Title: Bond Behavior of Normal and High-Strength Fiber Reinforced Concrete

Author(s): Ahmed Ezeldin and P. Balaguru

Publication: Materials Journal

Volume: 86

Issue: 5

Appears on pages(s): 515-524

Keywords: anchorage (structural); bond (concrete to reinforcement); cracking (fracturing); ductility; fiber reinforced concretes; high-strength concretes; metal fibers; pullout tests; silica fume; slippage; Materials Research

DOI: 10.14359/2141

Date: 9/1/1989

Abstract:
Experimental results on the bond behavior of normal and high-strength concrete made with and without fibers are reported. A total of 18 mixture proportions were investigated. The variables were: 1) silica fume content, 2) fiber length, 3) fiber content, and 4) bar size. The silica fume content was varied from 0 to 20 percent by weight of cement. Steel fibers with hooked ends were used in the quantities of 0, 50, 75, and 100 lb/yd3 (0, 30, 45, and 60 kg/m3). The fiber lengths and reinforcement bar sizes were 30, 50, and 60 mm and No. 3, 5, 6, and 8 (9, 16, 19, and 25 mm), respectively. The bond tests were conducted using a modified pullout test in which the concrete surrounding the bar was in uniform tension. The following conclusions can be drawn using the results obtained. Addition of silica fume results in higher bond strength but results in brittle bond failure. Fibers can be used to improve the ductility to a considerable extent. The slip (relative movement between the bar and the concrete) at maximum bond load increases with increase in fiber content. The contribution of fibers to bond strength is considerable for No. 5, 6, and 8, as compared to No. 3 bars. Post-peak behavior is substantially improved by the fibers.