Title: Fatigue Strength Toughness Indices of Fiber Reinforced Concrete
Author(s): Gordon B. Batson
Publication: Symposium Paper
Appears on pages(s): 715-728
Keywords: durability; fatigue (flexural); fibers (metallic, synthetic); reinforced concretes; Structural Research
Durability of concrete is commonly associated with the effects of aggressive environments, such as freeze-thaw cycles, or the penetration of liquids with high chloride ion concentrations into the matrix of the concrete that can degrade the physical and mechanical properties of concrete. Cyclic loading that causes a progressive disruption of the matrix structure by crack initiation and propagation allows aggressive environments to accelerate the rate of deterioration of the concrete and/or the reinforcement. The growth of cracks and their propagation during cyclic loading can be retarded or arrested by fibers incorporated in the concrete and thereby delay the formation of pathways for the penetration of aggressive environments or the formation of corrosion products that disrupt the matrix structure of the concrete. This paper presents test data on the flexural fatigue strength and toughness index of concrete reinforced with three types of metallic and one type of synthetic fiber in volume percentages ranging from 0.1 to 2.0. The beams reinforced with metallic fibers exhibited greater fatigue strength than beams reinforced with synthetic fibers. The fatigue strength increased with fiber volume percentage for each type of fiber. The fatigue strength of the beams varied with the deformed shape of the metallic fibers. The toughness index of the fiber reinforced beams was computed from the area under the static load-deflection curve. The toughness indexes for two of the three types of metallic fiber reinforced beams were greater than for the synthetic fiber reinforced beams. The toughness index increased with fiber volume percentage.