اثرات اندازه ذرات ZnO بر خواص آسفالت و ترکیب آسفالت Effects of ZnO particle size on properties of asphalt and asphalt mixture

1. Introduction Today researches on nanostructures are very popular because they are being used and pursued for optics, optoelectronics, catalysis, biological sciences and piezoelectricity. Atoms at the surface of particles will have highly activeness when materials are at the nanometer size, and the resulting materials are significantly different from macroscale materials composed of the same substance. Research in the nanostructures of materials has skyrocketed over the last decade. A variety of micro and nano materials have been used and studied to modify asphalt and concrete engineering, and the effects of nano materials were discussed. Amir et al. [1] found that nano clay and nano hydrated lime (HL) cloud enhance the tensile strength ratio (TSR) of asphalt mixes. Khodary et al. [2] proved that nanosize cement bypass could increase the physical, chemical, and rheological properties of modified nanomaterial-asphalt mixture for its high surface area. Khodary et al. [3] analyzed the impact of nano scale CaO on the stiffness properties of asphalt. Liu et al. [4] discovered that the nano CaCO3 had an advantage influence on the high temperature stability of the asphalt and asphalt mixtures. Tang et al. [5] found that nano-montmorillonite (Nano-MMT)/SBS can improve the high-temperature anti-deformation ability and decrease the softening point of the aged asphalt. Yao et al. [6] explored the effects of nano silica on the rutting and fatigue cracking resistance of asphalt binders. Xiao et al. [7] showed that carbon nanoparticles was helpful in enhancing the failure temperature, complex modulus, and elastic modulus values and in increasing rutting resistance of the RTFO binder. Guo et al. [8] prepared modified nano TiO2 by co-precipitation method and studied the influence of nano TiO2 on the properties of coal tar pitch. Zhang et al. [9] made spherical nano Fe3O4 particles modified asphalt successfully. In addition, nano-SiO2 has been reported to enhance concrete workability and compressive strength [10–12], to improve resistance to water penetration [13], and to contribute to control the leaching of calcium [14]. Nano-TiO2 could act as a trigger with the photocatalytic degradation of pollutants when it was contained in concrete [15,16]. Nano-Al2O3 has been shown to obviously improve the modulus of elasticity of asphalt [17]. However, the micro or nano materials with single size were often used in those researches listed above. Only several scholars had studied the effects of the size of HL on the properties of asphalt or asphalt mixture. Shen et al. [18] reported that sub nano-sized HL can improve about 10% in tensile strength ratio (TSR) for HMA. Aboelkasim et al. [19–21] suggested that the nano sized hydrated lime (NHL) could perform potential benefits compared with regular-sized hydrated lime (RHL) as a modifier of asphalt.