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Öğe Activation of Polypropylene (PP) Fiber Surface with 1-Vinyl-1,2,4-triazole and Vinyl Acetate: Synthesis, Characterization, and Application in Cementitious Systems(Mdpi, 2025) Kaya, Yahya; Balci, Petek; Ozen, Suleyman; Mardani, Ali; Kara, AliRecently, the potential of recycled materials to improve the performance of concrete and other building materials has become an important research topic. It is known that various methods are applied to improve the tensile strength and energy absorption capacity of cementitious systems. One of the most common of these methods is the addition of fibers to the mixture. In this study, the effects of surface-modified polypropylene (PP) fibers obtained from recycled masks on the mechanical properties of mortar mixtures were investigated. In order to improve the matrix-fiber interface performance, 6 mm and 12 mm long recycled PP fibers were chemically coated within the scope of surface modification using 1-Vinyl-1,2,4-Triazole and Vinyl Acetate. With this modification made on the surface of PP fibers, we aimed to increase the surface roughness of the fibers and improve their adhesion to the matrix. Thus, we aimed to increase the mechanical properties of mortar mixtures as a result of the fibers performing more effectively in the concrete matrix. FTIR AND SEM-EDS analyses confirmed the success of the modification and the applicability of 1-Vinyl-1,2,4-Triazole and Vinyl Acetate to the fiber surface and showed that the fibers were successfully modified. It is seen that the fibers modified with Vinyl Acetate exhibit superior performance in terms of both the workability and strength performance of cementitious systems compared to the fibers modified with 1-Vinyl-1,2,4-Triazole. This study provides a significant contribution to sustainable construction materials by revealing the potential of using recycled materials in cementitious systems.Öğe Effect of graphene oxide-coated jute fiber on mechanical and durability properties of concrete mixtures(Elsevier Sci Ltd, 2024) Ozen, Suleyman; Benlioglu, Arif; Mardani, Ali; Altin, Yasin; Bedeloglu, AyseVarious methods are applied in order to improve the mechanical properties of concrete and to provide ductility. The most common method is the addition of fiber to cementitious systems. The fibers used in cementitious systems are divided into two categories: artificial and natural. Natural fibers are preferred due to their lower production cost, lower environmental impacts such as lower carbon emissions and fossil fuel consumption, biodegradability, lower density and ease of manufacturing. On the other hand, graphene-derived materials have been proven to improve the mechanical and interface properties between fiber and matrix. In this study, the effect of surface treatment of jute fibers with various chemical treatments and graphene oxide coating on the mechanical and some durability performances of concrete mixtures was investigated. For this purpose, the surface of jute fibers was roughened with graphene oxide coating. Within the scope of the experimental study, different fiber concrete mixtures were prepared by adding jute fibers of 30 and 50 mm length to the mixture at 0.25 and 0.5 % of the total volume in addition to the fiber-free control mixture. The fiber was used in 2 different ways, both without any treatment and by coating the surface with graphene oxide. Slump tests were performed on the concrete mixtures produced. The 28-day hardened concrete specimens were tested for compressive strength, flexural strength, modulus of elasticity, ultrasonic pulse velocity and depth of water penetration under pressure. The resistance of the concrete specimens at 300 and 600 degrees C high temperatures and after 300 cycles of freeze-thaw was determined by examining their compressive strength. In addition, the microstructural properties of the jute fiber specimens were examined using Scanning Electron Microscopy (SEM).Öğe Effect of interlayer cold joint on mechanical properties and permeability of roller compacted concrete(Higher Education Press, 2025) Bayqra, Sultan Husein; Ozen, Suleyman; Mardani, Ali; Ramyar, KambizOne issue with layer application of roller compacted concrete (RCC) is the development of cold joints, which can cause damage to RCC structures. In this study, fly ash was used in place of 0%, 20%, 40%, and 60% of the cement or aggregate to examine the impact of interlayer cold joint formation on RCC mixtures. To promote cold joint formation, the second layer was placed and compacted with a delay of 0, 60, 120, or 180 min after the first layer. Three methods were tried for preventing cold joints from forming: one was to apply a bedding mortar to the interlayer, another was to add a set retarder admixture, and the third was to spray an adhesion-enhancing chemical additive on the surface of the first layer. Based on the 28 d specimens' compressive and splitting-tensile strengths as well as the depth of water penetration under pressure, the most effective method was found to be applying interlayer bedding mortar. Considering 180 min delayed layer castings, the splitting-tensile and compressive strengths of the control samples decreased by 31% and 17%, respectively, while the strengths of mixtures applying interlayer bedding mortar decreased by 9% and 10%. In addition, bedding mortar treatment decreased the water permeability by 59% compared to the control. Interlayer cold joint decreased all mixtures' moduli of elasticity, regardless of the age of the specimens. When the interlayer delay was 60 min, the modulus of elasticity decreased by 1%-4%. It was between 2% and 14%, and between 10% and 24% at 120 and 180 min for the interlayer delay. The longer the delay in placing the second RCC layer, the more detrimental the effect of the cold joint. This effect was most noticeable on mechanical and permeability properties tested with applied load or water pressure parallel to the cold joint, such as flexural and splitting tensile strengths and water penetration depth under pressure.Öğe Effects of Shrinkage Reducing Admixture and Polypropylene Fiber Utilization on Some Fresh State, Mechanical and Durability Properties of Khorasan Mortar(Taylor and Francis Ltd., 2024) İsafça-Kaya, Tuğçe; Karakuzu, Kemal; Özen, Süleyman; Mardani, Ali; Do?angün, AdemThis study aimed to improve the mechanical and durability properties of Khorasan mortar, a type of lime-based mortar, using polypropylene shrinkage reducing admixture (SRA) and fiber. In addition to the control mixture without fiber and chemical admixture, three series of mixtures were prepared. The first series contains 0.4–0.6-0.8% polypropylene fiber by total volume; the second series contains SRA at the 0.05–0.1-0.15% by binder weight; the third series consists of mixtures containing both fiber and the SRA. Within the scope of the study, some fresh state, mechanical and durability properties were determined. The results show that utilization of fiber and SRA reduced the length change depending on drying-shrinkage and mass loss due to abrasion compared to the control mixture. In addition, the 90-day flexural and compressive strength values for all mixtures were lower than the 28-day results. It was determined that the decrease in strength values is less than the control mixture with the utilization of fiber and SRA because of the degradation in drying-shrinkage. © 2022 Taylor & Francis.Öğe Evaluation of polycarboxylate ether-based grinding aids on clinker grinding performance: the influence of pH(Taylor & Francis Ltd, 2025) Kaya, Yahya; Kobya, Veysel; Samadpour, Nasim; Altun, Okay; Ozcan, Aydin; Kaya, Yunus; Mardani, AliThis study introduces an innovative approach by synthesizing PCE-based grinding aids (GAs) at three different pH levels (4, 7, and 9) to investigate how pH-induced structural variations impact grinding performance and cement quality. The GAs were applied at dosages of 0.025%, 0.05%, and 0.1% (by total weight of clinker and gypsum). Milling performance and final product properties were assessed, while thermogravimetric analysis (TGA) evaluated the thermal stability of the synthesized GAs. Additionally, molecular dynamics (MD) simulations were conducted to quantify the adsorption energies of the GAs on C-A and C-S clinker phases. Results showed that the low-pH PCE-based GA significantly enhanced grinding efficiency, achieving up to 17% improvement over the control, and delivered superior cement performance. This research provides new insights into the pH-dependent behavior of PCE-based GAs and offers a novel strategy for optimizing molecular design to achieve high-efficiency, performance-driven cement production.Öğe Impact of PCE-based grinding aids on hydration kinetics in fly ash substituted systems: Influence of pH and dosage(Elsevier Sci Ltd, 2025) Kaya, Yahya; Kobya, Veysel; Kaya, Yunus; Mardani, AliWhile the use of grinding aids (GAs) is commonly favored for their cost and energy efficiency benefits, these additives can also present challenges, such as incompatibility with water-reducing admixtures. This has led to interest in polycarboxylate-based water-reducing admixtures (PCEs) as potential grinding aid (GA). However, there is a significant gap in the literature concerning the interaction between these PCE-based GA properties and cementitious systems' morphological characteristics and hydration kinetics. This study investigated the effects of PCE-based GAs with varying pH levels on hydration kinetics, flowability, and compressive strength in cementitious systems containing fly ash. PCE-based GAs were synthesized at three different pH levels (4, 7, 9), while other parameters were held constant. Using these GAs, a total of 10 Portland cements, including one control, were produced at three different dosages. Additionally, two different fly ash substitution levels were used to prepare paste and mortar mixtures with these cements. This approach has enabled the investigation of fly ash substitution systems in the presence of PCE-based GAs and the assessment of environmental impact through life cycle analysis. The study aimed to contribute to the existing literature and offer an alternative approach to sustainable production. The findings revealed that the PCE-based GA with a low pH value (4) was the most optimal in terms of the evaluated properties.Öğe Influence of sulfonate and phosphate groups in polycarboxylate ethers on properties of fly ash blended cementitious systems(Elsevier Sci Ltd, 2025) Altun, Muhammet Gokhan; Karakuzu, Kemal; Ozen, Suleyman; Hatungimana, Daniel; Mardani, Ali; El-Mir, Abdulkader; Assaad, Joseph J.This investigation examines the effect of anionic monomer groups in polycarboxylate ether (PCE) superplasticizers on rheology, setting, compressive strength, and water absorption of cementitious systems containing fly ash additions. Five PCEs having the same backbone structure and different anionic groups are synthesized. The carboxylate functional group is replaced with 10 % or 30 % sulfonate or phosphate groups, while the total anionic monomer content, molecular weight, and side chain length are kept constant. Test results showed that the PCEs containing 30 % sulfonate or phosphate functional groups are effective in improving flow and reduce apparent viscosity, particularly in mixtures containing increased fly ash additions. Because of improved adsorption properties, setting times are extended, which consequently reduces the 1-day compressive strength when the carboxylates are gradually replaced by 10 % or 30 % sulfonate or phosphate functional groups. Yet, the late age strengths and water absorption are not affected by such replacements. Data reported in this paper can be of interest to admixture producers and concrete technologists seeking an efficient performance of PCE polymers in fly ash concrete mixtures.Öğe Modification of Polypropylene Fibers with Sodium Silicate: Enhancement of Pozzolanic Properties in Cement-Based Systems(Mdpi, 2025) Kaya, Yahya; Balci, Petek; Ozen, Suleyman; Mardani, Ali; Kara, AliThis study investigates the effect of sodium-silicate-based chemical surface modification of polypropylene (PP) fibers on the mechanical and fresh-state properties of cementitious composites. The proposed method introduces silanol and siloxane groups onto the PP surface through a radical-assisted chlorination route, aiming to enhance fiber-matrix interfacial bonding. Modified fibers increased the polycarboxylate ether (PCE) demand by 100% compared to the control mixture, while unmodified PP fibers caused a 58% increase at equivalent workability. The incorporation of PP fibers resulted in limited changes in compressive strength (1-7%), whereas silicate-modified fibers led to notable late-age flexural strength gains of 10% (28 days) and 17% (56 days). Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Fourier Transform Infrared Spectroscopy (FTIR) analyses confirmed successful surface functionalization, while the heterogeneous silicate deposition still contributed positively to interfacial transition zone (ITZ) performance. Overall, sodium-silicate-modified PP fibers improve flexural behavior and interfacial bonding in cement-based systems, offering a promising approach for enhanced mechanical performance and sustainability.Öğe Optimizing the Use of PCE-Based Grinding Aids: The Critical Role of pH on Early-Age Cement Hydration Kinetics(Asce-Amer Soc Civil Engineers, 2026) Kobya, Veysel; Kaya, Yahya; Mardani, Ali; Kaya, Yunus; Assaad, Joseph; Hamad, BilalPolycarboxylate ether (PCE) water-reducing admixtures have emerged as promising solutions to optimize clinker grinding and properties. The increased adsorption ability of PCE and creation of narrow particles, despite maintaining constant Blaine fineness, has sparked the interest of their use as grinding aids (GAs) in the cement industry. This study aims at synthesizing different PCEs at three distinct pH values (i.e., 4, 7, and 9), and assessing their interactions with the cement hydration kinetics and strength development at early ages. Ten cements were produced by incorporating the synthesized PCEs at three dosage rates of 0.025%, 0.05%, and 0.1%, by weight of clinker and gypsum materials. The mixtures were tested for Fourier-transform infrared spectroscopy (FTIR) spectra, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, setting time, heat calorimetry, and early-age strength. This comprehensive analysis revealed the significant pH impact on clinker comminution and sieve residues as well as the early-age hydration kinetics, formation of hydrated products, and strength development.Öğe Sustainable Cement Production: TEA-TIPA as Grinding Aids: Optimizing Ratios for Efficiency and Environmental Impact(Mdpi, 2025) Kobya, Veysel; Kaya, Yahya; Akgumus, Fatih Eren; Kaya, Yunus; Mardani, Naz; Mardani, AliIn line with sustainable construction goals, this study investigates the synergistic use of amine-based grinding aids (GAs), triethanolamine (TEA), and triisopropanolamine (TIPA) to enhance grinding performance and cement properties. GAs were physically blended at varying TEA/TIPA ratios, and their effects on grinding efficiency, CO2 emissions, and environmental footprint were assessed based on energy consumption per target Blaine fineness. The interaction of blended GAs with Ca2+ ions was modeled to understand adsorption behavior. Cement particle size distribution (PSD), Hausner ratio, Carr index, and angle of repose were analyzed to evaluate powder flowability. Scanning electron microscopy (SEM) was employed to examine microstructural changes. Finally, the Taguchi method statistically analyzed the effective parameters influencing system performance. Results demonstrated that the optimized blend containing 25% TEA and 75% TIPA improved grinding performance, enhanced polymer-ion interactions, refined PSD, and significantly increased powder flowability. Overall, the study underscores the potential of amine-based polymeric GAs in producing environmentally friendly, high-performance cement composites. Using a Taguchi design with the larger-is-better S/N criterion, the optimal formulation was determined to be 25% TEA and 75% TIPA at a dosage of 0.10%. ANOVA results indicated that the TEA content was the most significant factor, while the dosage had no statistically significant effect.Öğe Synthesis, characterization, and efficiency evaluation of next-generation grinding aids modified with organic acids(Elsevier Sci Ltd, 2025) Kaya, Yahya; Kobya, Veysel; Kaya, Yunus; Mardani, Ali; Ramyar, KambizGrinding aids (GAs) are continually modified to enhance grinding efficiency and cement's overall performance. Despite their widespread use in the industry, there is a lack of comprehensive research exploring GA modifications from a chemical standpoint. In this context, the present study focuses on the synthesis and performance evaluation of next-generation GAs achieved through chemical modification of commonly used compounds. To this end, nine modified GAs were synthesized by reacting carboxylic acids with varying carbon chain lengths (acetic, propanoic, and hexanoic acids) with triisopropanolamine (TIPA), diethanol isopropanolamine (DEIPA), and diethylene glycol (DEG). The chemical structures of the synthesized GAs were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Carbon-13 Nuclear Magnetic Resonance (13C NMR), and Gas Chromatography-Mass Spectrometry (GC-MS). Density functional theory (DFT) was also employed to analyze their molecular structures theoretically. Grinding efficiency was assessed through laboratory-scale experiments, while the adsorption potential of the modified GAs toward Ca2+ ions was examined via theoretical calculations. Zeta potential analysis of the obtained cements was conducted to corroborate experimentally the adsorption results derived from molecular modeling. The results indicated that chemical modifications enhanced both the milling efficiency and the adsorption performance of grinding aids, as confirmed by both experimental and modeling studies. These findings provide a valuable reference for developing energy-efficient and environmentally sustainable grinding aids.Öğe The Effect of Sulfonate and Phosphate Anionic Monomers of Water Reducing Admixtures on Fresh State and Mechanical Properties of Self Compacting Concrete(Bursa Uludağ Üniversitesi, 2022) Altun, Muhammet Gökhan; Özen, Süleyman; Karakuzu, Kemal; Mardani, AliIn this study, the effect of anionic monomer content of polycarboxylate-ether based water reducing admixture on various fresh and hardened state properties of self-compacting concrete (SCC)mixtures was investigated. For this purpose, in addition to the control admixture whose anionic monomer is 100% carboxylate, 5 different water reducing admixtures were synthesized by replacing the anionic monomer of the control admixture with 10% and 30% sulfonate and phosphate. According to the results, the substitution of the water reducing admixture anionic monomer with sulfonate increases the admixture requirement of the mixtures; had a positive effect on time-dependent flowing performances. In the case of phosphate substitution, the admixture requirement of the mixtures decreased, while the time-dependent flowing performance was adversely affected. The best performance among all mixtures was obtained with 10% sulfonate substituted admixture. The anionic monomer change did not cause any significant changes in the compressive strength, water absorption rates, ultrasonic pulse velocity (UPV) and dynamic elasticity modules of the SCC mixtures.
