Title: Thermodynamic Investigation of Allowable Admixed Chloride Limits in Concrete

Author(s): Vahid Jafari Azad, Prannoy Suraneni, David Trejo, W. Jason Weiss, and O. Burkan Isgor

Publication: Materials Journal

Volume: 115

Issue: 5

Appears on pages(s): 727-738

Keywords: allowable admixed chloride limits; chloride binding; Monte Carlo analysis; supplementary cementitious materials; thermodynamic modeling

DOI: 10.14359/51702349

Date: 9/1/2018

Abstract:
A thermodynamic modeling-based Monte Carlo analysis was conducted to investigate the effect of supplementary cementitious material (SCM) replacement level and reactivity on chemical binding of admixed chlorides and pore solution composition in ordinary portland cement (OPC) + SCM systems. Specifically, the validity of using total cementitious materials content, instead of cement content, as the basis for allowable admixed chloride limits was evaluated. The simulations showed that variability in the results was due to the variability of the compositions and reactivities of the cementitious materials. Even at low replacement levels, for some SCM compositions and reactivities, corrosion initiation was possible at admixed chloride levels within typical allowable limits. It was concluded that allowable admixed chloride limits can be prescribed in terms of cementitious material content with limits on SCM replacement levels. However, highly reactive SCMs might still make embedded reinforcement vulnerable to corrosion even when these SCM replacement limits are used for calculating maximum allowable chloride concentrations in concrete mixtures.