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    Permeation Properties of Self-Consolidating Concretes with Mineral Admixtures
    (Amer Concrete Inst, 2011) Guneyisi, Erhan; Gesoglu, Mehmet; Ozbay, Erdogan
    This paper addresses the permeation properties of self-consolidating concretes (SCCs) with different types and amounts of mineral admixtures. Portland cement (PC), metakaolin (MK), fly ash (FA), and ground-granulated blast-furnace slag (GGBFS) were used in binary, ternary, and quaternary cementitious blends to improve the durability characteristics of SCCs. For this, a total of 22 SCCs were designed that have a constant water-binder ratio (w/b) of 0.32 and a cementitious materials content of 926.75 lb/yd(3) (550 kg/m(3)). In addition to compressive strength and ultrasonic pulse velocity the permeation resistance of SCCs was determined by means of chloride ion permeability water permeability, and sorptivity tests. The test results indicated that the permeation properties of SCCs appeared to be very dependent on the type and amount of the mineral admixture used; the SCC mixtures containing MK were found to have considerably higher permeability resistance than the control mixture.
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    Properties of Mortars with Natural Pozzolana and Limestone-Based Blended Cements
    (Amer Concrete Inst, 2011) Guneyisi, Erhan; Gesoglu, Mehmet; Ozturan, Turan; Mermerdas, Kasim; Ozbay, Erdogan
    This paper presents the results of an experimental investigation on the consistency, compressive strength, water sorptivity, chloride ion permeability, electrical resistivity, and sulfate resistance of mortars made with plain and blended cements. Plain (CEM I 42.5 R) and blended cements, including portland pozzolana cements (CEM II A-P 42.5 R and CEM II B-P 32.5 R) and portland limestone cements (CEM II A-LL 42.5 and CEM II B-LL 32.5 R), were used in this study. Mortars with three different water-cement ratios (w/c) of 0.420, 0.485, and 0.550 were produced by using the plain and blended cements. In all the mixtures, the cement:sand ratio was kept constant at 1:2.75 by weight. The compressive strengths of the mortar specimens were tested at 1, 3, 7, 28, 90, and 180 days. Moreover, the water sorptivity, chloride ion permeability, and electrical resistivity of the mortar specimens were measured at 7, 28, 90, and 180 days. The sulfate resistance of the mortars was evaluated by the length change of the mortar specimens up to 30 weeks of exposure. The test results revealed that the use of blended cements decreased the water sorptivity and chloride ion permeability while increasing the electrical resistivity and sulfate resistance of the mortars at later ages compared to the normal portland cements.
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    Strength and drying shrinkage properties of self-compacting concretes incorporating multi-system blended mineral admixtures
    (Elsevier Sci Ltd, 2010) Guneyisi, Erhan; Gesoglu, Mehmet; Ozbay, Erdogan
    Drying shrinkage can be a major reason for the deterioration of concrete structures. The contraction of the material is normally hindered by either internal or external restraints so that tensile stresses are induced. These stresses may exceed the tensile strength and cause concrete to crack. The present study investigated compressive strength and particularly drying shrinkage properties of self-compacting concretes containing binary, ternary, and quaternary blends of Portland cement, fly ash (FA), ground granulated blast furnace slag (GGBFS), silica fume (SF), and metakaolin (MK). For this purpose, a total of 65 self-compacting concrete (SCC) mixtures were prepared at two different water to binder ratios. It was observed that drying shrinkage lessened with the use of FA, GGBFS, and MK while incorporation of SF increased the drying shrinkage. (C) 2010 Elsevier Ltd. All rights reserved.
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    Transport properties based multi-objective mix proportioning optimization of high performance concretes
    (Springer, 2011) Ozbay, Erdogan; Gesoglu, Mehmet; Guneyisi, Erhan
    In this study, multi-objective mix proportioning optimization of high performance concretes was performed. For this purpose, five factors; w/b ratio, total binder content (b), silica fume (SF) replacement ratio, fine to total aggregate ratio (s/a), and amount of superplasticizer (SP), were investigated to determine their effects on the transport and mechanical properties of high performance concrete. Slump, compressive strength, splitting tensile strength, modulus of elasticity, ultrasonic pulse velocity, water absorption, water penetration, and chloride ion penetration of mixtures were measured. Then, using mix proportion variables, mathematical formulations were obtained for the slump, mechanical and permeation properties via regression technique. To find out the best possible mix proportions for the simultaneous minimization of water absorption, water penetration and chloride ion penetration, a multi-objective optimization problem was defined and solved. In order to verify that the theoretically determined optimum mix proportions really minimized the transport properties of high performance concretes, an experimental study was conducted and it was observed that theoretically proposed optimum mix proportions can satisfy expected minimum permeation properties.