Petroleum asphalt basic knowledge
First, what is the asphalt
English name: Petroleum, asphalt. Petroleum asphalt is a product of crude oil processing, is black or dark brown viscous liquid at room temperature, semi-solid or solid, containing mainly soluble in trichlorethylene hydrocarbons and non-hydrocarbon derivatives, the nature of and composition vary with different crude oil sources and production methods. A black solid, semi-solid or highly viscous liquid of heavy petroleum products. , The largest output in a variety of sources of asphalt. Polycyclic, fused ring, heterocyclic (oxygen, sulfur, nitrogen, metal heterocyclic) a mixture of hydrocarbons and their derivatives, with an average molecular weight from 1000 to 5000. The composition of the petroleum asphalt broadly divided into the following sections: oil (heavy hydrocarbons); glial (fused ring heterocyclic compounds, hydrocarbon atomic ratio about 0.7, reddish-brown semi-solid); asphaltenes (thick ring and heterocyclic compounds, hydrocarbon atomic ratio of about 0.8, black solids); carbon green quality (high degree of condensation of fused ring heterocyclic compounds, hydrocarbon atomic ratio of about 0.8 to 0.85, a black solid). Asphaltenes, carbon green quality particulate dispersed in the oil and glia. Petroleum bitumen viscoelasticity: that was viscous fluid under high temperatures or prolonged overload, low temperature or short-term load flexibility, in addition to good adhesion, water resistance to corrosion and electrical insulation, is widely for road construction, building construction, water conservancy (the bonding of dikes, dams, channels stones, seepage, etc.), pipeline corrosion, electrical components and cable insulation.
Petroleum asphalt has excellent adhesive properties and water resistance, and resource-rich, low cost, has long been widely used in road building materials, waterproof materials and sealing materials. According to records, far away in the 3800-2500 years BC, humans began to use asphalt. 50 BC, human beings will be asphalt dissolved in olive oil in the manufacture of asphalt paint materials in the mid-19th century, Paris paved live roller compacted asphalt pavement. Today, the asphalt is widely used in various fields of road construction, construction, hydraulic engineering, equipment corrosion, the national economy.
Petroleum asphalt is a residue from crude distillation into a liquid, semi-solid or solid at room temperature, according to the different levels of refining. Petroleum asphalt color black and shiny, has a high temperature susceptibility. Petroleum asphalt can be classified according to the following system: production methods are divided into: straight-run bitumen, solvent deoiled asphalt, asphalt oxidation, blending asphalt, emulsified asphalt, modified asphalt; morphology is divided into: liquid asphalt, solid asphalt, diluent, emulsion, modified body, etc.; use is divided into: the paving asphalt, asphalt construction, waterproof moisture asphalt, named purpose or function-specific such as asphalt.
Production methods
A distillation: the crude oil is often pressure distillation to separate the gasoline, kerosene, diesel and other light distillate by vacuum distillation (residual pressure 10 ~ 100mmHg) the separation of VGO, and the remaining residue in line with road asphalt specifications can directly produce asphalt products, asphalt obtained also called straight-run bitumen, the main method of production of road asphalt.
2, solvent precipitation method: non-polar low molecular weight alkanes solvent components in the vacuum residue with different solubility, using solubility differences can be achieved separation of components, which can be removed from the vacuum residue on asphalt unfavorable nature of the components to produce asphalt products meet the specifications, which is the solvent precipitation method.
3, the oxidation method: vacuum residue in a range of high temperatures or deoiled asphalt blown into the air, its composition and performance changes resulting product is called the oxidation of asphalt. The vacuum residue in the heat and blow air under the action of vaporized at the same time a series of reactions of dehydrogenation, oxidation, polymerization condensation will occur. This is more than one component interaction is very complex reaction, not just the oxidation reaction, called oxidation and oxidation of asphalt on the habit, also known as air method of blowing and air blowing of asphalt.
4, adjusting legal and: tune legitimate production of asphalt originally refers to the same crude oil constitute a proportion of the four components of the asphalt quality requirements needed to re-blending, the resulting product is called synthetic asphalt or reconstruction of asphalt. With the development of process technology, the sources of blending components to expand. Example, from the same crude oil or crude oil, secondary processing residues or components as well as a variety of industrial waste oil and other blending components, which reduces the dependence on oil source selection in the asphalt production. With the increasing shortage of crude oil suitable for manufacture of asphalt, adjusting legitimate shows the flexibility and economy are increasingly valued and universal application.
Emulsion: Asphalt and surface tension of water a great difference in the normal or high temperatures are not miscible with each other. But when the asphalt by high speed centrifugation, cut from the mechanical action of hammering a particle size of 0.1 ~ 5μm particles and dispersed in aqueous media containing surfactant (emulsifier - stabilizer), due to the emulsifier can be directed adsorbed on the surface of the asphalt particles, thus lowering the interfacial tension of the water and asphalt, the asphalt particles can form a stable dispersion in water system, which is the oil in water emulsion. This decentralized system was dark brown, asphalt for the dispersed phase and water as continuous phase at room temperature with good mobility. From a sense of emulsified asphalt
Water to "dilute" asphalt, thus improving the fluidity of the asphalt.
6, modified bitumen: modern highways and roads many changes: traffic flow and driving frequency of the sharp growth, increasing the axle load of freight cars, the widespread use of sub-lane one-way travel requirements to further improve the road surface flow resistance, ie high temperature resistance to the capacity of the rut; improve the flexibility and elasticity, the ability of resistance to cracking in low temperatures; improve the wear resistance and extended service life. Modern buildings commonly used by large-span prestressed roof, the roofing materials to adapt to the larger displacement, more tolerance to the harsh climatic conditions of high and low temperature, durability, better, self-adhesive, to facilitate construction and reduce maintenance workload. These changes occurred in the use of the environment poses a severe challenge to the performance of petroleum asphalt. On petroleum bitumen, to adapt to these demanding requirements, has aroused people's attention. After decades of research and development, has a wide variety of modified road asphalt, waterproofing membranes and coatings, and show some practical engineering effects. But in view of the modified material prices are generally 2 to 7 times higher than ordinary petroleum asphalt, the performance of materials engineering have not been able to fully grasp the slow growth in the production of modified asphalt. Modified paving asphalt used in paving applications for airport runways, bridge deck waterproofing, parking lots, playgrounds, heavy traffic roads, intersections and road bend and other special occasions. Recently the European modified asphalt is applied to the conservation and reinforcement of the road network to promote the universal application of the modified road asphalt. Modified bitumen membrane and coatings for high-end building waterproofing. With the development of scientific and technological progress and economic construction cause, it will further promote the development of modified asphalt product development and production technology. The variety and preparation of the modified asphalt depends on the type of modifier, the composition and properties of addition and asphalt (ie, raw materials, asphalt). Due to the wide variety of modifiers, various shapes, in order to make the petroleum asphalt to form a uniform for the engineering and practical material for many years to evaluate various types of modifiers, and the development of appropriate formulations and preparation methods, but most engineering utility of the modified asphalt is patented technology and proprietary products.
Packaging and storage: asphalt in the process of production and use of storage may be required in the tank insulation, if handled appropriately, the asphalt can be repeated heating can keep for a long time at higher temperatures without its performance to be seriously damaged. However, if exposure to oxygen, light and overheating can cause the hardening of the asphalt, the most significant sign of the asphalt softening point rise, penetration decline, deterioration of ductility, the use of asphalt performance suffer.