Download or read book Evaluation of the Effect of Chloride Ingress and Freeze Thaw Cycles on Electrical Resistivity of Reinforced Concrete written by David Esteban Rodriguez Matiz and published by . This book was released on 2015 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Performing bridge inspections can be a very daunting task for every department of transportation (DOT) in the country. Because the leading cause of deterioration in reinforced concrete bridge decks is corrosion of the steel reinforcement, the ability to detect the concentration of corrosion-causing chlorides in the concrete, using a non-destructive method, would save DOTs time and resources by allowing reparative action to take place early in the deterioration process. These are the contexts in which the current investigation was carried out, with the primary objective of investigating the potential for surface resistivity to be used as a non-destructive tool to assess the deterioration of concrete due to chloride ingress and freeze-thaw action. In this study, electrical resistivity measurements were taken on concrete cylinders and at various locations on reinforced concrete slabs that were saturated with chlorides from commercially available magnesium chloride de-icing solution, which contained a corrosion inhibitor. The study also provides a deeper understanding of the effect of freeze-thaw cycles on chloride ingress and surface resistivity measurements taken on concrete slabs previously exposed to a de-icing solution. Additionally, chloride profiles were taken congruently with the electrical resistivity measurements to monitor the ingress of chlorides. Surface resistivity values for all concrete increased during the early part of the study, partly due to the hydration of the concrete. However, surface resistivity decreased at the latter half for the chloride-exposed concrete, while water-saturated concrete did not vary. This suggests that SR measurements could identify chloride ingress. As chlorides ingressed in the concrete over time, the amount of bound chlorides increase; however, this increase was dominated by the amount of free chlorides that were retained at a specific depth in the concrete. The increase in free chloride concentrations, which are known to initiate corrosion, may be a cause of the decrease in surface resistivity measurements. This observation was also confirmed by thermodynamic modeling; however, this will need to be studied further. Though the cause of behavior observed on the surface resistivity measurements that underwent freeze-thaw action is not clear, it is evident that freeze-thaw action has a significant negative impact on the rate of chloride ingress on the slabs. The chloride profiles strongly indicated that the penetrability of the OPC mixtures increased compared to the same slab that did not go through freeze-thaw action. An increase in transport of chlorides was not apparent for the HPC mixture and was not seen in the chloride profiles. It is suggested that additional freeze-thaw cycles continue in this study, especially until the concrete starts to fail, in order to evaluate the impact and permanency of deterioration on surface resistivity.
Download or read book Resistance of Concrete to Chloride Ingress written by Luping Tang and published by CRC Press. This book was released on 2011-10-06 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chloride ingress in reinforced concrete induces corrosion and consequent spilling and structural weakness, and it occurs world-wide and imposes an enormous cost. Yet it can be resisted by using test methods and relevant models for service life prediction.Resistance of Concrete to Chloride Ingress sets out current understanding of chloride transport
Download or read book PRO 38 3rd International RILEM Workshop on Testing and Modelling the Chloride Ingress into Concrete written by Carmen Andrade and published by RILEM Publications. This book was released on 2004 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Review of Chloride Ingress Into Structural Concrete written by P. B. Bamforth and published by Thomas Telford. This book was released on 1997-04-10 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: The deterioration of reinforced and prestressed concrete structures resulting from the corrosion of the steel reinforcement is a worldwide problem. As long as salt is used for de-icing or structures are built near the coast, chloride will continue to be a primary factor in compromising the durability of a structure. This report deals specifically with the ingress of salt from the environment, which can lead to severe corrosion of reinforcement. It reviews the international state-of-the-art with regard to chloride ingress into concrete and, in particular, considers: - The influence of concreting materials, mix design, curing and environment - methods for the detection of chloride ingress in structures - techniques used for studying chloride ingress
Download or read book The Effect of Chloride and Sulfate Ions on the Resistivity of Concrete written by Omar Shaikhon and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Electrical resistivity measurement is proving to be an essential tool for the durability assessment of concrete. It was mainly developed to assess reinforcement corrosion since moisture and chloride ingress are both factors that affect resistivity. The current method in use, the rapid chloride permeability (RCP) test, is outdated as specimen preparation is labor-intensive and the test is time-consuming. Resistivity measurement is the better alternative as it is non-destructive and comparatively faster, cheaper, and easier to use, as well as being more reliable. Due to the electrical nature of resistivity measurements, the presence of ions in contaminated concrete can alter resistivity measurements. The primary objective of this thesis was to study the effect of chloride and sulfate ions on the resistivity of concrete. Sodium chloride and anhydrous sodium sulfate were used to achieve the required concentration of chlorides or sulfates, respectively. Tests were conducted on specimens with increasing concentration, where each individual specimen had a constant concentration throughout, and on specimens with a concentration gradient. The resistivity measurement techniques utilized were surface resistivity using a Wenner array and bulk resistivity. Surface resistivity was performed on the cylinders as well as on the split faces after the cylinder has undergone a splitting tensile strength test. The effect of water-to-cement ratio (w/c) and the geometric proportions of the cylinder on the resistivity were also studied." --
Download or read book Experimental Investigation of the Effects of Embedded Rebar Cracks Chloride Ingress and Corrosion on Electrical Resistivity Measurements of Reinforced Concrete written by Monica Tiffany Morales and published by . This book was released on 2015 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of steel reinforcement, chloride-induced corrosion initiation, cracking and delamination on the electrical resistivity measurements using the Wenner probe technique were studied experimentally on custom-designed reinforced concrete slabs. Investigation parameters included (1) probe configurations with respect to rebar mesh, (2) rebar density, (3) epoxy coating on the rebar, (4) concrete cover thickness over embedded reinforcement, (5) chloride ingress, (6) corrosion of rebar, (7) crack and delamination properties, (8) probe configurations with respect to a crack, and (9) moisture content of concrete. The concrete moisture condition and cover thickness influenced the effect of rebar mesh. It was theorized that bound chlorides increased electrical resistivity measurements and counteracted the effect of free chlorides. It was observed that epoxy coated rebar did not significantly affect measurements. Uncoated rebar affected resistivity measurements, particularly for saturated and semi-saturated concrete. Conductive cracks had no significant effect or under-measured electrical resistivity and insulative cracks either over-measured or under-measured electrical resistivity. However, surficial microcracking had no significant effect on electrical resistivity measurements. Delamination of the concrete cover was detected by electrical resistivity measurements for small concrete cover thicknesses. Corrosion initiation was observed to have no significant effect on measurements. Larger concrete cover thicknesses provided for more discrepancy between half-cell potential and electrical resistivity measurements. Recommendations to increase electrical resistivity measurement accuracy on reinforced concrete slab surfaces are suggested.
Download or read book PRO 19 2nd International RILEM Workshop on Testing and Modelling the Chloride Ingress into Concrete written by Carmen Andrade and published by RILEM Publications. This book was released on 2001 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Durability Design of Concrete Structures written by Kefei Li and published by John Wiley & Sons. This book was released on 2017-05-01 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive coverage of durability of concrete at both material and structural levels, with design related issues Links two active fields in materials science and structural engineering: the durability processes of concrete materials and design methods of concrete structures Facilitates communication between the two communities, helping to implement life-cycle concepts into future design methods of concrete structures Presents state-of-the-art information on the deterioration mechanism and performance evolution of structural concrete under environmental actions and the design methods for durability of concrete structures Provides efficient support and practical tools for life-cycle oriented structural design which has been widely recognized as a new generation of design philosophy for engineering structures The author has long experience working with the topic and the materials presented have been part of the author's current teaching course of Durability and Assessment of Engineering Structures for graduate students at Tsinghua University The design methods and approaches for durability of concrete structures are developed from newly finished high level research projects and have been employed as recommended provisions in design code including Chinese Code and Eurocode 2
Download or read book An International Review of Chloride Ingress Into Structural Concrete written by P. B. Bamforth and published by . This book was released on 1997 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Freeze Thaw Durability of Concrete written by J. Marchand and published by CRC Press. This book was released on 2004-03-01 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete durability in climates where freezing and thawing occurs is a continuing problem. It is particularly acute for highway and bridge structures, where de-icing salts are used to combat the effects of frost, snow and ice. These salts can cause damage to concrete and accelerate corrosion of reinforcements. This book presents the latest international research on this area, with contributions from North America and Europe which were presented at an international RILEM workshop.
Download or read book ACI Materials Journal written by and published by . This book was released on 2002 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Frost Resistance of Concrete written by R Auberg and published by CRC Press. This book was released on 2004-03-01 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book forms the proceedings of the international workshop to be held in Essen, Germany. This workshop summarises the conclusion of the technical committee's investigations into the resistance of concrete to freeze-thaw attack, specific in this to resistance with or without de-icing chemicals. It presents the RILEM recommendations on testing the freeze-thaw and de-icing salt resistance of concrete.
Download or read book Chloride Ingress Into Reinforced Concrete Sustaining In Service Loads written by Amre Deif and published by LAP Lambert Academic Publishing. This book was released on 2010-10 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this study were to investigate the effect of sustained load on chloride ingress into concrete and to examine the reliability of spraying a AgNO3 solution onto concrete as a quick method to determine chloride penetration. An experimental program was carried out, in which a small-scale RC slab was subjected to wet and dry cycles with a saturated chloride solution while sustaining static service loads. The concrete slab was cast with three strips of different w/c ratios to represent diff- erent field condition. Supports were located to create both positive and negative moment regions in the top mat reinforcement of the slab. Chloride diffusion coefficients were obtained from the data obtained from spraying AgNO3 and titration of core samples taken at different sections of different stress levels at three time intervals, each of them after a wet/dry cycle of 90 days.The comparison between both sets of data reveals that the diff- erences diminish as the time of exposure increases. The chloride diffusivity along the span of the slab, relative to that of an unstressed section, was related to the applied bending moment.
Download or read book Effect of Corrosion Freeze thaw Cycles and Their Combined Effects on the Fatigue Behavior of Reinforced Concrete written by Talal Abdulmalek Radain and published by . This book was released on 1989 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Correlation of Chloride Diffusivity and Electrical Resistance for Cracked Concrete written by Stanley W. Merantus and published by . This book was released on 2017 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: The durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water interfaces of coastal structures. Therefore, chloride diffusivity, which correlates with the electrical resistivity, has a significant impact on the durability of concrete. Concrete chloride diffusivity has been experimented by multiple agencies and researchers on sound concrete, but there is a considerable need for investigation of the durability of cracked concrete in the marine environment. vii The two test methods carried out are presented: Standardized American Society for Testing and Materials (ASTM) C1202 for Rapid Chloride Permeability (RCP) and ASTM D257 for Surface Resistivity (SR), and Nordtest (NT) Build 492 for Rapid Chloride Migration (RCM) and Bulk Resistivity (BR) for both sound (uncracked) and cracked (micro and macro) concrete. The limitations of the ASTM method, due to measurements before the steady-state migration is reached, does not account for leakage in cracked concrete, and the heating of the specimen due to higher current that increase the conductivity are indicated. The Rapid Chloride Migration test provides for the non-steady state of diffusion. Again, Bulk Resistivity, in contradistinction to Surface Resistivity is more accurate for cracked concrete. The correlation betweeen RCM-BR are plotted. Chloride Permeability/Migration is an important parameter that governs the Durability of Concrete. The principal contribution is the highlighting of the inadequacy of the current widely used standard ASTM C1202 for diffusivity testing, and the need for revision with further investigation.
Download or read book Resistivity of Concrete written by Shu-Leung Norman Lee and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Resistivity of Concrete" by Shu-leung, Norman, Lee, 李樹樑, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Cement, a main composition of concrete, is the major contributor to the greenhouse effect. During the production of cement, a significant amount of carbon dioxide is released to the environment. As the world is moving towards a more sustainable environment, the durability of concrete becomes a concern. The durability of concrete can be improved with proper quality control and resistivity measurement is one of the methods used to indicate the quality of concrete. Because of the importance of resistivity, the present study is to achieve a better understanding of the electrical resistivity of concrete. The effect of various concrete mixtures to concrete resistivity is examined in this study. For the evaluation, surface resistivity is measured on 150mm concrete cubes. The concrete mixtures involves different combination of paste volume, W/C ratio, curing condition and supplementary cementitious materials / fillers. The supplementary cementitious materials are pulverised fuel ash (PFA), condensed silica fume (CSF) and the filler is limestone fines (LF). While PFA and CSF are used as cement replacement, the LF is used for the substitution of cement paste. The results have indicated that the electrical resistivity is affected by the paste volume, W/C ratio, curing condition and the combination of PFA, CSF and LF. Concrete resistivity increases as a result of a decrease in paste volume. A strong correlation exists between the W/C ratio and the surface resistivity. The R DEGREES2 = 0.9211 and 1 for 30% and 34% paste volume respectively. Also, the curing condition affect the moisture content of the concrete. The surface resistivity is higher for a drier surface. With the addition of PFA, CSF and LF, the surface resistivity increases significantly. The present study also examines the correlation between surface resistivity and different concrete properties such as compressive strength, moisture content, water penetration and rapid chloride penetration. The results shows that there is a strong correlation between surface resistivity and compressive strength for plain mixtures with R DEGREES2 = 1. However, this correlation decrease with the addition of other cementitious materials. As a result, the correlation would be better for a separated resistivity curve for different cementitious materials. The surface resistivity and the water penetration only has a moderate correlation. For plain mixtures, the correlation value is R DEGREES2 = 0.6814. R DEGREES2 = 0.7069 is the correlation value for concrete mixtures with PFA and CSF. Finally, there is a strong relationship between rapid chloride penetration and the surface resistivity. The surface resistivity is inversely proportional to the rapid chloride penetration with a correlation of R DEGREES2 = 0.9472. Subjects: Concrete - Electric
Download or read book Variability Analysis of the Bulk Resistivity Measured Using Concrete Cylinders written by Robert P. Spragg and published by . This book was released on 2011-11-12 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
