Research on the Chloride Ion Penetration Resistance of Magnesium Phosphate Cement (MPC) Material as Coating for Reinforced Concrete Structures

Yubing Du,Peiwei Gao,Feiting Shi,Jianming Yang

doi:10.3390/coatings10121145

Yubing Du, Peiwei Gao + Show 2 more

Open Access

https://doi.org/10.3390/coatings10121145

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Abstract

This study focuses on the chloride ion penetration resistance of a magnesium phosphate cement (MPC)-based composite material coating on the surface of silicate material. By means of electrical flux method and electric acceleration corrosion tests, the anti-chlorine ion permeation and reinforcement properties of MPC-based materials and Portland cement (OPC) mortar were compared and analyzed. The experimental results show that the electrical flux of the hardened body of the MPC-based material is much lower than that of the Portland cement mortar, and the electrical flux of the hardened body of the MPC mortar can be obviously reduced by adding silica-fume (SF) and fly ash (FA), which, when combined in a suitable proportion, will make the MPC’s hardened body more dense and impermeable. The addition of short cut fibers increases the number of pores, the pore size, and the electrical flux of the cement mortar’s hardened body. The adverse effects of the three fibers on the permeability of the MPC mortar against chlorine ions were as follows: polyvinyl alcohol fiber > glass fiber > basalt fiber. The electrical flux of MPC mortar or MPC paste coated on the surface of the OPC mortar was greatly reduced. Compared with silicate mortar, the MPC-based material has excellent protective performance under the condition of accelerated corrosion.

Highlights

Steel reinforcement used in infrastructure—even that covered with Portland cement concrete—can be corroded, resulting in cracks in the cement concrete, especially when chloride ions exist in the environment [1]
After adding the basalt fiber, the electrical flux increased by 10% and 2.18 times, respectively
The corrosion potential of the magnesium phosphate cement (MPC) material increased as the electrical time was prolonged, further increasing the corrosion resistance of the steel

Summary

Introduction

Steel reinforcement used in infrastructure—even that covered with Portland cement concrete—can be corroded, resulting in cracks in the cement concrete, especially when chloride ions exist in the environment [1]. These cracks can allow the quick invasion of oxygen, moisture, and chloride ions into the steel reinforcement, accelerating the corrosion process and concrete deterioration [2]. If a protective coating is applied on the surface of the reinforced concrete structure to effectively prevent the penetration and corrosion of a corrosive medium, and if the coating material has sufficient strength, the concrete structure can be strengthened to a certain extent.

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