Browsing by Author "Cosgun, Turgay"

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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.
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.
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.