Yazar "Brostow, Witold" seçeneğine göre listele

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    Effect of Elevated Temperatures on Properties of Blended Cements with Clinoptilolite
    (Kaunas Univ Tech, 2016) Beycioğlu, Ahmet; Aruntaş, Hüseyin Yılmaz; Gencel, Osman; Lobland, Haley E. Hagg; Şamandar, Ayhan; Brostow, Witold
    We have investigated the effect of elevated temperature on properties of clinoptilolite blended cements. Clinoptilolite was used at 5 %, 10 %, 15 % and 20 % replacement by weight for Portland cement while sand and water quantities were kept constant in all mix designs. Dry weights, flexural strengths, and compressive strengths of specimens were determined as a function of time. The same properties were again evaluated after specimens, having reached the age of 90 days, were exposed to 300 degrees C, 400 degrees C and 500 degrees C temperatures for 3 h. Initial setting times for all cements prepared were >= 60 minutes, the limiting time according to TS EN 197-1. The mortars with 5 % or 10 % cliniptilolite substitution have compressive strength exceeding 42.5 MPa after being subjected to 400 degrees C and 500 degrees C.
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    Effects of elevated temperatures on mechanical properties of concrete containing haematite evaluated using fuzzy logic model
    (Maney Publishing, 2013) Gençel, Osman; Brostow, Witold; del Coz Diaz, Juan Jose; Barrera, Gonzalo Martinez; Beycioğlu, Ahmet
    Concretes containing different proportions of haematite (15, 30, 45 and 60%) were fabricated and subjected to elevated temperatures (25, 200, 400, 600 and 800 degrees C). The cement content and water/cement ratio were 450 kg m(-3) and 0.38 respectively. The compressive strength and elasticity modulus of concretes were determined according to ASTM C39 and ASTM C469. A rule based Mamdani type fuzzy logic model for predicting the compressive strengths and elasticity modules of concretes containing haematite has been developed. The inputs were haematite content (%), exposure time (h) and temperature T (degrees C); the outputs were compressive strength and compressive elasticity modulus. It is shown that all the results of the model for elasticity modulus and compressive strength were in good correlation with the experimental results for all data sets.
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    Estimation of fracture energy of high-strength steel fibre-reinforced concrete using rule-based Mamdani-type fuzzy inference system
    (Walter De Gruyter Gmbh, 2012) Köksal, Fuat; Şahin, Yuşa; Beycioğlu, Ahmet; Gencel, Osman; Brostow, Witold
    In this study, we worked to estimate the fracture energy of steel fibre-reinforced concrete (SFRC) according to the water/cement ratio (w/c), tensile strength of steel fibre, steel fibre volume fraction and flexural strength of concrete sample as inputs using the Mamdani-type fuzzy inference system (FIS). In the study, the values obtained from the model and experimental divided three groups (each group has six experimental results) according to the w/c ratios to evaluate the fuzzy logic (FL) model approximate reasoning ability. As a result, the Mamdani-type FIS has shown a satisfying relation with the experimental results and suggests an alternative approach to evaluate the fracture energy estimation using related inputs.
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    Mechanical properties of blended cements at elevated temperatures predicted using a fuzzy logic model
    (Techno-Press, 2017) Beycioğlu, Ahmet; Gültekin, Adil; Aruntaş, Hüseyin Yılmaz; Gencel, Osman; Dobiszewska, Magdalena; Brostow, Witold
    This study aimed to develop a Rule Based Mamdani Type Fuzzy Logic (RBMFL) model to predict the flexural strengths and compressive strengths of blended cements under elevated temperatures. Clinoptilolite was used as cement substitution material in the experimental stage. Substitution ratios in the cement mortar mix designs were selected as 0% (reference), 5%, 10%, 15% and 20%. The data used in the modeling process were obtained experimentally, after mortar specimens having reached the age of 90 days and exposed to 300 degrees C, 400 degrees C, 500 degrees C temperatures for 3 hours. In the RBMFL model, temperature (C degrees) and substitution ratio of clinoptilolite (%) were inputs while the compressive strengths and flexural strengths of mortars were outputs. Results were compared by using some statistical methods. Statistical comparison results showed that rule based Mamdani type fuzzy logic can be an alternative approach for the evaluation of the mechanical properties of concrete under elevated temperature.