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Alkali-Silica Reactivity of Mortars Containing Natural Pozzolan

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Alkali-Silica Reactivity of Mortars Containing Natural Pozzolan UNLV Theses, Dissertations, Professional Papers, and Capstones December 2019 Alkali-Silica Reactivity of Mortars Containing Natural Pozzolan Arash Kian Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Civil Engineering Commons Repository Citation Kian, Arash, "Alkali-Silica Reactivity of Mortars Containing Natural Pozzolan" (2019). UNLV Theses, Dissertations, Professional Papers, and Capstones. 3813. http://dx.doi.org/10.34917/18608684 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. ALKALI-SILICA REACTIVITY OF MORTARS CONTAINING NATURAL POZZOLAN By Arash Kian Bachelor of Science in Industrial Engineering Azad Islamic University of Karaj 2006 A thesis submitted in partial fulfillment of the requirements for the Master of Science in Engineering - Civil and Environmental Engineering Department of Civil and Environmental Engineering and Construction Howard R. Hughes College of Engineering The Graduate College University of Nevada, Las Vegas December 2019 i Copyright by Arash Kian, 2019 All Rights Reserved ii Thesis Approval The Graduate College The University of Nevada, Las Vegas November 14, 2019 This thesis prepared by Arash Kian entitled Alkali-Silica Reactivity of Mortars Containing Natural Pozzolan is approved in partial fulfillment of the requirements for the degree of Master of Science in Engineering - Civil and Environmental Engineering Department of Civil and Environmental Engineering and Construction Nader Ghafoori, Ph.D. Kathryn Hausbeck Korgan, Ph.D. Examination Committee Chair Graduate College Dean Samaan Ladkany, Ph.D. Examination Committee Member Ying Tian, Ph.D. Examination Committee Member Pradip Bhowmik, Ph.D. Graduate College Faculty Representative ii Abstract Alkali-silica reactivity is one of the most recognized deleterious phenomena in Portland cement concrete resulting in cracks, spalling, and other deleterious mechanisms. The aim of this study was (i) to assess the extent of reactivity of the aggregates, quarried from seven different sources, suspected of being conducive to ASR, and (ii) to compare the effectiveness of industrial (Class F fly ash) and natural pozzolans in mitigation of alkali-silica reactivity of the studied aggregates. To this end, seven aggregate sources, four natural pozzolan sources, and one source of Class F fly ash were used. ASTM Type V Portland cement was replaced at four levels of 15, 20, 25, and 30% by different pozzolan types and sources. A uniform water-to- cementitious materials ratio of 0.47 was used. Beam shaped mortars were tested for ASR-induced expansion for eight weeks. In addition, companion mortar cubes cured for 90 days in a salt-water environment and in a controlled moisture room were tested in compression. The findings of this investigation revealed that the ASR mitigation of the studied aggregate depended on the aggregate source, natural pozzolan source and content, and immersion age. For nearly all natural and industrial pozzolans used in this study, 15% by weight of Portland cement was sufficient to mitigate alkali-silica reactivity of the studied reactive aggregates. The loss in strength of the studied mortars also depended on aggregate and natural pozzolan types and sources, and reduced with increases in Portland cement substitution level. Overall, the four natural pozzolan sources exhibited similar to better performance, in comparison to that of the class F Fly ash, in suppressing the alkali-silica reactivity of the reactive aggregates. iii Acknowledgements This study was funded by a grant made possible by the US Department of Transportation and Nevada Department of Transportation through Solaris Consortium. Thanks are extended to a number of producers who donated materials. I would like to express my sincere gratitude to Dr. Nader Ghafoori, for his guidance and patience through the entire study. His expertise was critical to the success of the study. Thank you for being my advisor and allowing me to take on this project. I would like to also express my deepest appreciation to my committee members, Dr. Samaan Ladkany, Dr. Ying Tian, and Dr. Pradip Bhowmik to contribution to my thesis. And I would like to thank to Mr. Ariful Hasnat for all his help and support. I can’t thank him enough for everything that he has done for making this work a possible one, and all the interns that aided me in the summer and semesters. The project would not had been possible without their assistance. Most importantly, I would like to thank my mom and dad for not giving up on me, even in times when I did not believe in myself. Without them, I would of not been able to finish the graduate program. iv Table of Contents Abstract ......................................................................................................................................... iii Acknowledgements ...................................................................................................................... iv List of Tables ................................................................................................................................ ix List of Figures .............................................................................................................................. xii Chapter 1 Introduction ............................................................................................................... 1 1.1 Background ........................................................................................................................... 1 1.2 Mechanism of Alkali-Silica Reactivity ................................................................................. 2 1.3 Cracking of Concrete Due to ASR ....................................................................................... 6 1.4 Factors Affecting ASR .......................................................................................................... 9 1.4.1 Reactive Silica ................................................................................................................... 9 1.4.1.1 Petrography of Reactive Silica ....................................................................................... 9 1.4.1.2 Particle Size .................................................................................................................. 11 1.4.1.3 Pessimum Effect ........................................................................................................... 12 1.4.2 Source of Alkali ............................................................................................................... 13 1.4.3 Moisture ........................................................................................................................... 14 1.4.4 Temperature ..................................................................................................................... 15 1.5 Test Methods to Assess ASR .............................................................................................. 15 1.5.1 Petrographical Examination ............................................................................................. 15 1.5.2 Accelerated Mortar-Bar Testing (ASTM C1260/C1597) ................................................ 15 1.5.3 Concrete Prism Testing (ASTM C1293) ......................................................................... 16 1.5.4 Carbonate Aggregate Testing (RILM AAR 5) ................................................................ 16 1.5.5 Quick Chemical Method (ASTM C289) ......................................................................... 16 1.6 AAR Mitigation Strategies ................................................................................................. 17 1.6.1 Use of Non-Reactive Aggregate ...................................................................................... 17 1.6.2 Use of Low-Alkali Cement .............................................................................................. 18 1.7 Past Studies on Use of Supplementary Cementitious Materials to Mitigate ASR ............. 19 1.7.1 Use of Fly Ash to Reduce ASR ....................................................................................... 20 1.7.2 Use of Silica Fume to Reduce ASR ................................................................................. 21 1.7.3 Use of Ground-Granulated Blast-Furnace Slag (GGBS) to Reduce ASR ....................... 21 1.7.4 Use of Natural Pozzolan to Reduce ASR ........................................................................ 21 1.8 Thesis Objectives ................................................................................................................ 27 v 1.9 Research Significance ......................................................................................................... 28 Chapter 2 Experimental Program ............................................................................................
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