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Advances in Materials Science and Engineering
Volume 2015, Article ID 486232, 7 pages
Research Article

Statistical Analysis of the Tensile Strength of Coal Fly Ash Concrete with Fibers Using Central Composite Design

1Department of Concrete Structures and Building Materials, Technical University in Iasi, 43 Mangeron Boulevard, 700050 Iasi, Romania
2Faculty of Textile, Leather Engineering and Industrial Management, Technical University in Iasi, 29 Mangeron Boulevard, 700050 Iasi, Romania
3Department of Environmental and Land Improvements, University of Agronomical Sciences and Veterinary Medicine in Bucharest, Marasti 59, 011464 Bucharest, Romania
4Department of Materials Engineering, University Politehnica in Bucharest, 313 Independentei, 060042 Bucharest, Romania
5Livestock Building Department, University of Agricultural Sciences and Veterinary Medicine in Iasi, 3 Sadoveanu, 700490 Iasi, Romania

Received 28 October 2014; Accepted 26 January 2015

Academic Editor: Sridhar Komarneni

Copyright © 2015 Marinela Barbuta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The influence of coal fly ash and glass fiber waste on the tensile strength of cement concrete was studied using central composite design. Coal fly ash was used to replace 10% of the cement in the concrete mix. Glass fiber was added to improve the tensile properties of the concrete in different dosages and lengths. In total, 14 mixes were investigated, one only with 10% coal fly ash replacement of cement and the other thirteen were determined by the experimental design. Using analysis of variance, the order of importance of the variables was established for each property (flexural strength and split tensile strength). From the nonlinear response surfaces, it was found that higher values of flexural strength were obtained for fibers longer than 12 mm and at a dosage of 1-2%. For split tensile strength, higher values were obtained for fibers with a length of 19–28 mm and at a dosage of 1–1.5%.