Asphalt concrete modifiers
Keywords
Asphalt concrete, modifier, lignin fiber, polyester fiber, diatomaceous earth, waste tire rubber powder
Asphalt concrete modifier refers to the addition of modifier to the thermally recycled asphalt mixture, which can significantly improve the road performance, stability, anti-loose performance and anti-fatigue durability of the thermally recycled asphalt mixture.
Types
At present, the main modifiers are:
Fibers: lignin fibers and polyester fibers
Other categories: waste tire rubber powder and diatomaceous earth
1. Lignin fiber
Lignin fiber is an organic fiber obtained by chemical treatment of natural wood, and its appearance is cotton wool, white or gray. Through screening, splitting, high temperature treatment, bleaching, chemical treatment, neutralization, and screening into fibers of different lengths and thicknesses to meet the needs of different application materials. Because the processing temperature is as high as 250 C or more, it is a chemically very stable substance under normal conditions. It is not corroded by ordinary solvents, acids and alkalis. It is harmless to the human body and is a green and environmentally friendly product, which is not available in other mineral fibers. The microstructure of the fiber is band-like curved, uneven, porous, and the intersection is flat, with good toughness, dispersion and chemical stability, strong water absorption, and excellent thickening and crack resistance. Lignin fiber is an organic fiber, which is mainly used in pavement and is an indispensable stabilizer.
2. Polyester fiber
Commonly known as "polyester". It is a synthetic fiber obtained by spinning polyester obtained by polycondensation of organic dibasic acid and dihydric alcohol, and belongs to high molecular compound.
2.1. Effectively improve the high temperature stability, so that the stability of fiber asphalt concrete is greatly improved.
2.2. Improve the low temperature crack resistance, enhance the low temperature crack resistance of the mixture, reduce the occurrence of temperature shrinkage cracks and prevent the development of reflection cracks.
2.3. Improve the fatigue resistance. Under the action of the external temperature environment, the asphalt pavement is subjected to the repeated action of the wheel load, and the uniform distribution of the fiber monofilament in the mixture increases the stiffness modulus and improves the resistance of the asphalt concrete. Fatigue performance.
2.4. Improve the water stability of water-stabilized asphalt pavement. The addition of polyester fibers increases the thickness of the asphalt film, reduces the strength of water-replaced asphalt, and reduces the amount of water infiltrating into asphalt concrete, coupled with the adsorption of fibers. Increase the viscosity of asphalt, improve the bonding force between asphalt and aggregate, and strengthen the ability of the interface film formed by asphalt and aggregate to resist water peeling in the asphalt mixture, thereby improving the water stability of the asphalt mixture.
3. Diatomite
A siliceous rock, also a biogenic siliceous sedimentary rock, consisting mainly of the remains of ancient diatoms. Its chemical composition is mainly SiO2, which can be represented by SiO2·nH2O.
It has excellent elongation, high impact strength, tensile strength, tear strength, light weight and softness, good internal grinding, and good compressive strength.
4. Dry mixing and direct injection of waste tire rubber powder
