Evaluation of Polymer Binder Technisoil G5® in Concrete Mixture

Plastic is everywhere, and with its increasing use in so many everyday materials, the production and demand of plastic has skyrocketed. Unfortunately, this has resulted in the accumulation of a mammoth amount of plastic waste and adverse effects on the environment. To optimize the huge amount of materials required by the pavement industry each year and reuse recycled plastics, the use of reclaimed asphalt pavement (RAP) has been common practice. This research studied the use of a binder completely made from recycled waste plastic named Technisoil G5® and compared it with performance grade PG 70-22 mix containing virgin aggregates and RAP aggregate. The study compared the mechanical properties, including fracture resistance and rutting resistance, and performed IDEAL Cracking Test (IDEAL CT) to evaluate the fracture resistance of samples. Results included that the fracture cracking resistance of Technisoil G5® samples is significantly lower than the PG 70-22 samples. Meanwhile, the peak load of Technisoil G5® samples is higher than PG 70-22 and can take a higher load before failure. Further testing is needed, but these and other results of this study are first steps toward testing and implementing sustainable development to conserve the environment

Performance Testing of Hot Mix Asphalt Modified with Recycled Waste Plastic

Plastic pollution has become one of the major concerns in the world. Plastic waste is not biodegradable, which makes it difficult to manage waste plastic pollution. Recycling and reusing waste plastic is an effective way to manage plastic pollution. Because of the huge quantity of waste plastic released into the world, industries requiring a large amount of material, like the pavement industry, can reuse some of this mammoth volume of waste plastics. Similarly, the use of reclaimed asphalt pavement (RAP) has also become common practice to ensure sustainability. The use of recycled waste plastics and RAP in HMA mix can save material costs and conserve many pavement industries’ resources. To successfully modify HMA with RAP and waste plastic, the modified HMA should exhibit similar or better performance compared to conventional HMA. In this study, recycled waste plastic, linear low-density polyethylene (LLDPE), and RAP were added to conventional HMA, separately and together. The mechanical properties of conventional and modified HMA were examined and compared. The fatigue cracking resistance was measured with the IDEAL Cracking (IDEAL CT) test, and the Hamburg Wheel Tracking (HWT) test was conducted to investigate the rutting resistance of compacted HMA samples. The IDEAL CT test results showed that the cracking resistance was similar across plastic modified HMA and conventional HMA containing virgin aggregates. However, when 20% RAP aggregates were used in the HMA mix, the fatigue cracking resistance was found to be significantly lower in plastic modified HMA compared to conventional HMA. The rutting resistance from the HWT test at 20,000 passes was found to be similar in all conventional and modified HMA

Sensitivity Analysis of the IDEAL CT Test Using the Distinct Element Method

Cracking is a primary mode of failure for asphalt concrete (AC), resulting in road damage and deterioration, and leading to an increase in road hazards and fatalities. Studying the fracture behavior of AC is an effective way to learn how to best enhance their cracking resistance. To do this, the indirect tensile cracking laboratory test (IDEAL-CT) was developed and used to assess the AC cracking behavior by defining a unique index that allows the ranking of different mixes’ cracking resistance. The sensitivity of the test results to the test parameters is needed to monitor the test’s performance. Several parameters impact the result of the IDEAL-CT. This study focuses on the variation of air voids, loading rate, aggregate shape, bonding type, and gradation mix. Performing more than 450 test scenarios—varying multiple factors and conducting enough tests for each variation—would require considerable resources and time. To solve the issue, the Particle Flow Code in two-dimension software (PFC2D) using the discrete element method (DEM) is adapted to mitigate the need for actual laboratory tests. Initial findings yielded a better understanding of the micromechanical behavior of each mix, showing that air void content has more impact than loading rate; a decrease of 2% in air voids resulted in an increase of more than 50% in cracking resistance. Additionally, different aggregate sources and bonding strengths affected the cracking resistance. These results can inform further studies on AC cracking in order to reduce road damage and deterioration to keep roads safe

Performance Testing of Hot Mix Asphalt Containing Biochar

In recent years, researchers have been able to identify asphalt binder additives, such as polymers and bio-binder, that can enhance the rheological and mechanical properties of asphalt binders. Earlier studies show that utilizing bio-binder as a partial replacement for asphalt binder has shown promising results in both mechanical and sustainability aspects. Biochar additions improved binder viscosity and low-temperature characteristics. Biochar, which is a byproduct of producing bio-binder, has shown enhanced rheological and mechanical properties when used as an additive to the asphalt binder. In this study, the mechanical properties of asphalt mixtures containing Biochar were investigated. In addition, its color degradation was investigated. The Semi-Circular Bending (SCB) test proved to be a suitable test method to analyze the fracture properties of asphalt mixtures. Similarly, the Hamburg Wheel Tracking (HWT) test is efficient in testing for and analyzing the rutting and moisture susceptibility of asphalt mixtures. This study used the SCB and HWT tests to investigate the mechanical properties of asphalt mixtures containing Biochar. The study incorporated conventional (virgin) and rubberized mixtures and investigated the effect of aging as well. The SCB results suggest that adding Biochar helped attain higher strain energy values for virgin and rubberized mixtures after aging. The HWT results showed that the addition of Biochar helped achieve lower rut depth for non-aged mixtures. After aging, and since Biochar reduces the effect of aging, aged Biochar mixtures achieved higher rut depth (less hardening) compared to virgin aged mixtures. As for color degradation, the addition of Biochar helped to decrease the color degradation of the asphalt mixture compared to the control mixture

Characterization of asphalt concrete using anisotropic damage viscoelastic-viscoplastic model

This dissertation presents the integration of a damage viscoelastic constitutive relationship with a viscoplastic relationship in order to develop a comprehensive anisotropic damage viscoelastic-viscoplastic model that is capable of capturing hot mix asphalt (HMA) response and performance under a wide range of temperatures, loading rates, and stress states. The damage viscoelasticity model developed by Schapery (1969) is employed to present the recoverable response, and the viscoplasticity model developed at the Texas Transportation Institute (TTI) is improved and used to model the irrecoverable strain component. The influence of the anisotropic aggregate distribution is accounted for in both the viscoelastic and viscoplastic responses. A comprehensive material identification experimental program is developed in this study. The experimental program is designed such that the quantification and decomposition of the response into viscoelastic and viscoplastic components can be achieved. The developed experimental program and theoretical framework are used to analyze repeated creep tests conducted on three mixes that include aggregates with different characteristics. An experiment was conducted to capture and characterize the three-dimensional distribution of aggregate orientation and air voids in HMA specimens. X-ray computed tomography (CT) and image analysis techniques were used to analyze the microstructure in specimens before and after being subjected to triaxial repeated creep and recovery tests as well as monotonic constant strain rate tests. The results indicate that the different loading conditions and stress states induce different microstructure distributions at the same macroscopic strain level. Also, stress-induced anisotropy is shown to develop in HMA specimens

TRUSTING THE PHARMACIST IN DELIVERING MEDICATION INFORMATION: A COMMUNITY-BASED PERSPECTIVE

Objective: Optimal disease management is influenced by a solid patient-health provider relationship; which includes trust in the provider. The study compares respondents’ trust in pharmacists and physicians for the delivery of drug information. Methods: Residents of 3 rural communities in Lebanon, aged 40 and above, were invited to participate in the study, 760 accepted. Participants were asked who they trust the most with information about their medication: their physician or their pharmacist. Results: Of the total sample, 154 chose the pharmacist as their most trusted source of medication information (20%). Characteristics associated with choosing the pharmacist were: being a male (29.3% vs 16.2% p<.001), of younger age (31.5% among<50 y, 18.8% among 50-64 y, and 14.6% among 65+years p<.001), single (31.6% vs 21.9% married and 9.3 others, p=0.023), working (39.2% vs15.7% p<.001), and insured (2.3% vs 16.4% p=0.048). The multivariate logistic regression model revealed that having a family member with hypertension (OR=1.86 95% 1.23-2.82), or cardiovascular (OR=3.39 95%CI 1.55-7.45) increased the likelihood of trusting pharmacists over medical doctor. On the other hand, a self-report of cardiovascular disease (OR=0.34 95% CI 0.12-0.95) and taking medication (OR=0.41 95% CI 0.25-0.67) were associated with a decrease in the trust in the pharmacist in favor of the physician. Conclusion: Although pharmacists are the drug specialists, the majority of the Lebanese rural community residents reported higher trust in their physicians with information about their medication(s)

Fracture Behavior Analysis of Semi-Circular Bending Test

The objective of this paper is to investigate the effect of air voids on the fracture properties of asphalt mixtures using SCB test in Discrete Element Method (DEM). Superpave and Coarse Matrix High Binder (CMHB) mixtures gradation were used to generate the percentages of aggregate, mastic, and air voids within the specimens. Aggregates and air voids were randomly generated for each asphalt mixture case. Model results illustrate that the crack initiation and propagation is controlled by the location of the aggregate particles and air voids in the mixture. Additionally, the absence of air voids above the tip of the notch increases the stiffness of the sample and increase its resistance to failure. The novelty of using DEM and the random generation technique for generating numerical specimens proved to be a useful approach in investigating the properties of the mastic, aggregate and interface as they relate to fracture of asphalt mixtures

Views of community pharmacists in lebanon on the unified prescription: A mixed method study

Background: The unified prescription was introduced in Lebanon in 2011; an aim was to save on medication expenditure. Aims: The aim of this study was to evaluate the views of community pharmacists on the effect and usefulness of the unified prescription. Methods: A cross-sectional telephone survey of community pharmacists from all governorates of Lebanon was conduct-ed. A questionnaire was used to collect demographic data, pharmacists’ views on the effect of the unified prescription on their work, the percentage of prescriptions in which the prescriber had indicated that the medicine should not be substituted with a generic equivalent and the percentage needing clarification from the prescriber. Face-to-face interviews were held with 12 pharmacists to explore their views further. Results: Of 251 pharmacists interviewed, 56.8% did not think the unified prescription was useful, 34.8% thought it complicated their work and 24.0% that it reduced their autonomy. The in-depth interviews showed that autonomy was perceived to be restricted because of the difficulty in convincing patients to accept a substitute generic medicine, which the unified prescription allowed. The unified prescription complicated pharmacists’ work because of increased paperwork and the need for more storage. Pharmacists felt that the large number of prescriptions in which the prescriber had indicated that the medicine should not be substituted undermined the purpose of the unified prescription. Conclusion: The implementation of the unified prescription was not considered a success by community pharmacists in Lebanon. Efforts are needed to improve communication with prescribers and educate the public about pharmacists’ role and generic medicines. © World Health Organization (WHO) 2020

Evaluation of the rutting susceptibility of Louisiana Superpave mixtures

This paper documents the performance of Louisiana Superpave mixtures through laboratory mechanistic tests, mixture volumetric properties, gradation analysis, and early field performance. Five Superpave mixtures were evaluated in this study. One of them were designed for high-volume traffic (\u3e30 million ESALs), two were designed for intermediate-volume traffic (between 3 and 30 million ESALs), and two for low-volume traffic (\u3c 3 million ESALs). Three performance tests: the Frequency Sweep at Constant Height Test (FSCH) Repetitive Shear at Constant Height Test (RSCH) and Simple Shear at Constant Height (SSCH) test were compared to the Asphalt Pavement Analyzer (APA) rut test. The results showed that the FSCH and RSCH were effective in characterizing mixtures susceptibility to rutting

Sustainable Mitigation of Stormwater Runoff Through Fully Permeable Pavement

This report presents the implementation of new design method developed using mechanistic-empirical design approach by University of California Pavement Research Center (UCPRC) through building two test sections at California State University Long Beach (CSULB). The study includes a literature review, pavement design procedure, mix design, construction procedure, instrumentation, and collection of performance data of the permeable asphalt and concrete pavement sections for validation and structural design calibration of the new design approach. Fully permeable pavements are characterized as those in which all layers are porous, and the pavement structure serves as a reservoir to store water and minimize the negative impacts of stormwater spillover. The California Department of Transportation (Caltrans) has shown interest in developing fully permeable pavement design for use in territories that convey substantial truck activity as a potential stormwater management best management practice (BMP) to give low-effect infrastructure and proficient framework operation. A location was selected within CSULB for the construction of the test sections. Pressure cells and strain gages were installed during the construction of pavements for measuring the stress on the top of subgrade on both test sections and the strain at the bottom of surface layer to assess the performance of the fully permeable pavements. In the study, the traffic count was also determined. The data acquisition device CDaq was installed at the site to collect the data. The recorded data was analyzed using the MATLAB program code. The data from pressure cells and strain gages are analyzed, and graphs were plotted to study the pattern in the data sets. The stress and strain measurements and the cracking (both sections) and rutting (asphalt section only) will be used to calibrate the pavement structural design procedure and hydraulic performance will also be monitored.View the NCST Project Webpag