%0 Journal Article
%T Drying Shrinkage Behaviour of Fibre Reinforced Concrete Incorporating Polyvinyl Alcohol Fibres and Fly Ash
%A Amin Noushini
%A Kirk Vessalas
%A Garo Arabian
%A Bijan Samali
%J Advances in Civil Engineering
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/836173
%X The current study assesses the drying shrinkage behaviour of polyvinyl alcohol fibre reinforced concrete (PVA-FRC) containing short-length (6£¿mm) and long-length (12£¿mm) uncoated monofilament PVA fibres at 0.125%, 0.25%, 0.375%, and 0.5% volumetric fractions. Fly ash is also used as a partial replacement of Portland cement in all mixes. PVA-FRC mixes have been compared to length change of control concrete (devoid of fibres) at 3 storage intervals: early-age (0¨C7 days), short-term (0¨C28 days), and long-term (28¨C112 days) intervals. The shrinkage results of FRC and control concrete up to 112 days indicated that all PVA-FRC mixes exhibited higher drying shrinkage than control. The shrinkage exhibited by PVA-FRC mixes ranged from 449 to 480 microstrain, where this value was only 427 microstrain in the case of control. In addition, the longer fibres exhibited higher mass loss, thus potentially contributing to higher shrinkage. 1. Introduction Concrete is recognised as the most prevalent used construction material in the world [1]. It is reputable that concrete provides notable mechanical performance, great versatility, and economic efficiency in comparison to other construction materials [2]. However, it must be noted that concrete is discredited for its brittleness and strength-to-weight ratio. Moreover, in service, structural concrete undergoes volume change due to moisture loss by hydration and evaporation. This volume change and movement experienced in this manner is termed shrinkage [2]. Shrinkage of concrete commonly occurs as a decrease in volume via four primary mechanisms: capillary tension, surface tension, disjoining pressure, and change in water within the matrix of cement [3]. Concrete tends to reach equilibrium with its service environment. If the environment is a dry atmosphere the exposed surface of the concrete loses water by evaporation. The rate of evaporation will depend on the relative humidity, temperature, water-cement ratio, and the area of the exposed surface of the concrete [4, 5]. The first water to be lost from concrete is that held in the large capillary pores of the hardened concrete. The loss of this water does not cause significant volume change [6]. However, as explained by Tam et al. [7], as water continues to evaporate from the capillary and gel pores, a meniscus is formed along the network of capillary pores and surface tension is created. With the reduction in the vapour pressure in the capillary pores, tensile stress in the residual water increases. These tensile stresses are in equilibrium with compressive stresses
%U http://www.hindawi.com/journals/ace/2014/836173/