Determining the influence of LC2 and FA on the iodide diffusion coefficient of in seawater and sea sand concrete: A novel modified RIM test method

Abstract

A novel modified Rapid Iodide Migration (RIM) test method was used to determine the influence of LC2 and FA on iodide ion diffusion coefficient of seawater and sea sand concrete (SSC). A 0.1 mol/L AgNO3 solution was selected as the indicator to develop the colour of iodide in SSC, and a lowered mass fraction of NaI solution was selected to improve the RIM test. An X-Ray Fluorescence (XRF) test was employed to detect the feasibility of the modified RIM test. Additionally, the effects of the w/c ratio, the type and substitution rate of supplementary cementitious materials (SCMs), and the compressive strength on the iodide ion diffusion coefficient of SSC were studied using the modified RIM test. The results show that it is completely feasible to use AgNO3 solution as an indicator. A lower mass fraction of NaI solution not only does not change the iodide ion diffusion coefficient of concrete but also reduces the test cost by 77.46% when using a 5 wt% NaI solution. Moreover, using SCMs to replace cement, liking fly ash (FA) and calcined clay and limestone (LC2), significantly reduces the iodide ion permeability of SSC, especially the use of LC2. Furthermore, there is a nonlinear relationship between the compressive strength and the iodide ion diffusion coefficient of SSC. This work is beneficial for the promotion of the application of modified RIM tests in studies of concrete contaminated with chloride and can provide a theoretical basis for the application of seawater and sea sand in engineering practices.