Date of Award
May 2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Civil Engineering
First Advisor
Nabil N. Suleiman
Abstract
Cementitious materials are fundamental to modern infrastructure; however, the environmental impact associated with cement production, which contributes approximately 7–8% of global CO₂ emissions, has driven the need for sustainable alternatives. This study investigates the development and performance of sustainable cementitious materials incorporating industrial and agricultural by-products as partial replacements for conventional cement. The research focuses on three material systems: coal combustion residues, CO₂-mineralized steel slag, and flax fiber-reinforced and hybrid cementitious composites. The feasibility of utilizing coal bottom ash (CBA) and coal boiler slag (CBS) as supplementary cementitious materials (SCMs) was evaluated by examining their effects on fresh, mechanical, durability, and environmental properties of concrete at a 20% cement replacement level. The results indicated that CBA-based concrete exhibited improved compressive, flexural, and splitting tensile strength, along with enhanced modulus of elasticity and chloride resistance, attributed to its pozzolanic activity. CBS-based mixtures also demonstrated acceptable performance, though comparatively lower than CBA in certain properties. Toxicity Characteristic Leaching Procedure (TCLP) analysis confirmed that heavy metal concentrations remained below regulatory limits, supporting the safe and beneficial reuse of coal combustion residues in concrete applications. The potential of steel slag as a low-carbon SCM was investigated through CO₂ mineralization (CO₂M), which promotes the formation of stable carbonate phases and enables carbon sequestration. Chemical and mineralogical analyses confirmed the transformation of reactive oxides into carbonate phases, while thermogravimetric analysis (TGA) and total inorganic carbon (TIC) measurements indicated measurable CO₂ uptake. TGA results showed approximately 6% mass loss associated with carbonate decomposition, while TIC analysis, which provides a more direct and reliable quantification of carbon content, indicated a CO₂ uptake of approximately 10.6%. Compressive strength testing demonstrated that mortar incorporating CO₂-mineralized steel slag achieved strength comparable to the control and satisfied ASTM C311 strength activity index requirements, whereas untreated slag exhibited lower performance. Microstructural observations revealed matrix densification and improved particle–matrix interaction following mineralization. TCLP results further confirmed that the mineralization process did not increase heavy-metal leachability, supporting its environmental safety. To address the inherent brittleness of cementitious materials, flax fiber (FF) was incorporated as a natural reinforcement at a dosage of 0.7% by weight of cement. Mechanical testing showed that flax fiber-reinforced mortar (FFRM) improved flexural strength by approximately 3.4% and splitting tensile strength by approximately 7.12% due to crack-bridging and fiber pull-out mechanisms. However, compressive strength was reduced, with FFRM achieving approximately 84.6% of the control strength at 28 days. Hybrid mixtures incorporating 0.7% flax fiber and 20% CO₂-mineralized steel slag achieved approximately 82.1% of the control compressive strength, indicating that the inclusion of a low-carbon binder did not significantly compromise load-bearing capacity relative to fiber-reinforced systems. Microstructural analysis confirmed effective fiber–matrix interaction and provided insight into crack-bridging behavior and interfacial transition zone characteristics.Overall, the findings demonstrate that industrial by-products such as coal combustion residues and CO₂-mineralized steel slag can be effectively utilized as sustainable cementitious materials while maintaining acceptable mechanical performance and environmental safety. In addition, flax fiber provides effective reinforcement for improving tensile and flexural behavior. The integration of these materials highlights the potential for developing low-carbon cementitious systems that balance mechanical performance with sustainability, supporting the advancement of resource-efficient and environmentally responsible construction practices.
Recommended Citation
Guteta, Lidya Emmanuel, "Development And Performance Evaluation Of Sustainable Cementitious Materials Incorporating Industrial And Agricultural By-Products For Low-Carbon Construction" (2026). Theses and Dissertations. 13946.
https://commons.und.edu/theses/13946