological stations and for different lake storage levels. The lake water level measurements were carried out in two campaigns in 2003. An analysis of the surface seiches in the lake was performed using the fast Fourier transform method. A spectral analysis of lake water level measurements reveals seiches with periods close to 5.9, 3, 2, and 1.5 h. A comparison with the periods calculated by the HAMSOM model indicates that these periods correspond to superficial seiches of the fundamental longitudinal mode of the lake and the subsequent three modes. The lake has undergone important changes in its storage level over time. Therefore, we modelled it with storage levels from the isobaths 90 to 95 m and found that surface seiche periods decreased to 5.2 h.

Analysis of the Behavior of SMA Mixtures with Different Fillers Through the Semicircular Bend (SCB) Fracture Test.

In most cases, stone mastic asphalt (SMA) mixtures placed in thin layers and subjected to stress develop early cracks (potentially resulting from being improperly affixed to the underlying layer, placed over previously cracked asphalt pavement, or placed over Portland cement concrete slabs). However, the filler used in SMA production is very influential on the performance of the mix. Fillers used in this type of mixture have a low plastic index or are inert (calcium carbonate or lime), so it is important to understand the effect of each material on the possible fissuring and cracking process of the SMA mixture. The objective of this study is to present an evaluation of the behavior of SMA asphalt mixtures with different types of filler and at different temperatures using the semicircular bend (SCB) fracture energy test. This research compares results between fracture energy and different types of filler in SMA asphalt mixtures at temperatures ranging from -10 to 25 °C.

An Internet-based writing intervention for PTSD in veterans: A feasibility and pilot effectiveness trial.

[Correction Notice: An Erratum for this article was reported in Vol 9(4) of Psychological Trauma: Theory, Research, Practice, and Policy (see record 2016-54154-001). In the article, the names of authors Adil Alaoui and Anas Belouali were misspelled as Adil Aloui and Anas Beloui respectively. All versions of this article have been corrected.] Objective: Veterans suffering from posttraumatic stress disorder (PTSD) may avoid or fail to follow through with a full course of face-to-face mental health treatment for a variety of reasons. We conducted a pilot effectiveness trial of an online intervention for veterans with current PTSD to determine the feasibility, safety, and preliminary effectiveness of an online writing intervention (i.e., Warriors Internet Recovery & EDucation [WIRED]) as an adjunct to face-to-face psychotherapy. Method: Veterans (N = 34) who had served in Iraq or Afghanistan with current PTSD subsequent to deployment-related trauma were randomized to Veterans Affairs (VA) mental health treatment as usual (TAU) or to treatment as usual plus the online intervention (TAU + WIRED). All research participants were recruited from the Trauma Services Program, VA Medical Center, Washington, DC. They completed baseline assessments as well as assessments 12 weeks and 24 weeks after the baseline assessment. The online intervention consisted of therapist-guided writing, using principles of prolonged exposure and cognitive therapy. The intervention was adapted from an evidence-based treatment used in The Netherlands and Germany for individuals who had been exposed to nonmilitary traumas. Results: In addition to showing that the online intervention was both feasible to develop and implement, as well as being safe, the results showed preliminary evidence of the effectiveness of the TAU + WIRED intervention in this patient population, with particular evidence in reducing PTSD symptoms of hyperarousal. Conclusion: With minor modifications to enhance the therapeutic alliance, this intervention should be tested in a larger clinical trial to determine whether this method of online intervention might provide another alternative to face-to-face treatment for veterans with PTSD. (PsycINFO Database Record

A preliminary study of an internet-based intervention for OEF/OIF veterans presenting for VA specialty PTSD care.

This preliminary study sought to evaluate the feasibility and potential effectiveness of a cognitive-behavioral, web-based intervention for posttraumatic stress in Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans who are not able to participate, or not eligible to participate, in evidence-based posttraumatic stress disorder (PTSD) treatments. The study used an uncontrolled pre-posttest design with a sample of 24 OEF/OIF veterans presenting to a VA PTSD specialty clinic. Participants used the afterdeployment.org, Post-Traumatic Stress (PTS) Workshop, which was supplemented with brief weekly telephone calls. Half of the participants (n = 12) completed at least 5 of the 8 workshop sessions. At posttreatment, 40.0% of completers demonstrated reliable reductions on PTSD symptoms and overall d = 1.04. Treatment satisfaction and acceptability was generally positive based on Likert ratings. This web-based intervention for PTS appears to be a feasible and potentially helpful intervention for veterans who may not otherwise receive psychosocial interventions. Given the minimal resources required and the potential reach, this web-based intervention could be a viable addition to services provided to OEF/OIF veterans seeking PTSD specialty care. Efforts to further develop and more rigorously evaluate this approach are warranted.