The Dead Sea — an economic resource for 10 000 years

The archaeological and historical record of the Dead Sea as an economic resource is longer than that of any other hypersaline lake. Although it is completely devoid of life, except for a few bacteria and algae, the climatic and geological conditions in the Dead Sea basin have produced circumstances which made this lake important for the economy of the area. The salt which was produced by evaporation of the water, or by quarrying from the salt diapir of Mt. Sodom, on the Dead Sea coast, is referred to in the Bible and in the Talmud. It was harvested until the 1930's. Potash has been extracted from the brine, by solar processes, since 1931 and today the Dead Sea is a major source of potash and bromine. The asphalt, which is found in seepages along the shores and in large blocks, occasionally found floating on the lake, has been used by the inhabitants of the area for waterproofing baskets and for decorative purpose, since the Pre-ceramic Neolithic Period, 10 000 years ago. Later, the asphalt became a major export item to Egypt. During the Early Bronze age, 4000 years ago, it was used mostly to glue flint implements to wooden handles and in the Graeco-Roman period it was used as one of the components in the embalming of Egyptian mummies. The area around the Dead Sea was the only source of balsam, perhaps the most important incense and medication of the Ancient World. Remains of a 7th century B.C. perfume factory, were found in Ein Gedi. During later periods, until the Arab conquest in the 7th century A.D., the growing of balsam was an imperial monopoly. The area of the Dead Sea was famous, for over 2000 years, for its dates and sugar. The therapeutical and medicinal properties of Dead Sea water and the hypersaline hot springs on its shore, were famous throughout the Ancient World. For example, King Herod the Great, 2000 years ago, used to visit the area to cure his many diseases. This practice continues today, and the lakes has become a major center for treatment of psoriasis. There is pictorial, archaeological and historical evidence to support the Dead Sea's importance as a trade artery for over 2300 years.     

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons as biomarkers of exposure in asphalt workers

Background. Fumes and vapours released during laying of hot asphalt mix have been recognised as a major source of exposure for asphalt workers. Objectives. We investigated the relationships between inhalation exposure to asphalt emissions and urinary biomarkers of polycyclic aromatic hydrocarbons (PAHs) in asphalt workers (AW, n=75) and in ground construction workers (CW, n=37). Methods. Total polyaromatic compounds (PAC) and 15 priority PAHs in inhaled air were measured by personal sampling. Hydroxylated PAH metabolites (OH-PAHs) (2-naphthol, 2-hydroxyfluorene, 3-hydroxyphenanthrene, 1-hydroxypyrene, 6-hydroxychrysene and 3-hydroxybenzo[a]pyrene) were determined in urine spot samples collected in three different times during the work week. Results. Median vapour-phase PAC (5.5 µg m^-3), PAHs (≤50 ng m^-3) and OH-PAHs (0.08-1.11 µg l^-1) were significantly higher in AW than in CW, except in the cases of air naphthalene and 2-naphthol. Airborne levels of particle-phase contaminants were similar in the two groups and much lower than vapour-phase levels; metabolites of particulate PAHs were never found in quantifiable amounts. An appreciable increase in OH-PAH levels during the work day and work week was found in AW; median levels for 2-hydroxyfluorene, 3-hydroxyphenanthrene and 1-hydroxypyrene were, respectively, 0.29, 0.08 and 0.18 at baseline; 0.50, 0.18 and 0.29, pre-shift; 1.11, 0.44 and 0.44 µg l^-1, post-shift. Each OH-PAH exhibited a characteristic profile of increase, reflecting differences in half-lives of the parent compounds. In non-smoking subjects, positive correlations were found between vapour-phase PAC or PAHs and OH-PAHs both in pre- and post-shift samples (0.34 ≤ r≤69). Smokers exhibited 2-5-fold higher OH-PAHs than non-smokers, at any time and at both workplaces. Conclusions. Our results suggest that OH-PAHs are useful biomarkers for monitoring exposure to asphalt emissions. The work-related exposure to PAC and PAHs was low in all AW, but urinary metabolites reflected exposure satisfactorily.     

Ultra‐High Surface Area Activated Porous Asphalt for CO2 Capture through Competitive Adsorption at High Pressures

This study reports an improved method for activating asphalt to produce ultra‐high surface area porous carbons. Pretreatment of asphalt (untreated Gilsonite, uGil ) at 400 °C for 3 h removes the more volatile organic compounds to form pretreated asphalt ( uGil‐P ) material with a larger fraction of higher molecular weight π‐conjugated asphaltenes. Subsequent activation of uGil‐P at 900 °C gives an ultra‐high surface area (4200 m² g^?1) porous carbon material ( uGil‐900 ) with a mixed micro and mesoporous structure. uGil‐900 shows enhanced room temperature CO₂ uptake capacity at 54 bar of 154 wt% (35 mmol g^?1). The CH₄ uptake capacity is 37.5 wt% (24 mmol g^?1) at 300 bar. These are relevant pressures in natural gas production. The room temperature working CO₂ uptake capacity for uGil‐900 is 19.1 mmol g^?1 (84 wt%) at 20 bar and 32.6 mmol g^?1 (143 wt%) at 50 bar. In order to further assess the reliability of uGil‐900 for CO₂ capture at elevated pressures, the authors study competitive sorption of CO₂ and CH₄ on uGil‐900 at pressures from 1 to 20 bar at 25 °C. CO₂/CH₄ displacement constants are measured at 2 to 40 bar, and found to increase significantly with pressure and surface area.     

Evaluation of thermo-mechanical properties of graphene/carbon-nanotubes modified asphalt with molecular simulation

A comparative study was conducted to determine the effects of graphene and carbon nanotubes on the thermo-mechanical properties of asphalt binder using molecular simulations and experiments. Micro-morphology of graphene and carbon nanotubes was measured by scanning electron microscopy. Thermal stability and glass transition temperature were investigated by differential scanning calorimeter. Simulation results indicated that the T_g had slightly changed for graphene-modified asphalt (GMA) and carbon nanotubes-modified asphalt (CNsMA) and that the thermal expansion coefficients and thermal conductivity increased along with the adding amount of graphene or carbon nanotubes. The T_g calculated by density–temperature method was closer than the experimental T_g and the T_g decreased in the order of CNsMA, GMA and asphalt. Young’s modulus of asphalt, GMA and CNsMA were 9.2658, 25.7563 and 17.8249 GPa at 298 K, respectively, which indicated that thermo-mechanical properties of asphalt showed considerable improvements after the addition of graphene or carbon nanotubes, and carbon nanotubes-modified asphalt and GMA were promising candidates for the future modified asphalt.     

Pneumoproteins and inflammatory biomarkers in asphalt pavers

Pneumoproteins, biomarkers of systemic inflammation and endothelial activation were studied across a season in 72 asphalt pavers, 32 asphalt plant operators and 19 asphalt engineers. Smokers had lower concentrations of Clara cell protein (CC-16) and surfactant protein A, but higher concentrations of surfactant protein D, interleukin 6, C-reactive protein, fibrinogen and intercellular adhesion molecule (ICAM)-1 than non-smokers. Smokers reporting wheezing had lower mean CC-16 concentration than smokers not reporting wheezing (5.7 vs 8.6 µg l^?1; p?=?0.05). Cholesterol, P-selectin and ICAM-1 were lower in pavers and operators at the end compared with the start of the season. This may be related to increased physical activity during the season.     

Chemical aspects of cold‐mix asphalt incorporating contaminated soil

The chemical aspects associated with the incorporation of petroleum hydrocarbons‐ and metals‐affected soil has been studied extensively with respect to pavement properties, leaching behavior, sensitivities to moisture damage, and function group analysis. These studies provide information that can be used to evaluate the stability of these constituents in soils that have been incorporated as an ingredient in asphalt. These studies also indicate that cold‐mix asphalt incorporating contaminated soil will be highly stable and perform adequately as an end product. Maximum chemical performance is achieved when the asphalt is comprised of high contents of pyridinic, phenolic, and ketone groups, which can be achieved by selectively choosing the source material. If the situation requires special stability or redundancy, small amounts of shale oil and lime can be used as additives. Situations and conditions that favor the presence of inorganic sulfur, monovalent salts, and high‐strength solutions in the asphalt should be avoided because these conditions decrease the chemical stability of the asphalt cement by disrupting the functional group‐aggregate bonds and by increasing the overall permeability. However, these conditions are not typically expected in the anticipated uses of asphalt cement to stabilize contaminants in soil using Environmentally Processed Asphalt? (EPA?)* or Asphaltic Metals Stabilization? (AMS?)** remedial technologies.     

Diffusion and interaction mechanism of rejuvenating agent with virgin and recycled asphalt binder: a molecular dynamics study

The quality of asphalt binder recycling is largely dependent on molecular diffusion between virgin asphalt binder, aged asphalt binder, and rejuvenator. In this study, molecular dynamics (MD) simulations were used to study diffusion and interaction mechanism of rejuvenating agent in recycled asphalt binder. The diffusion process of rejuvenator into virgin and aged asphalt binder was studied using a three-layered model. A mixture model of virgin and aged asphalt binder was built to evaluate the effect of rejuvenator on the molecular structure of asphalt binder, such as nanoaggregate behaviour and translational mobility. The simulation results of the layered model suggest that rejuvenator may improve blending efficiency of virgin and aged asphalt binder depending on temperature. The calculated inter-diffusion coefficients indicate that the rejuvenator diffuses faster into virgin asphalt binder than aged asphalt binder. The radial distribution functions of asphaltene, resin, and aromatic pairs show that rejuvenator causes the molecular structures of virgin and aged asphalt binder more similar to that of virgin asphalt binder. The rejuvenator reduces the self-association trends of asphaltene molecules, but saturates from local aggregation inside the rejuvenated asphalt binder. On the other hand, rejuvenator increases translational mobility of saturate, aromatic, resin and asphaltene fractions.     

A fuzzy-based risk assessment model for evaluations of hazards with a real-case study

Abstract

The effectiveness of the traditional risk analysis approach is enhanced by the integration of the fuzzy logic and Multi-Criteria Decision Making (MCDM) methods. In fact, human decisions are ambiguous and blurred and do not fit to express with absolute numerical values. For this reason, it is more realistic to use verbal variables in modeling human decisions. In this paper, a new fuzzy based hazard evaluation approach is proposed to deal with the risk assessment process. The proposed methodology consists on MCDM with a fuzzy system which includes a hybrid structure consists the Pythagorean Fuzzy Analytic Hierarchy Process (PFAHP) method with cosine similarity, and also Neutrosophic Analytic Hierarchy Process (NFAHP) to support facing of uncertainty in the risk assessment process for asphalt production, laying and coating services which are important and should be examined in terms of occupational health and safety. To the best of our knowledge, this study is the first to propose facing uncertainty in the hazard evaluations and risk assessment for asphalt production, laying, and coating services. As an outcome of the analysis by the proposed method, according to PFAHP and NFAHP methodologies the criterions “manometer size” and “calibration” are found to be most critical factors, respectively.     

Coal Tar‐Containing Asphalt Resource or Hazardous Waste?

Abstract: Coal tar was used in Sweden for the production of asphalt and for the drenching of stabilization gravel until 1973. The tar has high concentrations of polycyclic aromatic hydrocarbons (PAH), some of which may be strongly carcinogenic. Approximately 20 million tonnes of tar-containing asphalt is present in the public roads in Sweden. Used asphalt from rebuilding can be classified as hazardous waste according to the Swedish Waste Act. The cost of treating the material removed as hazardous waste can be very high due to the large amount that has to be treated, and the total environmental benefit is unclear. The transport of used asphalt to landfill or combustion will affect other environmental targets. The present project, based on three case studies of road projects in Sweden, evaluates the consequences of four scenarios for handling the material: reuse, landfill, biological treatment, and incineration. The results show that reuse of the coal tar-containing materials in new road construction is the most favorable alternative in terms of cost, material use, land use, energy consumption, and air emissions.