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Effects of High Alkalinity Cements on the Control of Alkali-Silica Reaction for Reinforced Concrete

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Date Issued:
2006
Summary:
In previous research, cements with high alkali content (EqA 1.0-1.2 percent) extended the corrosion initiation time of reinforcing steel in concrete. During this study, laboratory tests were performed to determine the suitability of high alkalinity cements to improve concrete durability without modifying physical properties and to control the risk of alkali-aggregate reaction (AAR). A mix design for the FOOT-Class V concrete served as base material for this study. On a cubic meter basis the cementitious material in this concrete included 363 kg of Type l/ll Portland cement and 83 kg of Class F fly ash. The water-to-cementitious material ratio of the concrete was 0.40. The fine aggregate used in the experimental concretes was quartz sand from a Florida source with no history of alkali-silica reactivity (ASR) susceptibility. A number of cement alkali contents were prepared by different additions of sodium hydroxide to the concrete mix (3.42 - 4.57 kglm\ in some cases, and by using different cements in others. Thus, effects on concrete susceptibility to ASR, electrical resistivity, and strength were studied. Pore water alkalinity was measured by ex-situ leaching and pore water extraction methods. It was concluded that leaching procedures were not appropriate to determine concrete pore water alkalinity in the presence of fly ash. Results suggested that it is feasible to use high alkali cement without the risk of ASR or the loss of strength for two of the seven coarse aggregates studied, given that supplementary cementitious materials and lithium nitrate admixtures are utilized. Criteria for qualification of a concrete as being ASR resistant was based on dimensional stability (less than 0.01% average specimen length change) and the absence of cracking over the one and two year exposure periods according to ASTM Cl293. Based on the fundamentals of the electric double layer theory, the incidence of bivalent cations adjacent to the surface of cement hydrates and reactive silica particles was proposed to provide an explanation for the effects of alkali addition on the electrical resistivity of concrete and the source of the expansive nature of the ASR gel.
Title: Effects of High Alkalinity Cements on the Control of Alkali-Silica Reaction for Reinforced Concrete.
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Name(s): Suarez, Jorge Alejandro
Hartt, William H., Thesis advisor
Florida Atlantic University, Degree grantor
College of Engineering and Computer Science
Department of Ocean and Mechanical Engineering
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Created: 2006
Date Issued: 2006
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, Fla.
Physical Form: application/pdf
Extent: 146 p.
Language(s): English
Summary: In previous research, cements with high alkali content (EqA 1.0-1.2 percent) extended the corrosion initiation time of reinforcing steel in concrete. During this study, laboratory tests were performed to determine the suitability of high alkalinity cements to improve concrete durability without modifying physical properties and to control the risk of alkali-aggregate reaction (AAR). A mix design for the FOOT-Class V concrete served as base material for this study. On a cubic meter basis the cementitious material in this concrete included 363 kg of Type l/ll Portland cement and 83 kg of Class F fly ash. The water-to-cementitious material ratio of the concrete was 0.40. The fine aggregate used in the experimental concretes was quartz sand from a Florida source with no history of alkali-silica reactivity (ASR) susceptibility. A number of cement alkali contents were prepared by different additions of sodium hydroxide to the concrete mix (3.42 - 4.57 kglm\ in some cases, and by using different cements in others. Thus, effects on concrete susceptibility to ASR, electrical resistivity, and strength were studied. Pore water alkalinity was measured by ex-situ leaching and pore water extraction methods. It was concluded that leaching procedures were not appropriate to determine concrete pore water alkalinity in the presence of fly ash. Results suggested that it is feasible to use high alkali cement without the risk of ASR or the loss of strength for two of the seven coarse aggregates studied, given that supplementary cementitious materials and lithium nitrate admixtures are utilized. Criteria for qualification of a concrete as being ASR resistant was based on dimensional stability (less than 0.01% average specimen length change) and the absence of cracking over the one and two year exposure periods according to ASTM Cl293. Based on the fundamentals of the electric double layer theory, the incidence of bivalent cations adjacent to the surface of cement hydrates and reactive silica particles was proposed to provide an explanation for the effects of alkali addition on the electrical resistivity of concrete and the source of the expansive nature of the ASR gel.
Identifier: FA00012578 (IID)
Degree granted: Dissertation (Ph.D.)--Florida Atlantic University, 2006.
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): College of Engineering and Computer Science
Subject(s): Reinforced con crete construction
Concrete--Deterioration
Alkali-aggregate reactions
Silica
Held by: Florida Atlantic University Libraries
Sublocation: Digital Library
Persistent Link to This Record: http://purl.flvc.org/fau/fd/FA00012578
Use and Reproduction: Copyright © is held by the author with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
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Host Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.