Title: Distribution of Chloride Accumulation in Marine Tidal Zone along Altitude

Author(s): Yi Zhang and Wei-Liang Jin

Publication: Materials Journal

Volume: 108

Issue: 5

Appears on pages(s): 467-475

Keywords: Altitude; chloride; convection; diffusion; dry-wet cycling; hysteresis.

DOI: 10.14359/51683255

Date: 9/1/2011

Abstract:
A new mathematical model of chloride transport in concrete under dry-wet cycling conditions is developed. The model considers the hysteresis of moisture evaporation and the accumulation of chlorides at the concrete surface. Unimodal distribution of chloride accumulation in marine tidal zones along altitude can be derived based on the sensitivity analysis for the proposed model—that is, with the increment of altitude, the accumulation of chloride is first aggravated for the increasing drying time proportion and accelerated evaporation rate, and then weakened for the reduction of contact time with a chloride-contained reservoir and the declining saturation of pores in concrete. The proposed model has been validated by experiments carried out in both the laboratory and the field. In laboratory tests, concrete specimens were exposed to dry-wet cycles in an artificial environmental chamber (AEC) for 2 to 3 months and then chloride concentration profiles were measured. In field tests, measurements were directly taken from a concrete harbor deck that was 55 months old. The comparison of the laboratory and field data with the model predictions demonstrates that the proposed model can be used to predict the transport of chlorides in the marine tidal zone.