Long-term effectiveness of carbonation resistance of concrete treated with nano-SiO2 modified polymer coatings

For studying the influences of nano-SiO2 on the long-term carbonation resistance of concrete treated with polymer coatings, three types of organic film-forming paints, such as polyurethane, epoxy resin, and chlorinated rubber, were selected, and nano-modified paints with the addition of 0.5, 1.5, and 3.0 wt% of nano-SiO(2 )particles were prepared and applied on concrete specimens. Ultraviolet radiation, natural exposure, and accelerated carbonation experiments were performed on coated concrete specimens. In addition, scanning electron microscopy and Fourier transform infrared spectroscopy experiments were conducted. The results indicate that the carbonation resistance of concrete with polymer coatings deteriorates gradually with aging. Nano-SiO2 particles can reduce the micro-defects in coating, and enhance the compactness of coating, thus increasing the carbonation resistance of coated concrete. Furthermore, the addition of nano-SiO2 can alleviate the damages of ultraviolet irradiation on polymer molecules, and then enhance the long-term effectiveness of carbonation resistance of coated concrete. However, a suitable nano-SiO2 dosage of about 1.5 wt% exists, and excessive dosage decreases or even loses the useful functions. Based on carbonation resistance of coated concrete and an S-shaped curve, a new service life prediction model for polymer coatings is established. Owing to the contribution of nano-SiO2, the average service life of chlorinated rubber, epoxy resin, and polyurethane coatings can be lengthened by 78%. (C) 2019 Elsevier Ltd. All rights reserved.