- Please check and comment entries here.
Corrosion-Induced Deterioration of Reinforced Concrete
Steel corrosion in reinforced concrete structures is critical to structural performance and also causes spalling of concrete cover, which poses a risk to occupants and any other person passing under the structure. It is well established that corrosion is initiated after the depassivation of the steel surface caused by the carbonation of the cover concrete and chloride ingress. For real structures in the field, it has been reported that corrosion was unlikely to be observed when the concrete was directly kept from moisture exposure, even when carbonation reached the reinforcing steel; however, corrosion can occur because of rainfall moisture and other sources.
In this study, he cover depth effect on corrosion-induced deterioration on-site in different Asian countries was surveyed focusing on the water penetration rather than the classical corrosion factors, such as carbonation and chloride ingress, and then to experimentally and numerically investigate the threshold of water penetration and drying in cover concrete to support the survey findings.
Reinforced concrete bridges were visually surveyed in Japan, Thailand, and Vietnam to study the deterioration caused by internal steel corrosion under different climates, focusing on the concrete cover depth. Spalling or cracking arising from corrosion is likely where water is supplied. According to prior studies and our surveys, a concrete cover depth of more than 40 mm was found to prevent spalling, regardless of environmental conditions and structure age. Because water supply at steel is a key corrosion factor, it was hypothesised that under natural conditions, the water penetration in concrete would remain at a depth of approximately 40 mm. Our laboratory study examined water penetration under drying and wetting conditions. The results also suggested that under periodic rainfall conditions, the threshold of water penetration was not exceeded. The numerical study indicated maximum moisture evaporation to facilitate oxygen diffusion occurred at a depth of approximately 30–40 mm unless the concrete was exposed to continuous drying for more than one month. It was experimentally and numerically concluded that an adequate cover depth of greater than 40 mm could inhibit moisture and oxygen penetration at the steel, which supported the survey findings of cover depth effect on a high resistance to corrosion-induced deterioration despite an increase in service life.
2. Background and research significance
The entry is from 10.3390/ma14133478
- ISO 16024:2000. Durability—Service Life Design of Concrete Structures; International Organization for Standardization: Geneva, Switzerland, 2012.
- FIB. Model Code for Service Life Design (Fib Bulletin No. 34); Federation Internationale du Beton: Lausanne, Switzerland, 2006.
- Japan Society of Civil Engineers. Standard Specifications for Concrete Structures-2007 (Design); Japan Society of Civil Engineers: Tokyo, Japan; Available online: (accessed on 27 May 2021).
- Tuutti, K. Service Life of Structures with Regard to Corrosion of Embedded Steel. Am. Concr. Inst. SP 1980, 65, 223–236.
- González, J.A.; Algaba, J.S.; Andrade, C. Corrosion of Reinforcing Bars in Carbonated Concrete. Br. Corros. J. 1980, 15, 135–139.
- Glass, G.; Page, C.; Short, N. Factors Affecting the Corrosion Rate of Steel in Carbonated Mortars. Corros. Sci. 1991, 32, 1283–1294.
- Stefanoni, M.; Angst, U.; Elsener, B. Corrosion Rate of Carbon Steel in Carbonated Concrete—A Critical Review. Cem. Concr. Res. 2018, 103, 35–48.
- Volkwein, A.; Springenschmid, R. Corrosion of Reinforcement in Concrete Bridges at Different Ages Due to Carbonation and Chloride Penetration. Proc. Sec. Int. Conf. Durab. Build. Mater. Compon. 1981, 1981, 199–209.
- Lollini, F.; Redaelli, E.; Bertolini, L. Corrosion Assessment of Reinforced Concrete Elements of Torre Velasca in Milan. Case Stud. Constr. Mater. 2016, 4, 55–61.
- Ishibashi, T.; Furuya, T.; Hamazaki, N.; Suzuki, H. Investigation of Falling on Concrete Fragments from RC Structures. Doboku Gakkai Ronbunshu 2002, 2002, 125–134.
- Maehara, S.; Iyoda, T. Study on the Effect of Rain Exposure on Carbonation-Induced Spalling/Falling of the Cover Concrete. J. Jpn. Soc. Civ. Eng. Ser. E2 Mater. Concr. Struct. 2018, 74, 80–87.
- Japan Society of Civil Engineers. Standard Specifications for Concrete Structures—2017 (Design); Society of Civil Engineers: Tokyo, Japan, 2017. (In Japanese)
- Ueda, H.; Sakai, Y.; Kinomura, K.; Watanabe, K.; Ishida, T.; Kishi, T. Durability Design Method Considering Reinforcement Corrosion due to Water Penetration. J. Adv. Concr. Technol. 2020, 18, 27–38.
- Thomas, M.D.A.; Matthews, J.D. Carbonation of Fly Ash Concrete. Mag. Concr. Res. 1992, 44, 217–228.
- Sulapha, P.; Wong, S.F.; Wee, T.H.; Swaddiwudhipong, S. Carbonation of Concrete Containing Mineral Admixtures. J. Mater. Civ. Eng. 2003, 15, 134–143.
- Otieno, M.; Ikotun, J.; Ballim, Y. Experimental Investigations on the Effect of Concrete Quality, Exposure Conditions and Duration of Initial Moist Curing on Carbonation Rate in Concretes Exposed to Urban, Inland Environment. Constr. Build. Mater. 2020, 246, 118443.
- Martys, N.S.; Ferraris, C.F. Capillary Transport in Mortars and Concrete. Cem. Concr. Res. 1997, 27, 747–760.
- Hall, C. Anomalous Diffusion in Unsaturated Flow: Fact or Fiction? Cem. Concr. Res. 2007, 37, 378–385.
- McDonald, P.J.; Istok, O.; Janota, M.; Gajewicz-Jaromin, A.M.; Faux, D.A. Sorption, Anomalous Water Transport and Dynamic Porosity in Cement Paste: A Spatially Localised 1H NMR Relaxation Study and a Proposed Mechanism. Cem. Concr. Res. 2020, 133, 106045.