Monitoring, reinforced concrete

R. B. Polder, Cathodic protection of reinforced-concrete stmctures in the Netherlands — experience and developments , in Corrosion of Reinforcement in Concrete - Monitoring, Prevention and Rehabilitation, Papers from Eurocorr" 97, J. Mietz,... 

G. Cavallero, D. Melodia, F. Panaro, Monitoring of stray current interference in the reinforced-concrete structures of the Turin underground railway loop , 54 NACE Corrosion 99, 1999. 

COST 521, Corrosion of Steel in Reinforced Concrete Structures Prevention - Monitoring - Maintenance, Final report, (Ed.) R. Weydert, Chapter 1, Preventative measures , to be published by the European Commission, 2003. 

Y. Schiegg, L. Audergon, B. Elsener, H. Bohni, On-line monitoring of the corrosion in reinforced-concrete structures , Eurocorr 2001, Associa-zione Italiana di Metallurgia, Milano, 2001 (CD-ROM). 

Monitoring of reinforced-concrete structures exposed to aggressive environmental loads with regard to the time evolution of their durabihty can optimize the management of stmctures and secure their reliabihty and safety. However, the monitoring strategy has to be clearly defined, otherwise heavily instrumented structures produce large amounts of data with httle or no practical value. The points below are discussed in more detail in references [18,25]. 

F. Hunkeler, Monitoring of repaired reinforced-concrete stmctures by means of resistivity measurements , in Repair of Concrete Structures, Svolvaer,... 

P. Broomfield, K. Davies, K. Hladky, Permanent corrosion monitoring in new and existing reinforced-concrete stmctures . Materials Peifomwmce, 2000, July, 66 70. 

Cathodic protection of reinforced-concrete structures exposed to the atmosphere was apphed for the first time to bridge decks contaminated by de-icing salts by R. F. StratfuU in California in 1973 [1,2]. In the years following, design and protection criteria were elaborated, as well as power supply and monitoring systems completely different from those used for cathodic protection of buried steel structures or structures operating in seawater. Above all, it was proved that cathodic protection was a rehable repair technique even in the presence of high chloride contents, where traditional systems of rehabilitation are inefficient or very costly. 

Rehabilitation is achieved by overlays such as latex-modified concrete, low-slump concrete, high-density concrete, and polymer concrete. They are commonly used for the rehabihtation of bridge decks. This procedure extends the life of a bridge deck by about 15 years. Impressed-current CP systems on bridge decks are now a routine rehabihtation teehnique because of the cooperative research with industry and states in the development of durable anodes, monitoring devices, and installation techniques. Titanium mesh anode, used in conjunction with a concrete overlay to distribute protective current, serves as a durable anode for use in impressed-current CP of reinforced concrete bridge deeks and widely accepted by state and other transportation agencies. 

The potential of the corroding surface can be monitored periodically by means of a reference electrode. One such example is the corrosion potential measurement of reinforced steel rebar in concrete structures. Corrosion of the steel in reinforced concrete is a major factor in the deterioration of highway and bridge infrastructure. A survey of the condition ofa reinforced concrete structure is the first step toward its rehabilitation. A rapid, cost-effective, and nondestructive condition survey offers key information to evaluate the corrosion, aids in quality assurance of concrete repair and rehabilitation. 

A. Brenna, F. Bolzoni, S. Beretta, M. OrmeUese, Long-term chloride-induced corrosion monitoring of reinforced concrete coated with commercial polymer-modified mortar and polymeric coatings, Constr. Build. Mater. 48 (2013) 734—744. 

Broomfield, J.P. (2000). Results of Long Term Monitoring of Corrosion Inhibitors Applied to Corroding Reinforced Concrete Structures. Corrosion 2000. Paper No. 791. 

Figure 5.2 A corrosion monitoring probe consisting of a reference eiectrode and an auxiliary electrode potted up in mortar in the process of installation into a continuously reinforced concrete pavement where corrosion monitoring is required due to the high level of chloride found in the mix water after laying several kilometres of concrete (Broomfield et a/., 2003) photograph. Courtesy BGB Projects Ltd.

McCartei W.J. and Vennesland, O. (2004). Sensor systems for use in reinforced concrete structures . Construction and Building Materials, 18 351-358. Raupach, M. and SchiessI, P. (Feb, 1995). Monitoring System for the Penetration of Chlorides, Carhonation and the Corrosion Risk for the Reinforcement. Proceedings of the 6th International Conference on Structural Faults and Repair. 

Broomfield, J., Davis, K. and Hladky, K. (April 1999). Permanent Corrosion Monitoring for Reinforced Concrete Structures. Paper 99559, Corrosion/99, NACE International, Houston, TX. 

Sohanghpurwalla, A.A., Islam, M. and Scannell, W. (1997). Performance and Long Term Monitoring of Various Corrosion Protection Systems used in Reinforced Concrete Bridge Structures. Proceedings of International Conference Repair of Concrete Structures, from Theory to Practice in a Marine Environment. 

NDIS 2421 (2000) Recommended practice for in situ monitoring of concrete stmctures by acorrstic emission. JSNDI, Tokyo Ohtsu M, Uchida M, Okamoto T, Yuyatna S (2002) Damage assessment of reinforced concrete beams qtralified by acoustic emission. ACI Stmctural Journal, 99-842 411-417... 

Ruzek B, Kvasnicka M (2001) Differential Evaluation Algorithm in the Earthquake Hypocenter Location. Pure and Applied Geophysics 158 667-693 Schechinger B, Vogel T (2006) Acoustic emission for monitoring a reinforced concrete beam subject to four-point-bending. Constraction and Building Materials, 21(3) 483-490... 

Modem AE research in concrete was started in the 1970 s. Wells studied AE waveforms, finding the relationship between strain measurement and AE events (Wells 1970). Studies on fundamentals of AE activity and the effects of mixture proportion were conducted (McCabe et al. 1976 Nielsen and Griffith 1977 Mlakar, Walker et al. 1984). A frequency analysis and a source location analysis were also reported (Fetis 1976 Niwa, Kobayashi et al. 1978 Reymond, Raharinaivo et al. 1983 Berthelot and Robert 1987 Weiler, Xu et al. 1997). In due course, applications to reinforced concrete strictures were investigated (Niwa, Kobayashi et al. 1977 Kobayashi, Hawkins et al. 1980). These studies have resulted in practical applications to monitor micro-cracks in concrete stmctures and going to be made practical as diagnostic applications (Ohtsu 1988). 

As stated in Chapter 4, the recommended practice for in situ monitoring of concrete structures by AE is currently established (NDIS-2421 2000). In order to assess the damage levels of reinforced concrete beams, one criterion to qualify the damage levels is proposed on the basis of two ratios associated with the Kaiser effect. A feasibility of this practice is experimentally examined by testing reinforced concrete beams, which have been damaged under incremental cyclic loading. 

J Stractmal Division, ASCE 102(ST2) 387-400 Hearn SW, Shield CK (1997) Acoustic emission monitoring as a nondestractive testing technique in reinforced concrete. ACI Materials Journal 94(6) 510-519... 

Shiotani T, Bisschop J, van Mier JG (2002) Drying shrinkage microcrack measurements in cementitious composites using AE and FLM. SEM Annual Conference on Experimental and Applied Mechanics, Milwaukee Tomoda Y, Ohtsu M (2005) Monitoring salt damage in reinforced concrete by AE. Proc. 3 US-Japan Sym. on Advancing Applications and Capabilities in NDE, Maui, pp 236-241... 

In an old reinforced concrete building, AE measurement was carried out in advance of rebuilding the house. A plan view of the two-story building is given in Fig. 13.1. Since the structure was old and not in service, the audible noises were readily observed due to the traffic load. At five locations circled in the figure, continuous monitoring was conducted for a week. To analyze AE data, two waveform parameters of the RA value and the averaged frequency stated in Chapter 4 were applied. 

Shigeishi M, Makizumi T, Jo H, Ueda J (2003) AE monitoring of a reinforced concrete road bridge. Structural faults and repair 11 (CD-ROM) NDTB-SHIG... 

The technique of corrosion monitoring is well established for cathodic protection of reinforced concrete structures where microprocessor controlled systems are linked by modem to remote monitoring stations and potentials and current floivs are monitored (Broomfield et rt/., 1987). However, very few such systems have been used on actively corroding... 

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