UTILIZATION OF WASTE PLASTIC BOTTLES IN ASPHALT MIXTURE

Nowadays, large amounts of waste materials are being produced in the world. One of the waste materials is plastic bottle. Generating disposable plastic bottles is becoming a major problem in many countries. Using waste plastic as a secondary material in construction projects would be a solution to overcome the crisis of producing large amount of waste plastics in one hand and improving the structure’s characteristics such as resistance against cracking on the other hand. This study aimed to investigate the effects of adding plastic bottles in road pavement. Marshall properties as well as specific gravity of asphalt mixture containing different percentages of plastic bottles were evaluated. Besides, Optimum Asphalt Content (OAC) was calculated for each percentages of plastic bottles used in the mix. The stiffness and fatigue characteristics of mixture were assessed at OAC value. Results showed that the stability and flow values of asphalt mixture increased by adding waste crushed plastic bottle into the asphalt mixture. Further, it was shown that the bulk specific gravity and stiffness of mixtures increased by adding lower amount of plastic bottles; however, adding higher amounts of plastic resulted in lower specific gravity and mix stiffness. In addition, it was concluded that the mixtures containing waste plastic bottles have lower OAC values compared to the conventional mixture, and this may reduce the amount of asphalt binder can be used in road construction projects. Besides, the mixtures containing waste plastic showed significantly greater fatigue resistance than the conventional mixture

Evaluating the performance of W-beam guardrail roadside safety barrier systems / Mehrtash Soltani

The last decade has witnessed an increase in the number and speed of vehicles on the roads; these situations greatly affect the occurrence of run-off crashes. Roadside safety barriers serve the purpose of redirecting errant vehicles in addition to providing high levels of safety during and after impacts. In this study, common guardrail systems, including strong-post systems, guardrails with kerbs, weak-post systems, Midwest systems and Thrie-beam rail systems are evaluated. The goal of this study is to examine the structural adequacy, the vehicle trajectory and the occupant risk factors. The implementation of a new standard Manual for Assessing Safety Hardware (MASH) for evaluating roadside safety hardware was issued in 2009. The important changes in this new standard are presented. It is found that several types of guardrail systems, including the G4(2W) guardrail system, are unable to satisfy the requirements of the MASH criteria. Therefore, in this study, several options are considered; they include improving the splice connections and adjusting the guardrail height and the post spacing to improve the performance of this system. In experimental and simulated static tests, the basic mechanical behaviour and the different stages of the deformation mechanism of the beams in a W-beam guardrail system are demonstrated. Based on the results of the static tests, the optimum mesh size for modelling a W-beam is identified for use in a full-scale model of the guardrail. The G4(2W) guardrail system is modelled in LS-DYNA and validated with a previous full-scale crash test conducted at the Texas A&M Transportation Institute. A parametric study based on the results of the LS-DYNA simulation is conducted to investigate key factors of guardrail systems, including the splice configuration, the post spacing and the guardrail height, to examine the hypotheses and to achieve the objectives of this study. The purpose of this is to find a model that satisfies the requirements of the MASH‟s criteria. Finally, a statistical analysis of the different systems highlights the effects of the main parameters, including the guardrail height and the post spacing, on the structural adequacy and the occupant risk factors. The objective is to examine the significance of each factor on the system‟s behaviour

Stiffness modulus of Polyethylene Terephthalate modified asphalt mixture: A statistical analysis of the laboratory testing results

Stiffness of asphalt mixture is a fundamental design parameter of flexible pavement. According to literature, stiffness value is very susceptible to environmental and loading conditions. In this paper, effects of applied stress and temperature on the stiffness modulus of unmodified and Polyethylene Terephthalate (PET) modified asphalt mixtures were evaluated using Response Surface Methodology (RSM). A quadratic model was successfully fitted to the experimental data. Based on the results achieved in this study, the temperature variation had the highest impact on the mixture's stiffness. Besides, PET content and amount of stress showed to have almost the same effect on the stiffness of mixtures. The optimal amount of PET was found to be 0.41% by weight of aggregate particles to reach the highest stiffness value. (C) 2014 Elsevier Ltd. All rights reserved

Evaluating the performance of roadside barrier using surrogate devices

Evaluating the crash test is one of the most important stages of providing safety on roads. Nowadays, two kinds of equipments named surrogate devices are used to evaluate guardrails specifically, pendulum and bogie vehicle. This paper provides a review of usage these equipments and procedure to test guardrails. Advantages of each method are analyzed and also for each method, suitable application is recommended. The result of tests shows that, the bogie and pendulum tests are suitable surrogate devices to evaluate the performance of the guardrail

Crashworthiness of G4 (2W) guardrail system: a finite element parametric study

In recent years, vehicle demographics have changed to include a relatively large proportion of light trucks, such as pickups, vans and sport-utility vehicles. It is found that several types of guardrail systems, including the G4(2W) guardrail system, are unable to redirect the pickup trucks to roadway safely. Therefore, in this study, several options are considered; they include improving the splice connections and adjusting the guardrail height and the post spacing to improve the performance of this system. The G4(2W) guardrail system is modelled in LS-DYNA and validated with a previous full-scale crash test conducted by the Texas A&M Transportation Institute. A parametric study based on the results of the LS-DYNA crash simulation according to Length of Need test 3-11 and 3-10 is conducted to investigate key factors of guardrail systems, including the splice configuration, the post spacing and the guardrail height. The purpose of this study is to find a model that satisfies the requirements of Test Level 3 outlined in Manual for Assessing Safety Hardware (MASH)'s criteria

Gender based disparity in performing aortic valve surgery in the united state before availability of percutaneous valve implantation

Background: Aortic valve surgery has been performed increasingly in high-risk patients. The goal of this study was to evaluate this trend based on gender in the United States before the availability of percutaneous aortic valve replacement. Method: The Nationwide Inpatient Sample (NIS) database was utilized to calculate the age-adjusted utilization rate for aortic valve surgery from 1988 to 2011 in the United States using ICD-9 coding for aortic valve surgery. Results: A total population of 258, 506 patients underwent aortic valve between 1988-2011 were available for our study over the age of 20. We found that the age-adjusted rate of aortic valve surgery gradually increased from 1988 until 2009 and stabilized thereafter with a persistently higher rate for men. For men age-adjusted rate in 1988 was 13.3 per 100,000 vs. 27.0 in year in the year 2011 per 100,000. For women, the age-adjusted rate in 1988 was 6.07 per 100,000 vs. 11.4 in year 2011 per 100.000). Conclusion: Aortic valve surgery utilization has stabilized in recent years in both genders in the United States. However, this rate has been persistently more than double in men. The cause of this higher utilization in males needs further investigation.12 month embargo; first published 30 November 2023This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]