scholarly journals STRUCTURAL DESIGN OF POLYMER PROTECTIVE COATINGS FOR REINFORCED CONCRETE STRUCTURES. PART I: THEORETICAL CONSIDERATIONS

2007 ◽  
Vol 13 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Zenonas Kamaitis
Keyword(s):  
Reinforced Concrete ◽  
Protective Coatings ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Polymer Coatings ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Coating Materials ◽  
Barrier Materials ◽  
Mechanism Of Degradation

In a number of situations reinforced concrete structures must be protected by barrier materials to prevent contact with aggressive agents. One of the ways to protect concrete structures from corrosion is to use protective polymer coatings. Polymers as coating materials are not totally resistant and impermeable to all aggressive agents. Gases, vapors and liquids penetrate into a polymer so that the polymer mass swells and eventually disintegrates. However, the penetration/disintegration progresses at a much lower rate than that in the concrete. Surface coatings are able to reduce considerably the penetration, to slow down the rate of deterioration of concrete cover and to overcome most durability problems associated with external attack. In this article the mechanism of degradation of polymer coatings are analyzed. Methodology and predictive models for the degradation over time caused by aggressive actions of polymer coatings are presented. Proposed models can be applied to design of polymer coatings. Such a design of coatings is presented in a simple form for engineering design purposes.

scholarly journals MODELLING OF CORROSION PROTECTION FOR REINFORCED CONCRETE STRUCTURES WITH SURFACE COATINGS/GELŽBETONINIŲ KONSTRUKCIJŲ SU PAVIRŠINĖMIS DANGOMIS KOROZINĖS APSAUGOS MODELIAVIMAS

2008 ◽  
Vol 14 (4) ◽  
pp. 241-249 ◽  
Author(s):  
Zenonas Kamaitis
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Protective Coatings ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Surface Coatings ◽  
Surface Barrier ◽  
Reinforced Concrete Structures ◽  
Protective System ◽  
Durability Of Concrete

Corrosion is a serious problem for the durability of reinforced concrete structures. These structures need to be protected from corrosion in a variety of exposure conditions ranging from atmospheric to continuous immersion in water or chemicals. One of the ways to protect reinforced concrete structures from corrosion is to use protective coatings. The surface barriers of non‐degradable materials are able to slow down considerably the rate of deterioration of concrete structures and to overcome most durability problems associated with external attack. Design of durability of concrete structures with protective coatings needs to be established. In this paper a general framework for service life prediction and reliability evaluation of anticorrosion protective system (CPS), which is represented by protective surface barrier, concrete cover, and steel reinforcement itself of reinforced concrete structures, is presented. This approach is based on a reasonable understanding of the main degradation processes of all components ensuring protection ability and durability of concrete structures. The effect of repair of CPS components on extending the service life of a whole protective system is considered. Numerical example for reliability verification of CPS is also given. Santrauka Korozija yra svarbi gelžbetoninių konstrukcijų ilgaamžiškumo problema. Gelžbetonines konstrukcijas būtina apsaugoti nuo korozijos įvairiomis sąlygomis, pradedant nuo atmosferos iki nuolatinio mirkymo vandenyje ar chemikaluose. Vienas iš apsaugos būdų yra polimerinės apsauginės dangos. Atsparus paviršinis barjeras gali labai sulėtinti gelžbetonio irimą ir išspręsti daugelį problemų, susijusių su išorine aplinka. Reikia sukurti gelžbetoninių konstrukcijų su apsauginėmis dangomis projektavimo metodiką. Straipsnyje nagrinėjama antikorozinės apsauginės sistemos, susidedančios iš paviršiaus apsauginio barjero, apsauginio betoninio sluoksnio ir pačios plieninės armatūros, patikimumas ir spėjamas gyvavimo laikotarpis. Šis modelis remiasi apsauginio barjero, betonio sluoksnio ir armatūros irimo procesų samprata. Skaitinis pavyzdys rodo antikorozinės apsauginės sistemos patikimumo patikrą.

Passive corrosion control and active corrosion prevention of the reinforced concrete structures by electrochemical chloride removal and inhibitors

2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Corrosion Control ◽  
Cell Potential ◽  
Content Type ◽  
Chloride Removal ◽  
Active Corrosion

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

Acoustic emission monitoring for bond integrity evaluation of reinforced concrete under pull-out tests

2016 ◽  
Vol 20 (9) ◽  
pp. 1390-1405 ◽  
Author(s):  
Ahmed A Abouhussien ◽  
Assem AA Hassan
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Acoustic Emission Signal ◽  
Concrete Structures ◽  
Signal Strength ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Bond Behavior ◽  
Emission Signal ◽  
Pull Out

This article presents the results of an experimental investigation on the application of acoustic emission technique for monitoring the steel-to-concrete bond integrity of reinforced concrete structures. A series of direct pull-out tests were performed on 54 reinforced concrete unconfined prism samples with variable rebar diameter (10, 20, and 35 mm), embedded length (50, 100, and 200 mm), and concrete cover (20, 30, and 40 mm). The samples were tested under incrementally increasing monotonic loading while being continuously monitored via attached acoustic emission sensors. These sensors were utilized to acquire different acoustic emission signal parameters emitted throughout the tests until failure. Also, an acoustic emission intensity analysis was implemented on acoustic emission signal strength data to quantify the damage resulting from loss of bond in all tested specimens. This analysis employed the signal strength of all recorded acoustic emission hits to develop two additional parameters: historic index ( H ( t)) and severity ( Sr). The results of bond behavior, mode of failure, and free end slip were compared with the recorded acoustic emission data. The results showed that the cumulative number of hits, cumulative signal strength, H ( t), and Sr had a good correlation with different stages of bond damage from de-bonding/micro-cracking until bond splitting failure and bar slippage, which caused cover cracking or delamination. The analysis of cumulative signal strength and H ( t) curves enabled early identification of two progressive stages of bond degradation (micro-cracking and macro-cracking) and recognized the various modes of failure of the tested specimens. The variations of bar diameter, concrete cover, and embedded length yielded significant impacts on both the bond behavior and acoustic emission activities. The results also presented developed intensity classification charts, based on H ( t) and Sr, to assess the bond integrity and to quantify the bond deterioration (micro-cracking, macro-cracking, and rebar slip) in reinforced concrete structures.

The Construction Quality Control Measures of Reinforced Concrete Cover Research

2014 ◽  
Vol 599-601 ◽  
pp. 1094-1097
Author(s):  
Shao Jun Zhang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Protective Layer ◽  
Concrete Cover ◽  
Control Measures ◽  
Reinforced Concrete Structures ◽  
Molding Process ◽  
Steel Bar ◽  
Reinforced Concrete Member ◽  
Design Production

reinforced concrete structures reinforced protective layer deviation will directly affect the mechanical properties and durability of the reinforced concrete member, in relation to the structure of the use of safety and service life. The control to the protective layer of reinforced concrete structures include the following aspects: to do a good job of double sample, reinforced the blue prints.the design, production and installation of template engineering, reinforcing steel bar colligation molding process, placed, binding of fixed steel protective layer block and the requirements on the installation of the steel skeleton.

scholarly journals Development of Bonded/Riveted Steel Anchorages of Prestressed CFRP Strips for Concrete Strengthening

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2217
Author(s):  
Bartosz Piątek ◽  
Tomasz Siwowski ◽  
Jerzy Michałowski ◽  
Stanisław Błażewicz
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Epoxy Adhesive ◽  
Full Scale ◽  
Steel Plates ◽  
Tensile Failure ◽  
Small Scale ◽  
Reinforced Concrete Structures ◽  
Flexural Strengthening

CFRP (carbon fiber reinforced polymer) strips are currently often used to strengthen reinforced concrete structures in flexure. In order to ensure effective strengthening, proper connection between FRP material and concrete structure is needed. CFRP strips can be applied passively (only by bonding to the concrete surface) or actively (by prestressing before bonding). In the case of passive strengthening, CFRP strips connecting by bonding to the surface along the strengthened element are usually sufficient. However, active (prestressing) CFRP strips should be additionally anchored at their ends. Anchoring of unidirectional CFRP strips to the reinforced concrete is difficult because of their weak properties in transverse directions. The paper presents a development of mechanical steel anchorages used in an active CFRP flexural strengthening system for reinforced concrete structures. The anchorages were made of steel plates connected to CFRP strips with steel rivets and epoxy adhesive. They were developed within series of tests on specimens from small-scale to full-scale tested in an axial tensile scheme. The paper describes successive modifications of the anchorages as well as the results of full-scale tests. The final version of the anchorage developed during the research had a tensile failure force of 185 kN, which is sufficient value for CFRP strengthening purposes.

scholarly journals Performance evaluation of plastic spacers: proposal and development of evaluation methods

2016 ◽  
Vol 9 (6) ◽  
pp. 911-952
Author(s):  
M. F. F. Menna Barreto ◽  
◽  
A. P. Maran ◽  
D. C. C. Dal Molin ◽  
J. R. Masuero
Keyword(s):  
Performance Evaluation ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
International Standards ◽  
Performance Criteria ◽  
Reinforced Concrete Structures ◽  
And Performance ◽  
Cover Thickness ◽  
Brazilian Standard

ABSTRACT The durability of reinforced concrete structures is highly dependent on the characteristics of the concrete cover to reinforcement and its thickness. The failure to obtain cover thickness is the factor with the largest influence on the premature corrosion of the reinforcement, which in turn is the main deterioration form of reinforced concrete structures. Studies indicate that the designed cover is not reached in the current constructions that adopt this structural solution, configuring a chronic, and not a sporadic problem. One of the observed causes for the failure in obtaining the minimum standardized cover is the incorrect use of spacers and the use of inadequate spacers. This is made more serious by the absence of a Brazilian standard to regulate the product and its use and, consequently, the absence of a quality certification from the responsible regulating agency. Focusing on spacers, requirements and performance criteria were proposed, in addition to methods for their assessment, with most being taken and adapted from international standards. Subsequently, some spacers available on the market were effectively tested according to the proposed methodology. No spacer model proved to be satisfactory according to the established performance approach. However, for each criteria and assessment methods proposed, there was, at least, one spacer model at the market which satisfied them, so it can be said that the criteria and methods are suitable for spacers performance evaluation. Faced with the performance diversity of the spacer models on offer, the need for a regulatory Brazilian standard for this product was confirmed in order to delimit the quality of spacers available on the market and to eliminate this variable as one of the causes for not obtaining the correct covering.

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