Simulated Environment Test on Weather Fastness of Fair-Faced Concrete for Urban Bridge

Abstract

To keep the perfect, artistic and natural characteristics of fair-faced concrete, it is necessary realizing its weather fastness. This paper introduces the simulated environment test for weather fastness of fair-faced concrete considering the environmental actions at all seasons such as washing of acid rain, sand blown by the wind, exposure to blazing sunlight, salt-fog, carbonization and freeze-thaw. Test methods for sand blown by the wind, washing of acid rain, slow freeze-thaw and exposure to blazing sunlight were invented. The mass change of concrete were measured, and the surface quality was evaluated by the glossiness, the pixel difference and the variance of pixel difference. The results showed that the mass had a little change under the comprehensive actions. The factors decreasing the surface quality in sequence from serious to slight were the washing of acid rain, the salt-fog, the freeze-thaw and the carbonization. The erosion degree increased with the increasing pH value in rainwater and the increasing density of sulfate-ion in salt-fog solution. The surface of concrete damaged by the long-term freeze-thaw and carbonization. The sand blown by the wind, and the exposure to blazing sunlight had little influence on the surface of concrete.