Static and Dynamic Carbonation of Lightweight Concrete Masonry Units Hilal El-Hassan Department of Civil Engineering and Applied Mechanics McGill University, Montreal December 2012 A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Engineering © Hilal El-Hassan, 2012 All Rights Reserved ABSTRACT Static and dynamic carbonation curing at early age was developed for ordinary Portland cement (OPC) and Portland limestone cement (PLC) concrete masonry units (CMU) production. It is intended to replace conventional steam curing, improve the CMU performance, reduce energy consumption, and permanently sequester carbon dioxide in concrete. Concrete slabs representing the face shell of a 20-cm CMU as well as full sized CMU were used throughout the carbonation process. In static carbonation, it was found that initial air curing was vital to maximize carbonation reaction. After a procedure of casting, air curing, carbonation curing, and water compensation in subsequent hydration, carbonated CMUs had shown equivalent strength to steamed CMU but much better resistance to freeze-thaw damage. Carbonate-reinforced cement matrix played a critical role in improving freeze thaw resistance. In dynamic carbonation, the initial air curing was combined with carbonation with controlled relative humidity. The production cycle was significantly reduced to avoid initial air curing. The process proved to be a valid replacement of the static system in terms of CO2 uptake and compressive strength. While both OPC and PLC concretes displayed the hydration and carbonation products, only OPC concrete demonstrated an intermix of these products in the form of calcium silicate hydrocarbonate and a phase transformation of poorly crystalline aragonite and vaterite into well crystalline calcite. Based on 24% CO2 uptake, the CMU production in US and Canada is capable of sequestering 2 million tons CO2 per year. It is equivalent to 2.5% carbon emission reduction for US and Canada cement industry. – i – RÉSUMÉ La carbonatation par méthode statique et dynamique a été développée pour la cure rapide de blocs de bétons composés à partir de ciment Portland ordinaire ainsi que de ciment Portland à base de calcaire. Cette approche vise à remplacer le procédé traditionnel de cure de blocs de bétons par étuvage afin d’améliorer leur performance, réduire la consommation d’énergie, et séquestrer le dioxyde de carbone de manière indéfinie. La façade extérieure d’un bloc de béton de 20-cm, représenté par une dalle de béton, ainsi qu’un bloc de pleine taille, ont été utilisés durant le procédé de carbonatation. Les résultats indiquent qu’il est essentiel de curer les blocs par air contrôlé avant d’employer la carbonatation statique. Suivant la procédure de moulage, cure à l’air, carbonatation, et compensation de l’eau à travers hydratation suivie, les blocs de bétons carbonatés ont témoigné une résistance comparable à celle de blocs durcis à la vapeur, cependant une résistance supérieure aux dégâts de gel-dégel. La microstructure du ciment carbonaté-renforcé a joué un rôle crucial dans l’amélioration de la résistance du gel- dégel. Dans la carbonatation dynamique, le durcissement initial par étuvage a été combiné avec carbonatation sous une humidité relative contrôlée. Afin de réduire le cycle de production, le durcissement initial par étuvage a été éliminé. La carbonatation dynamique s’est avérée être un remplacement valable du système statique en termes d’absorption de CO2 et résistance à la compression. Bien que le ciment Portland ordinaire ainsi que le ciment Portland à base de calcaire ont confirmé des produits d’hydratation et de carbonatation, seul le ciment Portland a fait preuve de la capacité de ses produits d’hydratation et de carbonatation de se mélanger sous la forme de calcium hydrocarbonate silicate . De plus, de l'aragonite mal cristallisé et de la vatérite ont subi une transformation de phase dérivant en calcite cristalline. Basé sur une capacité d’absorption de CO2 de 24%, la production de blocs de bétons aux États-Unis et au Canada a le potentiel annuel de séquestrer 2 millions de tonnes de CO2. Ce fait signifie que la réduction d’émissions de dioxyde de carbone de ces deux pays dans l’industrie de ciment est égale à 2.5%. – ii – ACKNOWLEDGEMENTS Foremost, I would like to thank my supervisor, Professor Yixin Shao, for his patient guidance, motivation, enthusiasm, and inspiration. I sincerely appreciate all his contributions of time and ideas to make my PhD experience productive and stimulating. The expanded slag aggregates and cement have been provided from Lafarge Canada. I would like to especially thank the President of Boehmer block, Mr. Paul Hargest, whose support and interest in our work motivated us to prosper for perfection. Microstructure study was carried out with the technical support of the Department of Mining and Materials Engineering, specifically Helen Campbell, Line Mongeon, and Pierre Hudon. The full understanding of lab equipment and experiments was possible through the aid of Ron Sheppard, Bill Cook, Marek Przykorski, and John Bartczak. Lastly, I would like to thank my fiancé, Nihale, for her patience, support, and understanding. The constant encouragement of my parents is what drove me to thrive for excellence throughout these years. Special thanks to my friend, Zaid Ghouleh, whose extensive help in the microstructure analysis was of great value. I would also like to thank my friend, Lana Tayyara, for translating the abstract to French. – iii – CONTRIBUTIONS OF AUTHORS The manuscripts included in this thesis and Chapters 3 to 8 will be or have been submitted for publication in scientific journals. The author was responsible for conducting the research, analyzing the data, and preparing the manuscripts. The author’s supervisor, Dr. Yixin Shao, provided general guidance and editorial revisions throughout the entire process. Also, Mr. Zaid Ghouleh contributed to the presented research particularly in microstructural analysis. – iv – TABLE OF CONTENTS Abstract ......................................................................................................................... i Résumé ......................................................................................................................... ii Acknowledgements ..................................................................................................... iii Contributions of Authors ............................................................................................. iv List of Tables ............................................................................................................... xi List of Figures ........................................................................................................... xiii Chapter 1 - Introduction ................................................................................................ 1 Overview ...................................................................................................................... 1 Steam curing ............................................................................................................ 1 Carbonation curing .................................................................................................. 2 CO2 utilization in concrete masonry units production............................................. 2 Carbon dioxide emission ......................................................................................... 3 Research Objectives .................................................................................................... 3 Thesis Structure........................................................................................................... 5 References ................................................................................................................... 6 Figures ......................................................................................................................... 8 Chapter 2 - Literature Review ....................................................................................... 9 Carbonation Curing of Concrete Masonry Units ........................................................ 9 Weathering carbonation ........................................................................................... 9 Early-age carbonation ............................................................................................ 10 Carbonation products ............................................................................................. 11 Other carbonation applications .............................................................................. 12 Factors influencing carbonation ............................................................................ 13 Quantification of CO2 Uptake ................................................................................... 14 Mass gain method .................................................................................................. 14 Mass curve method ................................................................................................ 15 Thermogravimetry (TG) method ........................................................................... 15 Constant temperature pyrolysis method ................................................................ 16 – v – Chemical analysis by hydrochloric acid titration method ..................................... 16 Strength Development..............................................................................................