Standardization Study On Test Of Chloride Ion Penetration And Carbonation Of Concrete

The durability of concrete structures has been the hotspots in the field of civil engineering ,and the durability test of concrete is an fundamental issue. Based on current research status of the durability test of concrete, a standardization study on tests of chloride ion penetration and carbonation of concrete was started. The basic concept, principle and research method of standardization of durability tests of concrete were firstly put forward. Then the multi-factor standard expressions of durability evaluating index of chloride ion penetration and carbonation were established. Based on the standard specimen decided by research group of durability of concrete structures of Zhejiang Unversity, tests of chloride ion penetration and carbonation of concrete were carried out and then influencing laws, influencing coefficient expressions and recommended values of material and environmental factors on chloride ion penetration and carbonation of concrete were given by means of data processing, discussion and analysis. In addition, the coupling effect of chloride ion penetration and carbonation of concrete was also studied qualitatively.In this paper, tests mainly include three parts: chloride ion penetration, carbonation and the coupling effect of chloride ion penetration and carbonation. Through chloride salt immersion, the influences of material and environmental factors on surface chloride ion concentration, its accumulating law and chloride ion diffusion coefficient were studied. A more perfect model was proposed to describe time-dependence of surface chloride ion concentration. The influencing coefficient expressions and recommended values of factors on diffusion coefficient were finially given. Through rapid carbonation test, the influences of material and environmental factors on carbonation depth and carbonation rate were studied' and the influencing coefficient expressions and recommended values of factors on carbonation rate coefficient were given. Through two contrast tests, the influence of carbonation on chloride ion penetration and the influence of chloride ion penetration on carbonation were studied respectively. Results show that there are positive and negative effects for the influence of carbonation on chloride ion penetration, and chloride ion penetration improves carbonation resistance of concrete. The mechanism of coupling effect was analyzed, which could be considered as a reference for durability evaluation of actual concrete structures.