Evaluation Of Self Consolidating Concrete And Class Iv Concrete Flow In Drilled Shafts
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Evaluation Of Self Consolidating Concrete And Class Iv Concrete Flow In Drilled Shafts
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Author :
language : en
Publisher:
Release Date : 2020
Evaluation Of Self Consolidating Concrete And Class Iv Concrete Flow In Drilled Shafts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Corrosion resistant materials categories.
University of South Florida researchers conducted laboratory and field experiments to determine causes and effects of mattressing in drilled shafts and to recommend construction practices that would help prevent this effect.
Evaluations Of Concrete Mix Stability For Below Grade Applications
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Author : Isaiah Vaught
language : en
Publisher:
Release Date : 2020
Evaluations Of Concrete Mix Stability For Below Grade Applications written by Isaiah Vaught and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Drilled shafts are a commonly utilized foundation type for bridge construction, especially for bridges involving large loads or difficult ground conditions. Proper construction is required to ensure satisfactory performance of the shafts, and concrete placement is among the most critical aspects of drilled shaft construction. Concrete has evolved to continuously be effective in the construction of modern drilled shafts as they continue to grow larger. Previous issues with concrete used in drilled shafts included flowability and ensuring the concrete was uniformly spread; these issues have been resolved with the introduction of high performance self-consolidating concrete but has introduced new problems with bleed and segregation. Concrete segregation describes the separation of concrete components causing a non-uniform mix. The term 'bleed' is a type of segregation but is specifically used to describe the separation of water from the concrete mix and can be seen, in varying amounts, rising to the surface of certain concrete pours. Occurrences of bleed and segregation can compromise the integrity of a drilled shaft. The research described in this report was initiated with the objective of quantifying bleed and segregation by addressing three questions: what is the best method to predict and quantify bleed and segregation of a concrete mix, what characteristics of a mix design cause the most bleed and segregation, and what are the consequences of bleed and segregation. A better understanding of concrete bleed and segregation predictors and effects can lead to more reliable drilled shaft concrete mix designs. To analyze these objectives, ten different concrete mixes were used to test and create scaled drilled shafts measuring 4 feet in diameter and 42 inches tall. Each concrete mix was run through a series of quality assurance/control (QA/QC) tests to then compare to data collected while the test shafts were being cured, which includes the total volume of bleed water produced, the bleed water flow rate, peak temperature in the concrete and pore pressures developed in the concrete. When comparing these bleed water test results with QA/QC tests and isolated mix design characteristics, conclusions can be made about the relationship between them. No current criterion exists that characterize what amount of bleed water is considered "excessive", but for this test program 10% of the total water in the test shaft was deemed excessive. Conclusions relating to QA/QC tests predicting bleed water: The ASTM Static Bleed test produced the most consistent results for predicting the amount of bleed a concrete mix would produce on a larger scale, with a cutoff quantifier of 1% bleed water in the test being used to distinguish a bleed prone batch. The Slump, Slump Flow, and Bauer Filter Press tests provide some ability to discriminate between bleed prone concrete mixes, with some exceptions with false positives and negatives. Findings from this research suggest that any mix with values greater than a 10-inch slump, 22-inch slump flow, or 40mL from the 5-minute Bauer test will likely produced excessive bleed. Although these tests are not the most reliable predictors, they are the most practical QA/QC test for concrete bleed at this time. This concludes that the biggest contributor to bleed water within a specific mix is the concrete's relationship with set-up versus time; the only QA/QC test that account for this relationship are the static bleed test and Bauer Filter Press. Conclusions relation to concrete mix design characteristics: A strong relationship exists between peak temperature, time to peak temperature, and the amount of bleed water produced. Both peak temperature and time to peak temperature are consistent predictors of how much bleed water is being produced in the concrete mix. Bleed water produced increases as time to peak temperature increases, and peak temperature decreases. All test mixes that exceed a time to peak temperature greater than 1100 minutes (18.3 hours) produced at least 10% bleed water by volume. The biggest variable effecting this cure time is the retarding admixture: the more retardant added, the more bleed water is produced. With one exception, all test mixes with 20 oz/CY or more retarder exceeded 10% bleed water. Another relationship contributing to cure time and peak temperature lies within the water/cement ratio (w/cm), which shows that the higher the w/cm ratio, the lower the peak temperature. Generally, aggregate moisture corrected w/cm ratios greater than 0.50 produces excessive bleed. More study is needed to confirm this finding, but mixes with fly ash contents exceeding 150 lb/CY (with concurrent reduction of Portland Cement content) all produced excessive bleed, which suggest that fly ash content should be carefully considered. The quantity of bleed water produced from test mixes decreases for mixes with higher coarse aggregate contents and lesser fine aggregate contents. This is contrary to current practices with self-consolidating concrete that use a higher fine aggregate content than traditional mixes. The consequences of excessive bleed are still unknown. Bleed channels or other compromising anomalies relating to bleed were searched for via sawing through the test shafts post curing however, no conclusive findings can be drawn from these specimens at this time. More study is necessary for finding relationships between excessive bleed and concrete structural stability.
Preparation And Testing Of Drilled Shafts With Self Consolidating Concrete
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Author : Hamdi Celik Ozyildirim
language : en
Publisher:
Release Date : 2012
Preparation And Testing Of Drilled Shafts With Self Consolidating Concrete written by Hamdi Celik Ozyildirim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Concrete categories.
In this study, self-consolidating concrete (SCC) was evaluated in drilled shafts and the integrity of drilled shafts was determined using cross-hole sonic logging (CSL), a low-strain nondestructive integrity testing technique. SCC has very high flowability. It was placed in the drilled shafts of the bridge on Route 28 over Broad Run in Bristow in Prince William County, Virginia. There were two bridges at the site; the one carrying the northbound traffic had drilled shafts using conventional concrete with high consistency (i.e., flowability). Half of the shafts of the bridge carrying the southbound traffic were cast with SCC. During placement, properties of the fresh concrete were tested and specimens were prepared to determine the hardened properties. The integrity of the shafts within the reinforcing cage was determined using CSL, with sonic echo/impulse response also used to evaluate several test shafts. The use of acousto-ultrasonic (AU) measurements to determine the cover depth outside the reinforcing cage was also evaluated during laboratory testing. In addition to the Route 28 shafts, three test shafts with conventional and SCC concretes were cast in an area headquarters. These shafts had intentional voids created through the use of sand bags and Styrofoam to investigate further the ability of the nondestructive test equipment. The results indicated that SCC is highly desirable for drilled shafts; it flows easily, filling the hole, and the removal of the temporary casing is facilitated by this highly workable material. CSL is a satisfactory nondestructive method to determine the integrity of shafts. Sonic echo/impulse response also showed promise as a method that complements CSL for determining the integrity of a shaft.
Self Consolidating Concrete For Precast Prestressed Concrete Bridge Elements
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Author : Kamal Khayat
language : en
Publisher: Transportation Research Board
Release Date : 2009
Self Consolidating Concrete For Precast Prestressed Concrete Bridge Elements written by Kamal Khayat and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Bridges categories.
At head of title: National Cooperative Highway Research Program.
An Evaluation Of The Use Of Self Consolidating Concrete Scc For Drilled Shaft Applications
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Author : Joseph Donald Bailey
language : en
Publisher:
Release Date : 2005
An Evaluation Of The Use Of Self Consolidating Concrete Scc For Drilled Shaft Applications written by Joseph Donald Bailey and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Concrete categories.
Comparison Of Conventional And Self Consolidating Concrete For Drilled Shaft Construction
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Author : Tyson David Rupnow
language : en
Publisher:
Release Date : 2015
Comparison Of Conventional And Self Consolidating Concrete For Drilled Shaft Construction written by Tyson David Rupnow and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Concrete piling categories.
Investigation Of The Performance Of Self Consolidating Concrete In Drilled Shafts
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Author : Andrew Hall (Engineer)
language : en
Publisher:
Release Date : 2011
Investigation Of The Performance Of Self Consolidating Concrete In Drilled Shafts written by Andrew Hall (Engineer) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Concrete piling categories.
The Application Of Self Consolidating Concrete Scc In Full Scale Drilled Shafts
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Author : Phillip Alain Gallet
language : en
Publisher:
Release Date : 2010
The Application Of Self Consolidating Concrete Scc In Full Scale Drilled Shafts written by Phillip Alain Gallet and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Concrete categories.
The Behavior And Durability Of Self Consolidating Concrete
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Author : Aly Said
language : en
Publisher:
Release Date : 2015
The Behavior And Durability Of Self Consolidating Concrete written by Aly Said and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Self-consolidating concrete categories.
This report focuses on the production of self-consolidating concrete using local materials from Las Vegas, Nevada. Tests were conducted on eight self-consolidating concrete mixtures having two different percentages of fly-ash replacement (25% and 35%) as well as the inclusion of the superplasticizer ADVA 195 and the viscosity modifying admixture V-MAR 3. The fresh properties tested were flowability, passing ability, and stability. Mechanical properties evaluated were compressive strength, splitting tensile strength, and the modulus of elasticity. The durability of specimens produced from the mixtures was tested for chloride ion resistance, sulfate resistance, and salt scaling. A key outcome of these tests for both fresh and hardened properties was that the mix design of self-consolidating concrete should be tailored according to the planned application (drilled shafts, precast products, repair concrete, etc....). Another key outcome was the importance mix design to accommodate the hauling time while maintaining consistent fresh properties of self-consolidating concrete at the delivery site. Recommendations for applications for self-consolidating concrete include using additional parameters to assess the suitability of the mixture to the designated application such as (T50, Jring), especially in critical applications where complications occur. And while additional testing may become a burden on the overall operation, it can be performed in trial batches and selectively during delivery. Another recommendation is to further investigate the use of techniques to control bleeding in large volume self-consolidating concrete casts.
Self Consolidating Concrete For Cast In Place Bridge Components
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Author : George Morcous
language : en
Publisher:
Release Date : 2016
Self Consolidating Concrete For Cast In Place Bridge Components written by George Morcous and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Bridges categories.
"National Cooperative Highway Research Program (NCHRP) Report 819: Self Consolidating Concrete for Cast in Place Bridge Components presents recommended guidelines for the use of self-consolidating concrete (SCC) in cast in place highway bridge components. These guidelines address the selection of constituent materials, proportioning of concrete mixtures, testing methods, fresh and hardened concrete properties, production and quality control issues, and other aspects of SCC. The report also presents proposed changes to the AASHTO LRFD Bridge Design and Construction Specifications to address use of SCC for cast in place highway bridge components. The information contained in the report will guide materials and bridge engineers in evaluating, selecting, and specifying SCC mixtures for use in cast in place concrete bridge components, thereby facilitating construction, improving the working environment and safety, and reducing cost."--Publisher's description