Compression specific toughness of normal strength steel fiber reinforced concrete (NSSFRC) and high strength steel fiber reinforced concrete (HSSFRC)

Khaled Marara,İbrahim Yitmena,Özgür Erenb

doi:10.1590/s1516-14392011005000042

Abstract

Compression toughness tests were carried out on concrete cylinders reinforced with three different aspect ratios of hooked-end steel fibers 60, 75, and 83 and six different percentages of steel fibers 0.5, 1.0, 1.25, 1.5, 1.75, and 2.0% by volume of concrete. The w/c ratio used for the normal strength steel fiber reinforced concrete mixes (NSSFRC) was 0.55, and the water-cementitious ratio (w/c+s) for the high strength fiber reinforced concrete mixes (HSSFRC) was 0.31. For each mix, three test cylinders were tested for compression specific toughness. The effect of fiber reinforcement index: volume of fibers × length/diameter ratio on compression specific toughness and also on the relationship between these two properties is presented in this paper. As a result, (a) equations are proposed to quantify the effect of fibers on compression toughness ratio of concrete in terms of FRI, (b) equations obtained in terms of FRI and compression specific toughness of plain concrete to estimate both compression specific toughness of NSSFRC and HSSFRC (N.m), (c) equations obtained which represent the relationship between compression toughness index and FRI for NSSFRC and HSSFRC, respectively, and (d) equations obtained to quantify the relationship between compression specific toughness index and fiber reinforcement index for NSSFRC and HSSFRC, respectively. The proposed equations give good correlation with the experimental values.

Highlights

High strength concrete (HSC) is defined as a concrete having a compressive strength above 55 MPa according to ACI Committee 3631
The main objectives of this study described in this paper is to produce relationships in terms of compression toughness of plain concrete and fiber reinforcement index for normal and high strength steel fiber reinforced concretes which counts for different l/d ratios different FRI’s, for a more detailed fiber volume fractions, and computations of compression toughness up to a strain of 0.0333, so that from these simple relationships we can calculate the compression specific toughness of normal strength steel fiber reinforced concrete mixes (NSSFRC) and High Strength Steel Fiber Reinforced Concrete (HSSFRC)
The experimental results indicate that workability of fresh mix NSSFRC and HSSFRC decrease with increase in fiber volume fraction and increase in fiber reinforcement index (FRI)

Summary

Introduction

High strength concrete (HSC) is defined as a concrete having a compressive strength above 55 MPa according to ACI Committee 3631. High strength concrete is a brittle material and brittleness can be reduced by the addition of short discrete fibers randomly distributed in concrete. The mechanical behavior such as compressive strength, tensile strength, flexural strength, impact strength[3,4,5,6], ductility and flexural toughness of high strength steel fiber reinforced concrete (HSSFRC) is governed by the size, type, fiber volume fraction (V ), aspect ratio of fibers:. Because of its superior energy absorption capability, fiber reinforced concrete has been widely used in a variety of civil engineering applications such as precast products, shotcrete, offshore structures, seismic structures, pavements, hydraulic structures, repairs, machine foundations, etc

Results

Discussion

Conclusion