Prediction of Time-Dependent Chloride Diffusion Coefficients for Slag-Blended Concrete

Abstract

The chloride diffusion coefficient is considered to be a key factor for evaluating the service life of ground-granulated blast-furnace slag (GGBS) blended concrete. The chloride diffusion coefficient relates to both the concrete mixing proportions and curing ages. Due to the continuous hydration of the binders, the capillary porosity of the concrete decreases and the chloride diffusion coefficient also decreases over time. To date, the dependence of chloride diffusivity on the binder hydration and curing ages of slag-blended concrete has not been considered in detail. To fill this gap, this study presents a numerical procedure to predict time-dependent chloride diffusion coefficients for slag-blended concrete. First, by using a blended cement hydration model, the degree of the binder reaction for hardening concrete can be calculated. The effects of the water to binder ratios and slag replacement ratios on the degree of the binder reaction are considered. Second, by using the degree of the binder reaction, the capillary porosity of the binder paste at different curing ages can be determined. Third, by using the capillary porosity and aggregate volume, the chloride diffusion coefficients of concrete can be calculated. The proposed numerical procedure has been verified using the experimental results of concrete with different water to binder ratios, slag replacement ratios, and curing ages.

Impact of Cyclic Loading on Chloride Diffusivity and Mechanical Performance of RC Beams under Seawater Corrosion

“…The sum of chloride content intension concrete mainly depended on the crack width which was controlled by max load. In this study, the values of different parameters are 0 = 80 days, 0 = 140 days, and = 0.28 following the research of Park et al [10] and the Chinese standard for durability assessment of concrete structures [27], 0 = 0.0008 mol/L. There are two unknown parameters and cl,ref,non remaining in (14).…”

“…Equation (13) can be obtained by comparing (10) and (12): Considering three boundary conditions, (1) the content of chloride ion on concrete surface is constant, ( = 0, ) = ; (2) the content of chloride ion in concrete is 0 at the initial time, ( , = 0) = 0 ; (3) the content of chloride ion in concrete is 0 at infinity, ( = ∞, ) = 0 , a special solution can be obtained from (13).…”

“…Park et al [10] considered binder hydration and curing ages and developed a numerical model to predict time-dependent chloride diffusion coefficients by slag-blended concrete. Fan and Wang [11] presented a numerical model to analyse cement hydration reaction and chloride ion penetration process simultaneously.…”

Exploring the Detection of Cl− Penetration in Portland Cement Mortars via Surface Electrical Resistivity

“…where D 28 is the reference diffusion coefficient (m 2 /s); w/b is the water/binder ratio; and % FA is the percentage substitution of Portland cement with fly ash in the mix [35,38].…”

Evaluation of Strengths from Cement Hydration and Slag Reaction of Mortars Containing High Volume of Ground River Sand and GGBF Slag

“…Binder materials with small particles can also improve the compressive strength due to the packing effect or filler effect by physically filling the spaces without any chemical reaction [14]. Furthermore, the replacement of PC with an optimal dosage of highly refined SCM can reduce the pore structure and porosity of concrete, resulting in dramatically decreased penetration of aggressive chloride ions into the concrete [15,16]. Many researchers [15,17,18] reported that ground river sand (GRS) in the form of quartz with the same particle size as PC and pozzolanic material can be used as an inert material to evaluate compressive strengths obtained from cement hydration, pozzolanic reactions, and packing effect.…”