Yazar "Tanyildizi, Harun" seçeneğine göre listele

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    Bacteria-Based Crack Healing of Nanosilica and Carbon Nanotube Modified Engineered Cementitious Composites
    (Asce-Amer Soc Civil Engineers, 2024) Tanyildizi, Harun; Bulut, Metehan; Ziada, Mahmoud
    This study investigated bacteria-based crack healing of nanosilica and carbon nanotube modified engineered cementitious composites (ECC). Nanosilica (NS) and carbon nanotubes (CNT) were used in ratios of 0%, 0.25%, 0.50%, and 0.75% of the cementitious materials by mass. NS and CNT modified ECC samples were produced and cured in plastic bags at 23 degrees C +/- 2 degrees C for 28 days. After 28 days, the microcracks were formed in the ECC specimens. Then, the healing procedure by a bacterial solution containing Sporosarcina pasteurii was applied to these samples. After this procedure, the splitting tensile strength, ultrasonic pulse velocity water permeability, and rapid chloride permeability were performed on the samples. Also, energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analyses were used to examine the morphology of healing products. This study found that 0.75 NS-ECC had a higher healing ability than all samples, and the splitting tensile strength recovery rate of this sample was 131.46%.
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    Comparison of artificial neural network and fuzzy logic models for prediction of long-term compressive strength of silica fume concrete
    (ELSEVIER SCI LTD, 2009) Oezcan, Fatih; Atis, Cengiz D.; Karahan, Okan; Uncuoglu, Erdal; Tanyildizi, Harun
    In this study, an artificial neural network (ANN) and fuzzy logic (FL) study were developed to predict the compressive strength of silica fume concrete. A data set of a laboratory work, in which a total of 48 concretes were produced, was utilized in the ANNs and FL study. The concrete mixture parameters were four different water-cement ratios, three different cement dosages and three partial silica fume replacement ratios. Compressive strength of moist cured specimens was measured at five different ages. The obtained results with the experimental methods were compared with ANN and FL results. The results showed that ANN and FL can be alternative approaches for the predicting of compressive strength of silica fume concrete. (C) 2009 Elsevier Ltd. All rights reserved.
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    Self-Healing Performance of Nanosilica-Modified Engineered Cementitious Composites Exposed to High Temperatures
    (Asce-Amer Soc Civil Engineers, 2024) Tanyildizi, Harun; Bulut, Metehan
    This study investigated the self-healing performance of nanosilica-modified engineered cementitious composites (ECCs) exposed to high temperatures. Nanosilica (NS) was used in 0%, 0.25%, 0.50%, and 0.75% proportions of cementitious materials by mass in the mixtures. NS-modified ECC cylindrical samples (o100x200 mm) were produced and cured at 23 degrees C +/- 2 degrees C for 28 days. Then, these samples were exposed to 20 degrees C +/- 2 degrees C, 100 degrees C, 200 degrees C, 300 degrees C, 400 degrees C, 500 degrees C, 600 degrees C, 700 degrees C, and 800 degrees C temperatures. After the samples were cooled at room temperature, microcracks were formed in the ECC samples, but the samples exposed to higher than 400 degrees C were dispersed when the crack was formed. The wetting-drying cycles were applied for the self-healing of cracked samples. Lastly, the splitting tensile strength, ultrasonic pulse velocity, and chloride ion permeability of the NS-modified ECC samples were determined. Scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses were also performed to examine the microstructure of NS-modified ECC samples. This study found that all samples were self-healed within 15 days, and the highest splitting tensile strength recovery rate was obtained from 0.75 NS-modified ECC samples with 107.44%.
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    The effect of carbon nanotube on self-healing properties of engineered cementitious composites subjected to high temperatures
    (Ernst & Sohn, 2024) Tanyildizi, Harun; Bulut, Metehan
    This study aims to examine the effect of carbon nanotubes (CNT) on the self-healing performance of engineered cementitious composites (ECC) subjected to high temperatures. In ECC samples, CNT was used at 0%, 0.25%, 0.50%, and 0.75% by weight instead of cementitious materials. The cylindrical specimens containing CNT (o100 x 200 mm) were manufactured. The produced specimens were subjected to temperatures of 23 +/- 2, 100, 200, 300, 400, 500, 600, 700, and 800 degrees C after being cured at 23 +/- 2 degrees C for 28 days, and then, they left to cool at 23 +/- 2 degrees C for 1 day. Then, these specimens were preloaded at 70% of the ultimate splitting tensile strength to produce microcracks. Lastly, wetting-drying cycles were performed on ECCs for self-healing. The ultrasonic pulse velocity (UPV), splitting tensile strength (fst), and rapid chloride permeability (RCPT) tests were applied to evaluate the self-healing performance of specimens. Moreover, microstructural analyses such as scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were accomplished to identify the healing products formed in self-healed cracks. According to the results of this study, the highest recovery rate of fst with 103.46% was attained from the ECC specimen containing 0.25% CNT exposed to 200 degrees C.