Aging Influence on Fatigue Characteristics of RAC Mixtures Containing Warm Asphalt Additives

Aging is an important factor to affect the long-term performance of asphalt pavement. The fatigue life of a typical warm mix asphalt (WMA) is generally related to various factors of rheological and mechanical properties of the mixture. The study of the fatigue behavior of the specific rubberized WMA is helpful in recycling the scrap tires and saving energy in terms of the conventional laboratory aging process. This study explores the utilization of the conventional fatigue analysis approach in investigating the cumulative dissipated, stiffness, and fatigue life of rubberized asphalt concrete mixtures containing the WMA additive after a long-term aging process. The aged beams were made with one rubber type (−40 mesh ambient crumb rubber), two aggregate sources, two WMA additives (Asphamin and Sasobit), and tested at 5 and 20ºC. A total of 55 aged fatigue beams were tested in this study. The test results indicated that the addition of crumb rubber extends the fatigue resistance of asphalt binder while WMA additive exhibits a negative effect. The study indicated that the WMA additive generally has an important influence on fatigue life. In addition, test temperature and aggregate source play an important role in determining the cumulative dissipated energy, stiffness, and fatigue life of an aged mixture

Evaluations of Nano-sized Hydrated Lime on the Moisture Susceptibility of Hot Mix Asphalt Mixtures

The objective of this study was to evaluate the effect of nano-sized hydrated lime on the moisture susceptibility of the hot mix asphalt (HMA) mixtures in terms of three methodologies to introduce into the mixtures. The experimental design for this study included the utilizations of one binder source (PG 64-22), three aggregate sources and three different methods introducing the lime. A total of 12 types of HMA mixtures and 72 specimens were fabricated and tested in this study. The performed properties include indirect tensile strength (ITS), tensile strength ratio (TSR), flow, and toughness. The results indicated that the nano-sized lime exhibits better moisture resistance. Introducing process of the nano-sized lime will produce difference in moisture susceptibility

Effect of Nanoparticle Surface Modification and Filling Concentration on Space Charge Characteristics in TiO 2

This paper focuses on the space charge characteristics in TiO2/cross-linked polyethylene (XLPE) nanocomposites; the unmodified and modified by dimethyloctylsilane (MDOS) TiO2 nanoparticles were added to XLPE matrix with different mass concentrations (1 wt%, 3 wt%, and 5 wt%). The scanning electron microscope (SEM) showed that the MDOS coupling agent could improve the compatibility between TiO2 nanoparticles and XLPE matrix to some extent and reduce the agglomeration of TiO2 nanoparticles compared with unmodified TiO2 nanoparticles; the volume resistivity testing indicated that the volume resistivity of TiO2/XLPE nanocomposites was higher than Pure-XLPE and increased with the increase of filling concentrations. According to the pulsed electroacoustic (PEA) measurements, it was concluded that the space charge accumulation was suppressed by filling TiO2 nanoparticles and the distribution of electric field in samples was improved greatly. In addition, it was found that the injection of homocharge was more obvious in MDOS-TiO2/XLPE than that in UN-TiO2/XLPE and the homocharge injection decreased with the increase of filling concentration

The fast light of CsI(Na) crystals

The responds of different common alkali halide crystals to alpha-rays and gamma-rays are tested in our research. It is found that only CsI(Na) crystals have significantly different waveforms between alpha and gamma scintillations, while others have not this phenomena. It is suggested that the fast light of CsI(Na) crystals arises from the recombination of free electrons with self-trapped holes of the host crystal CsI. Self-absorption limits the emission of fast light of CsI(Tl) and NaI(Tl) crystals.Comment: 5 pages, 11 figures Submit to Chinese Physics

The evaluation and specification development of alternate modified asphalt binders in South Carolina : final report.

SPR 703In this research project, asphalt binders containing various polymer modifiers were investigated throughexamining both binder and mixture properties.\ua0\ua0Two additional topics were also investigated, including: a) theeffects of liquid anti\u2010strip additives on asphalt mixtures; and b) the effects of natural sands in asphalt mixtures.\ua0\ua0The asphalt binder modifiers in this project included: two plastomers; an elastomer; PPA+SBS; terminallyblended ground tire rubber (GTR) binder; and a lab\u2010prepared GTR binder.\ua0\ua0The binder properties of 16 bindercombinations were obtained (e.g., viscosity, DSR, etc.) and compared.\ua0\ua0In addition, these modified binders wereused in mixtures with two aggregate sources, three anti\u2010strip additives, and varying RAP contents.\ua0\ua0There were32 different Superpave mix designs conducted for this project.\ua0\ua0Many engineering properties of the mixtureswere obtained, including: indirect tensile strength, tensile strength retained, rutting, and AMPT values.\ua0\ua0TheAMPT testing was conducted at different temperatures and frequencies.\ua0\ua0The results indicated that, in general,many of the alternate modified binders could be utilized in South Carolina hot mix asphalt (HMA) mixtures.\ua0\ua0Theresults also indicated that RAP and natural sand could be utilized, in limited quantities, in many mixtures usedon South Carolina secondary roads.\ua0\ua0In addition, the mixtures made with liquid anti\u2010strip additives in this projectin many cases produced moisture susceptibility values (e.g., ITS, TSR) that were compatible with those obtainedwith mixtures containing hydrated lime

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Development of Fatigue Predictive Models of Rubberized Asphalt Concrete (RAC) Containing Reclaimed Asphalt Pavement (RAP) Mixtures

In recent years, some by-products such as crumb rubber has been used to save money, protect the environment, and extend the life of asphalt pavements. In addition, the utilization of reclaimed asphalt pavement (RAP) is an acceptable practice in many states around the United States and many countries all over the world. However, the use of RAP containing crumb rubber has not been investigated in great detail, so it is essential to explore whether these materials have a positive effect on the fatigue life of asphalt pavement. In general, previous experience shows that the use of RAP has proven to be cost-effective, environmentally sound, and successful in improving some of the engineering properties of asphalt mixtures. Crumb rubber has also been used successfully in improving the mechanical characteristics of hot mix asphalt (HMA) mixtures in many parts of the world. Fatigue is considered to be one of the most significant distress modes in any flexible pavement which is subjected to repeated traffic loading or stress. Several researchers, for the last two decades, have developed some fatigue predictive models that predict the fatigue life of asphalt mixture in the laboratory and even in the field. However, there are no research studies in the area of developing prediction models for mixtures containing crumb rubber and RAP. For this research study, A total of 39 mix designs, including two types of aggregate source, were made and tested to perform fatigue analysis and modeling. Superpave mix design procedures were used for preparation of fatigue testing specimens. The major objective of this study was to develop a mathematical model to predict the fatigue life of rubberized asphalt concrete containing RAP and included: 1) evaluating the performance of the modified binder and mixture in the laboratory; 2) measuring the fatigue life, stiffness and dissipated energy of the fatigue specimens; 3) developing the mathematical model to predict the fatigue life of the modified composite using the conventional statistical regression analysis and artificial neural network (ANN) approaches; 4) validating the fatigue predictive models using modified mixtures made from a second aggregate source. The following conclusions were drawn based on the laboratory investigation: 1) the use of crumb rubber is effective in improving the aging resistance of rubberized asphalt concrete, 2) the addition of RAP decreased the virgin asphalt content and increased the ITS values, 3) the developed specific regression models predicted a reasonable fatigue response of mixture, and the measured and predicted fatigue values were found to be close regardless of the crumb rubber, RAP content, and even testing conditions, 4) ANN approach has been shown to be effective in performing fatigue testing data of mixture and the established ANN model was able to predict fatigue occurrence accurately