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Crumb Rubber
Crumb rubber is recycled rubber produced from automotive and truck scrap tires. During the recycling process, steel and tire cord (fluff) are removed, leaving tire rubber with a granular consistency. Continued processing with a granulator or cracker mill, possibly with the aid of cryogenics or by mechanical means, reduces the size of the particles further. The particles are sized and classified based on various criteria including color (black only or black and white). The granulate is sized by passing through a screen, the size based on a dimension (1/4 inch) or ''mesh'' (holes per inch : 10, 20, etc.). Crumb rubber is often used in artificial turf as cushioning. Background The first synthetic grass was placed over concrete in 1964 and became known as “Chem Grass”. It was later named "AstroTurf" when it was installed in the Houston Astrodome in 1966. Athletes did not like playing on these fields because of the risk of injury due to the hard surface. A new artificial turf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflective Crack
A reflective crack is a type of failure in asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term ... pavement, one of the most popular road surface types. Asphalt pavement is impacted by traffic and thermal loading. Due to loading, cracks can appear on pavement surface that can reduce the Pavement Condition Index (PCI) dramatically. The pavement can be maintained by overlay. Cracks under the overlay can cause stress concentration at the bottom of the overlay. Due to the repeated stress concentration, a crack starts in the overlay that has a similar shape to the crack in the old pavement. This crack is called a "reflective crack". Reflective cracking can be categorized as one of the distresses in asphalt pavement. It can affect the general performance and durability of the paveme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. Lead is toxic, even in small amounts, especially to children. Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USEPA
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on December 2, 1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its administrator, who is appointed by the president and approved by the Senate. The current administrator is Michael S. Regan. The EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D.C., regional offices for each of the agency's ten regions and 27 laboratories. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of environmental laws, in consultation with state, triba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volatile Organic Compound
Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a trait known as volatility. VOCs are responsible for the odor of scents and perfumes as well as pollutants. VOCs play an important role in communication between animals and plants, e.g. attractants for pollinators, protection from predation, and even inter-plant interactions. Some VOCs are dangerous to human health or cause harm to the environment. Anthropogenic VOCs are regulated by law, especially indoors, where concentrations are the highest. Most VOCs are not acutely toxic, but may have long-term chronic health effects. Definitions Diverse definitions of the term VOC are in use. Canada Health Canada classifies VOCs as organic compounds that have boiling points roughly in the range of . The emphasis is placed on commonly encountere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycyclic Aromatic Hydrocarbons
A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. PAHs are uncharged, non-polar and planar. Many are colorless. Many of them are found in coal and in oil deposits, and are also produced by the combustion of organic matter—for example, in engines and incinerators or when biomass burns in forest fires. Polycyclic aromatic hydrocarbons are discussed as possible starting materials for abiotic syntheses of materials required by the earliest forms of life. Nomenclature and structure The terms polyaromatic hydrocarbon or polynuclear aromatic hydrocarbon are also used for this concept. By definition, polycyclic aromatic hydrocarbons have multiple rings, precluding benzene from being considered a PAH. Some sources, such as the US EPA and CDC, consider naphthalene to be the simplest PAH. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artificial Turf
Artificial turf is a surface of synthetic fibers made to look like natural grass. It is most often used in arenas for sports that were originally or are normally played on grass. However, it is now being used on residential lawns and commercial applications as well. The main reason is maintenanceartificial turf stands up to heavy use, such as in sports, and requires no irrigation or trimming. Domed, covered, and partially covered stadiums may require artificial turf because of the difficulty of getting grass enough sunlight to stay healthy. Artificial turf does have its downside, however: limited life, periodic cleaning requirements, petroleum use, toxic chemicals from infill, and heightened health and safety concerns. Artificial turf first gained substantial attention in 1966, when it was installed in the year-old Astrodome. The specific product used was "ChemGrass", developed by Monsanto and rebranded as AstroTurf; this term since then became a generic trademark for any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon. Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items because of its toxicity. History Discovery The word "''benzene''" derives from "''gum benzoin''" ( ben ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzo(e)pyrene
Benzo 'e''yrene is a polycyclic aromatic hydrocarbon with the chemical formula C20H12. It is listed as a Group 3 carcinogen by the IARC. See also * Benzopyrene * Benzo 'a''yrene * Benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ... * Pyrene, a four-ring analogue References Polycyclic aromatic hydrocarbons IARC Group 3 carcinogens {{hydrocarbon-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzo(a)pyrene
Benzo 'a''yrene (B''a''P or B ) is a polycyclic aromatic hydrocarbon and the result of incomplete combustion of organic matter at temperatures between and . The ubiquitous compound can be found in coal tar, tobacco smoke and many foods, especially grilled meats. The substance with the formula C20H12 is one of the benzopyrenes, formed by a benzene ring fused to pyrene. Its diol epoxide metabolites (more commonly known as BPDE) react with and bind to DNA, resulting in mutations and eventually cancer. It is listed as a Group 1 carcinogen by the IARC. In the 18th century a scrotal cancer of chimney sweepers, the chimney sweeps' carcinoma, was already known to be connected to soot. Description Benzo 'a''yrene (B''a''P) is a polycyclic aromatic hydrocarbon found in coal tar with the formula C20H12. The compound is one of the benzopyrenes, formed by a benzene ring fused to pyrene, and is the result of incomplete combustion at temperatures between and . Sources The main ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysene
Chrysene is a polycyclic aromatic hydrocarbon (PAH) with the molecular formula that consists of four fused benzene rings. It is a natural constituent of coal tar, from which it was first isolated and characterized. It is also found in creosote at levels of 0.5–6 mg/kg.Anja Sörensen and Bodo Wichert "Asphalt and Bitumen" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2009. http://www.qrpoil.com/site/?bitumen The name "chrysene" originates from Greek ''Χρύσoς'' (''chrysos''), meaning "gold", and is due to the golden-yellow color of the crystals of the hydrocarbon, thought to be the proper color of the compound at the time of its isolation and characterization. However, high purity chrysene is colorless, the yellow hue being due to the traces of its yellow-orange isomer tetracene, which cannot be separated easily. Occurrence Chrysene is a constituent of tobacco smoke. Safety As with other PAHs, chrysene is suspected to be a human carcin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Chemicals Agency
The European Chemicals Agency (ECHA; ) is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA has to ascertain that companies comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern. It is located in Helsinki, Finland. ECHA is an independent and mature regulatory agency established by REACH. It is not a subsidiary entity of the European Commission. The agency, currently headed by Acting Executive Director Shay O’Malley, started working on 1 June 2007. Establishment The ECHA was created by European Union regulation dating from 18 December 2006 to manage the then-new legislation to regulate the manufacture and use of che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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