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Effect Of Self Consolidating Concrete Scc Mix Proportioning On Transfer And Development Length Of Prestressingstrands
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Book Synopsis Effect of Self Consolidating Concrete (SCC) Mix Proportioning on Transfer and Development Length of Prestressingstrands by : Mahmoodul Haq
Download or read book Effect of Self Consolidating Concrete (SCC) Mix Proportioning on Transfer and Development Length of Prestressingstrands written by Mahmoodul Haq and published by . This book was released on 2005 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigating the Bond of Prestressing Strands in Lightweight Self-consolidating Concrete by : Royce Woodrow Floyd
Download or read book Investigating the Bond of Prestressing Strands in Lightweight Self-consolidating Concrete written by Royce Woodrow Floyd and published by . This book was released on 2012 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lightweight self-consolidating concrete (LWSCC) is a relatively recent advancement in concrete technology. The reduced dead load from lightweight concrete is beneficial for precast elements and for elements where dead load is a significant portion of the total load, such as prestressed bridge girders. Self-consolidating concrete (SCC) is a specially proportioned concrete mixture that consolidates under its own weight without the need for vibration. The combination of lightweight concrete and self-consolidating behavior provides the benefits of both. Bond of prestressing steel has been a much debated topic since the 1950s. Limited data are available on the transfer and development length of strands cast in SCC and even less for strands cast in LWSCC. The differences in material properties resulting from the lightweight coarse aggregate and mix proportioning used for LWSCC have potential to lead to longer transfer and development lengths than those for conventional concrete, which can be detrimental to shear and flexural performance. The transfer and development length equations provided in the ACI Building Code Requirements for Structural Concrete and AASHTO Bridge Design specifications are based on studies performed using conventional concrete. This research project examined the transfer and development length of LWSCC specimens using 0.6 in. (15.2 mm) Grade 270 prestressing strand. Four specimens were cast from each mixture consisting of a combination of expanded clay, expanded shale, or limestone aggregate and a compressive strength of 4000 psi or 6000 psi (28 MPa or 41 MPa) at prestress release. Results were compared between the mixtures, to the code equations, and to previous research. The bond performance of LWSCC with a release strength of 6000 psi (41 MPa) was very similar to normal weight SCC, the transfer lengths for both strength levels were accurately predicted by the code equations, and the measured development lengths were significantly less than those predicted.
Book Synopsis Bond, Transfer Length, and Development Length of Prestressing Strand in Self-consolidating Concrete by : Krista Beth Porterfield
Download or read book Bond, Transfer Length, and Development Length of Prestressing Strand in Self-consolidating Concrete written by Krista Beth Porterfield and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Due to its economic advantages, the use of self-consolidating concrete (SCC) has increased rapidly in recent years. However, because SCC mixes typically have decreased amounts of coarse aggregate and high amounts of admixtures, industry members have expressed concerns that the bond of prestressing strand in SCC may be compromised. While the bond performance of prestressing strand in a new material such as SCC is an important topic requiring investigation, the results are only applicable if the research is completed on strands with similar bond quality as the strands used in the field. Therefore, the objectives of this research program were to investigate the transfer and development lengths of prestressing strand in SCC and also evaluate the effectiveness of two proposed bond tests in determining acceptable bond quality of strand. Transfer and development lengths of 0.5-in. diameter (12.5 mm), Grade 270 prestressing strand were evaluated using rectangular beams constructed from normal and high strength conventional concrete and SCC mixes. End slips at release and strain readings over 28 days were used to calculate transfer lengths, and development lengths were evaluated through four-point loading at varying embedment lengths. Additionally, the NASP bond test and Large Block Pullout Tests (LBPT) were evaluated with strand from three different sources to determine if one test could be considered more reliable at predicting acceptable bond. Results indicated that bond performance of SCC and conventional concrete were comparable, and that AASHTO and ACI equations for transfer and development length were generally conservative. The NASP bond test and LBPT were found to be equally valid, but the acceptance limits for both tests appear to require revisions"--Abstract, leaf iii
Book Synopsis Bond Strength of Self-consolidating Concrete for Prestressed Concrete Applications by : Amgad F. Girgis
Download or read book Bond Strength of Self-consolidating Concrete for Prestressed Concrete Applications written by Amgad F. Girgis and published by . This book was released on 2004 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Self-consolidating Concrete for the Design of Precast, Pretensioned Bridge Superstructure Elements by : Young Hoon Kim
Download or read book Characterization of Self-consolidating Concrete for the Design of Precast, Pretensioned Bridge Superstructure Elements written by Young Hoon Kim and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-consolidating concrete (SCC) is a new, innovative construction material that can be placed into forms without the need for mechanical vibration. The mixture proportions are critical for producing quality SCC and require an optimized combination of coarse and fine aggregates, cement, water, and chemical and mineral admixtures. The required mixture constituents and proportions may affect the mechanical properties, bond characteristics, and long-term behavior, and SCC may not provide the same inservice performance as conventional concrete (CC). Different SCC mixture constituents and proportions were evaluated for mechanical properties, shear characteristics, bond characteristics, creep, and durability. Variables evaluated included mixture type (CC or SCC), coarse aggregate type (river gravel or limestone), and coarse aggregate volume. To correlate these results with full-scale samples and investigate structural behavior related to strand bond properties, four girder-deck systems, 40 ft (12 m) long, with CC and SCC pretensioned girders were fabricated and tested. Results from the research indicate that the American Association of State Highway Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Specifications can be used to estimate the mechanical properties of SCC for a concrete compressive strength range of 5 to 10 ksi (34 to 70 MPa). In addition, the research team developed prediction equations for concrete compressive strength ranges from 5 to 16 ksi (34 to 110 MPa). With respect to shear characteristics, a more appropriate expression is proposed to estimate the concrete shear strength for CC and SCC girders with a compressive strength greater than 10 ksi (70 MPa). The author found that girder-deck systems with Type A SCC girders exhibit similar flexural performance as deck-systems with CC girders. The AASHTO LRFD (2006) equations for computing the cracking moment, nominal moment, transfer length, development length, and prestress losses may be used for SCC girder-deck systems similar to those tested in this study. For environments exhibiting freeze-thaw cycles, a minimum 16-hour release strength of 7 ksi (48 MPa) is recommended for SCC mixtures.
Book Synopsis Aggregates in Self-consolidating Concrete by : Eric Patrick Koehler
Download or read book Aggregates in Self-consolidating Concrete written by Eric Patrick Koehler and published by . This book was released on 2007 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-consolidating concrete (SCC) is an advanced type of concrete that can flow under its own mass without vibration, pass through intricate geometrical configurations, and resist segregation. SCC constituent materials and mixture proportions must be properly selected to achieve these flow properties. The effects of any changes in materials or mixture proportions on hardened concrete performance must be considered in evaluating SCC. A research project was conducted to investigate the role of aggregates in SCC. The objectives of this research were to evaluate the effects of aggregate characteristics and mixture proportions on the workability and hardened properties of SCC, to identify favorable aggregate characteristics for SCC, and to develop guidelines for proportioning SCC with any set of aggregates. The research indicated that although SCC can be proportioned with a wide range of aggregates, the selection of favorable aggregates can significantly enhance the economy and performance of SCC. The effects of aggregate grading; maximum size; shape, angularity, and texture; apparent clay content; and packing density were evaluated. The main effect of aggregates larger than approximately 75 [mu]m was found to be on the minimum required paste volume for achieving SCC workability. It was found that dust-of fracture microfines, defined as mineral material finer than approximately 75 [mu]m produced during the crushing of aggregates, could be an economical choice to comprise part of the paste volume. Based on the results of this research, a mixture proportioning procedure for SCC was developed. The procedure is based on a consistent, rheology-based framework and was designed and written to be accessible and comprehensible for routine use. In the procedure, SCC is represented as a suspension of aggregates in paste. Aggregates are selected on the basis of grading, maximum size, and shape and angularity. The paste volume is set based on the aggregate characteristics in order to achieve workability requirements. The paste composition is established to achieve workability and hardened property requirements.
Book Synopsis Self-consolidating Concrete, Applications for Slip Form Paving by : Kejin Wang
Download or read book Self-consolidating Concrete, Applications for Slip Form Paving written by Kejin Wang and published by . This book was released on 2005 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over-consolidation is often visible as longitudinal vibrator trails in the surface of concrete pavements constructed using slip-form paving. Concrete research and practice have shown that concrete material selection and mix design can be tailored to provide a good compaction without the need for vibration. However, a challenge in developing self-consolidating concrete for slip-form paving (SF SCC) is that the new SF SCC needs to possess not only excellent self-compactibility and stability before extrusion, but also sufficient "green" strength after extrusion, while the concrete is still in a plastic state. The SF SCC to be developed will not be as fluid as the conventional SCC, but it will (1) be workable enough for machine placement, (2) be self-compacting with minimum segregation, (3) hold shape after extrusion from a paver, and (4) have performance properties (strength and durability) compatible to current pavement concrete. The overall objective of this project is to develop a new type of SCC for slip-form paving to produce more workable concrete and smoother pavements, better consolidation of the plastic concrete, and higher rates of production. Phase I demonstrated the feasibility of designing a new type of SF SCC that can not only self-consolidate, but also have sufficient green strength. In this phase, a good balance between flowability and shape stability was achieved by adopting and modifying the mix design of self-consolidating concrete to provide a high content of fine materials in the fresh concrete. It was shown that both the addition of fine particles and the modification of the type of plasticizer significantly improve fresh concrete flowability. The mixes used in this phase were also found to have very good shape stability in the fresh state. Phase II will focus on developing a SF SCC mix design in the lab and a trial of the SF SCC in the field. Phase III will include field study, performance monitoring, and technology transfer.
Book Synopsis Effect of Mix Parameters on Restrained Shrinkage of Self Consolidating Concrete by : Carl Fleurimond
Download or read book Effect of Mix Parameters on Restrained Shrinkage of Self Consolidating Concrete written by Carl Fleurimond and published by . This book was released on 2011 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self Compacting Concrete (SCC) is a relatively new type of concrete that flows under its own self weight. In order for the concrete to achieve the SCC properties, an increased amount of cementitious material is needed. Increased amount of cementitious content is known to lead to increased amount of shrinkage, which in turn leads to cracking of concrete. The shrinkage of concrete is the main cause of cracking in bridge decks. Bridge decks tend to be restrained from shrinkage, and this restraint along with other factors causes the bridge to crack. The characteristics of SCC under restrained shrinkage are important to understand in order to predict the cracking behavior in actual structures. Mechanical properties testing of compressive strength, tensile strength, and elastic modulus are performed on each concrete mix. Restrained shrinkage testing is done in accordance to AASHTO testing protocol. Cracking patterns are observed due to changes in mixing parameters. The free shrinkage performance and cracking behavior were reported and compared when changing the sand to aggregate ratio and the water to cement ratio. The results showed that the sand to aggregate ratio between the limits of .45 to .55 had little effect on the cracking potential of the SCC mixes. Each of the mixes cracked within a couple days of one another. The water to cement ratio showed that as the water to cement ratio increases, cracking also increases. Free shrinkage specimens were used to correlate the free shrinkage to the cracking behavior of the mixes. Every mix contained 850 lbs of cementitious material (75% Portland type I cement, 20% Fly Ash, and 5% Silica Fume). The results of free shrinkage show that when a mix design has higher free shrinkage, it will crack in restrained shrinkage earlier than a mix with lower free shrinkage.
Book Synopsis Development and Testing of Chemically-based Self-consolidating Concrete by : Mark Daniel Ezzell
Download or read book Development and Testing of Chemically-based Self-consolidating Concrete written by Mark Daniel Ezzell and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Self-consolidating concrete (SCC) possesses several characteristics that can benefit the concrete construction industry including accelerated construction, a reduction in labor and equipment, and a reduction in construction noise through eliminating or reducing the need to vibrate the concrete. However, SCC has some potential downsides. These problems can usually be attributed to higher paste content, higher fines content, rounder aggregate, and higher water to cement (w/c) ratios used to increase the flow of the concrete. The goal of this research project was to develop a SCC that had improved material properties through the use of chemical admixtures instead of modifications to the mix proportions. After the SCC was developed, the material properties were compared to a more traditional or normal concrete (NC) mixture. Both the SCC and NC underwent testing of fresh and hardened properties. The SCC underwent the following tests: slump flow, J-ring, L-box, and segregation column. These tests aided with mixture proportioning and optimization. After the SCC mix design was selected, material properties were tested and compared for both NC and SCC. These tests included: compressive strength, modulus of rupture, shrinkage, and shear strength. These properties were compared between the two types of concrete and also with empirical models and design code provisions"--Abstract, leav iii
Book Synopsis Self-consolidating Concrete (SCC) Structural Investigation by :
Download or read book Self-consolidating Concrete (SCC) Structural Investigation written by and published by . This book was released on 2005 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Influence of Mix Design Parameters on Dynamic Segregation of Self-consolidating Concrete and Consequences on Performance of Precast Beams by : Aida Margarita Ley Hernandez
Download or read book Influence of Mix Design Parameters on Dynamic Segregation of Self-consolidating Concrete and Consequences on Performance of Precast Beams written by Aida Margarita Ley Hernandez and published by . This book was released on 2016 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Self-Consolidating Concrete (SCC) is more vulnerable to stability problems as a consequence of its high flowing ability compared to conventional vibrated concrete. Dynamic segregation refers to the tendency of the concrete constituents to separate from the suspended matrix, usually in horizontal direction while being cast into the formwork or due to an impact. Similarly to static segregation, dynamic segregation can affect the homogeneity of SCC. Therefore, it is highly essential to ensure a proper dynamic stability in order to enhance the uniformity of in-situ properties of pre-stressed beams. In this research project, the effects of SCC mix design parameters are investigated using the T-box test as a method to assess dynamic segregation. Changes in chemical admixture type and content, paste volume, sand-to-total aggregate ratio (S/A), w/cm and the width of the T-box have been evaluated. The results show that dynamic segregation of SCC is dependent on the rheological properties of the concrete, paste volume and S/A. In a second part, the influence of dynamic segregation on the uniformity of precast, pre-stressed beams is investigated. Six 9 m and three 18 m long beams were produced with SCC. To determine the uniformity of the mixture, a comparative survey across the beam height and along its length was performed. Also, the bond strength of pre-stress strands with SCC was investigated. Results from the UPV and compressive strength demonstrate a variation in the uniformity of the concrete, mainly at the casting point. For the bond strength, with increasing dynamic segregation, the bond between the strand and the concrete at the top 1/3rd of the beam height, relative to the bond in the middle 1/3rd, decreases"--Abstract, page iii.
Book Synopsis Development of Self-consolidating Concrete for Slip Form Paving by : Gang Lu
Download or read book Development of Self-consolidating Concrete for Slip Form Paving written by Gang Lu and published by . This book was released on 2005 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a new type of self-consolidating concrete for slip-form paving (SF SCC) was developed. Effects of materials and mix proportions on fresh concrete compact-ability, flow-ability, and shape stability were studied. Type I cement and class C and F fly ashes were used as cementitious materials. Air-entraining agent (AEA), viscosity modifying admixture (VMA), and superplasticizer were employed as admixtures. Normal river sand and limestone were utilized as aggregate. A total of 46 concrete mixes were studied, and non-rodding slump flow test, modified compaction factor test, IBB rheometer test, and "green" strength tests were performed for the concrete mixtures. In addition, a "mini-paver" was developed to simulate the field SF SCC paving in laboratory. The study has demonstrated that by engineering concrete materials and mix proportions, it is feasible to develop a new type of SCC for slip form paving application. Concrete mixtures having a compaction factor of approximate 1.0, slump of approximated 8", and spread of approximated 12" displayed not only to be able to self-compact but also to hold its shape right after placement. The test results also indicated that concrete compactibility increased but stability decreased with flow-ability. There was a nonlinear relationship between slump and spread for the concrete mixtures tested. The interception obtained from the IBB tests (similar to yield stress of the mixtures) had a good relationship with not only slump but also "green" strength of concrete.
Download or read book PCI Journal written by and published by . This book was released on 2009 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seventh International Symposium on Utilization of High Strength/ High Performance Concrete by : H. G. Russell
Download or read book Seventh International Symposium on Utilization of High Strength/ High Performance Concrete written by H. G. Russell and published by . This book was released on 2005 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Prestress Losses in Pretensioned High-strength Concrete Bridge Girders by : Maher K. Tadros
Download or read book Prestress Losses in Pretensioned High-strength Concrete Bridge Girders written by Maher K. Tadros and published by Transportation Research Board. This book was released on 2003 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The HCM includes three printed volumes (Volumes 1-3) that can be purchased from the Transportation Research Board in print and electronic formats. Volume 4 is a free online resource that supports the rest of the manual. It includes: Supplemental chapters 25-38, providing additional details of the methodologies described in the Volume 1-3 chapters, example problems, and other resources; A technical reference library providing access to a significant portion of the research supporting HCM methods; Two applications guides demonstrating how the HCM can be applied to planning-level analysis and a variety of traffic operations applications; Interpretations, updates, and errata for the HCM (as they are developed);A discussion forum allowing HCM users to ask questions and collaborate on HCM-related matters; and Notifications of chapter updates, active discussions, and more via an optional e-mail notification feature."--Publisher.
Book Synopsis Self-compacting Concrete by : Geert De Schutter
Download or read book Self-compacting Concrete written by Geert De Schutter and published by . This book was released on 2008 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the only book to offer a systematic and comprehensive source of information on SCC technology from its inception to latest developments. It is also the first book that enables engineers and architects to readily appreciate the full capabilities and potential of SCC.
Book Synopsis Self-consolidating Concrete for Precast, Prestressed Concrete Bridge Elements by : Kamal Khayat
Download or read book Self-consolidating Concrete for Precast, Prestressed Concrete Bridge Elements written by Kamal Khayat and published by Transportation Research Board. This book was released on 2009 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: At head of title: National Cooperative Highway Research Program.
