scholarly journals Durable Steel-Reinforced Concrete Structures for Marine Environments

2021 ◽  
Vol 13 (24) ◽  
pp. 13695
Author(s):  
Robert E. Melchers ◽  
Igor A. Chaves
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Localized Corrosion ◽  
Marine Environments ◽  
Reinforcement Corrosion ◽  
Rc Structures ◽  
Air Voids ◽  
Rc Structure ◽  
Alkali Aggregate Reactivity

Even in harsh marine environments, concrete structures reinforced with steel can show excellent long-term durability, with little or no reinforcement corrosion. Very few actual reinforced concrete (RC) structures have been closely scrutinized over many years and subject to interpretation using recent state-of-the-art understanding gained from detailed laboratory observations. Such a case is described for an 80-year-old RC structure observed annually over about 30 years in what is essentially an extraordinary long experiment. Despite very high chloride concentrations, field excavation evidence showed that reinforcement corrosion overall remains minimal, except where insufficient concrete compaction permitted air-voids to initiate quite severe, very localized corrosion even with still high concrete pH. It is possible that the use of blast furnace slag as aggregate may have assisted the observed durability. The case study supports other studies that show that it is possible to achieve long-term durable and therefore sustainable RC structures without additives and using only conventional reinforcement steels and conventional cements and aggregates. However, the potential dangers of deep narrow cracking extending to the reinforcement and the potentially deleterious effects of alkali–aggregate reactivity of some aggregates needs to be considered.

scholarly journals Effects of Tension Reinforcement Ratio on Ductility of Mid-Rise Reinforced Concrete Structures

2018 ◽  
Vol 1 (1) ◽  
pp. 702-708
Author(s):  
Onur Onat ◽  
Burak Yön
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Concrete Structures ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Beam Elements ◽  
First Case ◽  
Rc Structure ◽  
Determine Effect

Failure mode of reinforced concrete (RC) structures are classified according to tension reinforcement ratio of beam elements. To determine effect of tension reinforcement ratio on performance of RC structure, two planar RC structure were selected. One of them is 5 stories other of them is 7 stories. Two different concrete class, C20 and C25, were considered for analysis. Three tension reinforcement combinations were considered, three different tension reinforcement ratios were used. First case is the ratio of the tension reinforcement is lower than that of the compression reinforcement, second case is the ratio of the tension reinforcement is equal to the ratio of the compression reinforcement and third case is the ratio of the tensile reinforcement is higher than the compression reinforcement.

scholarly journals Long-Term Efficiency of Two Organic Corrosion Inhibitors for Reinforced Concrete

2010 ◽  
Vol 636-637 ◽  
pp. 1059-1064 ◽  
Author(s):  
E.V. Pereira ◽  
R.B. Figueira ◽  
Manuela M. Salta ◽  
I.T.E. Fonseca
Keyword(s):  
Reinforced Concrete ◽  
Environmental Conditions ◽  
Corrosion Inhibitors ◽  
Electrochemical Techniques ◽  
Concrete Structures ◽  
Concrete Slabs ◽  
Reinforced Concrete Structures ◽  
Reinforcement Corrosion ◽  
Organic Corrosion Inhibitors

In this paper the efficiency of two organic corrosion inhibitors, a migratory and an admixture inhibitor, was evaluated by electrochemical techniques in solutions simulating the interstitial electrolyte of concrete and on concrete slabs exposed to natural environmental conditions over a five-year period. From obtained results, the usefulness of the two products is discussed aiming its application in new structures to prevent chlorides induced corrosion and as a curative method for repairing reinforced concrete structures contaminated with chlorides and affected by reinforcement corrosion.

Residual Service Life Prediction of Offshore Concrete Structures With Chloride-Induced Damage: The State of the Art

2013 ◽  
Author(s):  
S. M. S. M. K. Samarakoon ◽  
R. M. Chandima Ratnayake
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Prediction Models ◽  
Laboratory Data ◽  
Concrete Structures ◽  
Residual Service Life ◽  
Reinforcement Corrosion ◽  
Rc Structures ◽  
Maintenance And Repair ◽  
Remaining Service Life

Offshore oil and gas (O&G) production and process facilities (P&PFs) consist of concrete components and structures with steel reinforcement and pre-stressing tendons. They are vulnerable to deterioration due to chloride-induced damage from being exposed to the severe marine environment. The aforementioned deterioration creates significant challenges to the life extension analysis presently required for P&PFs located in the North Sea. Currently, maintenance work has been carried out via in-service inspection and condition monitoring to assure the structural integrity at a pre-specified level of P&PFs. In this context, the knowledge from existing models forms a basis for making quantitative predictions of the remaining service life of structures and components made of concrete. The service life of reinforced concrete structures in relation to reinforcement corrosion is usually modeled considering the initiation period and the corrosion propagation period. The formation of optimal proactive maintenance and repair strategies for corrosion-damaged reinforced concrete (RC) structures is highly dependent on the results of prediction models. The combination of both field (i.e. inspection) and laboratory data with numerical modeling helps the formulation of models for the prediction of the time to pre-defined limit states or to estimate the time for carrying out necessary maintenance and repair. This manuscript provides a review of the available methods for predicting the remaining service life of RC structures in relation to reinforcement corrosion. It also highlights suitable methods for predicting the remaining service life of offshore ageing concrete structures in a severe corrosive environment.

scholarly journals Reinforcement corrosion in reinforced concrete Structures: Classification and overview

2021 ◽  
Vol 2 (1) ◽  
pp. 19-24
Author(s):  
Nour Eldeen Abo Nassar
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Control Measures ◽  
Reinforced Concrete Structures ◽  
Reinforcement Corrosion ◽  
Early Failure ◽  
Comprehensive Review ◽  
Rc Structures ◽  
Entire Structure ◽  
Steel Bars

Reinforced concrete (RC) structures have the ability to be extremely durable and able to withstand a diversity of different environmental cases. However, failure in these structures still happens due to precocious reinforcement erosion. If steel reinforcement corrodes in concrete structures, this leads to a decrease in the lifetime and durability of these structures, which cause early failure of the structures, costing significantly to inspect and maintain the deteriorating structures. Then, monitoring of reinforcement corrosion is of great importance to prevent early failure of structures. Structures corrosion can be decreased through correct monitoring and taking appropriate control measures in the appropriate period of time. When steel bars corrode, the formation of rust causes the concrete to be separated from the steel and then thereafter. In case this issue is not addressed, it may influence the entire structure. This paper attempts to present a comprehensive review of corrosion of rebar in RC structures, its mechanisms, monitoring and prevention.

scholarly journals Probabilistic Evaluation of Service Life for Reinforced Concrete Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sanjeev Kumar Verma ◽  
Sudhir Singh Bhadauria ◽  
Saleem Akhtar
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Probabilistic Models ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Rc Structure ◽  
Probabilistic Evaluation

Degradation of performance and deterioration of different components of reinforced concrete (RC) structures increase with the age of structure. This deterioration of reinforced component depends on several parameters. However, modeling service life of RC structure by considering all the parameters is a difficult job, as most of the parameters are uncertain in nature. Probabilistic models account well for the uncertainties in the parameters responsible for deterioration of RC structures. This paper presents a review of several recent service life models developed using probability based concepts.

scholarly journals Long-Term Durability of Marine Reinforced Concrete Structures

2020 ◽  
Vol 8 (4) ◽  
pp. 290 ◽  
Author(s):  
Robert E Melchers
Keyword(s):  
Reinforced Concrete ◽  
Experimental Work ◽  
Good Condition ◽  
Concrete Structures ◽  
The Other ◽  
Reinforced Concrete Structures ◽  
Reinforcement Corrosion ◽  
Physical Damage ◽  
Analysis And Design

The sustainability of reinforced concrete is critical, particularly for structures exposed to marine environments. Chlorides are implicated in causing or accelerating reinforcement corrosion and potentially earlier expensive repairs, yet there are many older reinforced concrete structures in good condition for many decades despite very high chloride levels at the reinforcement. The reasons for this are reviewed briefly, together with recent experimental work that better defines the role of chlorides. One is initiation of reinforcement corrosion but only through localized pitting at air-voids in concrete at the interface with the steel reinforcement. These tend to be small or negligible for high quality well-compacted concretes. The other role for chlorides has been shown, in experimental work, to accelerate the long-term loss of concrete alkali material. On the other hand, a review of practical experience shows that what has been termed chloride-induced reinforcement corrosion often is not that at all, but is the end-product of factors that impair the protective nature of the concrete. As reviewed herein, these include poor compaction, physical damage to concrete cover, concrete shrinkage, and alkali-aggregate reactions. The various observations presented are important for the proper understanding, analysis, and design of durable reinforced concrete structures exposed to chloride-rich environments.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Sign in / Sign up

Export Citation Format

Share Document