دانلود رایگان مقاله انگلیسی اثرات اندازه ذرات ZnO بر خواص آسفالت و ترکیب آسفالت - نشریه الزویر

abstract

Micro or nano zinc oxide (ZnO), as a modifier, can significantly improve some properties of asphalt and asphalt mixture, but the effect of ZnO particle size is still unclear. In this paper, three different spherical sized ZnO nanoparticles (2 mm, 80 nm and 350 nm in average diameter) were made by homogeneous precipitation method and sol-gel method. Asphalt binders and asphalt mixtures modified by ZnO and ZnO/ SBS (styrene-butadiene-styrene) were produced by means of a high shear mixer. The effects of ZnO particle size on physical properties of asphalt were analyzed through penetration test, softening point test, ductility test, dynamic shear rheological test (DSR), bending beam rheometer test (BBR) and aging test; and the effects on asphalt mixtures were characterized using the Marshall test, freeze-thaw splitting test, rutting test and a three-point bending beam test. Results show that the decrease of ZnO size in asphalt binder can weaken its creep stiffness, and increase its softening point, ductility, viscosity, anti-rutting factor, creep rate and anti-aging ability. In addition, with the decrease of ZnO size, the high temperature stability, water stability and low temperature crack resistance of asphalt mixture are improved. Finally, based on the test results, the optimum size of ZnO particle is determined as 80 nm.

5. Conclusions

The ZnO particles with different sizes were made in this paper. The penetration, softening point, ductility, rheological and aging property of asphalts were measured through penetration test, softening point test, ductility test, DSR test, BBR test and aging test; and the high temperature stability, water stability and low temperature crack resistance of asphalt mixture were measured through Marshall test, freeze-thaw splitting test, rutting test and a threepoint bending beam test. The effects of ZnO size on the properties of asphalt and asphalt mixture were discussed, and the following conclusions can be drawn.

(1) For both of ZnO modified asphalt and ZnO/SBS modified asphalt, the penetration decreased slightly but softening point and ductility increase obviously as the ZnO particle size decreases.

(2) In rheological tests, when the particle size is reduced from 2 mm to 80 nm, for dosages of SBS of 0%, 3% and 4%, the antirutting factors of asphalt are improved by 22.3%, 35.5% and 8.5% respectively. In low temperature creep test, with the decrease of ZnO particle size, the creep stiffness of asphalt decreased to a small extent, and the creep rate of asphalt increased to a small extent. In aging test with the decrease of ZnO size, the penetration ratio and ductility ratio increase to a small extent. In summary, when the ZnO size is 80 nm, the anti-rutting factor and ductility after aging of asphalt are the best.

(3) In the laboratory performance tests of asphalt mixture, when the particle size is reduced from 2 mm to 80 nm, for the dosages of SBS of 0% and 4%, the dynamic stabilities of asphalt mixture were improved by 17.9% and 14.9% respectively. In addition, the water stabilities, flexural tensile strengths and low temperature bending strains of asphalt mixtures are enhanced also when ZnO particle size decreases. In summary, when the ZnO size was 80 nm, the laboratory performances of asphalt mixture are the best.

(4) According to the analysis above, the size of 80 nm is recommended for ZnO particles.