Yazar "Gunes, Muhammet" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim Yok
    Öğe
    Comparison of Glass Powder and Fly Ash Effect on the Fresh Properties of Self-Compacting Mortars
    (Iop Publishing Ltd, 2017) Oz, Hatice Oznur; Yucel, Hasan Erhan; Gunes, Muhammet
    This study is aimed to determine effects of glass powder on fresh properties of self-compacting mortars. Self-compacting mortars incorporating glass powder (SCMGPs) were designed with a water/binder ratio of 0.40 and a total binder content of 550 kg/m(3). At first, the control mixture was produced with 20% fly ash and % 80 cement of the total binder content without using the glass powder. Then, glass powder was used in the proportions 5%, 10%, 15% and 20% instead of fly ash in the mortars. Mini-slump flow and mini-v funnel tests experimentally investigated on SCMGPs to compare the effect of fly ash and glass powder. With increasing the amount of glass powder used in SCMGPs increased the amount of superplasticizer used to obtain the desired mini-slump flow diameter. So, the use of glass powder reduced the flow ability of SCMGPs in comparison to fly ash. Additionally, the compressive strength and flexural strength of the mortar mixtures were determined at the 28th day. The test results indicated that the mechanical characteristics of SCMGPs improved when the fly ash was replaced with glass powder in SCMGPs.
  • Küçük Resim Yok
    Öğe
    Fly-ash-based geopolymer composites incorporating cold-bonded lightweight fly ash aggregates
    (Elsevier Sci Ltd, 2021) Oz, Hatice Oznur; Yucel, Hasan Erhan; Gunes, Muhammet; Koker, Turan Sevki
    In this study, effects of cold-bonded lightweight fine aggregate (LWFA) on the geopolymer composites (GCs) were investigated in terms of fresh, physical, mechanical and durability properties. LWFA and different diameters quartz aggregates were used in the production of fly-ash-based GCs. However, LWFA was only replaced with the quartz aggregate of 1.2-2.5 mm. A mixture of 12 M NaOH and Na2SiO3 solution was prepared as 1/2.5. Unit weight, specific gravity, water absorption, apparent porosity, compressive and flexural strengths, ultrasonic pulse velocity and water sorptivity coefficient of GCs were determined. According to the test results, workability of GCs improved as the usage rate of LWFA increased. Due to the surface characteristics of LWFA, the mechanical properties of GC were enhanced by the geopolymerization reaction conducted between LWFA with alkali activators. Thus, the compressive strength of GC with 25% LWFA was 39.6% higher than that of the control GC at 28th day. This conclusion supported by TGA/DTA and FTIR analysis indicated that N-A-S-H gel of GC incorporating 25% LWFA was higher compared to control mixture. Also, GCs incorporating 40% and higher LWFA showed lower performance than control GC. (C) 2020 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Life cycle assessment and shrinkage properties of high performance mortars incorporating synthetic wollastonite microfibers
    (Emerald Group Publishing Ltd, 2023) Oz, Hatice Oznur; Gunes, Muhammet; Yucel, Hasan Erhan; Ersoy, Orkun; Sever, Yunus; Demirel, Sevgi
    In this study, the use of an alternative material as supplementary cementitious material was researched for the design of high-performance mortars (HPMs). Synthetic wollastonite microfibres (SWMs) were produced from calcite and quartz sand. The SWMs were then replaced at ratios of 0, 3, 6, 9 and 12% by cement weight to investigate the fresh, mechanical and shrinkage properties of HPMs. Test results showed that the mechanical and shrinkage properties of HPMs improved up to 9% inclusion of SWMs. The compressive strength, flexural strength, modulus of elasticity, fracture toughness and fracture energy of HPM incorporating 9% SWM was higher than that of the control mixture by 8.8-9.1%, 7.5-9.9%, 4.7-6.7%, 8.9-4.6% and 13.2-2.5% at 28-90 days, respectively. Similarly, the ratios for maximum drying shrinkage and average crack width were determined as 10.5% and 58.3%, respectively, at the end of 60 days. These findings were also supported by microstructural analysis. Moreover, the potential environmental impacts resulting from the production of 1 kg SWM and HPM incorporating 9% SWM were evaluated using the life cycle analysis software (LCA) SimaPro 8.5.0.0. Based on the LCA results, SWMs can be used as an alternative material to develop sustainable concrete structures.
  • Küçük Resim Yok
    Öğe
    Rheological and microstructural properties of FA+GGBFS-based engineered geopolymer composites (EGCs) capable of comparing with M45-ECC as mechanical performance
    (Elsevier, 2023) Oz, Hatice Oznur; Gunes, Muhammet; Yucel, Hasan Erhan
    In this study, it has been aimed to obtain the fly ash + ground granulated blast furnace slag (FA GGBFS)-based engineered geopolymer composites (EGCs) having similar bearing strength and deformation capacity with the engineered cementitious composite (M45-ECC) known as M45. EGCs incorporating 70% FA and 30% GGBFS as binder were developed under three different groups in which the different ratios of alkali liquids/binder (AL/Bi) with the different content of AL + Bi. All of eight FA + GGBFS-based EGCs designed with 2.5 ratio of Na2SiO3/NaOH. FA GGBFS-based EGCs, which were kept in the mold under laboratory conditions for 24 h imme-diately after production, were kept in water at 60 degrees C until the test age. The fresh, rheogical, mechanical and microstructural properties of FA + GGBFS-based EGCs were determined. Test results indicated that FA + GGBFS-based EGCs can be developed with similar or higher compressive strength and ductility than that of M45-ECC. However, the flexural strength of M45-ECC was higher than those of all other composites. In addition, TGA/DTA and FTIR analysis supported that the excessive amount of AL + Bi content would not improve the characteristics of FA + GGBFS-based EGCs after the optimal production of C-S-H and N-A-S-H gels which acquired in geopolymerization. However, ductility continued to improve significantly as the AL + Bi content increased. Moreover, reduction of AL/Bi ratio increased the total gel content and thus, the compressive strength of composites developed.
  • Küçük Resim Yok
    Öğe
    Rheological properties, strength characteristics and flexural performances of engineered cementitious composites incorporating synthetic wollastonite microfibers with two different high aspect ratios
    (Elsevier Sci Ltd, 2021) Yucel, Hasan Erhan; Oz, Hatice Oznur; Gunes, Muhammet; Kaya, Yasin
    In this study, synthetic wollastonite microfiber (SWM) with high aspect ratio (44:1/SWM-I) developed with a special technique was used in different proportions instead of cement (C), fly ash (FA) and cement + FA (C-FA) in Engineered Cementitious Composites (ECC). SWM-I decreased the workability as a result of interlocking during flow due to its acicular particle structure. When SWM-I was used instead of C, it was determined that the compressive strength decreased and the ductility improved significantly due to the increased SWM-I content. The use of SWM-I instead of FA improved the mechanical performance up to 6% in terms of compressive strength and flexural performance. However, the mixtures prepared by using SWM-I instead of C-FA provided optimum data, considering both ''increasing deformation capacity'' and ''maintaining the bearing strength by fiber bridging after crack''. Therefore, the effect of SWM-II (30:1) was tested by using instead of C-FA. SWM-I with a higher aspect ratio has been improved the mechanical properties of ECC and reduced the workability of ECC more than that of SWM-II. Increasing FA content in ECC has been provided higher ductility but decreased significantly the compressive strength. The bearing strength and deformation capacity of the ECC designed with finer aggregate has been achieved the higher levels compared to larger aggregate size. As a result of all obtained findings, the data of the optimum mixture has been determined as follows: the compressive strength, flexural strength and ductility of ECC incorporating 6% SWM-I instead of C-FA have been reached higher levels than that of 19.0%12.5%, 12.0%-8.2% and 56.2%-25.5% at 7-28 days, respectively.
  • Küçük Resim Yok
    Öğe
    The effects of synthetic wollastonite developed with calcite and quartz on high performance mortars
    (Ernst & Sohn, 2020) Oz, Hatice Oznur; Gunes, Muhammet
    In this study, the effects on high performance mortar (HPM) of synthetic wollastonite (SW) mineral were researched. Through this work, firstly, wollastonite was synthetically obtained by a particular production method. Secondly, SW was utilized as cement replacement material from 0 to 12% by 3% steps of increment in the production of HPM. After determination of slump flow diameters of HPMs, mechanical and durability properties were observed at 28 and 90 days. Additionally, microstructural performance properties of HPMs designed with SW in the ratios 0, 9, and 12% was specified with TGA/DTA and FTIR analysis as well as SEM/EDX and XRD analysis. The test and analysis results showed that SW decreased the workability of HPMs. The improvement of the mechanical and durability properties of HPMs proceeded up to 9% of SW. Microstructural analysis showed that development effect of SW on the HPM can be attributed to its needle-shaped structure.