Characterizing the mechanical and structural performance of hydraulic-lime CMU wall components and assemblies
Haunt, Tucker Trostel
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Concrete is the most commonly used building material in the world. As a result, the production of portland cement accounts for seven percent of the carbon dioxide produced by industry worldwide. A more environmentally-friendly alternative to portland cement could significantly reduce carbon dioxide emissions, and thus reduce the carbon footprint of the concrete industry. One possible alternative to portland cement is hydraulic lime, which creates less carbon dioxide during its production than portland cement. Further, hydraulic lime reabsorbs carbon dioxide as it cures, through carbonation. Despite these advantages, there are some logistical issues associated with using hydraulic lime in modern construction (e.g., increased cure times). Using hydraulic lime in concrete masonry units provides an opportunity to overcome some of these limitations and thus take advantage of the environmental benefits associated with its use. While the use of lime as the binder in masonry construction is not a new concept, modern building codes have evolved around components made with portland cement rather than hydraulic lime. The, research discussed herein investigates the mechanical and structural performance of hydraulic lime masonry components, and evaluates the efficacy of simple mechanics models used to predict their performance. First, the performance of individual masonry components (i.e., mortar, grout, and block) are evaluated, followed by an evaluation of simple masonry assemblies (e.g., prisms). Finally, a series of five wall assemblies were tested to determine the in-plane shear resistance of hydraulic-lime wall systems. It was found that while the strength of the hydraulic lime masonry components/assemblies were significantly less than those made with portland cement, the use of hydraulic lime in this application is feasible.