Date of Graduation
12-2024
Document Type
Thesis
Degree Name
Master of Science in Civil Engineering (MSCE)
Degree Level
Graduate
Department
Civil Engineering
Advisor/Mentor
Barry, Michelle L.
Committee Member
Murray, Cameron D.
Second Committee Member
Hale, W. Micah
Keywords
3D Printing Concrete; AC Concrete; Additive Construction; Aggregates
Abstract
Aggregates play a crucial role in the overall properties of concrete. They provide volume stability, improve durability, and enhance mechanical properties such as compressive strength. This research presents a comprehensive comparative study of virgin aggregates (such as limestone, granite, and basalt) and recycled concrete aggregates (RCA) in the production of concrete, with a focus on both traditional and additive construction (AC) methods. The increasing demand for sustainable building practices and materials has brought RCA to the forefront of modern construction as a potential replacement for natural aggregates. This study aims to characterize the mechanical properties, durability, and sustainability impacts of sourced and recycled aggregates in concrete applications, assessing their respective performances in traditional construction techniques and innovative 3D concrete printing (3DCP) technologies.
The first sourced aggregates are characterized by well-defined strength, durability, and particle gradation, and the second is RCA, which, while offering environmental advantages, faces challenges related to its heterogeneous composition, high porosity, and the presence of adhered mortar. Extensive material testing was conducted, including Los Angeles Abrasion (LA) tests, Aggregate Crushing Value (ACV), and Aggregate Impact Value (AIV) tests, alongside detailed particle size distribution analyses. These tests were applied to both sourced aggregates and RCA to quantify their physical properties and establish correlations between these characteristics and concrete performance.
To assess concrete strength and durability, both sourced and RCA-based concrete mixtures were developed and tested under controlled laboratory conditions. Following ASTM standards, the concrete mixes were subjected to unconfined compression tests at curing periods of 7, 14, and 28 days. The study further investigated fresh concrete's workability and rheological properties, particularly focusing on pumpability and buildability, which are critical for 3D printing applications. These tests revealed that while sourced aggregates, mainly limestone and basalt, consistently exhibited superior mechanical properties, RCA-based concrete demonstrated significant potential when optimized for workability and admixture incorporation.
Overall, this research concludes that sourced aggregates remain the preferred choice for high-performance structural applications due to their superior strength and durability. However, RCA presents a viable, sustainable alternative for non-structural applications and additive manufacturing. RCA's use can significantly reduce the environmental impact of construction practices, making it a valuable component in the movement towards greener building technologies. Future research is recommended to further optimize the performance of RCA through advanced material processing techniques and chemical admixtures, focusing on enhancing its durability and strength for broader structural applications.
Citation
Lozano Casas, J. (2024). Evaluation of Aggregate Characteristics for Conventional and AC Concrete. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/5602
