Evaluation of the Chemical Durability of Iowa Fly Ash Concretes PDF Download
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Author: Scott Schlorholtz
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 5
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Book Description
The major objective of this research project is to investigate how fly ash influences the chemical durability of portland cement based materials. The testing program is evaluating how Iowa fly ashes influence the sulfate durability of portland cement-fly ash pastes, mortars, and concretes. Also, alkali-reactivity studies are being conducted on mortar bar specimens prepared in accordance with ASTM C311. Preliminary sulfate test results, based only on mortar bar studies, indicate that only the very high-calcium fly ash (29 percent CaO, by weight) consistently reduced the durabiity of test specimens exposed to a solution containing 5 percent sodium sulfate. The remaining four fly ashes that were used in the study showed negligible to dramatic increases in sulfate resistance. Concrete specimens were only beginning to respond to the sulfate solutions after about one year of exposure; and hence, considerably more time will be needed to assess their performance. Preliminary results from the alkali-reactivity tests have indicated that the Oreopolis aggregate is not sensitive to alkali attack. However, some of the test results have indicated that the testing procedure may be prone to delayed expansion due to the presence of periclase (MgO) in the Class C fly ashes. Research is being planned to: (1) verify if the periclase is influencing test results; and (2) estimating the magnitude of the potential error.
Author: Scott Schlorholtz
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 5
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Book Description
The major objective of this research project is to investigate how fly ash influences the chemical durability of portland cement based materials. The testing program is evaluating how Iowa fly ashes influence the sulfate durability of portland cement-fly ash pastes, mortars, and concretes. Also, alkali-reactivity studies are being conducted on mortar bar specimens prepared in accordance with ASTM C311. Preliminary sulfate test results, based only on mortar bar studies, indicate that only the very high-calcium fly ash (29 percent CaO, by weight) consistently reduced the durabiity of test specimens exposed to a solution containing 5 percent sodium sulfate. The remaining four fly ashes that were used in the study showed negligible to dramatic increases in sulfate resistance. Concrete specimens were only beginning to respond to the sulfate solutions after about one year of exposure; and hence, considerably more time will be needed to assess their performance. Preliminary results from the alkali-reactivity tests have indicated that the Oreopolis aggregate is not sensitive to alkali attack. However, some of the test results have indicated that the testing procedure may be prone to delayed expansion due to the presence of periclase (MgO) in the Class C fly ashes. Research is being planned to: (1) verify if the periclase is influencing test results; and (2) estimating the magnitude of the potential error.
Author: Chengsheng Ouyang
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 70
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Book Description
The freeze-thaw resistance of concretes was studied. Nine concrete mixes, made with five cements and cement-Class C fly ash combinations, were exposed to freeze-thaw cycling following 110 to 222 days of moist curing. Prior to the freeze-thaw cycling, the specimens were examined by a low-vacuum scanning electron microscope (SEN) for their microstructure. The influcence of a wet/dry treatment was also studied. Infilling of ettringite in entrained air voids was observed in the concretes tested. The extent of the infilling depends on the period of moist curing as well as the wet/dry treatment. The concretes with 15% Class C fly ash replacement show more infilling in their air voids. It was found that the influence of the infilling on the freeze-thaw durability relates to the air spacing factor. The greater the spacing factor, the more expansion under the freeze-thaw cycling. The infilling seems to decrease effective air content and to increase effective spacing factor. The infilling also implies that the filled air voids are water-accessible. These might lead to concrete more vulnerable to the freeze-thaw attack. By combining the above results with field observations, one may conclude that the freeze-thaw damage is a factor related to premature deterioration of PCC pavements in Iowa.
Author: Todd D. Hanson
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 246
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Book Description
"The objective of this report is to document various changes in specifications, pavement design and equipment for PCC paving from the early 1900s to present. This includes changes that were made to the specification book and supplemental specifications"--Technical report title page.
Author: Sam G. Moussalli
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 92
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Book Description
Fly ash was used in this evaluation study to replace 15% of the cement in Class C-3 concrete paving mixes.
Author: Library of Congress. Exchange and Gift Division
Publisher:
ISBN:
Category : State government publications
Languages : en
Pages : 1152
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Book Description
June and Dec. issues contain listings of periodicals.
Author: Iowa. Department of Transportation
Publisher:
ISBN:
Category : Transportation
Languages : en
Pages : 120
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Book Description
Author: Lawrence J. Kaetzel
Publisher:
ISBN:
Category : Expert systems (Computer science)
Languages : en
Pages : 274
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Book Description
Author:
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 300
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Book Description
In Phase I, the research team contacted each of 16 participating states to gather information about concrete and concrete material tests. A preliminary suite of tests to ensure long-term pavement performance was developed. The tests were selected to provide useful and easy-to-interpret results that can be performed reasonably and routinely in terms of time, expertise, training, and cost. The tests examine concrete pavement properties in five focal areas critical to the long life and durability of concrete pavements: (1) workability, (2) strength development, (3) air system, (4) permeability, and (5) shrinkage. The tests were relevant at three stages in the concrete paving process: mix design, preconstruction verification, and construction quality control. In Phase II, the research team conducted field testing in each participating state to evaluate the preliminary suite of tests and demonstrate the testing technologies and procedures using local materials.
Author: Iowa Academy of Science
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 544
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Book Description
List of members in each volume.
Author: Lawrence L. Sutter
Publisher: Transportation Research Board
ISBN: 0309283558
Category : Political Science
Languages : en
Pages : 91
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Book Description
"TRB's National Cooperative Highway Research Program (NCHRP) 749: Methods for Evaluating Fly Ash for Use in Highway Concrete presents suggested changes to coal fly ash specifications and test protocols contained in American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Transportation Materials and Methods of Sampling and Testing (AASHTO M 295). The changes suggested include modifications to the test methods currently specified for evaluating acceptability of fly ash for use in highway concrete as well as the introduction of new test methods for enhancing such evaluations. Attachment C: Details of the Research into Methods for Evaluating Fly Ash Use in Highway Concrete is only available online."--Publisher description.
