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Öğe Development of fly ash/slag based self-compacting geopolymer concrete using nano-silica and steel fiber(ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND, 2019) Gülşan, Mehmet Eren; Alzeebaree, Radhwan; Rasheed, Ayad Ali; Niş, Anıl; Kurtoğlu, Ahmet EminThis study investigates the simultaneous effect of nano-silica and steel fiber on the fresh and hardened state performance of self-compacting geopolymer concretes (SCGC). For this purpose, self-compacting geopolymer concretes without and with nano-silica (0, 1% and 2%), and without and with steel fiber (0, 0.5% and 1%) were produced. Hooked-end steel fibers were used with a length of 30 mm and an aspect ratio of 40. Self-compacting geopolymer mixes were produced using 50% fly ash (FA) and 50% ground granulated blast furnace slag (GGBFS) with a constant alkaline activator to binder ratio of 0.5. For the alkaline activator, sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) were utilized with a ratio (Na2SiO3/NaOH) of 2.5. Fresh state experiments were carried out via slump flow, L-Box, and V-funnel tests, while hardened state experiments were conducted using compressive strength, flexural strength, and bonding strength tests to estimate the effects of nano-silica and steel fiber together on the resulting performances of SCGC specimens. Test results were also evaluated statistically in order to clarify the contributions of the important parameters on the resulting performance. Moreover, correlations between the experimental data were studied to investigate the relationships between the fresh and hardened state performances. The results demonstrated that incorporation of nano-silica and steel fiber affected the fresh state properties adversely; however, a combined utilization of them improved bond strength and flexural performance of the SCGC specimens significantly. In addition, the effect of nano-silica was found to be dominant on fresh state properties and compressive strength, while the effect of steel fiber was found to be superior on flexural performance and bonding strength.Öğe Effect of nano-silica on the chemical durability and mechanical performance of fly ash based geopolymer concrete(ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND, 2018) Çevik, Abdulkadir; Alzeebaree, Radhwan; Humur, Ghassan; Niş, Anıl; Gülşan, Mehmet ErenIn this study, the effect of nano silica on the short term severe durability performance of fly ash based geopolymer concrete (GPC) specimens was investigated. Four types of GPC were produced with two types of low calcium fly ashes (FAI and FAII) with and without nano silica, and ordinary Portland cement concrete (OPC) concrete was also cast for reference. For the geopolymerization process, the alkaline activator has selected a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) with a ratio (Na2SiO3/ NaOH) of 2.5. Main objectives of the study were to investigate the effect of usability or replaceability of nano silica-based low calcium fly ash based geopolymer concretes instead of OPC concrete in structural applications and make a contribution to standardization process of the fly ash based geopolymer concrete. To achieve the goals, four types of geopolymer and OPC concretes were subjected to sulfuric acid (H2SO4), magnesium sulfate (MgSO4) and seawater (NaCl) solutions with concentrations of 5%, 5%, and 3.5%, respectively. Visual appearances and weight changes of the concretes under chemical environments were utilized for durability aspects. Compressive, splitting tensile and flexural strength tests were also performed on specimens to evaluate the mechanical performance under chemical environments. Results indicated that FAGPC concretes showed superior performance than OPC concrete under chemical attacks due to low calcium content. Amongst the chemical environments, sulfuric acid (H2SO4) was found to be the most dangerous environment for all concrete types. In addition, nano silica (NS) addition to FAGPC specimens improved both durability and residual mechanical strength due to the lower porosity and more dense structure. The FAIIGPC specimens including nano silica showed the superior mechanical performance under chemical environment.Öğe Effect of nano-silica on the chemical durability and mechanical performance of fly ash based geopolymer concrete (vol 44, pg 12253, 2018)(Elsevier Sci Ltd, 2019) Cevik, Abdulkadir; Alzeebaree, Radhwan; Humur, Ghassan; Nis, Anil; Gulsan, Mehmet Eren[Abstract Not Available]Öğe The Effects of Recycled Tire Rubbers and Steel Fibers on the Performance of Self-compacting Alkali Activated Concrete(BUDAPEST UNIV TECHNOLOGY ECONOMICS, PERIODICA POLYTECHNICA, BUDAPEST 1521, HUNGARY, 2021) Eren, Necip Altay; Alzeebaree, Radhwan; Çevik, Abdulkadir; Niş, Anıl; Mohammedameen, Alaa; Gülşan, Mehmet ErenIn this study, the effects of recycled tire rubbers (RTR) and steel fiber (SF) on the fresh and hardened state properties of the self-compacted alkali activated concrete (SCAAC) were investigated. The ground granulated blast furnace slag, 1 % hooked-end SF, and two types of RTR were utilized. The crumb rubbers (CR) and tire rubber chips (TCR) were used as a substation to natural aggregates at substation levels of 10 % and 15 %. The fresh state performances were evaluated by T50 value, slump flow, V-funnel, and L-Box tests, while mechanical performances were assessed through compressive, flexural, and splitting tensile strength tests. Also, detailed crack and microstructural analyses were conducted. The RTR adversely affected the fresh state properties, which reduced more with SF inclusions. Among the RTR, the TR specimens exhibited lower fresh state performance than the CR specimens. Similar mechanical strengths were obtained on the TR and CR specimens under the same replacement ratios. However, TR specimens exhibited higher deformation capacities than the CR specimens, when SF was utilized. The SCAAC specimens with 1 % SF and 15 % RTR showed more and wider flexural cracks, higher mechanical strength, and deformation capacity, which can be utilized in structural applications, particularly in high seismic zones.Öğe Fresh and hardened state performance of self-compacting slag based alkali activated concrete using nanosilica and steel fiber(Sage Publications Ltd, 2021) Eren, Necip Altay; Alzeebaree, Radhwan; Cevik, Abdulkadir; Nis, Anil; Mohammedameen, Alaa; Gulsan, Mehmet ErenThis study investigates the fresh and hardened state performance of slag-based self-compacting alkali-activated concretes (SCAAC) reinforced with steel fibers (SF) and nano-silica (NS), cured at an ambient temperature. Two different hooked-end SF with two fiber volumes and NS were used to examine the combined effect of the SF volume ratio, SF aspect ratio, and NS on the fresh and hardened state performance of SCAAC. In extension, the influence of specimen thickness to steel fiber length (d/F-L) ratio on the failure modes of the bending specimens was evaluated. The fresh state properties were evaluated via T-50 value, slump flow, V-funnel, and L-Box tests, while the hardened state properties were studied through compressive strength, splitting tensile strength, modulus of elasticity, and flexural tensile strength tests. The relationship analyses were carried out among fresh and hardened state properties, and scanning electron microscopy (SEM) was also conducted to examine the microstructure. The results indicated that fresh state performance was favorably affected by NS inclusion but adversely influenced by SF content and aspect ratio. The hardened state performances enhanced with a higher amount of SF volume and an aspect ratio. Also, the NS improved the splitting tensile and flexural strength but decreased the compressive strength and elasticity modulus of the specimens. The d/F-L ratio was found a significant parameter on failure modes, and the specimens having a d/F-L ratio of 3.33 showed flexural cracks. In contrast, the specimens having a d/F-L ratio of 1.25 exhibited inclined flexural-shear cracks, especially for 1% SF.Öğe Mechanical and durability performance of FRP confined and unconfined strain hardening cementitious composites exposed to sulfate attack(ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND, 2019) Mohammedameen, Alaa; Gülşan, Mehmet Eren; Alzeebaree, Radhwan; Çevik, Abdulkadir; Niş, AnılIn this study, the performance of Fiber Reinforced Polymer (FRP) confined and unconfined Strain Hardening Cementitious Composite (SHCC) specimens exposed to sulfate attack under static and cyclic loading were investigated. Two types of FRP fabrics (Basalt (BFRP) and Carbon (CFRP)) and two types of fly ash (Low calcium (LCFA) and high calcium (HCFA)) were studied. In addition, FRP fabrics as a rehabilitation material was also investigated for the sulfate deteriorated specimens. LCFA-SHCC specimens showed superior performance than HCFA-SHCC specimens in the sulfate environment. In addition, confined specimens with FRP fabrics significantly improved compressive strength, ductility, and durability of the specimens.Öğe Mechanical and durability properties of fly ash and slag based geopolymer concrete(Techno-Press, 2018) Kurtoglu, Ahmet Emin; Alzeebaree, Radhwan; Aljumaili, Omar; Nis, Anil; Gulsan, Mehmet Eren; Humur, Ghassan; Cevik, AbdulkadirIn this paper, mechanical and short-term durability properties of fly ash and slag based geopolymer concretes (FAGPC-SGPC) were investigated. The alkaline solution was prepared with a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) for geopolymer concretes. Ordinary Portland Cement (OPC) concrete was also produced for comparison. Main objective of the study was to examine the usability of geopolymer concretes instead of the ordinary Portland cement concrete for structural use. In addition to this, this study was aimed to make a contribution to standardization process of the geopolymer concretes in the construction industry. For this purpose; SGPC, FAGPC and OPC specimens were exposed to sulfuric acid (H2SO4), magnesium sulfate (MgSO4) and sea water (NaCl) solutions with concentrations of 5%, 5% and 3.5%, respectively. Visual inspection and weight change of the specimens were evaluated in terms of durability aspects. For the mechanical aspects; compression, splitting tensile and flexural strength tests were conducted before and after the chemical attacks to investigate the residual mechanical strengths of geopolymer concretes under chemical attacks. Results indicated that SGPC (100% slag) is stronger and durable than the FAGPC due to more stable and strong cross-linked alumina-silicate polymer structure. In addition, FAGPC specimens (100% fly ash) showed better durability resistance than the OPC specimens. However, FAGPC specimens (100% fly ash) demonstrated lower mechanical performance as compared to OPC specimens due to low reactivity of fly ash particles, low amount of calcium and more porous structure. Among the chemical environments, sulfuric acid (H2SO4) was most dangerous environment for all concrete types.Öğe Mechanical performance and statistical analysis of natural and synthetic zeolite-warm mix asphalt as a function of compaction efforts(Elsevier, 2023) Al-Hadidy, A. I.; Alzeebaree, Radhwan; Abdal, Juma Abdulla; Nis, AnilThe compaction effort of mixes should be studied with caution since it significantly influences the mixtures' performance. A laboratory evaluation of warm mix asphalt (WMA) including synthetic zeolite (SZ) and natural zeolite (NZ) was conducted in this study. Marshall properties, tensile strength ratio, indirect tensile strengths at 25 and 60 & DEG;C, resilient modulus at 25 & DEG;C, and creep compliances at 40 & DEG;C were all examined. The NZ and SZ binders were produced by mixing one base binder (40/50 penetration grade) with 5% NZ and SZ binder components by weight. The 90 specimens were produced using the Marshall compactor at three different compaction efforts (35, 50, and 75 blows/face). Statistical analysis was conducted to examine the behavior and outcomes of asphalt binders. The results showed that (1) Both NZWMA and SZWMA combinations require 35 blows/face compaction effort to meet the minimum criteria of 8 kN stability, 2-4 mm flow, 85% tensile strength ratio, 14% VMA, and 448 kPa unconditioned tensile strength; (2) The production of NZWMA mixtures saves more time and fuel in the field than SZWMA mixtures while meeting the Marshall properties, creep performance, and moisture susceptibility at 35 blows/face compaction effort; and (3) A general trend of the Marshall, creep compliance, tensile strength, and resilient modulus performance as a function of compaction effort was observed for the NZWMA and SZWMA mixes used in this study.Öğe Mechanical performance of FRP-confined geopolymer concrete under seawater attack(Sage Publications Inc, 2020) Alzeebaree, Radhwan; Cevik, Abdulkadir; Mohammedameen, Alaa; Nis, Anil; Gulsan, Mehmet ErenIn the study, mechanical properties and durability performance of confined/unconfined geopolymer concrete and ordinary concrete specimens were investigated under ambient and seawater environments. Some of the specimens were confined by carbon fiber and basalt fiber-reinforced polymer fabric materials with one layer and three layers under chloride and ambient environments to observe mechanical strength contribution and durability performances of these hybrid types of materials. These fiber-reinforced polymer fabric materials were also evaluated in terms of retrofit purposes especially in the marine structures. In addition, microstructural evaluation is also conducted using scanning electron microscope on geopolymer concrete and ordinary concrete specimens to observe the amount of deterioration in microscale due to the chloride attacks. Results indicated that confined specimens exhibited enhanced strength, ductility, and durability properties than unconfined specimens, and the degree of the enhancement depended on the fiber-reinforced polymer confinement type and the number of fiber-reinforced polymer layer. Specimens confined by carbon fabrics with three layers showed superior mechanical properties and durability performance against chloride attack, while specimens confined by basalt fabrics with one layer exhibited low performance, and unconfined specimens showed the worst performance. Both fiber-reinforced polymer fabric materials can be utilized as retrofit materials in structural elements against chloride attacks. The results also pointed out that seawater attack reduced the ductility performance of the geopolymer concrete and ordinary concrete specimens. Furthermore, geopolymer concrete specimens were found more durable than the ordinary concrete specimens, and both types of concretes exhibited similar fracture properties, indicating that geopolymer concrete can be utilized for structural elements instead of ordinary concretes.Öğe Microstructural and Durability Assessment of Various Concrete Types Under Different Chemical Environments(Springer Science and Business Media Deutschland GmbH, 2024) Niş, Anıl; Alzeebaree, Radhwan; Mohammedameen, Alaa; Çevik, Abdulkadir; Gülşan, Mehmet E.The research investigates the microstructural analyses and durability performances of a geopolymer concrete (GPC), two different engineered cementitious concretes (ECC), and an ordinary Portland cement concrete (NC) under 3.5% seawater (SW), 5% magnesium sulfate (MS), and 5% sulfuric acid (SA) environments. The nanosilica (NS) and F-type fly ash incorporated GPC specimen was activated using a mixture of sodium silicate and sodium hydroxide solution with a sodium silicate/hydroxide ratio of 2.5. The low-calcium (LCFA-ECC) and high-calcium (HCFA-ECC) fly ash-based ECC specimens were produced, and the NC was also cast for comparison. The durability performances of concretes were assessed by visual inspections, weight changes, and compressive strength tests, and microstructures of the chemically exposed specimens were compared to that of the unexposed specimens by Scanning Electron Microscopy (SEM) micrographs. The results showed that LCFA-ECC samples showed the best performance, while NC samples performed the worst performance against all chemical attacks. The GPC specimens showed a better durability performance than HCFA-ECC specimens under SW and MS attacks, while HCFA-ECC specimens exhibited better chemical resistance against SA attack. SEM images confirmed that sulfuric acid is the most hazardous environment since increased dosage of sulfates was observed on the surfaces, interfacial transition zone (ITZ), and polyvinyl alcohol (PVA) fibers. © The Author(s), under exclusive licence to Shiraz University 2024.Öğe Performance of FRP confined and unconfined engineered cementitious composite exposed to seawater(Sage Publications Ltd, 2019) Mohammedameen, Alaa; Cevik, Abdulkadir; Alzeebaree, Radhwan; Nis, Anil; Gulsan, Mehmet ErenConventional concrete suffers from brittle failures under mechanical behaviour, and lack of ductility results in the loss of human life and property in earthquake zones. Therefore, the degree of ductility becomes significant in seismic regions. This paper investigates the influence of poly-vinyl alcohol fibers, basalt fiber-reinforced polymer (BFRP) and carbon fiber-reinforced polymer (CFRP) fabrics on the ductility and mechanical performance of low (LCFA) and high (HCFA) calcium fly ash-based engineered cementitious composite concrete. The study also focuses on the mechanical behaviour of the CFRP and BFRP materials using different matrix types exposed to 3.5% seawater environment. Cyclic loading and scanning electron microscopy observations were also performed to see the effect of chloride attack on mechanical performance and ductility of the specimens. In addition, utilization of CFRP and BFRP fabrics as a retrofit material is also evaluated. Results indicated that the degree of ductility and mechanical performance were found to be superior for the CFRP-engineered cementitious composite hybrid specimens under ambient environment, while LCFA-CFRP hybrid specimens showed better performance under seawater environment. The effect of matrix type was also found significant when engineered cementitious composite is used together with fiber-reinforced polymer materials. In addition, both fiber-reinforced polymer materials can be used as a retrofit material under seawater environment.Öğe Performance of FRP confined and unconfined geopolymer concrete exposed to sulfate attacks(TECHNO-PRESSPO BOX 33, YUSEONG, DAEJEON 305-600, SOUTH KOREA, 2018) Alzeebaree, Radhwan; Gülşan, Mehmet Eren; Niş, Anıl; Mohammedameen, Alaa; Çevik, AbdulkadirIn this study, the effects of magnesium sulfate on the mechanical performance and the durability of confined and unconfined geopolymer concrete (GPC) specimens were investigated. The carbon and basalt fiber reinforced polymer (FRP) fabrics with 1-layer and 3-layers were used to evaluate the performances of the specimens under static and cyclic loading in the ambient and magnesium sulfate environments. In addition, the use of FRP materials as a rehabilitation technique was also studied. For the geopolymerization process of GPC specimens, the alkaline activator has selected a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) with a ratio (Na2SiO3/NaOH) of 2.5. In addition to GPC specimens, an ordinary concrete (NC) specimens were also produced as a reference specimens and some of the GPC and NC specimens were immersed in 5% magnesium sulfate solutions. The mechanical performance and the durability of the specimens were evaluated by visual appearance, weight change, static and cyclic loading, and failure modes of the specimens under magnesium sulfate and ambient environments. In addition, the microscopic changes of the specimens due to sulfate attack were also assessed by scanning electron microscopy (SEM) to understand the macroscale behavior of the specimens. Results indicated that geopolymer specimens produced with nano-silica and fly ash showed superior performance than the NC specimens in the sulfate environment. In addition, confined specimens with FRP fabrics significantly improved the compressive strength, ductility and durability resistance of the specimens and the improvement was found higher with the increased number of FRP layers. Specimens wrapped with carbon FRP fabrics showed better mechanical performance and durability properties than the specimens wrapped with basalt FRP fabrics. Both FRP materials can be used as a rehabilitation material in the sulfate environment.Öğe Using of recycled clay brick/fine soil to produce sodium hydroxide alkali activated mortars(Sage Publications Inc, 2021) Alzeebaree, Radhwan; Mawlod, Arass Omer; Mohammedameen, Alaa; Nis, AnilIn the study, the recycled clay brick powder/fine soil powder-based sodium hydroxide alkali-activated mortar (AAM) specimens were prepared by mixing different percentages (100/0, 80/20, 60/40, 40/60, 20/80, and 100/0, respectively) to investigate the mechanical and durability performance of sustainable AAM specimens for the possible utilization instead of OPC. The constant ratio of glass powder was used in the production of AAM to increase the alkalinity and improve the mechanical properties of alkali-activated mortar. Also, the influences of sodium hydroxide molarity concentrations (8, 10, 12, 14, and 16 M) on the performance of AAM specimens were studied. The compressive strength, water absorption, and water sorptivity tests were conducted on the AAM specimens and the relationships between the investigated parameters were analyzed. The obtained results revealed that the fine soil powder replacement with clay brick powder improved the compressive strength, and reduced water absorption and water sorptivity up to 80% replacement ratios, and the superior mechanical and durability performance was obtained in the 80% fine soil powder-based AAM specimens. For the higher fine soil powder replacement ratio (100%), the performances of the AAM specimens were found to be adversely affected. Besides, the concentration of NaOH solution significantly influenced the material performances of the fine soil powder-based AAMs and 12 M NaOH concentration performed superior mechanical and durability performance. The strength enhancement of the AAMs was found to be significant after 90 days of ambient curing period.
