Search:

Results 1 to 10 of 13 |

Guide specification for concrete subject to alkali-silica reactions / by Portland Cement Association.Durability Subcommittee.; American Concrete Pavement Association.(CARDINAL)289501; National Ready Mixed Concrete Association.(CARDINAL)289522;
Includes bibliographical references.
Subjects: Concrete; Alkali-aggregate reactions.;
Available copies: 1 / Total copies: 1
unAPI

Diagnosis and control of alkali-aggregate reactions in concrete / by Farny, James A.,1962-(CARDINAL)289523; Kerkhoff, Beatrix.(CARDINAL)289507; Portland Cement Association.(CARDINAL)141087;
Includes bibliographical references (pages 23-25).
Subjects: Alkali-aggregate reactions.; Concrete; Concrete; Portland cement.; Silicates.;
Available copies: 1 / Total copies: 1
unAPI

Investigation of differences in deterioration of two north Carolina bridges due to alkali-silica reactivity (ASR) / by Leming, Michael L.(CARDINAL)196868; Nguyen, Bao Q.(CARDINAL)214574; North Carolina State University.Center for Transportation Engineering Studies.(CARDINAL)182954;
Includes bibliographical references (pages 102-103).Final report.In cooperation with the North Carolina Dept. of Transportation.
Subjects: Concrete bridges; Alkali-aggregate reactions.;
Available copies: 5 / Total copies: 6
On-line resources: Suggest title for digitization;
unAPI

Eliminating or minimizing alkali-silica reactivity / by Stark, D.(David)(CARDINAL)324795; Construction Technology Laboratories (Portland Cement Association)(CARDINAL)286967; Strategic Highway Research Program (U.S.)(CARDINAL)298325;
Includes bibliographical references (pages 265-266).Executive summary -- Introduction -- Nature and extent of ASR -- Rapid test to evaluate potential of aggregate for ASR -- Effects of lithium salts on ASR -- Mitigating ASR in existing concrete -- Summary -- Recommendations -- Appendices -- References.This investigation into various aspects of alkali silica reactivity (ASR) as it affects performance of highway structures, emphasized the practical needs of the concrete engineer with respect to the evaluation of the potential of aggregate for expansive ASR in new concrete, procedures to evaluate material for safe use in new concrete, and means to mitigate ASR and associated adverse effects in existing concrete. A rapid test method, based on immersion of mortar bars in sodium hydroxide solution, originated by the National Building Research Institute of South Africa was evaluated and extended to identify cement alkali levels and pozzolan proportions required to prevent deleterious ASR with particular aggregate. The efficacy of using lithium salts in concrete to suppress expansion due to ASR was researched.Performing organization: Construction Technology Laboratories, Inc., under contract no.
Subjects: Aggregates (Building materials); Alkali-aggregate reactions.; Pavements, Concrete; Silica.;
Available copies: 1 / Total copies: 1
unAPI

Evaluation of ASR using Carolinas aggregates in accordance with ASTM P 214 / by Patel, Sunjay R.(Sunjay Raman); American Concrete Institute.North Carolina Chapter.; University of North Carolina at Charlotte.College of Engineering.(CARDINAL)306676;
Includes bibliographical references (pages 41-45).
Subjects: Aggregates (Building materials); Alkalies.; Silica.; Alkali-aggregate reactions.; Concrete;
Available copies: 1 / Total copies: 1
unAPI

Investigation of alkali silica reactivity in North Carolina highway structures / by Leming, Michael L.(CARDINAL)196868; North Carolina State University.Center for Transportation Engineering Studies.(CARDINAL)182954;
Includes bibliographical references.Final report.In cooperation with N.C. Dept. of Transportation.
Subjects: Alkali-aggregate reactions.; Concrete; Bridges; Pavements;
Available copies: 7 / Total copies: 8
On-line resources: Suggest title for digitization;
unAPI

Use of fly ash, slag, or silica fume to inhibit alkali-silica reactivity / by Lane, D. Stephen(Daniel Stephen)(CARDINAL)314554; Ozyildirim, H. Celik(Hamdi Celik)(CARDINAL)311389; Virginia Transportation Research Council.(CARDINAL)195142;
Includes bibliographical references (pages 26-27).Final report;This study had two objectives: (1) to evaluate the effectiveness of particular mineral admixtures when combined with portland cements of varying alkali content in preventing expansion due to alkali-silica reactivity (ASR), and (2) to determine if set minimum amounts of various types of mineral admixtures could be established for use with cements of varying alkali content to provide protection from ASR. Mortar bars made with Pyrex glass aggregate were stored moist at 38 ° C for 366 days and measured periodically for length change. Control mortars were mixed with portland cements having an alkali content ranging from 0.18% to 0.92% Na20 equivalent. Test mortars were mixed replacing various percentages of portland cement with Class F fly ash (15%, 25%, and 35%), slag (20%, 35%, and 50%), or silica fume (3% and 7%). Test mortars were also mixed using IP cement produced using Class F fly ash (18%, 20%, and 22%). Expansions of control mortars with alkali contents of 0.4% or less were negligible through the 336-day test period. With cements having an alkali content above 0.4%, equilibrium between cement alkali content and mortar bar expansion was reached at 56 days, when a strong linear relationship between increasing expansion and increasing alkali content developed. A regression analysis was performed on data from the control batches, and the resulting equation was used to normalize data from the test batches. The expansion of mortars containing fly ash, slag, and silica fume was lower than the expansion of the control batches for portland cement having an alkali content of 0.6% and above for all replacement levels of the tested materials. The amount of expansion varied with the type of material, percentage replacement, and cement alkali content. Using an expansion of 0.10% as the maximum indicative of acceptable performance in inhibiting ASR, minimum amounts of Class F fly ash, slag, and silica fume were established for use with portland cement depending on the alkali content of the cement.Sponsored by the Virginia Department of Transportation, in cooperation with the U.S. Department of Transportation, and the Federal Highway Administration, under project no.
Subjects: Technical reports.; Alkali-aggregate reactions.; Fly ash.; Pavements, Concrete; Waste products as road materials.;
Available copies: 1 / Total copies: 1
unAPI

Alkali-silica reactivity in Virginia / by Lane, D. Stephen(Daniel Stephen)(CARDINAL)314554; Virginia.Department of Transportation.(CARDINAL)291718; University of Virginia.(CARDINAL)141178; Virginia Transportation Research Council.(CARDINAL)195142;
Includes bibliographical references (pages 41-45).Final report;This project examined occurrences in Virginia of alkali-silica reactivity, which is a major cause of the deterioration of concrete. Concretes were studied to determine the mineral aggregates being affected, and test methods for identifying such aggregates were evaluated. Technical literature on alkali-silica reactivity was reviewed to develop a way of dealing with this problem. The results of this study reveal that the mineral primarily affected by alkali-silica reactivity in Virginia is quartz, particularly when microcrystalline or metamorphically strained. Quartz in these forms is present in most aggregate resources in Virginia. The results obtained in evaluating a proposed aggregate test method did not permit the establishment of acceptable criteria for differentiating between those aggregates that were susceptible to this reaction and those that were not. Specific issues regarding alkali-silica reactivity in need of further research are delineated. However, because of the numerous aggregate resources in the state that are potentially susceptible to alkali-silica reactivity, the way to prevent this problem in new construction is to use cementitious materials that minimize the potential for the reaction to occur. The Virginia Department of Transportation implemented specifications that require the use of pozzolans or ground slag in concretes made with cements with an alkali content greater than 0.40.Sponsored by the Virginia Department of Transportation and the University of Virginia, under project no.
Subjects: Technical reports.; Aggregates (Building materials); Alkali-aggregate reactions.; Pavements, Concrete;
Available copies: 1 / Total copies: 1
unAPI

Mitigating the detrimental effects of the alkali-silica reaction with fly ash / by Ensley, Curtis L.; Hanks, David L.(CARDINAL)552404; University of North Carolina at Charlotte.Department of Civil Engineering.(CARDINAL)290431;
Includes bibliographical references (pages 11-12).
Subjects: Alkali-aggregate reactions.; Concrete; Fly ash.; Concrete; Aggregates (Building materials);
Available copies: 1 / Total copies: 1
unAPI

Alkali-silica reactivity : an overview of research / by Helmuth, R. A.(CARDINAL)324794; Construction Technology Laboratories (Portland Cement Association)(CARDINAL)286967; Strategic Highway Research Program (U.S.)(CARDINAL)298325;
Includes bibliographical references.Executive summary -- Part I: Mechanisms of damage to concrete by alkali-silica reactivity -- Introduction -- Reaction chemistry -- The physical nature of alkali-silica reaction swelling gels -- Mechanical effects of alkali-silica reactivity -- Environmental effects -- Concluding discussion -- Part II: Gaps in our knowledge of alkali-silica reactions in concrete -- Introduction -- Rapid and reliable test methods to identify potentially reactive aggregates in concrete -- Moisture conditions on concrete in highway structures -- Effects of salts and direct participation of chloride ions in alkali-silica reactivity -- Role of sulfate reactions accompanying expansion caused by reactivity -- Measurement of aggregate reactivities unimpeded by external diffusion processes -- Effects of restraint of expansion on reaction kinetics -- Mechanisms by which pozzolans inhibit expansion -- Pozzolan and mineral admixture test methods and specifications to prevent deleterious alkali-silica reactivity -- Inhibiting expansion due to reactivity by chemical agents.Part I of this report is a synthesis of knowledge of mechanisms of damage to concrete by alkali-silica reactivity. The details of the alkali silica reaction are discussed, and it is noted that the process is complicated by the effects of drying and growth of shrinkage cracks in exposed surfaces. The presence of chloride salts accelerates alkali-silica reactions. Formation of Friedel's salt and other complex chloride containing salts complicates test results. Part II of the report identifies 10 specific gaps in knowledge of alkali-silica reactions in concrete that limit the ability to control these reactions or to predict performance of concrete with reactive aggregates. These involve rapid and reliable test methods; moisture conditions in highway structures; effects of salts, role of sulfate reactions accompanying expansions caused by reactivity; measurement of aggregate reactivities; effect of restraint on kinetics; mechanisms by which pozzolans prevent expansion; test methods and specifications for pozzolans; and inhibition of reactivity by chemical agents.Performing organization: Construction Technology Laboratories, Inc., under contract no.
Subjects: Aggregates (Building materials); Alkali-aggregate reactions.; Pavements, Concrete; Silica.;
Available copies: 1 / Total copies: 1
unAPI

Results 1 to 10 of 13 |