Browsing by Author "Aydin, A.C."

Now showing 1 - 4 of 4

Durability of green rubberized 3D printed lightweight cement composites reinforced with micro attapulgite and micro steel fibers: Printability and environmental perspective
(2024.01.01) Bodur, B.; Isik, M.A.M.; Benli, A.; Bayrak, B.; Öz, A.; Bayraktar, O.Y.; Kaplan, G.; Aydin, A.C.
The increasing amount of tires manufactured annually worldwide has made waste tire management a major environmental concern. The goal of this work is to investigate the potential applications of waste tire aggregates (WTA) in a novel class of affordable, recycled composite materials. This study assesses the material behavior of rubberized 3D printed lightweight cement composites (3DLC) reinforced with raw micro attapulgite (ATP) and micro steel fibers (MSF) using WTA as a 100 % replacement for fine aggregate manufactured through 3D printing. The paper takes advantage of 3D concrete printing's advantages and addresses the environmental issues associated with waste tires. The extrudability and buildability properties of 3DLC are determined in the fresh state. Physical and thermal properties of 3DLC were determined. Mechanical properties of 3DLC including compressive, flexural, shear strength and flexural toughness were assessed. 3D printed samples were exposed to high temperature and sulfate (MgSO4), and their durability properties were determined. The microstructures of the mixes was analyzed. The CO2 emissions and costs of the blends were also assessed. The outcomes revealed that, the 3DLC mixture with 10 % ATP and 2 % MSF showed the greatest compressive strength performance, with increases of 17.82 and 29.51 % at 28 and 90 days, respectively relative to the mixture without ATP. Regardless of MSF level, at 28 and 90 days, all mixes with 10%ATP content showed the largest flexural strengths. The 3DLC mixture with 10 % ATP and 2 % MSF had the highest measured thermal conductivity. The blends with 20 % ATP and 0 % MSF showed the lowest thermal conductivity. The mixture containing 10 % ATP and 2 % MSF demonstrated the greatest high temperature performance, demonstrating strength enhancement of 21.85, 6.72 and 3.36 % at 200,400 and 600 degrees C respectively. Replacing cement with 10 and 20%ATP greatly increased the sulfate resistance of 3DLC mixtures and the mixture with 20%ATP and 2%MSF exhibited the best sulfate performance. The lowest CO2 emission and cost were determined for the mixture containing 20%ATP and 0%MSF (A20S0).
Performance assessment of fiber-reinforced coral aggregate-based lightweight foam concrete for sustainable marine construction
(2024.01.01) Bayraktar, O.Y.; Danish, A.; Bodur, B.; Kaplan, G.; Aydin, A.C.; Ozbakkaloglu, T.
Based on the storage of raw materials and the high energy consumption associated with marine transportation, using coral aggregates to produce cementitious composites is the most promising candidate to counter these challenges. This research evaluates the suitability of coral aggregate and polypropylene fibers (PPF) to produce lightweight foam concrete. Quartz aggregate was replaced with coral aggregate in percentages of 25, 50, and 100 % along with 0-3 % incorporation of PPF. The performance assessment (through physical, mechanical, and durability tests) and economic and ecological analysis were conducted on the concrete mixtures. Based on the properties assessed, the optimal percentages of coral aggregate in specimens containing 0 %, 1.5 %, and 3 % PPF are 50 %, 50 %, and 100 %, respectively. This research may serve as a guide for future studies, focusing on coral aggregates as an effective alternative to conventional aggregates in cementitious composite production, with the goal of promoting their commercial applications for resource conservation.
Physical, mechanical and microstructural properties of one-part semi-lightweight geopolymers based on metakaolin modified with gypsum and lime
(Elsevier Ltd, 2024) Shi, J.; Bayraktar, O.Y.; Bayrak, B.; Bodur, B.; Oz, A.; Kaplan, G.; Aydin, A.C.
The elemental composition of precursors is crucial for the performance development of geopolymers. Metakaolin (MK) was used to produce one-part geopolymers (OPG), and the influence of calcium-based components (lime and gypsum) on their properties was investigated. The experimental results show that the use of lime instead of MK increases the fluidity of the mixture, while the addition of gypsum decreases the fluidity. Meanhwlie, the use of lime to replace a small amount of MK increases the concentration of activator by consuming water and the dissolution of calcium ions also participates in the geopolymerization reaction, which enhances the mechanical properties and durability of OPG. When 10 % lime is applied, the 7-d and 28-d compressive strengths of OPG are increased by 210 % and 157.14 % compared with the plain sample, respectively. The addition of gypsum generates AFt in OPG, which reduces the compactness of the microstructure, which is not conducive to the development of the strength and durability of OPG. When 10 % gypsum is applied, the 28-d compressive and flexural strengths of OPG are decreased by 32.14 % and 26.67 % compared with plain samples, respectively. As the lime content increases, further addition of gypsum to OPG has a more negative effect on OPG due to the plundering of calcium ions in the lime. The 28-d dry density of OPG is between 1585 and 1729 kg/m3, which makes it have a lower thermal conductivity (0.87–0.94 W/m·K).
Physical, mechanical and microstructural properties of one-part semi-lightweight geopolymers based on metakaolin modified with gypsum and lime
(2024.01.01) Shi, JY.; Bayraktar, O.Y.; Bayrak, B.; Bodur, B.; Oz, A.; Kaplan, G.; Aydin, A.C.
The elemental composition of precursors is crucial for the performance development of geopolymers. Metakaolin (MK) was used to produce one-part geopolymers (OPG), and the influence of calcium-based components (lime and gypsum) on their properties was investigated. The experimental results show that the use of lime instead of MK increases the fluidity of the mixture, while the addition of gypsum decreases the fluidity. Meanhwlie, the use of lime to replace a small amount of MK increases the concentration of activator by consuming water and the dissolution of calcium ions also participates in the geopolymerization reaction, which enhances the mechanical properties and durability of OPG. When 10 % lime is applied, the 7-d and 28-d compressive strengths of OPG are increased by 210 % and 157.14 % compared with the plain sample, respectively. The addition of gypsum generates AFt in OPG, which reduces the compactness of the microstructure, which is not conducive to the development of the strength and durability of OPG. When 10 % gypsum is applied, the 28-d compressive and flexural strengths of OPG are decreased by 32.14 % and 26.67 % compared with plain samples, respectively. As the lime content increases, further addition of gypsum to OPG has a more negative effect on OPG due to the plundering of calcium ions in the lime. The 28-d dry density of OPG is between 1585 and 1729 kg/m3, which makes it have a lower thermal conductivity (0.87-0.94 W/m & sdot;K).