What Is Road Oil?

Road oil refers to the materials used for paving the road, divided into petroleum pitch and coal pitch.

Asphalt materials used in asphalt pavements must meet road requirements and technical standards in order to adapt to the repeated effects of automobile traffic for many years. For light and medium-sized highways of grades 3 and 4, ordinary road petroleum asphalt can be used, with the prefix "A". Asphalt pavements of heavy roads and highways and highways need to use heavy asphalt road asphalt, which is denoted by "AH".

The main indicators reflecting the road properties of asphalt are:

Sticky

The viscosity of the asphalt is expressed by the penetration, that is, the depth at which a 100 g mass styli is inserted into the asphalt for 5 seconds at a temperature of 25 ° C, and the unit is 0.1mm. Such as heavy traffic asphalt AH-90, its penetration range is 80 to 100 (0.01mm). Obviously, the smaller the penetration of asphalt, the greater its viscosity.

2. Plasticity

The plasticity of the asphalt indicates its deformability, and its ductility is expressed as the length of the asphalt specimen at a deformation speed of 5 mm per minute in the water tank at 15 ° C until it is broken. Such as AH-90 heavy traffic asphalt, its ductility should be greater than 100cm.

3. Temperature stability

The temperature stability of asphalt is expressed by the comparison point. In the test, the water in the glass beaker was heated from 5 ° C, and the heating rate was 5 ° C per minute. The softening point is the temperature when two steel balls immersed in water fall from two small copper rings filled with asphalt samples to the bottom of the board. Trial used

Petroleum pitch is the product of various crude oils (such as gasoline, diesel, etc.) and lubricating oil, which are refined by distilling petroleum crude oil. The product is brown or dark brown. By using crude oil of different origin and different refining and processing methods, a variety of petroleum asphalt varieties with different compositions and properties can be obtained. According to different uses, petroleum asphalt is divided into road petroleum asphalt, construction petroleum asphalt, waterproof, moisture-proof petroleum asphalt, and ordinary petroleum asphalt.

Coal tar is a by-product of coke and gas production. The volatile matter of bituminous coal during the dry distillation process, the black viscous liquid formed by condensation is called coal tar, and the residue obtained after fractional distillation to extract light oil, medium oil, heavy oil and anthracene oil is coal pitch.

Depending on the degree of distillation. Coal asphalt is divided into three types: low-temperature asphalt, medium-temperature asphalt, and high-temperature asphalt. The coal pitches used in civil engineering are mostly viscous or semi-solid low-temperature pitches.

The main components of coal pitch are oil, grease, free carbon, etc., and also contain a small amount of acid and alkali substances. Compared with petroleum pitch, the performance characteristics of coal pitch are as follows:

(1) Great temperature sensitivity. Its components contain many soluble resins, and the temperature interval from the solid or viscous state to the viscous fluid state (or liquid state) is narrow. It is easy to soften and flow in summer and brittle in winter.

(2) Poor atmospheric stability. It contains many volatile components and components with poor chemical stability. Under the long-term comprehensive effects of heat, sunlight, and oxygen, the composition of coal tar pitch changes greatly, which is easy to be brittle.

(3) Poor plasticity. It contains a lot of free carbon and is easy to crack due to deformation.

(4) Because it contains more surface-active substances, it has stronger adhesion to the surface of the mineral.

(5) Good corrosion resistance. Because it contains toxic and odorous substances such as phenol and anthracene, and has a strong antiseptic ability, it is suitable for antiseptic treatment of wood. But it is not as waterproof as petroleum asphalt (because phenol is easily soluble in water). During the construction, it is necessary to abide by relevant operating and labor insurance regulations to prevent poisoning. ^[2]

Compared with petroleum pitch, coal pitch has some differences in properties.

(1) Low temperature stability. Coal tar has a large amount of soluble resin, which is easily softened by heat and dissolved in oil. Therefore, the heating temperature and time must be strictly controlled, and it is not easy to repeatedly heat, otherwise it will cause a sharp deterioration in properties.

(2) Poor atmospheric stability. Coal asphalt has a large amount of unsaturated hydrocarbons and is easy to deteriorate.

(3) Poor plasticity. Coal tar contains more free carbon, which is susceptible to cracking and cracking under stress, especially brittle and hard under low temperature conditions.

(4) Good adhesion to minerals. Coal tar contains more polar substances, it gives coal tar more high surface activity, can adhere well to the mineral, and can improve the bonding strength.

(5) Poisonous, odorous, and strong antiseptic ability. Coal tar contains volatile and toxic components such as phenol and anthracene, which are harmful to the human body during construction. It is not suitable for urban roads and pavement surfaces, but it has better antiseptic effect on wood.

(6) Coal asphalt has a higher density than petroleum asphalt. ^[3]