Study of chloride penetration in concretes exposed to high-mountain weather conditions with presence of deicing salts

摘要

The durability of reinforced concrete (RC) is a challenge. One of the most aggressive and frequent ions is chloride, which frequently affects RC structures by steel corrosion. Many studies have concluded that the use of mineral admixtures improves concrete durability. This paper examines the transport process of chloride ions in non-saturated concrete. Three types of concrete have been designed and tested: the first one with only CEM I 52,2 R (CP), the second with 10% of silica fume (CPHS) and the third with 20% of blast furnace slag (CPEAH). An experimental programme was designed with the aim of studying the influence of external condition variation in a high-mountain environment with presence of deicing salts. The total time duration of the programme was 210 days. The specimens were conditioned at different temperatures, relative humidity and chloride surface concentrations in five phases to reproduce the seasons annually. The experimental chloride concentration profiles were obtained at the end of each phase for each concrete. These profiles were mainly influenced by two transport mechanisms: diffusion and capillary suction. The chemical chloride binding and physical adsorption of chlorides in the concretes with silica fume (CPHS) and blast steel furnace (CPEAH) were two decisive factors in the chloride penetration processes. A numerical model for simulating chloride ion transport in non-saturated concrete is presented. It considers the diffusive and advective flux. In addition, the concrete pore network and the associate properties, such as chloride binding capacity and chloride precipitation, are also taken into account. The model has been implemented in a finite element programme. The chloride concentration profiles obtained by the model at the end of each phase for each concrete properly fit the experimentally obtained. (C) 2016 Elsevier Ltd. All rights reserved.