Successful Use of Reclaimed Asphalt Pavement in Asphalt Mixtures

Over 99 percent of reclaimed asphalt pavement (RAP) is put back to use, with most of it in asphalt pavements. Using RAP in asphalt mixtures can provide initial cost savings by replacing a portion of the aggregate and virgin asphalt binder in the asphalt mixture. It is important to consider the engineering performance of mixture containing RAP, as well as sustainable benefits and recognize that long RAP transportation distances can offset the environmental benefits. This keeps the RAP from being discarded in landfills. Improvements in mixture design and materials processing and handling have increased the amount of RAP that can be used in asphalt mixtures. The performance history of RAP mixtures over the past 50 years, when properly engineered, produced, and constructed, can provide comparable levels of service as asphalt mixtures with no reclaimed materials, referred to as virgin asphalt mixtures. The participating State DOTs indicated that optimizing RAP for good pavement performance can be accomplished through: 1) regular review of DOT specifications and mixture design procedures; 2) monitoring pavement performance; 3) working with asphalt producers, and 4) performing research as a basis for changes. However, in some cases, the durability of asphalt mixtures containing RAP has been poor. Additionally, State DOT rationale for using RAP can be for very different reasons with different goals. Virtual field visits of State DOTs regularly using RAP in asphalt mixtures revealed that DOTs with detailed policy and specifications on RAP use had obtained good control and pavement performance. A wide range of techniques and criteria used by State DOTs specifying and designing mixtures and pavements incorporating RAP were identified and summarized. All of the participating State DOTs indicated the desire to use mixture performance tests. Some wanted to use them for mixture designs in a BMD approach, for test strips (startup evaluations) and production or acceptance. Common themes with this were the need to get adequate virgin asphalt binder in mixtures, the need for appropriately setting performance test criteria and recognition of the benefit of long-term aging cracking test specimens. Another common theme was recognition that the resources required to implement BMD or use of performance tests on a regular basis are significant and may not be available in the short-term

Cold Asphalt and Hot In-place Asphalt Recycling Technologies

Virtual site visits and interviews of five key State Departments of Transportation (DOTs) plus the two Federal Lands Highway Divisions, along with material producers and paving contractors that served these agencies were conducted to learn more regarding successful use of cold asphalt and hot in-place recycling technologies. Practices investigated were project selection, recycling technology selection, structural pavement design, materials, mixture design, field construction and acceptance, quality control, curing and opening to traffic, lessons learned, pavement performance, contractor perspectives, and agency best practices were collected and synthesized in this report. Some agencies used a single recycling technique while others used multiple. The summary of this information includes practices used by State DOTs to implement cold asphalt and hot in-place asphalt recycling technologies. Examples of positive practices, lessons learned, and challenges from States and Federal Lands Highway Divisions are presented.U.S. Department of Transportatio

Increased Density to Improve Pavement Durability Demonstration Project - NDOT 3716

The fact that Department of Transportation (DOT) specifications always include compaction provisions reflects that asphalt pavement technologists have recognized the impact of in place density on pavement performance for many decades. However, an increase in durability related performance issues in the mid 2010’s placed renewed focus on it. A recent literature review summarized past lab and field work which conservatively showed a 1 percent increase in density improves pavement life by 10 percent. It included information from the WesTrack project in Nevada that showed a 1 percent increase in density resulted in an improvement in rutting performance of 7 to 66 percent and 8 to 44 percent improvement in fatigue performance. The Federal Highway Administration (FHWA) has supported an Increased In-Place Density Initiative since 2015 with focus on communicating and providing education on the benefits of increasing in-place density of asphalt concrete pavements that State DOTs could volunteer to participate in. This report describes a density demonstration project conducted by the Nevada Department of Transportation (NDOT). The project scope included two test sections for the typical roadway reconstruction under special provisions that increased the NDOT standard specification in-place mat density minimum requirements by one percent and two percent, respectively. A control section was also constructed. The contractor had the flexibility to make operational and equipment changes in the two test sections to improve in place density. Collectively, use of intelligent compactors, additional density QC staff, additional roller coverages and potentially an increase in asphalt content above the JMF target led to increased mat density and improved consistency when compared to the control data.Nevada Department of Transportatio

A Practice for Including Intelligent Construction Equipment in Quality Assurance Programs

Many State departments of transportation (DOTs) include density of the asphalt mat as a quality characteristic in their quality assurance (QA) programs. Density values are determined from point-specific laboratory tests. State DOTs desire real-time tests to evaluate asphalt mixture consistency and mat density across the entire width and length of a paving lot. Two innovative devices that have emerged for use in evaluating the uniformity and density of asphalt mixtures are the paver-mounted thermal profiler (PMTP) and the dielectric profiling system(DPS). Both technologies generate a significant amount of real-time data using hardware and software with spatia lreferencing sources. The DPS is used to test the asphalt mat after final rolling and is considered to be in the field demonstration stage or just entering the field pilot stage of research deployment. The PMTP is attached to the paver for monitoring the surface temperatures of the asphalt mat and is currently at the field pilot and specification development stage. A few State DOTs have deployed the PMTP in their QA program. A third innovative technology referred to as intelligent compaction (IC) is used to map roller coverage of the mat during construction and monitor relative mat stiffness during breakdown rolling. The IC technology is discussed in this report, but it is still considered to be in the initial field demonstration stage. This report provides information and suggestions for using intelligent construction equipment in a QA program conforming to 23 CFR part 637, subpart B. The document focuses on asphalt mat density and temperatureU.S. Department of Transportation Federal Highway Administratio

Responsible Use of Polyphosphoric Acid (PPA) Modification of Asphalt Binders

Polyphosphoric acid (PPA) has been used to chemically modify asphalt binders to improve high temperature rheological properties, without adversely affecting low temperature rheological properties, since the early 1970s.(1) Since the introduction of Superpave performance-grade (PG) binders, PPA has been used as an additive for adjusting rheological properties to meet PG specification parameters. PPA has also been used to modify asphalt binders that need an extended range between the high and low temperature performance requirements to meet PG specification limits. Since the early 1990s, PPA has also been used in combination with polymer modifiers in polymer modified asphalt binders to enhance the quality of paving grade asphalt binders. This report discusses use of PPA as an asphalt binder modifier and presents information on detection and quantification of PPA in asphalt binders.US Department of Transportation Federal Highway Administratio

Bayesian modeling of recombination events in bacterial populations

Background: We consider the discovery of recombinant segments jointly with their origins within multilocus DNA sequences from bacteria representing heterogeneous populations of fairly closely related species. The currently available methods for recombination detection capable of probabilistic characterization of uncertainty have a limited applicability in practice as the number of strains in a data set increases. Results: We introduce a Bayesian spatial structural model representing the continuum of origins over sites within the observed sequences, including a probabilistic characterization of uncertainty related to the origin of any particular site. To enable a statistically accurate and practically feasible approach to the analysis of large-scale data sets representing a single genus, we have developed a novel software tool (BRAT, Bayesian Recombination Tracker) implementing the model and the corresponding learning algorithm, which is capable of identifying the posterior optimal structure and to estimate the marginal posterior probabilities of putative origins over the sites. Conclusion: A multitude of challenging simulation scenarios and an analysis of real data from seven housekeeping genes of 120 strains of genus Burkholderia are used to illustrate the possibilities offered by our approach. The software is freely available for download at URL http://web.abo.fi/fak/ mnf//mate/jc/software/brat.html

Data Trends and Variability in Quality Control for Performance and Pay for Performance Specifications: Statistical Analysis

Quality assurance programs for hot-mix asphalt (HMA) have evolved from method specifications to quality assurance specifications that distribute responsibilities and risks between contractors and owners. The Illinois Department of Transportation (IDOT) developed two acceptance specifications, quality control for performance (QCP) and pay for performance (PFP), integrating contractor pay incentives and/or disincentives associated with air voids (AV), voids in mineral aggregate (VMA), and in-place density limits. A major factor that could compromise contractors’ pay in both specifications is the variability of test results due to mix production, construction, sampling, and/or inherent testing variability. Therefore, the objective of this project was to understand the distribution and variability of the test results observed under QCP and PFP specifications, as well as the potential causes of variability. The assessment approach included statistical analysis of the test results obtained for the 2015–2017 construction seasons and on-site field observations of 11 projects visited during the 2018 construction season. The pay factors of the 2015–2017 construction seasons showed contractors earned pay incentives under the PFP specification but received disincentives under QCP and PFP specifications. Contractors appeared to have more experience working with QCP projects than PFP projects. The statistical analysis identified that more than 80% of the test results between the contractor and the district were not significantly different. In those cases, it is likely that issues with mix production or construction were the reasons that led to a disincentive. However, there are possible testing issues that need to be addressed by the district and contractor such as reheating consistency and test weight control. Density was a major factor driving contractor disincentives in both specifications, followed by AV. Finally, the site visit identified mix production and construction issues that can lead to possible causes of pay disincentives, including mix switching, dust control, and aggregate contamination.IDOT-R27-189Ope

Transcriptional repressor ZEB2 promotes terminal differentiation of CD8⁺ effector and memory T cell populations during infection

ZEB2 is a multi-zinc-finger transcription factor known to play a significant role in early neurogenesis and in epithelial-mesenchymal transition-dependent tumor metastasis. Although the function of ZEB2 in T lymphocytes is unknown, activity of the closely related family member ZEB1 has been implicated in lymphocyte development. Here, we find that ZEB2 expression is up-regulated by activated T cells, specifically in the KLRG1(hi) effector CD8(+) T cell subset. Loss of ZEB2 expression results in a significant loss of antigen-specific CD8(+) T cells after primary and secondary infection with a severe impairment in the generation of the KLRG1(hi) effector memory cell population. We show that ZEB2, which can bind DNA at tandem, consensus E-box sites, regulates gene expression of several E-protein targets and may directly repress Il7r and Il2 in CD8(+) T cells responding to infection. Furthermore, we find that T-bet binds to highly conserved T-box sites in the Zeb2 gene and that T-bet and ZEB2 regulate similar gene expression programs in effector T cells, suggesting that T-bet acts upstream and through regulation of ZEB2. Collectively, we place ZEB2 in a larger transcriptional network that is responsible for the balance between terminal differentiation and formation of memory CD8(+) T cells

The Suppressor of AAC2 Lethality SAL1 Modulates Sensitivity of Heterologously Expressed Artemia ADP/ATP Carrier to Bongkrekate in Yeast

The ADP/ATP carrier protein (AAC) expressed in Artemia franciscana is refractory to bongkrekate. We generated two strains of Saccharomyces cerevisiae where AAC1 and AAC3 were inactivated and the AAC2 isoform was replaced with Artemia AAC containing a hemagglutinin tag (ArAAC-HA). In one of the strains the suppressor of ΔAAC2 lethality, SAL1, was also inactivated but a plasmid coding for yeast AAC2 was included, because the ArAACΔsal1Δ strain was lethal. In both strains ArAAC-HA was expressed and correctly localized to the mitochondria. Peptide sequencing of ArAAC expressed in Artemia and that expressed in the modified yeasts revealed identical amino acid sequences. The isolated mitochondria from both modified strains developed 85% of the membrane potential attained by mitochondria of control strains, and addition of ADP yielded bongkrekate-sensitive depolarizations implying acquired sensitivity of ArAAC-mediated adenine nucleotide exchange to this poison, independent from SAL1. However, growth of ArAAC-expressing yeasts in glycerol-containing media was arrested by bongkrekate only in the presence of SAL1. We conclude that the mitochondrial environment of yeasts relying on respiratory growth conferred sensitivity of ArAAC to bongkrekate in a SAL1-dependent manner. © 2013 Wysocka-Kapcinska et al

Detection of Galaxy Cluster Motions with the Kinematic Sunyaev-Zel'dovich Effect

Using high-resolution microwave sky maps made by the Atacama Cosmology Telescope, we for the first time detect motions of galaxy clusters and groups via microwave background .temperature distortions due to the kinematic Sunyaev.Zel'dovich effect. Galaxy clusters are identified by their constituent luminous galaxies observed by the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey III. The mean pairwise momentum of clusters is measured. at a statistical. significance of 3.8 sigma, and the signal is consistent with the growth of cosmic structure in the standard model of cosmolog