Browsing by Author "Uysal, Mucteba"

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Alternating Current Curing of Conductive Fly Ash-Slag Geopolymer Mortars: Performance, Characterization and Optimization
(Springernature, 2024) Aygun, Beyza Fahriye; Uysal, Mucteba; Bilir, Turhan; Cosgun, Turgay; Dilbas, Hasan
This research seeks to pinpoint the most robust series by subjecting geopolymer mortars (GMs) to electrical curing (AC) at 20 V based on different NaOH concentrations and GBFS/FA ratios. To enhance the electrical conductivity of GMs displaying optimal mechanical properties, carbon fiber (CF), steel fiber (SF), waste wire erosion (WWE) (0.25%, 0.50%, and 0.75%), and carbon black (CB) (1%, 2%, and 3%) were introduced into the chosen series. A comprehensive assessment encompassing compressive strength, flexural strength, ultrasonic pulse velocities, direct tensile strength and splitting tensile strengths were conducted on mixtures undergoing 24 h of AC. The study's findings indicated a substantial improvement in mechanical properties through electrical curing compared to ambient curing conditions. Notably, a correlation of up to 99% was established between direct and splitting tensile properties. The investigation revealed that the highest compressive strength, reaching 72.41 MPa at 1 day strength, was achieved through the thermal curing method with electric curing, particularly in the 100GBFS series. On the other hand, the optimum bending strength, approximately 19 MPa, was observed in the SFA075WWE series. These results highlight the efficacy of the thermal curing method with electric curing in enhancing the compressive strength of the 100GBFS series and the flexural strength of the SFA075WWE series, underscoring the potential benefits of specific curing methods for different series within the study.
Durability Performance of Fiber-Reinforced Metakaolin-Based and Red Mud-Fly Ash-Slag Geopolymers With Recycled Aggregates
(Springer Heidelberg, 2023) Yilmaz, Arin; Ergun, Seckin; Uysal, Mucteba; Dilbas, Hasan; Aygormez, Yurdakul; Canpolat, Orhan
In the concept of green geopolymer, a good start would be if all/many of the geopolymer components were made from recycled materials. In this research, high recycled material consumption was aimed for forming a geopolymer. Binder materials were selected as 40% metakaolin, 20% fly ash, 20% granulated ground furnace slag, and 20% red mud, and, also the aggregates were selected as recycled material (50% recycled aggregate powder and 50% marble powder). In addition, different types of fibers (brass-coated steel fiber, polyamide fiber and polypropylene fiber) at different ratios (0-0.25-0.50-0.75-1.00%) were used. Compressive strength, bending strength, ultrasound pulse velocity were obtained in the tests and nonlinear fracture parameters such as initial fracture toughness and unstable fracture toughness were determined by equations. Besides, the durability properties (abrasion resistance, high-temperature (up to 600 & DEG;C) resistance, freeze-thaw (up to 300 cycles) resistance, and sodium/magnesium sulfate attack) of the best geopolymers were considered and the best series for each fiber type was determined by a decision support system. According to the test results, the bending strength was improved by curing age and all types of fibers. Besides, the first crack and unstable crack propagation are delayed by fibers. 0.75% polypropylene fiber with a high curing time (up to 56 days) can be proposed for higher performance of geopolymer. In addition, consideration of a decision support system eases finding the best solution among the huge experimental data and gives better results instead of the conventional singular evaluation approach.
An Investigation on Physical, Mechanical and Microstructural Properties of Electricity-Based Cured Gbfs-Fa Geopolymer
(Elsevier Sci Ltd, 2025) Aygun, Beyza Fahriye; Uysal, Mucteba; Bilir, Turhan; Cosgun, Turgay; Dilbas, Hasan
This paper aimed to investigate and develop curing process of geopolymer as a building material of the future. As well-known, the geopolymer may require heat while hardening and gaining strength. Application of heat treatment to the geopolymer on-site with heat sources are solutions, but it can be said that it is one of the most difficult processes of geopolymer. Thus, on-site electricity curing has been developed to overcome the difficulties in geopolymer curing. The developed curing process depended on application of AC voltage (10 V, 20 V, and 30 V) and the electrical resistance of geopolymer ensured a heat on geopolymer while curing process. In this experimental study, different NaOH and different GBFS/FA ratios were employed to seek the best solution. Also, the electrical resistance/conductivity of geopolymer was regulated with the addition of carbon fiber (CF), steel fiber (ST), waste wire erosion (WWE) (0.25 %, 0.50 %, and 0.75 %), and carbon black (CB) (1 %, 2 % and 3 %). Compressive strength (CS), flexural strength (FS), ultrasound pulse velocity (UPV), water absorption, void ratio, and unit weight were investigated parameters of geopolymer and were used to determine the best geopolymer mixtures. The internal and surface temperatures of geopolymer can be regulated by electricity-based thermal curing and it ensured a capability to set the optimum temperature on geopolymer. 20 V applications had the best efficiency in activating the geopolymerization reaction and the compressive strength positively affected, resulting the highest compressive strength as 78.02 MPa for SFA05WWE. Electricity-based thermal curing had a significant potential to surpass on-field-challenges in curing process of geopolymer and to obtain desired strength grade in not only indoor but also outdoor engineering applications.
Metakaolin-Based and Blast Furnace Slag-Activated Geopolymer Cement With Waste Powders
(Springer int Publ Ag, 2023) Kabirova, Aigul; Husem, Metin; Dilbas, Hasan; Uysal, Mucteba; Canpolat, Orhan
Sustainability leads a cementless materials branch in material engineering and science. Geopolymer is one part/leaf of the sustainability branch and has many advantages (i.e., less carbon emission and low energy consumption in production) attracting attention itself. The recent dizzying progress observed in geopolymers has now turned its direction towards environmentally friendly waste-based geopolymers. Accordingly, many types of waste produced in various industries have come to life in geopolymer seeming like a positive approach from the environmental point of view. However, this area is still a virgin and is worth studying. Hence, to contribute to this field, this experimental study was conducted. Accordingly, 25-50-75% basalt powder (BP), limestone powder (LSP), recycled aggregate powder (RAP), and waste marble powder (WMP) (< 63 mu m) were employed in the experiments to produce a durable and sustainable metakaolin (MK) based geopolymer with blast furnace slag (BFS). Thirteen mixtures were produced, and reference was included in the experiments. The main binder as a composition of MK, BFS, and an activator (1:2 NaOH/Na2SiO3) was considered. At the first stage of the experiments, the main properties of the geopolymer mortars were determined by conducting the tests of the mechanical properties and the physical properties. Then, the tests of the durability properties were applied to the reference and the best geopolymer specimens selected by different multi-criteria decision support methods (MCDMs). In this point, CDMs are useful tools to find the best choice and two MCDMs, such as TOPSIS and HDM, were considered to obtain the best geopolymer mix. As a result, ages-based evaluation showed that 28-day-old specimens had the high results. BP provided satisfactory results with a dense and compact structure in geopolymer. The best geopolymer mixture included 75% BP and had a significant mechanical and durability performance compared to reference with satisfactory properties. Examining the experimental results with a MCDM may give excellent results than the conventional singular evaluation technique.
Multi-Criteria Decision-Making Optimization-Based Fiber-Reinforced Waste Ceramic Powder-Based Geopolymer: Toward a Sustainable Net Zero/Low Co2 Emission Building Material
(Springernature, 2024) Kilic, Aysen Tahire; Uysal, Mucteba; Aygun, Beyza Fahriye; Nazir, Khizar; Canpolat, Orhan; Dilbas, Hasan
In this study, geopolymers (GMs) were produced using basalt fiber, polyamide fiber, and polypropylene fiber-reinforced and ground blast furnace slag (GBFS) waste ceramic powder (WCP). In the initial phase of the study, the optimal ingredient proportions were identified, and an ideal geopolymer was selected based on its highest compressive strength. Subsequently, at the second stage of the study, various fibers with differing proportions were incorporated into the ideal geopolymer, and the resulting properties were evaluated through laboratory testing. In the third stage, the optimal GMs were determined through a holistic approach, employing a multi-criteria decision-making method. A total of ten mixtures, comprising 23 properties (230 parameters in total), were subjected to a multi-criteria decision support method (TOPSIS). The optimal GM mixture with the proportions and suitable components was identified. The findings indicated that a 20% substitution of WCP with GBFS resulted in an optimal and cost-effective mixture in a 10 M NaOH solution, serving as a reference point or ideal unreinforced mixture in this research. With regard to the addition of fibers, all three types of fibers were observed to enhance the compressive, flexural, and splitting tensile strength of the WCP-GBFS-based GM. Maximum compressive strength was observed to be 60.15 MPa, while the flexural strength was 12.98 MPa and the splitting tensile strength was 3.45 MPa for the polyamide fiber (PA)-reinforced GM. Furthermore, all reinforced GMs exhibited enhanced abrasion resistance, with the inclusion of polypropylene fibers yielding the best results. Additionally, these fiber-reinforced GMs demonstrated significant resistance to high temperatures, even as temperatures increased. The TOPSIS results indicated that PA0.8 was the optimal GM, and its components with suitable components were recommended as a sustainable net zero/low CO2 emission building material.
Optimization of Synthetic Fiber-Reinforced Calcined Bentonite-Based Recycled Aggregate Geopolymer Composites Based on Multicriteria Decision Support Method
(Asce-Amer Soc Civil Engineers, 2025) Sahin, Furkan; Aladag, Cenk; Uysal, Mucteba; Dilbas, Hasan; Bendjilali, Fatiha; Ayguen, Beyza Fahriye
The study evaluated the mechanical and durability properties of synthetic fiber-reinforced, metabentonite (MB)-based geopolymer composites (GCs) using 50x50x50-mm cubes for compressive strength and 40x40x160-mm prisms for flexural strength, according to standards for density and void analysis, direct tensile strength, and splitting tensile strength. Durability assessments included abrasion resistance and high-temperature effects, with the latter potentially adhering to standards for fire resistance tests of construction materials. First, a preliminary study was adopted on the calcination of bentonite, which was carried out at 900 degrees C. GCs were prepared in various MB/ground granulated blast furnace slag (GBFS) ratios (25%, 50%, 75%, and 100%) with molar concentrations (8M, 10M, 12M, and 14M) and 2:1 Na2SiO3/NaOH. Synthetic fiber reinforcement such as polypropylene fiber (PPF) polyamide fiber (PAF), and basalt fiber (BF) with 0.5%, 1%, 1.5%, and 2% consumption ratios were employed for the mixtures of GCs. This comprehensive study followed a series of steps. The first step depended on determining the mechanical behavior. The second step included the durability behavior of the best GCs for each fiber type inclusion. The best solution chosen/mixture optimization of GCs step depended on a multicriteria decision-making method and a capable method (TOPSIS-Technique for Order of Preference by Similarity to Ideal Solution) to evaluate the results. Accordingly, the best GCs were obtained, and the durability index of the best GC was determined. The GCs were subjected to high temperatures of 200 degrees C, 400 degrees C, 600 degrees C, and 800 degrees C, and the results showed that optimal GCs based on TOPSIS-multicriteria decision support method have 1% PPF, 0.5% PAF, and 0.5% BF fiber content. The BF-containing series showed the best performance among the fiber types. The offered GCs were the possible net-zero/low-carbon materials for future cities.
Red-Mud Additive Geopolymer Composites With Eco-Friendly Aggregates
(Elsevier Sci Ltd, 2024) Uysal, Mucteba; Dilbas, Hasan; Cosgun, Turgay; Bendjilali, Fatiha
Geopolymers have an increasing importance and a crucial task in engineering, especially structural engineering. Geopolymers are sustainable composites with low carbon emissions rather than cement composites. It leads to be an alternative to cement composites and the structure of geopolymer composites can allow to utilize various industrial and non-industrial wastes and by-products. In this point, there is an unclarity of waste material contributions to the geopolymeric composites and this issue is worth to study and an area of ongoing research. In this paper, it is aimed to produce red mud additive sustainable geopolymer composites with various eco-friendly fillers (brick powder, waste marble powder, glass powder, ceramic powder, and rice husk ash). 28 mixtures were designed, many specimens produced, and tested. In the first step of the experimental stage, the physical, the mechanical and the durability properties were determined and evaluated. At second, the best geopolymer composites were determined with a multi-criteria decision-making method (MCDM). 22 geopolymer parameters were employed in MCDM. As a results, 25% marble dust, 25% brick powder, 75% ceramic powder, 50% rice husk ash and 50% glass powder were the optimum ratios to obtain maximum compressive strength in terms of waste types and the highest compressive strength is obtained for 25% brick powder among the results. The best geopolymer composite was determined as GWGP50 with 50% glass powder + 50% recycled aggregate in a holistic manner with TOPSIS. Results showed that geopolymer GWGP50 had aspects that were open to development.
Relative Performance of Limestone, Marble, and Basalt Powders in Replacement of a Recycled Fine Aggregate From Red Mud and Metakaolin-Based Geopolymer Mortar
(Springer int Publ Ag, 2022) Chakkor, Ouiame; Altan, Mehmet Fatih; Canpolat, Orhan; Dilbas, Hasan; Uysal, Mucteba
The current investigation was conducted to reduce the environmental impact of wastes comprising a green, sustainable recycled geopolymer composition (RGC) including granulated-ground-blast-furnace slag (GGBS), metakaolin (MK), red mud (RM) and recycled fine aggregate (RFA). In addition, leftover industrial materials, such as limestone (LS), marble (MR), and basalt (BS) powders, are employed as fillers to replace RFA in various proportions (25, 50, and 75%). Thus, a green RGC consists of wastes. Here, sodium silicate and sodium hydroxide are preferred to prepare a 12 M alkali solution for RGC. Then, physical ultrasound pulse velocity and mechanical compressive and bending strengths are applied to RGC, and the results are evaluated. In addition, to find the best solution for the RGC mixtures, TOPSIS is employed, and the best RGCs are determined for each group, with respect to their physical and mechanical properties. Also, the durability tests are conducted on RGCs determined by TOPSIS. It is found that the best RGC mixture includes 25% RFA with 75% BS.