Title: A Comparative Evaluation of Concrete Reinforced with Straight Steel Fibers and Fibers with Deformed Ends Glued Together into Bundles

Author(s): V. Ramakrishnan, Terje Brandshaug, W.V. Coyle, and Ernest K. Schrader

Publication: Journal Proceedings

Volume: 77

Issue: 3

Appears on pages(s): 135-143

Keywords: compression tests; compressive strength; consistency tests; cracking (fracturing); energy absorption; evaluation; fatigue tests; fiber reinforced concretes; flexural strength; flexural tests; impact strength; metal fibers; pozzolans

DOI: 10.14359/12280

Date: 5/1/1980

Abstract:
This paper presents a comparative evaluation of two types of steel fibers used as reinforcing material in concrete. The fibers used were 1 in. (25.4 mm) long straight fibers, and 2 in. (51 mm) long fibers with deformed ends which were glued together into bundles with water-soluble adhesive. The test program included (1) flexural fatigue; (2) static flexural strength including strain, deflection, modulus of rupture, load-deflection curves, determination of first crack load, and determination of post-cracking strength for two sizes of beams; (3) impact strength to first crack and ultimate failure; (4) compressive strength; and (5) Rlastic workability including Vebe, slump, and the inverted cone time immediately after miving and after 1 hr. The complete series of tests was run for two concentrations of the collated and hooked fibers and with pozzolan and straight cement mixes. Special care was taken to insure consistency with cement, aggregates, admixtures, procedures, and mix temperatures. One major finding is that about 60 percent of the bundled fibers with hooked ends will give essentially the same concrete properties as 100 percent of the straight fibers. Bundling enables the fibers to be mixed into aggregate without tangling or "balling." These fibers were easy to handle.