Chinese researchers recently found that a near-infrared reflective blending coatings had better optical and cooling performance, thereby reducing the absorbed energy of pavement in permafrost regions and other special regions. 

Researchers from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS) took TiO₂ and CuO blending coating as an example, and they investigated their optical and cooling performances. 

They first adopted three types of functional reflective particles, TiO₂ nanoparticles (NPs), CuO NPs and CuO micro-particles (MPs) as pigments to obtain 12 types of TiO₂ and CuO blending coatings, then they measured and compared the spectral reflectance of these blending coatings, and finally selected eight types of these blending coatings to study their cooling performances. 

They painted these selected blending coating to the asphalt blocks and then monitored the surface temperature. 

Results show that the spectral reflectance for the TIO₂ NPs and CuO NPs blending coating increases slightly while that for TiO₂ NPs and CuO MPs increases largely with the increase of TiO₂ NPs. 

Besides, the spectral reflectance of the CuO NPs and TiO₂ NPs blending coating is higher than that of the CuO MPs and TiO₂ NPs blending coating when the TiO₂ NPs mass percentage is lower than 15.88%. 

Results also indicate that the cooling performances of these selected near-infrared reflective blending coatings are different under the summer of autumn meteorological condition. 

This study provides a reference and insight to the design and fabricating of near-infrared reflective blending coating, thereby reducing the undesired pavement absorbed energy. 

This study has been published in Solar Energy in an article entitled "Experimental study of optical and cooling performances of CuO and TiO₂ near-infrared reflective blending coatings."