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

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

The Atacama Cosmology Telescope: Dynamical Masses and Scaling Relations for a Sample of Massive Sunyaev-Zel'dovich Effect Selected Galaxy Clusters

We present the first dynamical mass estimates and scaling relations for a sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters. The sample consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455 sq. deg. area of the southern sky. Deep multi-object spectroscopic observations were taken to secure intermediate-resolution (R~700-800) spectra and redshifts for ~60 member galaxies on average per cluster. The dynamical masses M_200c of the clusters have been calculated using simulation-based scaling relations between velocity dispersion and mass. The sample has a median redshift z=0.50 and a median mass M_200c~12e14 Msun/h70 with a lower limit M_200c~6e14 Msun/h70, consistent with the expectations for the ACT southern sky survey. These masses are compared to the ACT SZE properties of the sample, specifically, the match-filtered central SZE amplitude y, the central Compton parameter y0, and the integrated Compton signal Y_200c, which we use to derive SZE-Mass scaling relations. All SZE estimators correlate with dynamical mass with low intrinsic scatter (<~20%), in agreement with numerical simulations. We explore the effects of various systematic effects on these scaling relations, including the correlation between observables and the influence of dynamically disturbed clusters. Using the 3-dimensional information available, we divide the sample into relaxed and disturbed clusters and find that ~50% of the clusters are disturbed. There are hints that disturbed systems might bias the scaling relations but given the current sample sizes these differences are not significant; further studies including more clusters are required to assess the impact of these clusters on the scaling relations.Comment: 15 pages, 4 figures. Accepted for publication in The Astrophysical Journal; matches published version. Full Table 8 with complete spectroscopic member sample available in machine-readable form in the journal site and upon request to C. Sif\'o

First Measurement of the Cross-Correlation of CMB Lensing and Galaxy Lensing

We measure the cross-correlation of cosmic microwave background lensing convergence maps derived from Atacama Cosmology Telescope data with galaxy lensing convergence maps as measured by the Canada-France-Hawaii Telescope Stripe 82 Survey. The CMB-galaxy lensing cross power spectrum is measured for the first time with a significance of 3.2, which corresponds to a 16% constraint on the amplitude of density fluctuations at redshifts ~ 0.9. With upcoming improved lensing data, this novel type of measurement will become a powerful cosmological probe, providing a precise measurement of the mass distribution at intermediate redshifts and serving as a calibrator for systematic biases in weak lensing measurements

A measurement of the millimetre emission and the Sunyaev-Zel'dovich effect associated with low-frequency radio sources

We present a statistical analysis of the millimetre-wavelength properties of 1.4GHz-selected sources and a detection of the Sunyaev–Zel’dovich (SZ) effect associated with the haloes that host them. We stack data at 148, 218 and 277GHz from the Atacama Cosmology Telescope at the positions of a large sample of radio AGN selected at 1.4GHz. The thermal SZ effect associated with the haloes that host the AGN is detected at the 5σ level through its spectral signature, representing a statistical detection of the SZ effect in some of the lowest mass haloes (average M 200 ≈ 10 13 M. h −1 70 ) studied to date. The relation between the SZ effect and mass (based on weak lensing measurements of radio galaxies) is consistent with that measured by Planck for local bright galaxies. In the context of galaxy evolution models, this study confirms that galaxies with radio AGN also typically support hot gaseous haloes. Adding Herschel observations allows us to show that the SZ signal is not significantly contaminated by dust emission. Finally, we analyse the contribution of radio sources to the angular power spectrum of the cosmic microwave background

The Atacama Cosmology Telescope: Relation Between Galaxy Cluster Optical Richness and Sunyaev-Zel'dovich Effect

We present the measured Sunyaev-Zel'dovich (SZ) flux from 474 optically-selected MaxBCG clusters that fall within the Atacama Cosmology Telescope (ACT) Equatorial survey region. The ACT Equatorial region used in this analysis covers 510 square degrees and overlaps Stripe 82 of the Sloan Digital Sky Survey. We also present the measured SZ flux stacked on 52 X-ray-selected MCXC clusters that fall within the ACT Equatorial region and an ACT Southern survey region covering 455 square degrees. We find that the measured SZ flux from the X-ray-selected clusters is consistent with expectations. However, we find that the measured SZ flux from the optically-selected clusters is both significantly lower than expectations and lower than the recovered SZ flux measured by the Planck satellite. Since we find a lower recovered SZ signal than Planck, we investigate the possibility that there is a significant offset between the optically-selected brightest cluster galaxies (BCGs) and the SZ centers, to which ACT is more sensitive due to its finer resolution. Such offsets can arise due to either an intrinsic physical separation between the BCG and the center of the gas concentration or from misidentification of the cluster BCG. We find that the entire discrepancy for both ACT and Planck can be explained by assuming that the BCGs are offset from the SZ maxima with a uniform random distribution between 0 and 1.5 Mpc. Such large offsets between gas peaks and BCGs for optically-selected cluster samples seem unlikely given that we find the physical separation between BCGs and X-ray peaks for an X-ray-selected subsample of MaxBCG clusters to have a much narrower distribution that peaks within 0.2 Mpc. It is possible that other effects are lowering the ACT and Planck signals by the same amount, with offsets between BCGs and SZ peaks explaining the remaining difference between measurements. (Abridged)Comment: 10 pages; version matches that accepted by ApJ - minor additions to tex