High-Performance Fiber Reinforced Concrete—Optimizing Interfacial Properties for High-Modulus and Low-Modulus Fibers


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Title: High-Performance Fiber Reinforced Concrete—Optimizing Interfacial Properties for High-Modulus and Low-Modulus Fibers

Author(s): A. Dubey and N. Banthia

Publication: Special Publication

Volume: 189


Appears on pages(s): 223-252

Keywords: adhesion; bond; debonding; fiber reinforced concretes; friction; interfaces; micromechanics; toughness

Date: 1/1/2000

A new mathematical model to study the problem of fiber pullout in fiber reinforced cementitious composites is briefly introduced. However, with an objective of optimizing fiber-matrix interfacial properties, the main focus of this paper is on the parametric studies carried out using the proposed model. Stresses required to cause initial, partial and complete depending of the fiber-matrix interface are analyzed based on shear lag theory, and closed-form solutions are derived to predict the complete pullout response. Influence of radial stresses (normal contact stress) acting at the interface is considered using the shrink-fit theory of elasticity. Analysis show that the interfacial frictional shear stress decreases with increase in Poisson's contraction of fiber. Furthermore, based on energy considerations, an analytical solution derived to compute interfacial coefficient of friction depicts that interfacial coefficient of friction decreases with increase in pullout distance. Increase in matrix wear resulting with fiber pullout is most likely responsible for the decay of coefficient of friction. Parametric studies are carried out to investigate the influence of fiber-matrix interfacial properties (adhesion bond shear strength, normal contact stress coefficient of friction) and elastic modulus of fiber. Results suggest that for a given set of interfacial properties, initial depending stress, maximum pullout stress, catastrophic debond length, interfacial shear stress distribution, and overall pullout response significantly depend upon fiber elastic modulus. Given the fiber elastic modulus, recommendations are made as to how efficiency of fiber in pullout could be improved by modifying the interfacial properties.