Effect of carbonation on the corrosion behavior of steel rebar embedded in magnesium phosphate cement

TY - JOUR

T1 - Effect of carbonation on the corrosion behavior of steel rebar embedded in magnesium phosphate cement

AU - Wang, Danqian

AU - Yue, Yanfei

AU - Qian, Jueshi

N1 - © 2023 Elsevier Ltd. All rights reserved.

PY - 2024/1/1

Y1 - 2024/1/1

N2 - Magnesium Potassium Phosphate Cement (MKPC) as a protective binder for steel rebars has been well-established. However, corrosion performance of steel rebars in MKPC subjected to carbonation is still unknown. This investigation aimed at revealing the impact and mechanism of carbonation on corrosion performance of steel rebars in MKPC using electrochemical techniques and surface analyses. The findings indicate that, unlike Portland cement (PC) system, carbonation positively influences corrosion performance of steel rebars when embedded in MKPC, as demonstrated by comparable (M/P = 7) or even higher (M/P = 12) corrosion resistance values. Under carbonation, the ingressive CO2 reacts with Mg-bearing phases in MKPC to form nesquehonite with a higher pH, while the MgO still keep supersaturated. The resultant increase in pH facilitates formation of ferrous oxide and iron phosphate/borate within oxide film developed on steel surface, which enhances protective capability of oxide film and consequently improves the corrosion resistance of the steel rebars.

AB - Magnesium Potassium Phosphate Cement (MKPC) as a protective binder for steel rebars has been well-established. However, corrosion performance of steel rebars in MKPC subjected to carbonation is still unknown. This investigation aimed at revealing the impact and mechanism of carbonation on corrosion performance of steel rebars in MKPC using electrochemical techniques and surface analyses. The findings indicate that, unlike Portland cement (PC) system, carbonation positively influences corrosion performance of steel rebars when embedded in MKPC, as demonstrated by comparable (M/P = 7) or even higher (M/P = 12) corrosion resistance values. Under carbonation, the ingressive CO2 reacts with Mg-bearing phases in MKPC to form nesquehonite with a higher pH, while the MgO still keep supersaturated. The resultant increase in pH facilitates formation of ferrous oxide and iron phosphate/borate within oxide film developed on steel surface, which enhances protective capability of oxide film and consequently improves the corrosion resistance of the steel rebars.

KW - Carbonation-induced corrosion

KW - Durability

KW - Magnesium phosphate cement

KW - Oxide film

KW - Steel rebar

U2 - 10.1016/j.compositesb.2023.111088

DO - 10.1016/j.compositesb.2023.111088

M3 - Article

SN - 1359-8368

VL - 268

JO - Composites Part B: Engineering

JF - Composites Part B: Engineering

M1 - 111088

ER -