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Öğe Detection and quantification of alkali-silica-reaction (ASR) gel in cement-based mortars using microwave spectral and temporal transmission properties(Elsevier Sci Ltd, 2023) Hasar, Ugur Cem; Ozturk, Hamdullah; Korkmaz, Huseyin; Tasdemir, Ahmet; Bute, Musa; Nis, Anil; Karaaslan, MuharremMicrowave transmission measurements in time-domain, as a new measurement tool, were carried out to detect and quantify alkali-silica-reaction (ASR) within mortar specimens. To examine the potential of time-domain transmission measurements for ASR detection and its any possible quantification, transmission measurements in frequency-domain and time-domain of two different sets (reactive and non-reactive) of mortar specimens were performed approximately every 2 or 3 days over 29 days after demolding the specimens, by a rectangular waveguide operated at 2.60-3.95 GHz. Thickness expansion measurements of reactive and non-reactive sets were also performed. Additionally, SEM micrographs and energy-dispersive X-ray spectroscopy tests of specimens were implemented to support microwave and expansion measurements. After performing some analysis for the correlation between microwave and expansion measurements, it is observed for the first time in the literature that transmission measurements via expansion tests could be effectively applied for quantification of ASR level within cement-based materials.Öğe Effect of ceramic waste powder content and sodium hydroxide molarity on the residual mechanical strength of alkali-activated mortars(Elsevier Science Sa, 2023) Erol, Ferhat; Al-mashhadani, Mukhallad M.; Aygormez, Yurdakul; Nis, AnilIn the study, the effects of various ceramic waste powder (CWP) additions (5, 10, and 15%) and sodium hydroxide (SH) molarity (8 M and 16 M) on the residual mechanical properties of different ambient-cured alkaliactivated mortar (AAM) samples were investigated under the elevated temperatures (300, 600, and 900 degrees C) and freeze-thaw (100 cycles) attacks. The fresh (flowability, initial and final setting time, water absorption, and void ratio) and hardened (compressive and flexural strength, ultrasonic pulse velocity, and weight loss) state performances were evaluated. Also, XRD and SEM analyses were carried out. The findings pointed out that flowability enhanced up to 15% of CWP replacements. The initial and final setting time was reduced with higher molarity, while improved with further CWP incorporations. The water absorption and void ratio decreased with higher CWP incorporations and SH molarity. Moreover, mechanical strengths increased with time, which were found to be more with a higher CWP replacement ratio and SH molarity. After elevated temperature, the average compressive strength losses were about 50% at 600 degrees C and 85% at 900 degrees C, while average flexural strength losses were about 70% at 600 degrees C and 85% at 900 degrees C. Meanwhile, similar residual compressive strengths were obtained at elevated temperatures, irrespective of the SH molarity and CWP incorporations. However, both CWP incorporation and high SH molarity slightly enhanced the residual flexural strengths. After freeze-thaw attacks, an average of 23% compressive strength loss and 29% flexural strength loss was obtained, and almost similar mechanical strength losses were observed with varying SH molarity and CWP replacement ratio.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 Engineering properties of different fiber-reinforced metakaolin-red mud based geopolymer mortars(Elsevier Sci Ltd, 2023) Nazir, Khizar; Canpolat, Orhan; Uysal, Mucteba; Nis, Anil; Kuranli, Omer FarukIn this research, fiber reinforced metakaolin-red mud based geopolymer mortar was produced by using recycled concrete aggregate and industrial waste glass powder as filler materials. Three different types of fibers were used to reinforce the geopolymer mortar, namely brass-coated steel fibers, polyamide fibers, and polyethylene fibers, with four different proportions by volume (0.25%, 0.5%, 0.75%, and 1.00%). Experiments for compressive strength, flexural strength, splitting tensile strength, flexural toughness factor, ultrasonic pulse velocity, and abrasion resistance were conducted to investigate the influence of fibers on mechanical properties. Specific gravity, porosity, and water absorption tests were conducted to examine the physical properties. Additionally, Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analyses were performed. The results indicate that 50% replacement of recycled concrete aggregate and glass powder as filler material yielded the optimum strength properties. Moreover, addition of fibers enhanced the strength properties of the geopolymer mortar, for instance, the mixture having polyethylene fibers with a fiber volume of 0.75% improved the flexural strength up to 48.72%, and the mixture containing steel fibers with a fiber fraction of 0.25% showed the highest value of splitting tensile strength and improved up to 40% when compared to non-fibrous control mixture. Polyethylene fiber-reinforced mixture showed a notable toughening impact and showed a flexural toughness factor up to 66.29% more than the control sample. The reason of this improvement is because of the bridging effect of fibers. According to the findings, the 0.25% steel fibrous samples showed the best result in terms of minimum weight loss due to abrasion and showed 36.08% more abrasion resistance compared to non-fibrous control mixture. Moreover, increase in porosity was observed in fiber-reinforced mixtures. The lack of CaO content is found responsible for poor mechanical strength and bending performance of fibrous metakaolin-red mud based geo-polymer mortars specimens.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 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 MECHANICAL STRENGTH DEGRADATION OF SLAG AND FLY ASH BASED GEOPOLYMER SPECIMENS EXPOSED TO SULFURIC ACID ATTACK(Yildiz Technical Univ, 2019) Nis, Anil; Altundal, Melis B.In this study, mechanical properties and durability performances of fly ash based geopolymer concrete (FAGPC) and slag based geopolymer concrete (SGPC) were investigated against 5% sulfuric acid attack. The low calcium (F-type) fly ash (FA) and ground granulated blast furnace slag (GGBS) were utilized as binder materials with an amount of 360 kg/m(3), and a combination of sodium silicate and 14 M sodium hydroxide with a silicate to hydroxide ratio of 2.5 were used as an alkaline activator in order to produce geopolymer concretes. The binder amounts were selected in accordance with the XA3 chemical environmental condition given in TS EN 206 standard. An ordinary Portland cement concrete (OPC) was also produced and exposed to sulfuric acid attacks for comparison. The effect of sulfuric acid on 150x150x150 mm cube and 100x200 mm cylinder specimens was evaluated by visual inspection, weight change, compressive and splitting tensile strength tests. Results indicated that similar surface deterioration was observed on the cube and cylinder specimens due to acid exposure. However, cube specimens showed more weight loss than the cylinder specimens, which can be attributed to the higher acid influenced area due to the size effect. In addition, the SGPC specimens exhibited superior mechanical performance, while FAGPC specimens showed the poorest mechanical performance when low binder amounts (360 kg/m(3)) were utilized under sulfuric acid attack. The results also pointed out that slag based geopolymer concrete can be utilized in structural applications instead of ordinary Portland cement concrete.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 PUMICE AGGREGATE BASED LIGHTWEIGHT CONCRETES UNDER SULFURIC ACID ENVIRONMENT(Serban Solacolu Foundation, 2022) Nis, Anil; Al-Antaki, Taha Salah WahhabIn this study, volcanic pumice aggregate incorporated different lightweight concretes (LWC) were investigated under a 5% sulfuric acid environment. For this purpose; OPC, OPC-FA, OPC-S, OPC-FA+S with 0%, 50%, and 100% pumice incorporations were manufactured considering cement efficiency factors for fly ash (FA) and slag (S) given in the TS13515 and EN 206-1 to evaluate the applicability of cement efficiency factors in the water and sulfuric acid environments. The visual appearance, weight change, and compressive strength tests were executed, and strength gain index and strength loss index parameters were utilized for the evaluation. The results indicated that the cement efficiency factors for the fly ash and slag were found appropriate for the pumice aggregate replacements up to 100% for the LWC incorporating only fly ash or slag. However, when the fly ash and slag were used together, the cement efficiency factors should be reduced from 0.4 to 0.35 for FA and from 0.8 to 0.75 for slag materials.Öğe Residual mechanical performance of lightweight fiber-reinforced geopolymer mortar composites incorporating expanded clay after elevated temperatures(Sage Publications Ltd, 2022) Aljanabi, Maysam; Cevik, Abdulkadir; Nis, Anil; Bakbak, Derya; Kadhim, SarahThis research provides an experimental investigation on the properties of fiber reinforced composite materials consisting of lightweight expanded clay aggregates (LECA) and polyvinyl alcohol (PVA) fibers. The influence of temperature (room temperature, 250 degrees C, and 500 degrees C) on the lightweight geopolymer mortar (LWGM) composite materials is also explored. LECA is used as a partial replacement to river sand with 60% and 80%. The base material utilized for LWGM is slag activated by a mixture of sodium silicate and sodium hydroxide solutions. The fresh properties in terms of workability and density were performed. A series of experiments, such as compression, flexural and uniaxial tensile strength tests, were executed to assess the mechanical properties of LWGM composite materials. In addition, the microscopic variations due to the elevated temperature were also evaluated by scanning electron microscopy (SEM) to understand the macro-scale behavior of the samples. The results indicated that increasing the level of LECA replacement caused a reduction in the density and compressive strength of the LWGM. Also, incorporating a 1% PVA fiber volume fraction significantly enhanced the flexural and uniaxial tensile behavior of LWGM composite materials. The compressive strength enhancements were observed at 250 degrees C due to further geopolymerization, while compressive strength reductions were obtained at 500 degrees C due to the vapor impact and difference in thermal expansion. In addition, the load-carrying capacity of all samples increased, and displacement capacity decreased under flexural tests at 250 degrees C. However, the ductile behavior of the PVA incorporating specimens changed to brittle due to the melting of PVA fibers.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.
