As the chemical composition of asphalt is complex, it is difficult to analyze its composition, and its chemical composition cannot reflect the difference of asphalt properties, so it is generally not used for chemical analysis of asphalt.In general, from the perspective of use, the bitumen is divided into several groups according to their similar chemical and physical and mechanical properties. These groups are called "components".The components and properties of petroleum bitumen are as follows: oil content, colloidal substance and bituminous substance.
Oil is a yellowish to reddish brown oily liquid with a molecular weight of 100 ~ 500 and a density of 0.71 ~ 1.00g/cm3. It is soluble in most organic solvents but not in alcohol.In petroleum asphalt, the oil content is 40% ~ 60%.Asphalt is given mobility by oil content.
Colloidal, semisolid, yellowish-brown or reddish brown, with a molecular weight of 600 ~ 1000 and a density of 1.0 ~ 1.1g/cm3.Under certain conditions, it can be transformed from low-molecular compounds into macromolecular compounds into bituminous and carbonic bitumen.
The bituminous is dark brown to black solid non-qualitative superfine particle solid powder, the molecular weight is 2000 ~ 6000, the density is more than 1.0g/cm3, insoluble in gasoline, but soluble in carbon disulfide and carbon tetrachloride.Asphalt is an important component that determines the temperature sensitivity and viscosity of petroleum asphalt.The content of asphalt in asphalt is between 10% and 30%. The higher the content, the higher the softening point and the higher the viscosity, the harder and more brittle it is.
Petroleum asphalt also contains 2% ~ 3% of bituminous carbon and carboloy (black solid powder), which is the most molecular weight in petroleum pitch and will reduce the adhesion of petroleum pitch.Petroleum asphalt also contains wax, which can reduce the adhesion and plasticity of petroleum asphalt.It is also sensitive to temperature (i.e. poor temperature stability).
Petroleum tar is the residue of crude oil distillation.It is made into liquid, semi-solid or solid at room temperature according to the degree of extraction.Petroleum pitch is black and shiny with high temperature sensitivity.
The petroleum bitumen can be classified according to the following system:
According to the production method, it can be divided into: straight-run asphalt, solvent deoiled asphalt, oxidized asphalt, blending asphalt, emulsified asphalt, modified asphalt, etc.
It can be divided into liquid bitumen, solid bitumen, diluent, emulsion, modified substance, etc.
It can be divided into road bitumen, building bitumen, waterproof and moisture-proof bitumen, all kinds of special bitumen named after use or function.