Supplementary cementitious materials (SCMs) are a key ingredient of today's concrete and can vastly improve the durability and sustainability of concrete mixtures. While the demand for traditional pozzolans (i.e., pulverized coal fly ash and slag) continue to grow, the supply of high-quality and economically available pozzolans has been shrinking. As such, there is a significant need and interest to search for alternative SCM sources due to supply-and-demand concerns in the future. One of the most promising alternative sources are calcined clays since they have not yet reached their full potential as cement replacement and clay is an abundant and widespread material resource. Calcined clays other than metakaolin (high purity calcined kaolinite clay) are not currently used as SCMs in the concrete industry due to the complexity of clay minerals and insufficient knowledge of the underlying reaction mechanisms. Also, their performance as concrete pozzolans are not well understood. To address these knowledge gaps, the purpose of this research is to identify, characterize, improve, and facilitate the use of impure calcined clays (CC) as viable SCMs in Portland cement concrete and as a precursor in geopolymer concrete. To increase the service life and expand the use of high-performance concrete, it is critical to provide a high-quality, durable, and cost-competitive concrete; as such, a stable and abundant supply of SCM is required. Toward this objective, three calcined clays were obtained from eastern, central, and western United States which had different amorphous contents while the balance included minerals such as quartz, feldspar, iron oxides, and other clay minerals. The key starting point of this study consists of a detailed chemical, mineralogical and physical characterization of impure calcined clays (CC) and evaluation of their performance as a pozzolan in Portland cement concrete or as an aluminosilicate source for geopolymer concrete. In addition, to assess the pozzolanic reactivity of CCs, isothermal calorimetry and bound water were used to measure the heat of hydration and chemically bound water, respectively, in the lime-pozzolan paste systems (aka R3 test, ASTM C1897-20). The results were compared with quantifying the unreacted pozzolan and as a function of time (by acid dissolution) and portlandite consumption (by TGA) within the R3 paste. A low-purity clay was obtained from a large commercial aggregate production facility. Several methods included centrifuging to classify based on particle size and density, membrane filtration to separate based on particle size, and dispersant-assisted sedimentation were used for separating the clay and non-clay minerals and enrichment of low-purity kaolinite clays to improve their reactivity and performance in concrete. Both low-purity and purified clay were calcined and tested in mortar and concrete mixtures for their fresh properties (slump, air content, and time of setting), hardened properties (air content, compressive strength) and durability (drying shrinkage, alkali-silica reaction, and rapid chloride permeability). The results were compared to control mixture (100% Portland cement, PC). Further, the low-purity CC was used in combination with slag cement as a partial replacement of PC (~50%) in ternary concrete mixtures. The performance of ternary binder was evaluated in mortar and concrete mixtures and the results were compared with control (100% PC) and two binary (20% CC and 50% slag) mixtures. Also, the possibility to make a coupled substitution of PC with CC and limestone (LS) was tested to allow higher levels of cement replacement up to 55%. For this purpose, a statistical design of experiment (DoE) approach combined with machine learning (i.e., artificial neural network, ANN) was adopted to determine the optimum PC, CC, and LS contents in mortar mixtures, leading to the best strength versus time. The best mixture was selected considering the compressive strength, cost, and CO2 emission of each mixture. Besides, the possibilities for eliminating the use of PC, and thus minimizing the CO2 footprint of concrete, were explored via a one-part liquid (just add water) geopolymer binder. Some routine tests were performed on mortar mixtures such as flowability, flow retention, time of setting, compressive strength, and volume stability. This study can provide sufficient knowledge on reactivity of impure CC sources and facilitates large-scale and high-volume usage of these sources in concretes to ensure their long-term performance and low life-cycle cost, and improved sustainability. The impact of this research is to advance the science, technology, and practice to facilitate doubling the supply of concrete pozzolans in the U.S. within the next decade. The research work in this dissertation will result in six journal publications, and several conference presentations/posters.

This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main topics are geology of clays, hydration and performance of blended system with calcined clays, alkali activated binders, applications in concrete and mortar, durability of concrete under various aggressive conditions, and economic and environmental impacts of the use of calcined clays in cement based materials. This book compiles the different contributions of the 2nd International Conference on Calcined Clays for Sustainable Concrete, which took place in La Habana, December 5th-7th, 2017.The papers update the latest research in their field, carried out since the last conference in 2015. Overall it gives a broad view of research on calcined clays and their application in the field of construction, which will stimulate further research into calcined clays for sustainable concrete.

This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended system with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest research in their field. It contains nearly 80 papers and abstracts. Overall, this work gives a broad view of research on calcined clays in the field of construction and will stimulate further research into calcined clays for sustainable concrete.

This volume comprises the proceedings of the Third International Conference on Calcined Clays for Sustainable Concrete held in New Delhi, India in October 2019. The papers cover topics related to geology of clay, hydration and performance of blended systems with calcined clays, alkali activated binders, and economic and environmental impacts of the use of calcined clays in cement-based materials. The book presents research on influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, and the environmental impact of use of calcined clays in cement and concrete and field applications of calcined clay in concrete. Apart from giving an overview of the progress of research during the last two years, this work also covers the state-of-the art on the practical aspects of production and use of calcined clays in construction. The contents of this volume will prove useful to researchers and graduate students working in the areas of cement chemistry, cement production, and concrete design.

Recent studies have shown that certain clays can be altered to become effective supplementary cementitious materials (SCMs). In this project, University of South Florida researchers examined a number of Florida clays to determine if they could be used in this way.

The goal of producing concrete that provides longterm durability with regard to properties such as improved sulfate resistance and reduced susceptibility to alkali-silica reactions (ASR) has led to the development of several high-performance materials. While the use of fly ashes and ground granulated blast-furnace slags (GGBFS) in concrete is gaining acceptance in various applications, the mineralogical composition of such byproduct materials cannot be as easily controlled as a manufactured pozzolan. Since 1993, Ash Grove has developed and directed the manufacture of pozzolans to improve concrete durability, while avoiding the potential problems of byproduct pozzolan availability and uniformity. Processing of these performance-enhancing pozzolans is accomplished by thermally treating and converting crystalline clay materials to amorphous alumino silicates. These pozzolans can be interground with portland cement clinker and gypsum to produce a Type IP blended cement or they can be ground separately as mineral admixtures for concrete. These two products are produced under the specification requirements of ASTM C 1157 or ASTM C 595 for hydraulic cements and ASTM C 618 for mineral admixtures, respectively. In ASTM C 618, the classification for raw or calcined natural pozzolans is Class N. The data contained in this paper describe some of the choices that are available to manufacturers of blended hydraulic cements to "engineer" into the cementitious system the desired properties for concrete such as improved sulfate resistance, reduced permeability, and the ability to strongly mitigate ASR.

The book is an outcome of the author’s active professional involvement in research, manufacture and consultancy in the field of cement chemistry and process engineering. This multidisciplinary title on cement production technology covers the entire process spectrum of cement production, starting from extraction and winning of natural raw materials to the finished products including the environmental impacts and research trends. The book has an overtone of practice supported by the back-up principles.