TY - JOUR
T1 - Effects of initial defects within mortar cover on corrosion of steel and cracking of cover using X-ray computed tomography
AU - Zhang, Xiaogang
AU - Zuo, Guiqin
AU - Memon, Shazim Ali
AU - Xing, Feng
AU - Sun, Hongfang
N1 - Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/10/30
Y1 - 2019/10/30
N2 - In actual reinforced concrete structures, plenty of initial defects exist, which may greatly influence the behavior of steel corrosion and cracking within concrete cover. Thus, this paper presents an experimental investigation into the effects of initial defects within mortar cover on the corrosion of a steel bar in mortar and on the cracking of mortar cover using X-ray computed tomography. The influence of initial defects with mortar cover at three different positions i.e. interface, middle and surface was investigated for 5%, 30% and 55% corrosion levels of steel. From experimental investigations, it was found that the specimen with interface defect has significant accumulation of corrosion products. The position of cracking within mortar cover induced by steel corrosion was examined. At least one crack connected steel with the initial defects or reached close to the defect. These cracks formed the basis of the development of other cracks. The cracking level was defined in terms of the number of cracks and the volumes of total cracks and followed the sequence of S-SF > S-MD > S-IF, which is consistent with the sequence of volume expansion ratio of steel. The degree of release of rusts was found to depend on the position of the initial defects i.e. the closer the initial defect is to the steel, the better would be the releasing effect of rusts. Finally, comparison between the external and internal corrosion parameters reflecting corrosion level was performed.
AB - In actual reinforced concrete structures, plenty of initial defects exist, which may greatly influence the behavior of steel corrosion and cracking within concrete cover. Thus, this paper presents an experimental investigation into the effects of initial defects within mortar cover on the corrosion of a steel bar in mortar and on the cracking of mortar cover using X-ray computed tomography. The influence of initial defects with mortar cover at three different positions i.e. interface, middle and surface was investigated for 5%, 30% and 55% corrosion levels of steel. From experimental investigations, it was found that the specimen with interface defect has significant accumulation of corrosion products. The position of cracking within mortar cover induced by steel corrosion was examined. At least one crack connected steel with the initial defects or reached close to the defect. These cracks formed the basis of the development of other cracks. The cracking level was defined in terms of the number of cracks and the volumes of total cracks and followed the sequence of S-SF > S-MD > S-IF, which is consistent with the sequence of volume expansion ratio of steel. The degree of release of rusts was found to depend on the position of the initial defects i.e. the closer the initial defect is to the steel, the better would be the releasing effect of rusts. Finally, comparison between the external and internal corrosion parameters reflecting corrosion level was performed.
KW - 3D
KW - Corrosion induced cracking
KW - Defects
KW - Non-destructive
KW - Steel corrosion
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U2 - 10.1016/j.conbuildmat.2019.06.172
DO - 10.1016/j.conbuildmat.2019.06.172
M3 - Article
AN - SCOPUS:85068269720
SN - 0950-0618
VL - 223
SP - 265
EP - 277
JO - Construction and Building Materials
JF - Construction and Building Materials
ER -