Durability, physical and mechanical properties of fiber-reinforced concretes at low-volume fraction T.A. Söylev a,⇑ , T. Özturan b a Dept. of Civil Engineering, Yeditepe University, Kayıs ßdag ˘ı Cad., 34755 Atas ßehir/ _ Istanbul, Turkey b Dept. of Civil Engineering, Bog ˘aziçi University, 34342 Bebek/ _ Istanbul, Turkey highlights  Air content of concrete increased with fiber addition.  Fibers caused variations in the permeability of concrete.  Polypropylene and glass fiber concretes exhibited higher rate of rebar corrosion.  Fiber addition can significantly affect the resistance against corrosion.  This effect becomes significant in long-term exposure. article info Article history: Received 30 June 2014 Received in revised form 9 September 2014 Accepted 24 September 2014 Keywords: Steel Polypropylene Glass Fiber concrete Strength Durability abstract Steel, polypropylene, and glass fiber concretes at low-volume fractions, which have been successfully used for crack control in many structural applications, were tested for different properties including water absorption, electrical resistivity, sorptivity, depth of chloride penetration, chloride profiles, rebar corrosion half-cell potential, and corrosion current density. Compressive strength and splitting tensile strength, flexural strength, and fracture toughness were also determined. Two different water–cement ratios and two curing types were used in the study. Fibers caused physical changes in concrete, which were reflected to the tested properties. The effect on durability was more significant in longer-term tests like corrosion. Moist curing was found to be more effective in fiber concrete for mechanical properties. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Fibers have been widely used for years in various civil engineer- ing applications. The improved post-cracking tensile and flexural strength of fiber concrete leads to an increase in toughness. The main benefit of the use of fibers is the control of cracking. Steel fibers are mainly used for crack control when ductile con- struction is required. Steel fiber volume as low as 0.5% was efficient in various applications like concrete pavements, slabs and tunnel linings [1–4]. Volume proportion of 0.1% glass and polypropylene fibers is sufficient for plastic and drying shrinkage cracking control [5,6]. In low volume concentrations, the effect of fibers is like a sec- ondary reinforcement for concrete because fibers control cracking but they do not contribute to the load carrying capacity. Literature data shows that the improvement in compressive strength by low steel fiber content is very limited. Splitting tensile and flexural strengths were much more affected by the presence of steel fibers [7–12]. When the fiber volume increases from 0.5% to 1% or 1.5%, the effect of steel fibers on strength becomes more significant. This increase in fiber content is more directly reflected to tensile strength results [9–12]. However, there are also some results that indicate decrease in compressive [13,14] and flexural strength [12] by steel fiber addition. Previous research on polypropylene fiber concrete (PFC) and glass fiber concrete (GFC) is scarce compared to SFC. However, slight contribution to strength was reported in some research studies [9,15–17]. Their contribution to the tough- ness of concrete is more significant [16,18], but improvement in toughness by steel fiber addition is much better compared to other fibers [9]. Fiber addition may alter some physical properties of concrete. Increased porosity and permeability was reported in the literature. Huang [19] suggests that the volume of coarser capillary pores http://dx.doi.org/10.1016/j.conbuildmat.2014.09.058 0950-0618/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Construction and Building Materials 73 (2014) 67–75 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat