Permeation Characteristics and Surface Accumulation of Chloride in Different Zones of Concrete along Altitude in Marine Environments

Hong Chang,Zhanguo Ma,Xinshuo Huang,Yongsheng Ji,Zhicheng Zhang

doi:10.3390/cryst11070722

Abstract

The accumulation characteristics of surface chloride in concrete in different zones are different in the marine environment. A series of laboratory experiments were conducted to investigate the surface chloride and permeation characteristics of concrete in a simulated marine environment. The experimental results indicated that the surface chloride and chloride profiles of concrete in different zones of marine environment decreased in the following order: tidal zone > splash zone > submerged zone > atmospheric zone. The width of the ascent zone of Cl− concentration at tidal and splash zones was far less than that of the influential depth of moisture transport (IDMT), and the range of convection zone was dependent on the IDMT. Cl− at splash and tidal zones penetrated into concrete as a bulk liquid by non-saturated permeation driven by a humidity gradient. The change of chloride profiles in concrete along the altitudinal gradient was consistent with that of the cyclic water absorption amount (CWAA). The transport rate of chloride was the highest at the highest point of the tide.

Highlights

The durability of concrete structures in marine environments remains a longstanding challenge mainly due to the complex chloride-induced corrosion of steel bars [1]
The conclusions in this study are as follows: Surface chloride concentrations in different zones of the marine environment decreased in the following order: tidal zone > splash zone > submerged zone > atmospheric zone
The surface chloride concentration in the submerged zone did not vary with time

Summary

Introduction

The durability of concrete structures in marine environments remains a longstanding challenge mainly due to the complex chloride-induced corrosion of steel bars [1]. Chloride ions penetrate into concrete, largely affecting the durability of marine concrete structures [2]. The penetration mechanisms of chlorides in different zones are different due to the influences of environmental conditions. The maximum concentration of Cl− is usually located within the concrete cover, according to the measurement result. The length of the Cl− concentration increase zone can be determined using the Cl− concentration distribution curve. This length is used to represent the depth affected by the convective zone [6].

Methods

Results

Conclusion