Asphalt is a complex black-brown mixture composed of hydrocarbons of different molecular weights and their non-metallic derivatives. It is a high viscosity organic liquid. It mostly exists in the form of liquid or semi-solid petroleum, with a black surface and is soluble in carbon disulfide and carbon tetrachloride . Asphalt is a waterproof, moisture-proof and anti-corrosion organic gelling material . It can be mainly divided into three types: coal coke asphalt , petroleum asphalt and natural asphalt . Among them, coal-coke asphalt is a by-product of coking; petroleum asphalt is the residue after crude oil distillation; natural asphalt is stored underground, and some form ore layers or accumulate on the surface of the earth's crust.
Under low temperature or short-term loading, the asphalt material is close to the elastomer, and its deformation is basically elastic deformation , but it will not be like the elastomer. Once the load is removed and the deformation is instantly restored, but is affected by viscosity and gradually recovered. As the temperature increases, especially as the loading time increases and the number of times increases, bituminous materials gradually approach plastics. Under the long-term or repeated loading, residual deformation will occur due to creep, which is irreversible. Therefore, with asphalt materials, as the temperature decreases, their elastic components increase and their viscous components decrease.
modified asphalt is an asphalt bonding material made by adding rubber, resin, polymer , natural asphalt, finely ground rubber powder or other materials, to improve the performance of asphalt or asphalt mixture .
Classification of modified asphalt
Add modifier
•Improved mechanical properties:
Rubber SBR, Elastomer SBS, Plastic PE
•Improved adhesion:
Anti-flaking agent: metal soap, organic amine
•Aging resistance:
Anti-aging agent
Physical modification
•Minite filler:
Carbon black Physical modification
•Minite filler:
Carbon black Physical modification
•Minite filler:
Carbon black Physical modification
•Minite filler:
Carbon black l2, sulfur , ligno fiber
•waste tire rubber powder
asphalt blending
•orch mixed natural asphalt:
lake asphalt, rock asphalt, etc.
process modification
·semioxidized asphalt, foam asphalt
modification mechanism
modifier has many types, the most studied is polymer modified asphalt. Here is a discussion on the mechanism of polymer modified asphalt. Currently, the recognized modification mechanisms include physical blending and chemical blending modification mechanisms.
Physical blending
•Asphalt refers to the minimum dose of polymer forming network structure as the critical content.
Figure 1: 4% SBS modified asphalt
Figure 2: 5% SBS modified asphalt
Figure 3: 4% EVA modified asphalt
Figure 4: 5% EVA modified asphalt
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0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 chemical blending
• chemical blending theory : Asphalt not only contains alkane , olefin and aromatic hydrocarbons, but also contains polar and non-polar compounds. There are organic functional groups such as hydroxyl , carbonyl and ester group , which can undergo chemical reactions with a variety of substances, produce chemical crosslinking or chemical addition, and generate new chemical bond binding.
•Chemical addition reaction : There are free radical and olefins in the asphalt, which can undergo chemical addition reaction with organic compounds, unsaturated monomers or low-molecular compounds to produce new compounds. These include radical addition reaction, electrophilic addition reaction, nucleophilic addition reaction and synergistic cycloaddition reaction.
modified asphalt preparation method and production equipment process
•There are the following methods:
2) Direct delivery method: put the modifier into the mixing pot on site, and mix it with ore and asphalt to prepare a modified asphalt mixture. Such as SBR latex, fiber and fine grinding powder. SBR latex can be sprayed directly into the mixing pot.
3) Mechanical stirring method: EVA, SBR and some modifiers with good compatibility with asphalt use this method.
4) Colloid grinding and high-speed shearing method: shear and crush the modifier to promote swelling . Generally, it is necessary to go through three stages: swelling of the modifier, dispersing and fine grinding, and continued development and stability. SBS, EVA, etc.
SBS modified asphalt production equipment flow chart
•Modified asphalt production process flow:
SBS asphalt ingredients—swelling mixing—colloid grinding—finished product development stability—finished product factory inspection—pumping and loading factory
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