Crack Shape of Corrosion-Induced Cracking in the Concrete Cover

SADDAM HUSEIN. Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton (dibimbing oleh Rudi Djamaluddin dan Rita Irmawaty) Struktur beton bertulang yang menggunakan tulangan baja pada daerah korosif, menjadi rawan terhadap kerusakan atau penurunan kekuatannya akibat korosi.Korosi pada tulangan baja merupakan salah satu faktor penyebab menurunnya kekuatan struktur beton bertulang. Salah satu material yang dikembangkan mengatasi korosi adalah penggunaan material tulangan GFRP (Glass Fiber Reinforced Polymer). Penelitian ini bertujuan untuk menganalisa kapasitas lentur dan pola kegagalan balok beton tanpa selimut dengan menggunakan material tulangan GFRP bar. Desain penelitian merupakan eksperimental laboratorium dengan rekapitulasi sebanyak 6 sampel yang terdiri dari 2 Balok beton menggunakan tulangan baja dengan selimut beton, 2 balok beton menggunakan tulangan GFRP bar dengan selimut beton, 2 balok beton menggunakan GFRP bar tanpa selimut beton. Metode pengujian dilakukan dengan dengan pengujian lentur statik monotonik dan Analisis data menggunakan uji kondisi retak awal dan kondisi ultimit. Hasil penelitian ini menunjukkan bahwa kapasitas lentur pada balok dengan tulangan GFRP bar lebih besar dibandingkan dengan balok tulangan baja dan mampu meningkatkan kapasitas lentur balok dalam menahan beban sebesar 39.76 %, pola kegagalan beton yang terjadi pada balok tulangan baja mengalami kegagalan lentur tekan ditandai dengan retakan yang terjadi pada sisi tertekan dan membentuk retakan tegak dengan sumbu netral beton yang tertekan, sedangkan pada balok beton tulangan GFRP tanpa selimut mengalami kegagalan keruntuhan tekan geser dengan kondisi tulangan berdeformasi (bi-linear) dengan retak miring dan secara tiba-tiba menjalar menuju sumbu netral beton yang tertekan sehingga terjadilah keruntuhan secara tiba-tiba. SADDAM HUSEIN.Failure mode analysis of concrete Beams Using GFRP rebar Without concrete cover (supervised by Rudi Djamaluddin and Rita Irmawaty) Reinforced concrete that uses rebar steel in corrosive areas, are prone to damage or decreased strength due to corrosion. Corrosion in the steel reinforcement is one of the factors that decreasing strength of reinforced concrete. One of the materials developed to overcome corrosion is the use of GFRP (Glass Fiber Reinforced Polymer) reinforcement material. This study aims to analyze the flexural capacity and failure mode of concrete beams without concrete cover using material GFRP bar as reinforcement. The research design was an experimental laboratory with a recapitulation of 6 samples consisting of 2 beams using steel reinforcement with concrete cover.2 concrete beams using reinforcement GFRP bar with concrete cover, 2 beams using GFRP bars without concrete cover. The research method uses the monotonic static flexure and analyzing the data using the initial crack condition and ultimate conditions test. The results of the research indicate the flexural capacity of the beams with GFRP bar reinforcement is higher than steel reinforcement beams and can increase 39.76% of the flexural capacity of the beams in holding loads , the failure mode analysis occurs in steel reinforcing beam experiences compressive failure. Failure was characterized by cracks that occur on the depressing side and form an upright crack with the neutral axis of the compressed concrete, whereas in GFRP reinforced concrete beams without concrete cover, failure of shear compression with conditions of deformed reinforcement (bi-linear) with sloping cracks and suddenly spread towards the neutral axis of the compressed concrete so that there was a sudden collapse.

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Influence of Patching on the Shear Failure of Reinforced Concrete Beam without Stirrup

Infrastructures ◽

10.3390/infrastructures6070097 ◽

2021 ◽

Vol 6 (7) ◽

pp. 97

Author(s):

Stefanus Adi Kristiawan ◽

Halwan Alfisa Saifullah ◽

Agus Supriyadi

Keyword(s):

Reinforced Concrete ◽

Shear Failure ◽

Numerical Study ◽

Unsaturated Polyester ◽

Reinforced Concrete Beam ◽

Concrete Cover ◽

Shear Capacity ◽

Rc Beam ◽

Shear Span ◽

Shear Cracking

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

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Modelling of Corrosion-Induced Concrete Cover Cracking Due to Chloride Attacking

Materials ◽

10.3390/ma14061440 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1440

Author(s):

Pei-Yuan Lun ◽

Xiao-Gang Zhang ◽

Ce Jiang ◽

Yi-Fei Ma ◽

Lei Fu

Keyword(s):

Service Life ◽

Corrosion Current ◽

Practical Experience ◽

Concrete Cover ◽

Premature Failure ◽

Rc Structures ◽

Structural Capacity ◽

Cover Cracking ◽

Deterioration Process ◽

Cracking Process

The premature failure of reinforced concrete (RC) structures is significantly affected by chloride-induced corrosion of reinforcing steel. Although researchers have achieved many outstanding results in the structural capacity of RC structures in the past few decades, the topic of service life has gradually attracted researchers’ attention. In this work, based on the stress intensity, two models are developed to predict the threshold expansive pressure, corrosion rate and cover cracking time of the corrosion-induced cracking process for RC structures. Specifically, in the proposed models, both the influence of initial defects and modified corrosion current density are taken into account. The results given by these models are in a good agreement with practical experience and laboratory studies, and the influence of each parameter on cover cracking is analyzed. In addition, considering the uncertainty existing in the deterioration process of RC structures, a methodology based on the third-moment method in regard to the stochastic process is proposed, which is able to evaluate the cracking risk of RC structures quantitatively and predict their service life. This method provides a good means to solve relevant problems and can prolong the service life of concrete infrastructures subjected to corrosion by applying timely inspection and repairs.

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Behavior of Quarry Rock Dust, Fly Ash and Slag Based Geopolymer Concrete Columns Reinforced with Steel Fibers under Eccentric Loading

Applied Sciences ◽

10.3390/app11156740 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6740

Author(s):

Rana Muhammad Waqas ◽

Faheem Butt

Keyword(s):

Fly Ash ◽

Concrete Cover ◽

Steel Fibers ◽

Structural Behavior ◽

Partial Replacement ◽

Geopolymer Concrete ◽

Fiber Reinforced ◽

Conventional Concrete ◽

Source Materials ◽

Rock Dust

Geopolymer concrete, also known as an earth-friendly concrete, has been under continuous study due to its environmental benefits and a sustainable alternative to conventional concrete construction. The supplies of many source materials, such as fly ash (FA) or slag (SG), to produce geopolymer concrete (GPC) may be limited; however, quarry rock dust (QRD) wastes (limestone, dolomite, or silica powders) formed by crushing rocks appear virtually endless. Although significant experimental research has been carried out on GPC, with a major focus on the mix design development, rheological, durability, and mechanical properties of the GPC mixes; still the information available on the structural behavior of GPC is rather limited. This has implications in extending GPC application from a laboratory-based technology to an at-site product. This study investigates the structural behavior of quarry-rock-dust-incorporated fiber-reinforced GPC columns under concentric and eccentric loading. In this study, a total of 20 columns with 200 mm square cross-section and 1000 mm height were tested. The FA and SG were used as source materials to produce GPC mixtures. The QRD was incorporated as a partial replacement (20%) of SG. The conventional concrete (CC) columns were prepared as the reference specimens. The effect of incorporating quarry rock dust as a replacement of SG, steel fibers, and loading conditions (concentric and eccentric loading) on the structural behavior of GPC columns were studied. The test results revealed that quarry rock dust is an adequate material that can be used as a source material in GPC to manufacture structural concrete members with satisfactory performance. The general performance of the GPC columns incorporating QRD (20%) is observed to be similar to that of GPC columns (without QRD) and CC columns. The addition of steel fibers considerably improves the loading capacity, ductility, and axial load–displacement behavior of the tested columns. The load capacities of fiber-reinforced GPC columns were about 5–7% greater in comparison to the CC columns. The spalling of concrete cover at failure was detected in all plain GPC columns, whereas the failure mode of all fiber-reinforced GPC columns is characterized with surface cracking leading to disintegration of concrete cover.

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Spalling of concrete cover induced by reinforcement

Engineering Structures ◽

10.1016/j.engstruct.2021.112188 ◽

2021 ◽

Vol 237 ◽

pp. 112188

Author(s):

Francesco Moccia ◽

Miguel Fernández Ruiz ◽

Aurelio Muttoni

Keyword(s):

Concrete Cover

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Effect of steel fibers and concrete cover on bond behavior between steel deformed bar and concrete under high temperature

Structures ◽

10.1016/j.istruc.2021.03.062 ◽

2021 ◽

Vol 32 ◽

pp. 1507-1521

Author(s):

Habib Akbarzadeh Bengar ◽

Fatemeh Ahmadi Zarrinkolaei

Keyword(s):

High Temperature ◽

Concrete Cover ◽

Steel Fibers ◽

Bond Behavior ◽

Deformed Bar

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Durability and Time-Dependent Properties of Low-Cement Concrete

Materials ◽

10.3390/ma13163583 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3583 ◽

Cited By ~ 1

Author(s):

Keila Robalo ◽

Eliana Soldado ◽

Hugo Costa ◽

Luís Carvalho ◽

Ricardo do Carmo ◽

...

Keyword(s):

Concrete Cover ◽

Time Dependent ◽

Sustainable Construction ◽

Cement Concrete ◽

Carbonation Resistance ◽

Shrinkage And Creep ◽

Binder Ratio ◽

Reference Curves ◽

Long Lifetime ◽

Formulation Parameters

The sustainability concerns of concrete construction are focused both on the materials’ eco-efficiency and on the structures’ durability. The present work focuses on the characterization of low cement concrete (LCC), regarding time-dependent and durability properties. LCC studies which explore the influence of the formulation parameters, such as the W/C (water/cement ratio), W/Ceq, (which represents the mass ratio between water and equivalent cement), W/B (water/binder) ratio, and the reference curves, on the aforementioned properties are limited. Thus, several LCC mixtures were formulated considering two dosages of binder powder, 350 and 250 kg/m3, the former with very plastic consistency and the latter with dry consistency, which were combined with a large spectrum of cement replacement rates (up to 70%), through adding fly ash and limestone filler, and with different compactness levels. The main objectives were to study the influence of the formulation parameters on the properties: shrinkage and creep, accelerated carbonation and water absorption, by capillarity, and by immersion. The lifetime of structures produced with the studied LCC was estimated, considering the durability performance, regarding the carbonation effect on the possible corrosion of the steel reinforcement. LCC mixtures with reduced cement dosage and high compactness, despite the high W/C ratios, have low shrinkage and those with higher strength have reduced creep, however depending on W/Ceq ratio. Those mixtures can be formulated and produced presenting good performance regarding carbonation resistance and, consequently, a long lifetime, which is mandatory for a sustainable construction. LCC with 175 kg/m3 of cement dosage is an example with higher lifetime than current concrete with 250 kg/m3 of cement; depending on the XC exposure classes (corrosion induced by carbonation), the amount of cement can be reduced between 37.5% and 42%, since the LCC with 175 kg/m3 of cement allows reducing the concrete cover below the minimum recommended, ensuring simultaneously the required lifetime for current and special structures.

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

Anti-Corrosion Methods and Materials ◽

10.1108/acmm-03-2012-1156 ◽

2013 ◽

Vol 61 (1) ◽

pp. 32-37 ◽

Cited By ~ 3

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.

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The Application Research of Reinforced Concrete Multi-Ribbed Hollow Composite Slab in the Road Slab Culvert

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.368-373.307 ◽

2011 ◽

Vol 368-373 ◽

pp. 307-311

Author(s):

Dong Qi Zhao ◽

Yi Jun Tang ◽

Hui Li ◽

Gui Feng Song ◽

Feng Ling Guan

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Concrete Cover ◽

Reinforced Concrete Beams ◽

Application Research ◽

Composite Slab ◽

The Road ◽

High Integrity ◽

Cover Design ◽

Bottom Slab

Reinforced concrete cover in the road culvert cover design, in order to facilitate the construction, usually using precast reinforced concrete solid slab, but the overall cost is not low. This article researched a reinforced concrete multi-ribbed hollow composite slab, it based on the theory of reinforced concrete multi-ribbed slab structures, using a precast reinforced concrete ribbed slab as the bottom die, then poured reinforced concrete beams and panels rib ,and them constituted a whole stack of reinforced concrete ribbed hollow slab. This kind of cover, compared with the precast reinforced concrete solid cover, is not only good mechanical properties, high integrity, but also saving concrete, steel, and bottom slab appeared smooth and fine, lower construction cost.

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