Date of Defense
12-5-2026 5:00 PM
Location
Room 1043, Mechanical and Aerospace Engineering Department Meeting Room, F1 Building
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Mechanical Engineering
College
College of Engineering
Department
Mechanical and Aerospace Engineering
First Advisor
Abdelhamid Ismail Mourad
Keywords
Innovative sulfur-based concrete; industrial by-products; carbide lime; design of experiments; durability; sustainable infrastructure; circular economy; biomass activated carbon
Abstract
Portland cement (PC) is a significant player in the construction industry, which is one of the largest global carbon footprint sectors, contributing approximately 8% of total anthropogenic CO₂ emissions worldwide. In arid and developing countries such as the UAE, the negative impacts of PC are amplified by the piling of industrial wastes, and hence there is an urgent need to develop efficient and cost-effective waste management solutions. This dissertation reports on the design and characterization of a novel sulfur-based concrete made from locally available industrial waste materials, with an emphasis on improving the performance and durability of the material as well as paving the way toward the commercialization of low-carbon concrete products. A performance-based experimental design approach was used to convert the typically employed trial-and-error sulfur concrete recipes into predictable engineered material systems. Statistical Design of Experiments (DOE) coupled with particle packing theory and modified sulfur binder were used to optimize the mixture proportions across four test groups (SSC, SSSG, SLDLG, and SBAC) comprising approximately 60 distinct mixture combinations. Modified sulfur concrete was prepared using elemental sulfur (with 99.9% purity) as a primary binder, along with carbide lime, ladle furnace slag, steelmaking dust, dune sand, and biomass-derived activated carbon. Extensive laboratory tests were carried out to evaluate the mechanical performance, durability, and microstructure of the modified sulfur concrete using state-of-the-art characterization tools, including SEM, XRD, and TGA. Response surface methodology (RSM) was utilized to rigorously quantify the interactions between factors and to establish performance-based criteria for optimization, achieving prediction models with R² values exceeding 0.97 for compressive strength and 0.99 for splitting tensile strength. The optimized mixture, comprising 22% modified sulfur, 38% crushed limestone, 25% dune sand, 5% ladle furnace slag, and 10% ground granulated blast furnace slag, achieved a compressive strength of 63.67 MPa and a splitting tensile strength of 4.45 MPa, with densities ranging between 2.277 and 2.488 g/cm³. The 7% replacement of carbide lime with biomass-activated carbon yielded a 23.9% increase in compressive strength, reaching 52 MPa. Long-term durability assessment over 18 months demonstrated outstanding chemical resistance, with strength reductions limited to 1.25% in water at 22 °C, 2.35% in water at 60 °C, 2.66% in 20% sulfuric acid, and 2.50% in 5% saline solution. Wet/dry cycling testing across 39 cycles revealed temperature-dependent fatigue, with strength losses of 3.2%, 6.5%, and 10.8% at 22 °C, 45 °C, and 60 °C, respectively. The vital role of carbide lime in enhancing packing density (achieving porosity below 2%) and microstructural stability in the thermoplastic matrix was demonstrated. In general, this dissertation provides a complete roadmap for designing locally-sourced waste-derived sulfur-based concrete by addressing the existing knowledge gaps in mix optimization, durability performance, and industrial application.
Included in
Development and Characterization of Sulfur-Based Concrete from Industrial Waste By-Products
Room 1043, Mechanical and Aerospace Engineering Department Meeting Room, F1 Building
Portland cement (PC) is a significant player in the construction industry, which is one of the largest global carbon footprint sectors, contributing approximately 8% of total anthropogenic CO₂ emissions worldwide. In arid and developing countries such as the UAE, the negative impacts of PC are amplified by the piling of industrial wastes, and hence there is an urgent need to develop efficient and cost-effective waste management solutions. This dissertation reports on the design and characterization of a novel sulfur-based concrete made from locally available industrial waste materials, with an emphasis on improving the performance and durability of the material as well as paving the way toward the commercialization of low-carbon concrete products. A performance-based experimental design approach was used to convert the typically employed trial-and-error sulfur concrete recipes into predictable engineered material systems. Statistical Design of Experiments (DOE) coupled with particle packing theory and modified sulfur binder were used to optimize the mixture proportions across four test groups (SSC, SSSG, SLDLG, and SBAC) comprising approximately 60 distinct mixture combinations. Modified sulfur concrete was prepared using elemental sulfur (with 99.9% purity) as a primary binder, along with carbide lime, ladle furnace slag, steelmaking dust, dune sand, and biomass-derived activated carbon. Extensive laboratory tests were carried out to evaluate the mechanical performance, durability, and microstructure of the modified sulfur concrete using state-of-the-art characterization tools, including SEM, XRD, and TGA. Response surface methodology (RSM) was utilized to rigorously quantify the interactions between factors and to establish performance-based criteria for optimization, achieving prediction models with R² values exceeding 0.97 for compressive strength and 0.99 for splitting tensile strength. The optimized mixture, comprising 22% modified sulfur, 38% crushed limestone, 25% dune sand, 5% ladle furnace slag, and 10% ground granulated blast furnace slag, achieved a compressive strength of 63.67 MPa and a splitting tensile strength of 4.45 MPa, with densities ranging between 2.277 and 2.488 g/cm³. The 7% replacement of carbide lime with biomass-activated carbon yielded a 23.9% increase in compressive strength, reaching 52 MPa. Long-term durability assessment over 18 months demonstrated outstanding chemical resistance, with strength reductions limited to 1.25% in water at 22 °C, 2.35% in water at 60 °C, 2.66% in 20% sulfuric acid, and 2.50% in 5% saline solution. Wet/dry cycling testing across 39 cycles revealed temperature-dependent fatigue, with strength losses of 3.2%, 6.5%, and 10.8% at 22 °C, 45 °C, and 60 °C, respectively. The vital role of carbide lime in enhancing packing density (achieving porosity below 2%) and microstructural stability in the thermoplastic matrix was demonstrated. In general, this dissertation provides a complete roadmap for designing locally-sourced waste-derived sulfur-based concrete by addressing the existing knowledge gaps in mix optimization, durability performance, and industrial application.