Behavior of novel cementitious composites for use in sustainable construction and rehabilitation

Cementitious composites are a class of cement-based materials that incorporate a cement paste and other constituents to form a composite material. Cementitious composites may include coarse and/or fine aggregate, admixtures, supplementary cementitious materials (SCMs), or fibers in order to achieve a desired workability, strength, or durability property. Recently, material scientists and engineers have developed a variety of novel cementitious composites for the purpose of new construction, rehabilitation, and reconstruction applications. Such materials can be used to improve the sustainability of civil infrastructure through the use of recycled, repurposed, or low-embodied carbon materials. Since many of the qualification standards and tests that exist are conceived for ordinary portland cement concrete in new construction, there is a need to qualify and test novel cementitious composites in accordance with their conceived use case. It is for this reason that the study of concrete durability and combined deterioration mechanisms is necessary to gain a more comprehensive understanding of the theoretical service life of in-situ repairs and structural elements comprised of novel materials. Gaining insight into the behavior of novel cementitious composites can inform specification development and design. Recently, material scientists and engineers have developed a variety of novel cementitious composites for the purpose of new construction, rehabilitation, and reconstruction applications. Such materials can be used to improve the sustainability of civil infrastructure through the use of recycled, repurposed, or low-embodied carbon materials. Since many of the qualification standards and tests that exist are conceived for ordinary portland cement concrete in new construction, there is a need to qualify and test novel cementitious composites in accordance with their conceived use case. It is for this reason that the study of concrete durability and combined deterioration mechanisms is necessary to gain a more comprehensive understanding of the theoretical service life of in-situ repairs and structural elements comprised of novel materials. Gaining insight into the behavior of novel cementitious composites can inform specification development and design. In this dissertation, mechanical and durability properties of a variety of novel cementitious composites (NCCs) are tested and discussed. Specifically, fiber-reinforced cementitious composites (FRCCs) and recycled aggregate concrete (RAC) materials are investigated in terms of load-displacement and ultimate mechanical strength. Additionally, laboratory testing methodologies are detailed in terms of the applicable concrete qualification tests and their modifications. Further, computational modeling approaches are also considered. The outcomes of the various studies presented herein highlight the importance of the proper adoption and implementation of experimental methods and setups that deliver useful insights when working with NCCs. Furthermore, the properties of NCC constituents for which accurate and repeatable qualification standards do not exist were determined to be sensitive enough to treatment and placement conditions to warrant novel testing program development and control over specific variables. Some of the standard testing procedures for cement composites are directly implemented into the experimental programs, while other procedures are modified to fit the needs of the experiment. In all experiments, constituent variables such as water-cement ratio (w/cm), volume of aggregates, and water content were kept constant, while other experimental mixture design variables are altered in order to capture certain mechanical strength outcomes resulting from mixture composition differences, In one study, the ability of a novel testing setup to capture the effect of an environmental conditioning protocol on bond performance is evaluated. Finally, this dissertation will highlight the importance of qualifying and testing novel cement composites. The testing standards and methodologies selected for qualifying these materials is chosen to capture the desired experimental outputs