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Enhanced Entrained Air Void System Characterization For Durable Highway Concrete
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Book Synopsis Enhanced Entrained Air Void System Characterization for Durable Highway Concrete by : Anthony Torres
Download or read book Enhanced Entrained Air Void System Characterization for Durable Highway Concrete written by Anthony Torres and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The air void system in concrete provides a strong influence on the behavior of cementitious materials in both the fresh and hardened state, especially as it relates to freeze-thaw resistance and deicer scaling. The most common test procedure to characterize the air void system is ASTM C457 – Standard Test method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete, which involves microscopic determination of the air content, paste content, air-void size distribution, and spatial dispersion of a sawn concrete sample. This procedure is reliant on the user to make hundreds of critical decisions per sample, which requires significant time, and is potentially subject to human error. Additionally, ASTM C457 provides minimal guidance regarding the exact steps and equipment necessary to prepare a sample for evaluation. The outcome of this research not only provides specific information regarding sample preparation for hardened concrete air void analysis, it also develops an alternative characterization technique that drastically minimizes evaluation time, human error, and increases reliability of key hardened air void characterization parameters. Specific results show on average air void difference of 0.5% and 0.7% between the alternative method versus ASTM C457 Procedure A and B, respectively. The results also show a significant reduction of analysis time from approximately 2 – 4 hours per sample to 15 minutes per sample when using the alternative method.
Book Synopsis Entrained Air-Void System For Durable Highway Concrete by : Siamak Riyazi
Download or read book Entrained Air-Void System For Durable Highway Concrete written by Siamak Riyazi and published by . This book was released on 2020 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the US, the most commonly used F-T test method is AASHTO T 161 “A.” The equipment for variant A of the test is relatively low cost (~$22, 000) and compact. The relatively low cost stems from the basic construction of a refrigerant-based cooling system and resistive heating elements. These units are easily repaired by conventionally trained heating and air conditioning technicians and economically modified using readily available controls. Consequently, proposed factors and modifications to the test method are based on this piece of equipment. Sufficient background information exists in the research literature and current global applications to recommend improvements/modifications to the F-T test method, such as changes to the cooling rate, degree of saturation, and sample conditioning method. Based on an analysis of significant factors reported in the literature, in this study, a series of procedural and functional changes were proposed to better describe F-T durability as a function of the air void system. These changes include: 1- Procedural modifications including longer curing times to better encompass requirements for higher SCM mixtures and the introduction of a drying period to better simulate actual field exposure conditions, 2- Functional modifications including introducing water through capillary suction and changing the freezing solution to incorporate deicing salts, 3- A combination of modification approaches including application of a concentrated pre-storm brine followed by drying.The F-T research was performed in three phases. The first phase involved calibration and modification of the AASHTO T 161 “A” freeze-thaw cabinet using the proposed CDF-A procedure. A modification procedure was developed, and an appendix to the final report was described the steps taken to achieve the desired test requirements. The second phase involved evaluating three separate variants of the proposed test not encompassed by current test methods including the impact of curing time, deicer type, and deicer pretreatment. The third phase involved evaluating a wide range of concrete samples with varying levels and qualities of air systems.
Book Synopsis Evaluating Air-entraining Admixtures for Highway Concrete by : Mohamad Nagi
Download or read book Evaluating Air-entraining Admixtures for Highway Concrete written by Mohamad Nagi and published by Transportation Research Board. This book was released on 2007 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This report presents a recommended procedure for evaluating air-entraining admixtures used in highway concrete. The procedure involves the testing of non-air-entrained concrete and concrete containing the air-entraining admixture under simulated field conditions. Criteria are proposed for acceptance of admixtures for use in either highway pavements or structures. The recommended procedure and acceptance criteria will guide materials engineers in evaluating and selecting air-entraining admixtures that should contribute to appropriate freeze-thaw durability and thus to good performance and long service life. The content of the report will be of immediate interest to materials engineers, researchers, and others concerned with the design of concrete mixtures for use in highway pavements and structures."--taken from Foreword, page [v].
Book Synopsis Control of Air Content in Concrete by : David Whiting
Download or read book Control of Air Content in Concrete written by David Whiting and published by Transportation Research Board National Research. This book was released on 1983 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of the Air Void System in Concrete Using Thermography by : Chao Xiao
Download or read book Characterization of the Air Void System in Concrete Using Thermography written by Chao Xiao and published by . This book was released on 2010 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis INFLUENCE OF AIR-VOID SYSTEM ON FREEZE-THAW DURABILITY OF CONCRETE. by : ZAFAR AHMED MALIK
Download or read book INFLUENCE OF AIR-VOID SYSTEM ON FREEZE-THAW DURABILITY OF CONCRETE. written by ZAFAR AHMED MALIK and published by . This book was released on 1991 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-way analysis of variance showed that type of air entraining agent, quality of aggregate, and content of condensed silica fume have a major effect on freeze-thaw durability of concrete.
Book Synopsis Jahresstatistik über die Kriegsopferversortung... 1959- by :
Download or read book Jahresstatistik über die Kriegsopferversortung... 1959- written by and published by . This book was released on 1959 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of Air-void System in Hardened Concrete from a Three-dimensional Perspective by :
Download or read book Analysis of Air-void System in Hardened Concrete from a Three-dimensional Perspective written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laboratory Investigation of Air-void Systems Produced by Air-entraining Admixtures in Fresh and Hardened Mortar by : Daniel Stephen Lane
Download or read book Laboratory Investigation of Air-void Systems Produced by Air-entraining Admixtures in Fresh and Hardened Mortar written by Daniel Stephen Lane and published by . This book was released on 2006 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The air-void systems produced by two commercially available air-entraining admixtures (AEA), one a vinsol resin formulation and the other a tall oil formulation, were studied in mortars. Mortars were composed of four different portland cements and two Class F fly ashes (20 percent by mass) with concrete sand. The mortar proportions were based on Virginia Department of Transportation Class A4 concrete with a water-cementitious material ratio of 0.45. Foam index tests were conducted on all cementitious combinations, and the results were used to determine the dosage of AEA in the mortars. The air content of the mortars was determined gravimetrically, and specimens were cast for subsequent linear traverse analysis of the air-void system. With both AEAs, mortar air contents in the target range produced spacing factors much lower than necessary to provide resistance to freezing and thawing, suggesting that the ranges for air content currently used in VDOT specifications could be reduced to lessen the potential for acceptance problems associated with excessive air content. Further study is recommended to verify that the relationships observed in this study are also observed in concrete and to define improved air content specifications.
Book Synopsis Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020) by : José Sena-Cruz
Download or read book Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020) written by José Sena-Cruz and published by Springer Nature. This book was released on 2021-07-13 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers peer-reviewed contributions presented at the 3rd RILEM Spring Convention and Conference, held at Guimarães and hosted by the University of Minho, Portugal, on March 9-14, 2020. The theme of the Conference was “Ambitioning a Sustainable Future for Built Environment: comprehensive strategies for unprecedented challenges”, which was aimed at discussing current challenges and impacts of the built environment on sustainability. The present volume is dedicated to the topic “Service life extension of existing structures”, which covers the most recent scientific and technological developments in the understanding of the evolution and degradation of construction materials and structural systems. Analytical and numerical, as well as experimental approaches, aimed at characterizing, modelling and predicting the evolution of the physical, chemical and mechanical properties of construction materials and structural systems are regarded. Multiphysics models are also considered, as well as other strategies that contribute for an accurate characterization and prediction the service life and the evolution of existing and novel construction materials under normal or extreme environmental exposure or loading conditions. New strategies to promote the smart repairing or the recovery of material properties, as well as the service life extension, are also considered. The following subtopics are included: service life models and multiphysics approaches; smart structures, innovative monitoring and intervention strategies; management and optimized maintenance strategies; integrated rehabilitation and strengthening approaches.
Book Synopsis The Effect of Entrapped Air on Air-void System Parameters in Hardened Concrete by : John T. Price
Download or read book The Effect of Entrapped Air on Air-void System Parameters in Hardened Concrete written by John T. Price and published by . This book was released on with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Expanded Study on the Effects of Aggregate Coating and Films on Concrete Performance by :
Download or read book Expanded Study on the Effects of Aggregate Coating and Films on Concrete Performance written by and published by . This book was released on 2007 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Standard Method of Test for Characterization of the Air-void System of Freshly Mixed Concrete by the Sequential Pressure Method by :
Download or read book Standard Method of Test for Characterization of the Air-void System of Freshly Mixed Concrete by the Sequential Pressure Method written by and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This method covers determination of the air content and sequential air method (SAM) number of freshly mixed concrete from observation of the change in volume of concrete with a sequential change in test pressure. This method is intended for use with concretes and mortars made with aggregates for which the aggregate correction factor can be satisfactorily determined by the technique described in Section 7. It is not applicable to concretes made with light-weight aggregates, air-cooled blast-furnace slag, or other aggregates with high porosity. This test method is also not applicable to nonplastic fresh concrete such as is commonly used in the manufacture of pipe and concrete masonry units.
Book Synopsis Durability of Concrete in Cold Climates by : M. Pigeon
Download or read book Durability of Concrete in Cold Climates written by M. Pigeon and published by CRC Press. This book was released on 2014-04-21 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive and authoritative review of durability of the frost resistance of concrete. It will enable both concrete materials specialists and practising engineers to better understand the deterioration processes which take place during freezing and thawing, and the effects of de-icing salts on concrete. It shows how test pro
Book Synopsis The Practical Application of a Flatbed Scanner for Air-Void Characterization of Hardened Concrete by : Karl Peterson
Download or read book The Practical Application of a Flatbed Scanner for Air-Void Characterization of Hardened Concrete written by Karl Peterson and published by . This book was released on 2009 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past 30 years, with the advent of computers and digital imaging, many automated systems have been introduced for the purpose of air-void characterization. The majority of the systems employs a contrast-enhancement procedure where a polished cross-section of concrete is darkened with paint, and white powder is forced into the depressions left by air-voids. The system described here follows the same approach and uses a flatbed scanner to collect a single digital image of the entire sample. For all of the systems based on contrast enhancement, the first step is to select a threshold level. Image pixels brighter than the threshold level represent air and image pixels darker than the threshold level represent non-air (i.e., paste or aggregate). Further digital processing steps may be employed but the initial selection of threshold level exerts a strong influence on whether a pixel in the final data set is classified as air or non-air. A systematic approach for threshold determination has been proposed based on an iterative procedure that compares automatically determined air-void parameters to manually determined air-void parameters from a set of training specimens. The calibration procedure finds a single optimum threshold level for the automated system that is to be used for all subsequent analyses. The approach was tested on a population of 88 specimens with manually determined air-void parameters, with the goal of determining an appropriate value for the number of training specimens.
Book Synopsis Evaluation of the Critical Air-Void System Parameters for Freeze-Thaw Resistant Ternary Concrete Using the Manual Point-Count and the Flatbed Scanner Methods by : Mateusz Radlinski
Download or read book Evaluation of the Critical Air-Void System Parameters for Freeze-Thaw Resistant Ternary Concrete Using the Manual Point-Count and the Flatbed Scanner Methods written by Mateusz Radlinski and published by . This book was released on 2010 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research was conducted to verify whether the semi-automatic method of air-void system characterization (using a flatbed scanner) could be used in lieu of the manual (ASTM C457) method. This research objective was accompanied by evaluating the critical air-void system parameters required to ensure freeze-thaw resistance of ternary concrete containing ordinary portland cement (OPC), 20 % of fly ash (FA), and 5 % of silica fume (SF). It was observed that, due to adverse effect of high superplasticizer dosage on air-void system quality (particularly on specific surface), the majority of high slump ternary mixtures exhibited poor freeze-thaw resistance, even if spacing factor was below the 0.20 mm recommended value. However, when the ternary mixtures were prepared with slump below the limit commonly specified for bridge deck applications (190 mm), the critical air-void system parameters of the OPC/FA/SF concrete were comparable to those typically associated with adequate quality air-void system in conventional concrete. Furthermore, since the critical value of specific surface was independent of slump (i.e., superplasticizer dosage), specific surface appeared to be more objective and reliable predictor of freeze-thaw resistance than spacing factor. When comparing the semi-automatic and manual methods of air-void system characterization, a reasonably strong agreement was obtained for such parameters as air content, void frequency, and spacing factor. Although the results of these methods did not match perfectly, the data suggested that the flatbed scanner technique could be efficiently used for discerning between freeze-thaw durable and non-durable concretes.
Book Synopsis Properties of Air Bubbles in Air Entrained Concrete by : Le Tuan Pham
Download or read book Properties of Air Bubbles in Air Entrained Concrete written by Le Tuan Pham and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is widely accepted that air entrainment, a purposeful introduction of small air bubbles in concrete, is critical to the long-term durability of concrete in freeze-thaw environments. Air entraining admixtures (AEA) are added to the mixture to stabilize air bubbles created during mixing, ensuring a proper air void system in the hardened concrete. Despite the complexity of creating a suitable air void system in concrete, previous study and experience established the reliability and robustness of such systems under a variety of conditions through use of neutralized vinsol resin (NVR) AEA products. In recent years, synthetic AEAs have been used more frequently due to limited supply of NVR to the concrete industry. With the use of synthetic AEAs, there are more reports of new problems including difficulties in accurately measuring the air content. This study was conducted to find the root cause of the increasing difficulties in controlling the air contents in portland cement concrete associated with synthetic AEAs. Main challenges included the lack of existing techniques to evaluate AEAs and air bubbles in concrete, and lack of data to help identify causes. Given these challenges, a multi-scale experimental study that included testing of field and laboratory concrete, and testing of foam and individual air bubbles was undertaken. The results indicate that the disparity between QC test results and the actual air contents in concrete pavements associated with the use of synthetic AEAs could be attributed to less robust air bubbles stabilized with synthetic AEAs compared to those entrained with NVR and the resulting increased loss of these air bubbles during concrete sampling. The cause of this decreased robustness and resulting air loss was traced directly to the properties of the bubble shells. The shells of air bubbles in concrete entrained with synthetic AEAs were thinner and less stiff than those associated with an NVR AEA. Through this research new test protocols were developed to measure stiffness and thickness of the shell of air bubbles extracted from cement paste and to quantify stability of foams of AEAs in a cementitious environment. These tests could be used by researchers and practitioners who are interested in developing new admixtures and/or identifying admixtures with undesirable performance.
