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Expansive Mineral Growth and Concrete Deterioration: a Microstructural and Microanalytical Study Hyomin Lee Iowa State University

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Expansive Mineral Growth and Concrete Deterioration: a Microstructural and Microanalytical Study Hyomin Lee Iowa State University Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1999 Expansive mineral growth and concrete deterioration: a microstructural and microanalytical study Hyomin Lee Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Geochemistry Commons, Geology Commons, and the Geotechnical Engineering Commons Recommended Citation Lee, Hyomin, "Expansive mineral growth and concrete deterioration: a microstructural and microanalytical study " (1999). Retrospective Theses and Dissertations. 12583. https://lib.dr.iastate.edu/rtd/12583 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced fix>m the microfilm master. UMI films the text direct^ fix}m the origmal or copy submitted. Thus, some thesis and dissertation copies are in typewriter &ce, while others may be from any type of computer printer. The quality of this reproduction is dependent apon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adverse^ affect rq>roduction. In the unlikely event that the author did not send UMI a complete manuscript and there are mis^g pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, b^jnning at the upper left-hand comer and continuing from left to right in equal sections with small overiaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been rq)roduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. UMI ABdl&HowdHnfimiBUionConyany 300 NoithZceb Road. Ann Aiixv MI 48106-1346 USA 313/761-4700 800/521-0600 Expansive mineral growth and concrete deterioration: A microstructural and microanatytical study by Hyomin Lee A dissertation submitted to the graduate faculty in partial fidfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major Geology Major Professor Robert D. Cody Iowa State University Ames, Iowa 1999 XJMX Number: 9924737 UMI Microform 9924737 Copyright 1999, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying mider Title 17, United States Code. UMI 300 North Zeeb Road Ann Ariwr, MI 48103 u Graduate College Iowa State University This is to certify that the Doctoral dissertation of Hyomin Lee has met the dissertation requirements of Iowa State University Signature was redacted for privacy. Coinimttee Member Signature was redacted for privacy. Committee Member Signature was redacted for privacy. Committee Member Signature was redacted for privacy. Committee Member Signature was redacted for privacy. Major Professor Signature was redacted for privacy. For the Major Signature was redacted for privacy. Ul TABLE OF CONTENTS ABSTRACT vii GENERAL INTRODUCTION 1 Expansive Mineral Growth and E>eterioration of Iowa Highway Concrete Deterioration 1 The Role of Deicer in Concrete Deterioration 2 Calcium Magnesium Acetate (CMA) as an Alternative Deicer 3 Effect of Crystallization Inhibitors on the Formation of Secondary Mineral Growth in Concrete. 3 RESEARCH OBJECTIVES 5 PART L EXPANSIVE MINERALS FEATURES OF IOWA HIGHWAY CONCRETES 7 INTRODUCTION 8 METHODS OF STUDY 10 Collection of Highway Concrete Samples 10 General Procedures and Instrumentation 10 CHARACTERISTICS OF IOWA HIGHWAY CONCRETE SAMPLES 13 Durable and Non-Durable Concretes 13 Dolomite Coarse Aggregate Characteristics 13 Crystallinity and Crystal Size 13 Reaction Rim Development 14 Chemical Composition 15 Pyrite Inclusions 15 Fine Aggregate Characteristics 17 Cement Paste Characteristics 18 Chemical Composition of Cement Paste 18 Air-Entrainment Voids 20 RESULTS AND DISCUSSION 21 Brucite Occurrence in Iowa Concretes 21 Forms and Distribution 21 Brucite Formation in Iowa Concretes 23 Mechanisms of Brucite Formation in Iowa Concretes 25 iv Ettringite Occurrence in Iowa Concretes 27 Forms and Distribution 27 Relationship of Ettringite to Pyrite Inclusions 28 Mechanisms of Ettringite Formation 32 EXPANSIVE MECHANISMS AND IOWA CONCRETE DETERIORATION 40 Cement-Aggregate Expansive Reactions 40 Alkali-Carbonate Reactions 40 Alkali-Silica Reactions 41 Alkali-Silicate Reactions 41 Brucite Expansive Reactions 42 E^ansion Mechanisms 42 Brucite-hiduced Expansion in Iowa Concrete 43 Ettringite Expansive Reactions 44 Expansion Mechanisms 44 Ettringite-Ihduced Expansion in Iowa Concretes 47 SUMMARY AND CONCLUSIONS 49 PART n. EXPERIMENTAL DETERIORATION OF IOWA HIGHWAY CONCRETE 54 INTRODUCTION 55 EXPERIMENTAL METHODS 56 Wet/Dry (W/D) Experiments 56 Freeze/Thaw (F/T) Experiments 57 Termination of Experiments and Thin Sectioning 57 RESULTS AND DISCUSSION 59 Relative Aggressiveness of Salt Solutions 59 Calcium Magnesium Acetate 59 Sodium Sulfate 59 Magnesium Chloride 61 Calcium Chloride 61 Sodium Chloride and Water 61 Effects on Concrete Samples 62 Secondary Mineral Formation 62 Effects of Water 64 Effects of Calcium Chloride Solutions 64 Effects of Magnesium Chloride Solutions 66 Effects of Sodium Chloride Solutions 69 Effects of Sodium Sul&te Solutions 70 Effects of Calcium Magnesium Acetate (CMA) Solutions 71 V Role of Calciiun and Magnesium in CMA 73 Effects of Magnesium Acetate Solutions 73 Effects of Calcium Acetate Solutions 74 Effect of Ca/Mg ratios in CMA induced deterioration 75 Stability of Expansive Minerals 79 SUMMARY AND CONCLUSIONS 81 PART. in. THE EFFECT OF CRYSTALLIZATION INHIBITOR ON EXPANSIVE MINERAL GROWTH AND CONCRETE DETERIORATION 83 INTRODUCTION 84 CRYSTALLIZATION INHIBmON 87 EXPERIMENTAL MATERIALS AND METHODS 89 Selection of Crystallization Inhibitors 89 Experimental Methods 89 Analytical Methods and Instrumentation 95 RESULTS AND DISCUSSION 96 Effects of Sodium Sulfate and Crystallization Inhibitor on Ettringite Formation 96 Experimentally Induced Concrete E^qpansion on Sulfate Experiments 97 Effect of Crystallization Inhibitors on Expansion 100 Effects of Crystallization Inhibitors on Ettringite Formation 106 Effects of Crystallization Inhibitor on CMA-induced Deterioration 122 SUMMARY AND CONCLUSIONS 127 GENERAL CONCLUSIONS 132 RECOMMENDATIONS 135 vi APPENDIX A. ADDITIONAL FIGURES (PART I)- EXPANSIVE GROWTH IN IOWA HIGHWAY CONCRETE SAMPLES 138 APPENDIX B. ADDITIONAL FIGURES (PART II)- EXPERIMENTALLY ALTERED IOWA HIGHWAY CONCRETE SAMPLES 179 APPENDIX C. ADDITIONAL FIGURES (PART HI)- CRYSTALLIZATION INHIBITOR TREATED CONCRETE SAMPLES 246 APPENDIX D. ETTINGITE STRUCTURE 263 APPENDIX E. EXPANSION MEASUREMENT DATA 267 REFERENCES 277 ACKNOWLEDGMENTS 292 vii ABSTRACT In order to evaluate the role of newly-foimed minerals in the premature deterioration of highway concrete, a three-phase study was undertaken. In the first phase, petrographic and SEM/EDAX analyses were performed to determine chemical and mineralogical changes in the aggregate and cement paste of samples taken fit)m Iowa hi^ways that showed premature deterioration. In the second phase, experimental simulations of environmental changes in highway concrete after applying different deicer chemicals were conducted to evaluate the role of deicers in premature deterioration. In the third phase, experiments were done to evaluate whether crystallization inhibitors can reduce damage and the growth of secondary minerals in concrete and to help understand the mechanism of deterioration by secondary mineral growth in concrete. In the first phase of study, it was evidenced that two major expansive minerals, ettringite and brucite, were responsible for premature deterioration. Severe expansion cracking of cement paste was often closely associated with ettringite locations, and strongly suggests that secondary ettringite was a major cause. Brucite forms in cement paste of concretes containing reactive dolomite aggregate via dedolomitization reactions. No cracking was observed to be spatially associated with brucite, but expansion stresses associated with its growth at innumerable microlocations might be relieved by cracking at weaker locations in the concrete. Deicer salts cause characteristic concrete deterioration by altering dedolomitization rims at the coarse-aggregate paste inter&ce, altering cement paste and/or fomiing new secondary minerals. Magnesium in deicer solutions caused the most severe paste viii deterioiadon by forming non-cementitious magnesium silicate hydrate and bnicite. Chloride in deicer solutions promotes decalcification of paste and alters ettringite to chloroaluminate. CMA and Mg-acetate produced the most deleterious effects on concrete, with Ca-acetate being much less aggressive. In order to use CMA as an alternative deicer and to prevent premature deterioration, it is recommended that it possess a high Ca/Mg ratio. Three types of commercially inhibitor chemicals, polyphosphonate, polyacrylate, and phosphate ester,
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