Browsing by Author "Öz, A."

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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).
Durability of green rubberized 3D printed lightweight cement composites reinforced with micro attapulgite and micro steel fibers: Printability and environmental perspective
(Elsevier Ltd, 2024) Bodur, B.; Mecit Işık, M.A.; Benli, A.; Bayrak, B.; Öz, A.; Bayraktar, O.Y.; Kaplan, G.; Aydın, 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°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).
Impact of rice husk ash on physico-mechanical, durability and microstructural features of rubberized lightweight geopolymer composite
(2024.01.01) Zeyad, A.M.; Bayraktar, O.Y.; Tayeh, B.A.; Öz, A.; Özkan, I.G.M.; Kaplan, G.
This study investigates the effects of incorporating rice husk ash (RHA) on the characteristics of lightweight geopolymer concrete (LWGC), which includes waste tire aggregate (WTA). This study utilized RHA to replace 15 % of ground blast furnace slag (GBFS) in LWGC. The LWGC also included WTA as a partial substitute for pumice aggregate, with varying rates of 10 %, 25 %, and 50 % by volume. In addition, curing temperatures of 75 degrees C and 100 degrees C were utilized for 3 h following the casting process. 16 LWGC blends were created, each with a dry density below 1800 kg/m 3 . To study the features of hardened LWGC, various tests included apparent porosity, water absorption, capillary water absorption, dry density, compressive and flexural strength. In addition, freezing and thawing cycles (20, 40, and 60 cycles) and elevated temperatures of 250 and 500 degrees C affect compressive strength and density loss in addition to examining the thermal conductivity coefficient and morphological imaging by SEM on microscopic structure. The results showed that adding 15 % RHA as a partial replacement for GBSF led to a decrease in the density of hardened concrete to about 1561 kg/m 3 . At the same time, the compressive strength decreased to 24 and 21 MPa for the samples subjected to 75 and 100 degrees C heat treatments, respectively. Including 15 % RHA also reduced the thermal conductivity coefficient to 0.978 W/mK. Regarding the inclusion of WTA as a substitute for pumice aggregate, it led to a decrease in density and compressive strength as the replacement rate increased. In addition, the thermal conductivity coefficient decreases to its lowest level when WTA replaces 50 % of the pumice.
Impact of rice husk ash on physico-mechanical, durability and microstructural features of rubberized lightweight geopolymer composite
(Elsevier Ltd, 2024) Zeyad, A.M.; Bayraktar, O.Y.; Tayeh, B.A.; Öz, A.; Özkan, İ.G.M.; Kaplan, G.
This study investigates the effects of incorporating rice husk ash (RHA) on the characteristics of lightweight geopolymer concrete (LWGC), which includes waste tire aggregate (WTA). This study utilized RHA to replace 15 % of ground blast furnace slag (GBFS) in LWGC. The LWGC also included WTA as a partial substitute for pumice aggregate, with varying rates of 10 %, 25 %, and 50 % by volume. In addition, curing temperatures of 75 °C and 100 °C were utilized for 3 h following the casting process. 16 LWGC blends were created, each with a dry density below 1800 kg/m3. To study the features of hardened LWGC, various tests included apparent porosity, water absorption, capillary water absorption, dry density, compressive and flexural strength. In addition, freezing and thawing cycles (20, 40, and 60 cycles) and elevated temperatures of 250 and 500 °C affect compressive strength and density loss in addition to examining the thermal conductivity coefficient and morphological imaging by SEM on microscopic structure. The results showed that adding 15 % RHA as a partial replacement for GBSF led to a decrease in the density of hardened concrete to about 1561 kg/m3. At the same time, the compressive strength decreased to 24 and 21 MPa for the samples subjected to 75 and 100 °C heat treatments, respectively. Including 15 % RHA also reduced the thermal conductivity coefficient to 0.978 W/mK. Regarding the inclusion of WTA as a substitute for pumice aggregate, it led to a decrease in density and compressive strength as the replacement rate increased. In addition, the thermal conductivity coefficient decreases to its lowest level when WTA replaces 50 % of the pumice.
Performance assessment and cost analysis of slag/metakaolin based rubberized semi-lightweight geopolymers with perlite aggregate: Sustainable reuse of waste tires
(Elsevier Ltd, 2024) Bayraktar, O.Y.; Benli, A.; Bodur, B.; Öz, A.; Kaplan, G.
Low-carbon binders or industrial waste can reduce or even eliminate the demand for Portland cement and other natural resources, which reduces environmental pollution in accordance with the principles of sustainable development. The assessment of the mechanical, durability and microstructural properties of slag/metakaolin based rubberized semi-lightweight geopolymer composites (LWGC) with perlite aggregate (PA) is the main objective of this study. Waste tires aggregates (WTA) was produced from discarded waste tires, another environmental pollutant, and used in LWGC mixtures as substitution for the fine perlite aggregate by 0%, 20%, 45%, and 60% replacement. Metakaolin (MK) and ground granulated blast furnace slag (GBFS) were used as precursors in the synthesis of LWGC. Sodium hydroxide and sodium silicate solution was used as activators. Eight mixtures were created; four of them had 100% GBFS, while the other four contained 90% GBFS slag and 10% MK. All eight mixtures were then cured for 5 h at 60 °C and 100 °C. The effects of curing temperature, WTA, and MK on the compressive, flexural strength, physical properties, and sorptivity of the LWGC were examined as well as flowability. The performance of the blends at high temperatures, freeze thaw cycles and sulfate attack was also evaluated. Microstructure analyses of the mixtures were also done using SEM. CO2 emissions and costs of the mixtures were also evaluated. The results showed that inclusion of WTA instead of PA and MK instead of GBFS decreased the flow diameter. Thermal conductivity and dry density of the mixtures also decreased considerably with the addition of WTA. The findings showed that 10%MK incorporated mixture with 60%WTA produced a compressive strength of 25.10 MPa at curing temperatures of 100 °C. The results indicated compressive strength of MK incorporated mixture with 60%WTA increased by 48.10% and 31.20% at heat curing of 60 °C and 100 °C, respectively. The mixture WT60MK0 cured at 100 °C exhibited the best high temperature resistance and the same mixture also presented the best F-T performance regardless of curing temperature. The mixture WT40MK0 cured at 60 °C and the mixture WT60MK10 cured at 100 °C performed the best sulfate resistance.
Performance assessment and cost analysis of slag/metakaolin based rubberized semi-lightweight geopolymers with perlite aggregate: Sustainable reuse of waste tires
(2024.01.01) Bayraktar, O.Y.; Benli, A.; Bodur, B.; Öz, A.; Kaplan, G.
Low-carbon binders or industrial waste can reduce or even eliminate the demand for Portland cement and other natural resources, which reduces environmental pollution in accordance with the principles of sustainable development. The assessment of the mechanical, durability and microstructural properties of slag/metakaolin based rubberized semi-lightweight geopolymer composites (LWGC) with perlite aggregate (PA) is the main objective of this study. Waste tires aggregates (WTA) was produced from discarded waste tires, another envi-ronmental pollutant, and used in LWGC mixtures as substitution for the fine perlite aggregate by 0%, 20%, 45%, and 60% replacement. Metakaolin (MK) and ground granulated blast furnace slag (GBFS) were used as pre-cursors in the synthesis of LWGC. Sodium hydroxide and sodium silicate solution was used as activators. Eight mixtures were created; four of them had 100% GBFS, while the other four contained 90% GBFS slag and 10% MK. All eight mixtures were then cured for 5 h at 60 degrees C and 100 degrees C. The effects of curing temperature, WTA, and MK on the compressive, flexural strength, physical properties, and sorptivity of the LWGC were examined as well as flowability. The performance of the blends at high temperatures, freeze thaw cycles and sulfate attack was also evaluated. Microstructure analyses of the mixtures were also done using SEM. CO2 emissions and costs of the mixtures were also evaluated. The results showed that inclusion of WTA instead of PA and MK instead of GBFS decreased the flow diameter. Thermal conductivity and dry density of the mixtures also decreased considerably with the addition of WTA. The findings showed that 10%MK incorporated mixture with 60%WTA produced a compressive strength of 25.10 MPa at curing temperatures of 100 degrees C. The results indicated compressive strength of MK incorporated mixture with 60%WTA increased by 48.10% and 31.20% at heat curing of 60 degrees C and 100 degrees C, respectively. The mixture WT60MK0 cured at 100 degrees C exhibited the best high temperature resistance and the same mixture also presented the best F-T performance regardless of curing temperature. The mixture WT40MK0 cured at 60 degrees C and the mixture WT60MK10 cured at 100 degrees C performed the best sulfate resistance.
Sustainable Use of Waste Tire Rubbers in Eco-Friendly and Lightweight Alkali-Activated Slag-Silica Fume Mortars
(American Society of Civil Engineers (ASCE), 2024) Dheyaaldin, M.H.; Bayraktar, O.Y.; Öz, A.; Kaplan, G.
This study examines the benefits of substituting waste tire aggregate (WTA) for pumice aggregate in alkali-activated slag mortars at replacement ratios of 0% to 60% (by volume). Additionally, silica fume (SF) was added to mortar mixes at a concentration of 10% by volume to improve their compressive and flexural strength, water absorption, water sorptivity, porosity, density, thermal conductivity, and microstructural properties. The influences of chemical sulfate attacks, exposed temperatures, and compressive strength were investigated. Test findings showed that using WTA severely decreased mechanical strength and durability. Conversely, a mixture with 60% WTA reacted at a lower strength and durability compared with different percentages of WTA for all the properties examined in this study. SF has led to significant enhancements in mechanical strength and durability, especially at an early age. On the eighth day of the specimen curing period, the compressive and flexural strength increased by 20%. Additionally, by raising the curing temperatures by 80°C enhances the polymerization process, the polymerization process is strengthened, boosting durability characteristics and improving mechanical strength and durability. When exposed to higher temperatures, the mechanical strength and durability reduced the specimens' strength and weight. Specimens exposed to sulfate attack solutions can reduce the mechanical strength by 1%-3% for a 120-day curing period in a chemical solution, even more reducing the weight of specimens and shapes after visual inspection.