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Öğe Application of destruction specific energy for characterisation of concrete paving blocks(THOMAS TELFORD PUBLISHING, 2009) Atici, U.; Ersoy, A.; Ozturk, B.Concrete interlocking paving blocks (CIPB) are used in a variety of commercial, municipal and industrial applications. This study aimed to develop a prescription (optimum parameters of aggregate proportion, water/cement (w/c) ratio and dosage) for producing CIPB based on destruction specific energy (SE(des)), strength, hardness and abrasion resistance. In developing countries, CIPB are being produced by a trial and error method, which results in uneconomical and low engineering properties. This may arise as a result of the lack of confidence and the lack of technical experience in the CIPB field. In order to gain these qualifications, optimum water/cement (w/c) ratio and dosages, and optimum aggregate characteristics at different ages are determined for CIPB within the scope of the presented study. Recently defined SEdes, which is estimated from the area (integral) under the stress strain envelope in unconfined compression test, is used. The splitting and flexural tensile strengths, rebound hardness and abrasion resistance results showed consistency with the SEdes. The optimum parameters of aggregate proportion, w/c ratio and dosage are obtained. Accordingly, the application of SEdes for production of CIPB results in lower cost and higher quality engineering properties for CIPB.Öğe Assessment of the modulus of elasticity at a triaxial stress state for rocks using gene expression programming(Pouyan Press, 2020) Atici, U.Rocks were subjected to the deformation test under five different confining stresses (0, 5, 10, 15, and 20 MPa) using the Hoek cell to determine changes in the elastic properties of the rocks under confining stress, and the results were evaluated based on density, porosity, Schmidt hardness, and compressive strength. A total of nine different rocks, two granites, two andesites, two limestones, one tuff, one diorite, and one marble, were used. When the confining stress was increased from 0 MPa to 5 MPa and from 5 MPa to 10 MPa, elasticity increased by approximately 20%. When the confining stress was increased from 10 MPa to 20 MPa, the increase was 7% in comparison with the previous value. Then, to formulate the modulus of elasticity for rocks under the triaxial stress conditions, a new and intelligent approach to gene application, gene expression programming was utilized. The success of the model was thoroughly assessed based on measurable criteria such as the root mean square error, mean absolute percentage error, and coefficient of determination. Furthermore, the success of the model was comprehensively assessed based on the model testing, and 0.88 and 0.81 R2 values were obtained for training and validation, respectively. The performance of the gene expression programming-based formulation was compared with the formulae previously proposed in the literature. The gene expression method exhibited the best performance, and it was identified to calculate the modulus of elasticity under triaxial stress conditions more effectively. © 2020 The Author. Published by Pouyan Press.Öğe Correlation of specific energy of cutting saws and drilling bits with rock brittleness and destruction energy(ELSEVIER SCIENCE SA, 2009) Atici, U.; Ersoy, A.The focus of this study is to statistically evaluate the correlations between brittleness, destruction specific energy (SEdes), and both cut-ability and drillability using the optimum data obtained from the experimental works. Applying regression analyses, the predictive models of cutting specific energy (SEcut) and the drilling specific energy (SEdrill) were developed based on the rock brittleness and rock destruction energy data. The models were verified by statistical tests and found to be reliable on being used in practical situations. Good linear, polynomial and exponential relationships between SEcut of circular diamond saw blades and the brittleness B-1 (the ratio of compressive strength to tensile strength), B-2 (the ratio of compressive strength minus tensile strength) and B-3 (compressive strength multiple tensile strength divided by two) were found. There are no correlations between SEdrill of polycrystalline diamond compact (PDC) core bits, impregnated diamond both core and non-core bits and brittleness values. The newly defined destruction specific energy (SEdes) was estimated from the area (integral) under stress-strain envelope in unconfined compression test. This method provides a better understanding of the relationships between SEcut, SEdrill, drilling and cutting rate, and the main mechanical rock character. SEdes was found to be directly related to brittleness of B-1, B-2 and B-3. Each method of measuring brittleness has its own usage in rock processing depending on practical utility (C) 2008 Elsevier B.V All rights reserved.Öğe Evaluation of destruction specific energy of fly ash and slag admixed concrete interlocking paving blocks (CIPB)(ELSEVIER SCI LTD, 2008) Atici, U.; Ersoy, A.Concrete interlocking paving blocks (CIPB) are widely used in flooring and covering applications such as city roads, pedestrian foots, gardening architecture and many surface coverings. The focus of this study is to evaluate destruction specific energy (SEdes) of CIPB containing fly ash and blast-furnace slag at different curing conditions. The SEdes is estimated from the area (integral) under stress-strain envelope for an unconfined compression test. This method provides a better understanding between performance and the main mechanical character of CIPB. Compressive strength, splitting tensile and flexural tensile strengths, rebound hardness and abrasion resistance tests at 3, 7, 28, 90 and 180 days were carried out. The test results showed that fly ash (FA) and blast-furnace slag (BFS) can replace the cement by amounts of 10-20%, 30-40% of mass, respectively. This helps to produce CIPB with lower cost and better engineering properties. The relationship between SEdes, strength, hardness. and abrasion are defined for CIPB. (C) 2007 Elsevier Ltd. All rights reserved.Öğe Prediction of the strength of mineral admixture concrete using multivariable regression analysis and an artificial neural network(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Atici, U.This study applies multiple regression analysis and an artificial neural network in estimating the compressive strength of concrete that contains various amounts of blast furnace slag and fly ash, based on the properties of the additives (blast furnace slag and fly ash in this case) and values obtained by non-destructive testing rebound number and ultrasonic pulse velocity for 28 different concrete mixtures (M(control) and M(1)-M(27)) at different curing times (3, 7, 28, 90, and 180 days). The results obtained using the two methods are then compared and discussed. The results reveal that although multiple regression analysis was more accurate than artificial neural network in predicting the compressive strength using values obtained from non-destructive testing, the artificial neural network models performed better than did multiple regression analysis models. The application of an artificial neural network to the prediction of the compressive strength in admixture concrete of various curing times shows great potential in terms of inverse problems, and it is suitable for calculating nonlinear functional relationships, for which classical methods cannot be applied. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Prediction of the strength of mineral-addition concrete using regression analysis(ICE PUBL, 2010) Atici, U.The aim of this study was to develop a method for estimating concrete strength through non-destructive testing (NDT) methods. 27 different concrete mixtures were prepared with additions of high-volume fly ash and blast-furnace slag in place of Portland cement. Tests were then conducted to determine compressive strength (CS), splitting tensile strength (STS), flexural tensile strength (FTS), rebound number (RN) and ultrasonic pulse velocity (UPV) at 3, 7, 28, 90 and 180 days after preparation. The well-known traditional RN and UPV tests were used in this study, and correlations between NDT data and the strength properties of concrete were statistically evaluated using simple regression analysis. The analysis revealed exponential, geometric and power relationships between RN and CS, STS and FTS, respectively, with moderate correlation coefficients of 0.73, 0.72 and 0.72. Exponential and hyperbolic relationships were found between UPV and CS, STS and FTS, yielding correlation coefficients of 0.85, 0.85 and 0.79, respectively. Taking advantage of the fact that UPV and RN are related to different concrete properties, a combined method was applied to estimate concrete strength. The correlation coefficients of the models for CS, STS and FTS were 0.90, 0.84 and 0.88, respectively. The accuracy of the model in predicting CS was verified by statistical tests, and it was found to be reliable in practical situations.
