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The process of reclaimed asphalt pavement (RAP) recycling may occur multiple times during the life of the pavement. This study investigates the effect of multiple recycling on binder properties by employing a virgin 3045 PEN grade binder that was aged in the laboratory intended to simulate aging of binders in RAP. The aged binder was rejuvenated using two bio-oils and one softer binder. The doses of the bio-oils and softer binder were determined by matching the continuous high-temperature performance grade (PGH) of the rejuvenated RAP binder to that of the virgin binder. This aging and rejuvenation cycle was repeated three times. Finally, fatigue and rutting performance of the binder was evaluated for the three reuse levels. Results indicate that the material can be reused up to three cycles keeping good performance on fatigue or rutting. However, care should be taken regarding the cumulative effect of bio-oils causing an over-softening effect on the of the RAP. [ABSTRACT FROM AUTHOR]

The use of reclaimed asphalt pavement (RAP) in road construction has become a common practice in the asphalt industry due to environmental and economic benefits. However, since RAP is an aged material, recycling agents are typically used to reduce the stiffness of the recycled asphalt mixture and make it less prone to cracking at high RAP contents. This study evaluates the effect of ageing and the use of recycling agents on the rheological, microstructural, and micromechanical properties of binder blends with high RAP contents. A total of 27 binder blends were prepared with different recycled binder ratios (0.22, 0.31 and 0.5), recycling agent doses (0%, 1.2%, 5.5% and 9%), virgin binder performance grades (PG 58-28 and PG 52-34) and ageing conditions. The microscopic properties of the binder blends were characterised using atomic force microscopy (AFM). AFM results provided an evaluation of the microstructural homogeneity of the blends, with a good correlation with the binder blends macroscopic rheological properties. The addition of recycling agents improved the homogeneity of the binder blends by reducing the variation in modulus among the different phases in the microstructure. AFM proved to be a useful tool to evaluate rejuvenated binder blends at the microscale level. [ABSTRACT FROM AUTHOR]

Warm mix asphalt (WMA) is increasingly recognised as a green paving technology in terms of energy saving and emission reduction. The reduction in mix production temperature associated with the WMA additives is very desirable from the environmental aspect. However, researchers and practitioners desire a comparable performance with hot mix asphalt (HMA). The major issue with WMA is their moisture susceptibility especially in the pavement early life. Therefore, this study aims at investigating moisture susceptibility of WMA using both laboratory characterisation and field performance compared to HMA. Three mixtures were investigated, namely; HMA mixture, foaming and Evotherm WMA mixture. The laboratory tests included; resilient modulus (MR), Indirect Tensile test, and Hamburg wheel tracking test. Test sections on Farm to Market FM 973 Highway near Austin, Texas, were constructed using these three mixtures. The results of field performance monitoring for five years are represented in this paper. Laboratory test results revealed small differences between measured dry and wet tensile strength and MR of HMA and WMA which shows some improvements using antistripping agents. The field performance evaluation showed that the Evotherm WMA mixture had the least transverse and reflected cracks while the HMA performed better in both ravelling and longitudinal cracking. [ABSTRACT FROM AUTHOR]

Recycled asphalt mixtures with high amounts of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) can be excessively stiff, brittle, and prone to cracking. The use of recycling agents, or rejuvenators, can significantly reduce mixture stiffness and improve performance, specifically cracking resistance. In this study, the performance of recycled and rejuvenated asphalt mixtures from several field projects, located in different environmental zones across the United States, was evaluated considering various recycling agent dosages determined by the contractors. Field core test results and the visual distress surveys of the field projects demonstrated that using the field recycling agent dosages yielded poor mixture performance. Laboratory test results demonstrated that adding the recycling agent at the dosage to match the continuous high-temperature performance grade (PGH) of the rejuvenated binder blend (virgin/base binder, recycled binder, and recycling agent) to that of the target binder PGH specified based on climate and traffic requirements yielded improved mixture performance. The rejuvenated mixtures at this recycling agent dosage showed significant reduction in stiffness and improved cracking resistance, and facilitated the use of higher quantities of recycled materials, regardless of aging level, while maintaining rutting resistance after short-term aging. [ABSTRACT FROM AUTHOR]

Background: The relationship between clinical decision support systems (CDSS) and quality is a relatively new, and in light of the new health information technology (HIT) legislation, policy-relevant area. Moreover, very few studies exist examining the link between HIT and healthcare disparities. The purpose of this article is to examine the association between CDSS and the treatment of pneumonia care within high-minority (≥29.1% non-White, non-Hispanic) and low-minority (<29.1%) Zip Code Tabulation Areas (ZCTAs).Research Design: This study employed a cross-sectional design and used 2009 data from the American Hospital Association, the Centers for Medicare and Medicaid Services and the Research Triangle Institute. Adjusted analysis controlled for a hospital's propensity to use CDSS.Results: In the unadjusted analysis, hospitals in high-minority ZCTAs had lower pneumonia quality composite scores than their low-minority counterparts. When adjusting for other hospital and ZCTA-level variables, we found that CDSS use had stronger positive associations with quality in high-minority hospitals.Conclusions: Results support policy directives may support higher quality improvements by focusing CDSS adoption in high-minority hospitals. [ABSTRACT FROM AUTHOR]

Durability of porous or permeable friction courses (PFC) is an important aspect to address when designing this type of hot mix asphalt. At present, several agencies perform the mix design of PFC primarily by determining volumetric mixture properties. This approach ensures adequate mixture functionality, but it does not guarantee mixture durability. This paper evaluates the Cantabro loss test, the Hamburg Wheel-Tracking test (HWTT) and the Overlay test (OT) to determine the one most appropriate for mix design and laboratory performance evaluations. The Cantabro loss test, performed in both dry and wet conditions, is recommended for PFC mix design to corroborate the suitability of the optimum asphalt content defined based on volumetric determinations. The HWTT and the OT are not recommended, since the variability of the test results indicated that these tests may not be suitable for PFC mixtures. [ABSTRACT FROM AUTHOR]

Dissipated pseudo strain energy (DPSE) and Paris' law fracture coefficients constitute input parameters for fracture characterization of hot-mix asphalt concrete (HMAC) mixtures in continuum fracture-damage mechanics and energy based fatigue analysis approaches. In this paper, numerical analysis models for computing DPSE and Paris' law fracture coefficients from surface energy (SE) and uniaxial strain-controlled tension test data are presented. The applicability of the DPSE, Paris' law fracture coefficients, and the associated laboratory tests for comparatively quantifying HMAC mixture fracture properties including investigating the effects of aging is also presented. Analysis of the results indicated that the models utilized together with the computed parameters and the related laboratory tests provide a fundamental methodology of comparatively characterizing the fracture properties of HMAC mixtures. The numerical values obtained were within theoretical expectations. The results further showed that aging has a detrimental effect on the HMAC mixture fracture properties. However, more HMAC mixture characterization is recommended to further validate the general applicability of the models and the associated laboratory tests. [ABSTRACT FROM AUTHOR]