What are the characteristics of modified bitumen? What is Modified Asphalt Uses of Asphalt

Asphalt is a widely used waterproof material and anti-corrosion material, mainly used in the ground, underground structure of waterproofing, let's learn about modified asphalt together.

What is modified bitumen.

Bitumen is a complex mixture of organic compounds. It is divided into two categories: ground asphalt and tar asphalt, and ground asphalt is divided into natural asphalt and petroleum asphalt. Solid, semi-solid or liquid at room temperature; The color is brown and dark to black without jujubes, with good adhesion, plasticity, impermeability and chemical resistance, and is one of the main raw materials for waterproofing membranes, coatings, ointments, asphalt adhesives and anticorrosive coatings.

There are two types of asphalt generally used for building waterproofing projects: petroleum asphalt and coal asphalt.

Uses of bitumen.

Petroleum asphalt is the residue of petroleum ** after distillation and other extractions of gasoline, kerosene, diesel and lubricating oil, and then processed. It is divided into solid, semi-solid and liquid petroleum asphalt, and the construction petroleum asphalt in semi-solid asphalt is the main raw material of waterproofing materials. Coal pitch is coal tar, a by-product of coking or gas production, which is obtained by fractional distillation to extract various oil qualities.

In the past, coal asphalt was one of the main raw materials used for outdoor waterproofing and anti-corrosion coatings in basements, but due to its toxicity and environmental pollution, the waterproofing materials produced by coal asphalt in recent years are being restricted and eliminated. Modified asphalt refers to the product after the modification of asphalt by means of oxygen oxidation, catalyst oxidation, and non-metallic vulcanizing agent.

Coal coke asphalt is a by-product of coking, and petroleum asphalt is the residue after the original distillation, natural asphalt is stored underground, some form a mineral layer or accumulate on the surface of the earth's crust, asphalt is mainly with coatings, plastics, rubber and other industries and paving roads, asphalt is a hydrophobic material, impermeable, and almost insoluble in water, acetone, dilute ether, etc. Withered reeds are dismantled.

Because asphalt and its smoke have the best properties for the popular ** mucous membrane, there is a phototoxic effect and carcinogenic effect, and the toxicity of the main three types of asphalt is: coal coke asphalt, leaf rock asphalt, petroleum asphalt, the first two are carcinogenic, asphalt for the damage of ** are: phototoxic dermatitis, melanosis, verrucous vegetations, etc., in addition to dizziness, chest tightness, nausea and other ** states.

Among the four kinds of asphalt, the harm of coal coke asphalt is the greatest, a large amount of asphalt smoke is emitted in the production of point electrode roaster, because it contains fluorescent substances, which contain carcinogens benzopyrene up to, volatilized with the flue gas during high temperature treatment, asphalt flue gas is yellow gas, which is tar fine mist particles, and the asphalt smoke contains benzopyrene.

There are small molecule hydrocarbons in asphalt, such as paraffin, etc., which make the physical properties of asphalt sensitive to temperature, and the asphalt becomes brittle at low temperature, and the asphalt is easy to deform and flow at high temperature; In addition, too many active groups reduce the aging resistance of asphalt. Therefore, the polymerization of small molecule hydrocarbons by the above means reduces the active groups in the asphalt, improves the physical properties of asphalt, and plays a role in reducing the temperature sensitivity of asphalt and improving the heat resistance and low temperature resistance. At the same time, it also improves the degradation and fission resistance of asphalt molecules and prolongs the service life of the material.

The asphalt used in construction must have certain physical properties. It should be elastic and plastic under low temperature conditions, have sufficient strength and stability under high temperature conditions, have the ability to resist "aging" under processing and use conditions, and should also have strong adhesion to various mineral materials and structural surfaces, as well as adaptability to component deformation and fatigue resistance. Usually the asphalt processed by the petroleum processing plant may not fully meet these requirements, especially most of the asphalt produced by Daqing Oilfield in China, if only the heat resistance (softening point) is controlled, it is difficult to meet the requirements in other aspects, resulting in serious leakage of asphalt waterproof roof, and short service life.

For this purpose, asphalt needs to be modified with rubber, resin and mineral filler source materials.

The modified types of petroleum asphalt are: mineral filler modified asphalt. Due to the wetting and adsorption of asphalt on mineral fillers, asphalt can be arranged on the surface of mineral particles (or fibers) in a monomolecular form to form a strong asphalt film, some call it "structural asphalt".

Structural asphalt has high viscosity and temperature stability. The outside of the structural asphalt layer is free asphalt, so that the asphalt mixture still has a certain toughness at low temperature. Rubber asphalt. Rubber is an important modified material of asphalt, which has good miscibility with asphalt, and can make asphalt have many advantages of rubber, such as small deformation at high temperature and good flexibility at low temperature; Synthetic resin-based modified asphalt.

The addition of synthetic resin can improve the waterproofness, cohesiveness and low-temperature performance of asphalt, especially the improvement effect of heat resistance and temperature stability.