Investigation of the Formation Mechanism and Environmental Risk of Tire—Pavement Wearing Waste (TPWW)

Tire—pavement interaction behaviours result in large amounts of wearing waste matter, which attaches to the surface of the pavement and is directly exposed to the surrounding environment. This kind of matter imposes a great challenge to the environment of the road area. The current study is devoted to carrying out a comprehensive investigation of the formation mechanism of tire—pavement wearing waste (TPWW), as well as the resulting environmental risks. A self-developed piece of accelerated polishing equipment, the Harbin advanced polishing machine (HAPM), was employed to simulate the wearing process between vehicle tires and pavement surfaces, and the TPWW was collected to conduct morphological, physical, and chemical characterisations. The results from this study show that the production rate of TPWW decreases with the increase in polishing duration, and the coarse particles (diameters greater than 0.425 mm) account for most of the TPWW obtained. The fine fraction (diameter smaller than 0.425 mm) of the TPWW comprises variously sized and irregularly shaped rubber particles from the tire, as well as uniformly sized and angular fine aggregates. The environmental analysis results show that volatile alkanes (C9–C16) are the major organic contaminants in TPWW. The Open-Graded Friction Course (OGFC) asphalt mixture containing crumb rubber as a modifier showed the highest risk of heavy metal pollution, and special concern must be given to tire materials for the purpose of improving the environmental conditions of road areas. The use of polyurethane as a binder material in the production of pavement mixtures has an environmental benefit in terms of pollution from both organic contaminants and heavy metals.

Technique for gas-chromatographic measurement of volatile alkanes from single-breath samples.

For detection of small quantities of alkanes that are present in expired breath, these gases have hitherto been concentrated, either by passing large volumes of breath through a liquid-nitrogen-cooled precolumn or by use of a closed collection system. Here, we describe a technique for analyzing small volumes of gas from single-breath samples from humans, in which no precolumn is required. Results are linearly related to sample concentrations of ethane, propane, butane, and pentane in the range 0 to 13 nmol per liter of air (r = 0.999). Within-run coefficients of variation were less than 15%. Breath samples could be stored for as long as 10 h without loss of the alkanes. We also report alkane concentrations in samples of alveolar gas and total breath collected from normal subjects. This technique appears to be well suited for measuring alkane concentrations in single-breath samples.