Graduation Semester and Year
Winter 2025
Language
English
Document Type
Thesis
Degree Name
Master of Science in Civil Engineering
Department
Civil Engineering
First Advisor
Professor Maria S. Konsta-Gdoutos
Abstract
Off-spec supplementary cementitious materials (SCMs) remain underutilized due to variability in reactivity and non-conformance with existing standards. This study evaluates the hydration behavior and fresh-state and mechanical performance of these materials in Portland limestone cement (PLC) systems. One Class F fly ash (FA), one bottom ash (BA), and two calcined clays (HACC and LACC) were evaluated as 20 % replacements to PLC. Hydration behavior was characterized using isothermal calorimetry and thermogravimetric analysis (TGA), while fresh-state and mechanical performance were assessed through flow table, Vicat setting time, load–crack mouth opening displacement (CMOD) flexural testing, and compressive strength testing. HACC increased compressive strength and modulus of elasticity (MOE) by approximately 6–8 % relative to PLC, consistent with greater dehydroxylation and higher reactive alumina indicated by TGA. LACC exhibited limited mechanical gains, corresponding to partial dehydroxylation and retention of kaolinitic phases. BA, characterized by coarse, porous particles and high moisture content, improved flow but 2 caused a significant reduction in mechanical performance. Mechanical testing confirmed that HACC outperformed all other materials in flexural strength, MOE, and compressive strength. These results show that extent of dehydroxylation and intrinsic reactivity govern the performance of off-spec SCMs in PLC systems. HACC exhibited the highest mechanical performance, whereas BA and LACC exhibited limitations associated with particle morphology and partial dehydroxylation.
Keywords
Off-spec supplementary cementitious materials(SCMs), Fly ash, Bottom ash, Pozzolanic reactivity, Portland limestone cement (PLC), Calcined clays, Dehydroxylation, Mechanical performance
Disciplines
Civil and Environmental Engineering | Civil Engineering | Mechanics of Materials | Other Civil and Environmental Engineering | Other Materials Science and Engineering | Structural Materials
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Qubty, George A., "Integrating Off-Spec SCMs into PLC Blends" (2025). Civil Engineering Theses. 469.
https://mavmatrix.uta.edu/civilengineering_theses/469
Included in
Civil Engineering Commons, Mechanics of Materials Commons, Other Civil and Environmental Engineering Commons, Other Materials Science and Engineering Commons, Structural Materials Commons