Evaluation of the Combined Effects of Recycled Asphalt Pavement (RAP), Recycled Asphalt Shingles (RAS), and Different Virgin Binder Sources on Performance of the Blended Binder for Mixes with Higher Percentages of RAP and RAS

This report summarizes the main findings from a project funded by the National Center for Sustainable Transportation (NCST) to investigate the use of higher percentages of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) as a replacement for a percentage of the virgin binder in new asphalt mixes in California. The research focused on testing procedures that do not first require chemical extraction and recovery of the age-hardened asphalt binders from the RAP and RAS. Five different asphalt binders covering two performance grades (PG 64-16 and PG 58-22) and sourced from three California refineries were evaluated in this study. The influence of two different percentages of RAP (25 and 40 percent by binder replacement) and one percentage of RAS (15 percent by binder replacement) were evaluated through partial factorial asphalt binder testing and full factorial fine aggregate matrix (FAM) mix testing. The effect of a petroleumbased rejuvenating agent added to selected mixes (with 40 percent RAP and 15 percent RAS) was also investigated. Testing was limited to the intermediate temperature properties of the mixes (i.e., 4°C to 40°C). Based on the findings from this study, FAM mix testing is considered to be a potentially appropriate procedure for evaluating the properties of blended asphalt binder in mixes containing relatively high quantities of RAP and RAS. Further testing on a wider range of asphalt binder grades, asphalt binder sources, and RAP and RAS sources is recommended to confirm this conclusion and to develop models for relating binder properties determined from FAM mix testing to those determined from conventional performance grade testing. Chemical analyses of blended binders may provide additional insights for interpreting test results and warrant further investigation.View the NCST Project Webpag

Evaluation of the Combined Effects of Recycled Asphalt Pavement (RAP), Recycled Asphalt Shingles (RAS), and Different Virgin Binder Sources on Performance of the Blended Binder for Mixes with Higher Percentages of RAP and RAS

This report summarizes the main findings from a project funded by the National Center for Sustainable Transportation (NCST) to investigate the use of higher percentages of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) as a replacement for a percentage of the virgin binder in new asphalt mixes in California. The research focused on testing procedures that do not first require chemical extraction and recovery of the age-hardened asphalt binders from the RAP and RAS. Five different asphalt binders covering two performance grades (PG 64-16 and PG 58-22) and sourced from three California refineries were evaluated in this study. The influence of two different percentages of RAP (25 and 40 percent by binder replacement) and one percentage of RAS (15 percent by binder replacement) were evaluated through partial factorial asphalt binder testing and full factorial fine aggregate matrix (FAM) mix testing. The effect of a petroleumbased rejuvenating agent added to selected mixes (with 40 percent RAP and 15 percent RAS) was also investigated. Testing was limited to the intermediate temperature properties of the mixes (i.e., 4°C to 40°C). Based on the findings from this study, FAM mix testing is considered to be a potentially appropriate procedure for evaluating the properties of blended asphalt binder in mixes containing relatively high quantities of RAP and RAS. Further testing on a wider range of asphalt binder grades, asphalt binder sources, and RAP and RAS sources is recommended to confirm this conclusion and to develop models for relating binder properties determined from FAM mix testing to those determined from conventional performance grade testing. Chemical analyses of blended binders may provide additional insights for interpreting test results and warrant further investigation.View the NCST Project Webpag

The Effects of Vitamin D on Kynurenine Level in Children With Attention Deficit Hyperactivity Disorder: An Epidemiological Study

Background and aims: Attention deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders with a worldwide prevalence of 5%. The prevalence is even higher among school age children ranging from 8% to 12%. ADHD is predominantly childhood-onset disorder and can persist into adolescence and adulthood to inflict long-term harm. The aim of this study was to identify the epidemiological features of ADHD and investigate the effects of vitamin D on kynurenine level in children with ADHD in Iran using ELISA method. Methods: A case-control study was designed. The study participants consisted of 40 patients with ADHD and 40 healthy participants as control group. It was conducted in Isfahan Hasht Behesht hospital from July to November 2015. All samples were treated with 1000 U of vitamin D as a tablet twice daily. The level of kynurenine was measured in blood samples using enzyme-linked immunosorbent assay (ELISA) method. Data analysis was done using SPSS software. Results: The results of this study showed that the mean vitamin D levels were 49.73 and 73.72, respectively before and after treatment in patient group, which seem significant. The mean vitamin D level after treatment was higher in patient group in comparison with control group. On the other hand, the mean kynurenine levels were 608.1 and 662.9, respectively before and after treatment in patient group. The mean kynurenine level was the same before and after treatment. Conclusion: According to the results of the study, we can conclude that vitamin D did not have a significant effect on kynurenine level in children with ADHD

Repeatability and sensitivity of FTIR ATR spectral analysis methods for bituminous binders

Bituminous binders as organic materials are prone to aging mainly by oxidation. Aging changes the viscoelastic behavior of the material over time towards higher stiffness and brittleness. FTIR has been increasingly used lately to investigate impacts of oxidative aging on the chemical structure of bitumen. Especially the carbonyl and sulfoxide bands are affected by aging and commonly used to describe changes due to evolving oxidation of a binder. However, spectra obtained from FTIR can be analyzed in fundamentally different ways and the analysis method applied to a spectrum has an impact on the gathered results and especially on the repeatability and sensitivity with regards to oxidative changes. For the presented study, two bituminous binders, a PG 64-16 and an SBS modified PG 76-22 PM were aged by RTFO and PAV and subsequently measured by FTIR. The obtained spectra (up to 90 individual spectra per aging state) were analyzed employing various methods using either the original or a normalized spectrum, a band maximum or integration based calculation of indices from an absolute or tangential baseline. By analyzing the coefficient of variation of the different analysis methods, it was found that not all analysis methods exhibit the same repeatability and sensitivity. From the findings of the study it can be recommended to work with normalized spectra, use an absolute baseline and work with integration of areas for index production in favor over band maximum based methods

Development of Performance-Based Specifications for Asphalt Rubber Binder: Interim Report on Phase 1 and Phase 2 Testing

In the United States, the Superpave Asphalt Binder Performance Grading (PG) system proposed by the Strategic Highway Research Program (SHRP) is the most common method used to characterize the performance-related properties of unmodified and polymer-modified asphalt binders. Dynamic shear modulus (G*) and phase angle (δ) are the two main binder properties and they are measured using a dynamic shear rheometer (DSR) with parallel plate geometry and either a 1-mm or 2-mm gap between the plates. Since these Superpave parameters were developed for binders that do not contain additives or particulates, the California Department of Transportation (Caltrans) does not use them for asphalt rubber binder specifications. Instead, penetration and viscosity are used as acceptance of quality control; however, these parameters do not necessarily provide a satisfactory link between the measured binder properties and potential performance in the field over a range of operating temperatures. In California, current specifications require that crumb rubber particles used to produce asphalt rubber binder in the “wet process” must be smaller than 2.36 mm (i.e., 100 percent passing the #8 sieve), and typically these particles vary in size between 1 mm and 2 mm. Consequently, when the parallel plate geometry is used to test this type of binder, the larger incompletely digested rubber particles can contact the plates. If this occurs, the rubber particle rheology can potentially dominate the results, which in turn may not be representative of the modified binder as a whole. To address this problem, a potentially more appropriate DSR testing protocol using concentric cylinder geometry was investigated in Phase 1 of this study to explore an alternative means of determining the performance properties of asphalt rubber binders. Phase 2 of the study, documented in this report, continued the investigation into the use of the concentric cylinder geometry and alternate parallel plate geometry with a 3-mm gap. The use of these geometries for intermediate-temperature testing and multiple stress creep recovery testing was also investigated, along with modified procedures for short- and long-term aging in the rolling thin-film oven and pressurized aging vessel, respectively, and specimen preparation procedures for bending beam rheometer (BBR) testing. Limited mix testing was also conducted to relate high- and low-temperature mix performance to the performance grades determined for the binders used in the mixes. The concentric cylinder testing approach to measuring the rheological properties of asphalt rubber binders is considered feasible, and that with its use, the edge effects and trimming issues associated with parallel plate testing can be eliminated. However, the concentric cylinder method requires a longer testing time and a larger binder sample than the parallel plate test method. Initial findings from performance grading and related mix testing indicate that the incompletely digested rubber particles, which have different sensitivities to temperature and applied stress and strain than the asphalt binder, appear to dominate the test results. This will need to be factored into analyses and interpretation of rheology and mix performance test results. The proposed modifications to the short- and long-term aging procedures and to the BBR specimen preparation procedures are considered to be more aligned with the original intent of the tests and will likely reduce the variability between replicate specimens during testing. The results from Phase 2 support the continuation of testing, which should be in line with the original workplan and objectives of this research effort. The research should continue to refine the testing procedures on additional field binder sources, assess the repeatability and reproducibility of any proposed test methods, and evaluate the applicability of the results to the actual performance properties of mixes produced with asphalt rubber binders

Development of Performance-Based Specifications for Asphalt Rubber Binder: Interim Report on Phase 1 and Phase 2 Testing

In the United States, the Superpave Asphalt Binder Performance Grading (PG) system proposed by the Strategic Highway Research Program (SHRP) is the most common method used to characterize the performance-related properties of unmodified and polymer-modified asphalt binders. Dynamic shear modulus (G*) and phase angle (δ) are the two main binder properties and they are measured using a dynamic shear rheometer (DSR) with parallel plate geometry and either a 1-mm or 2-mm gap between the plates. Since these Superpave parameters were developed for binders that do not contain additives or particulates, the California Department of Transportation (Caltrans) does not use them for asphalt rubber binder specifications. Instead, penetration and viscosity are used as acceptance of quality control; however, these parameters do not necessarily provide a satisfactory link between the measured binder properties and potential performance in the field over a range of operating temperatures. In California, current specifications require that crumb rubber particles used to produce asphalt rubber binder in the “wet process” must be smaller than 2.36 mm (i.e., 100 percent passing the #8 sieve), and typically these particles vary in size between 1 mm and 2 mm. Consequently, when the parallel plate geometry is used to test this type of binder, the larger incompletely digested rubber particles can contact the plates. If this occurs, the rubber particle rheology can potentially dominate the results, which in turn may not be representative of the modified binder as a whole. To address this problem, a potentially more appropriate DSR testing protocol using concentric cylinder geometry was investigated in Phase 1 of this study to explore an alternative means of determining the performance properties of asphalt rubber binders. Phase 2 of the study, documented in this report, continued the investigation into the use of the concentric cylinder geometry and alternate parallel plate geometry with a 3-mm gap. The use of these geometries for intermediate-temperature testing and multiple stress creep recovery testing was also investigated, along with modified procedures for short- and long-term aging in the rolling thin-film oven and pressurized aging vessel, respectively, and specimen preparation procedures for bending beam rheometer (BBR) testing. Limited mix testing was also conducted to relate high- and low-temperature mix performance to the performance grades determined for the binders used in the mixes. The concentric cylinder testing approach to measuring the rheological properties of asphalt rubber binders is considered feasible, and that with its use, the edge effects and trimming issues associated with parallel plate testing can be eliminated. However, the concentric cylinder method requires a longer testing time and a larger binder sample than the parallel plate test method. Initial findings from performance grading and related mix testing indicate that the incompletely digested rubber particles, which have different sensitivities to temperature and applied stress and strain than the asphalt binder, appear to dominate the test results. This will need to be factored into analyses and interpretation of rheology and mix performance test results. The proposed modifications to the short- and long-term aging procedures and to the BBR specimen preparation procedures are considered to be more aligned with the original intent of the tests and will likely reduce the variability between replicate specimens during testing. The results from Phase 2 support the continuation of testing, which should be in line with the original workplan and objectives of this research effort. The research should continue to refine the testing procedures on additional field binder sources, assess the repeatability and reproducibility of any proposed test methods, and evaluate the applicability of the results to the actual performance properties of mixes produced with asphalt rubber binders

Evaluation of the Relationship Between Primary Spontaneous Pneumothorax and Exercise and Return to Previous Activities in Patients Referring to Hospitals of Rasht during 2015-2017

BACKGROUND: The most common cause of primary spontaneous pneumothorax (PSP) is subpleural bleb apical rupture. Little is known about the relationship between PSP and exercise and return to exercise the time. In this study, we tend to investigate the relationship between training and PSP and time of return to exercise and previous activities.METHOD: This study was designed as a case series and the sample size included all patients diagnosed with PSP in Razi and Poursina and Aria hospitals of Rasht during 2015-2017 based on inclusion criteria. Variables were analyzed using Fisher's exact test, Chi-square, Mann Whitney U and t-test (p<0.05).RESULTS: The most common treatment type in patients was transaxillary thoracotomy with pleurodesis with iodine (TTP) in 58.2% and tube thoracostomy and pleurodesis in 41.7%, which was not statistically significant between athletes and non-athletes (p=0.806). Athletes who underwent TTP after four weeks and those treated with tube thoracostomy and pleurodesis after 8-12 weeks were advised to return to their previous activity. Of athletes, 9.5% had a recurrence; of non-athletes, 9.8% had a recurrence. Of athletes, 4.8% did not tolerate returning to their last activity; of non-athletes, 7.3% did not tolerate returning to their previous activity regardless of treatment, and this difference was not significant.CONCLUSION: Our study showed no significant difference between clinical manifestations and image findings and the frequency of treatment and complications in both athlete and non-athlete patients. There is no increase in recurrence and intolerance at the time recommended for return to previous activity