Hooked-End Steel Fibers Affecting Damping Ratio of Modified Self-Compacting Concrete with Rubber and Marble/Granite Additions

Abstract

The aim of this investigation is to determine the effects of hooked-end steel fibers on both the fresh and hardened properties of modified self-compacting concretes (SCC). For this purpose, the steel fibers are associated with other residue contents (i.e., marble, granite, and rubber). These concatenated material contents constitute a novelty since no investigations are reported. It is found that with the increase in rubber content, a better ability to absorb energy is observed. This indicates that a good alternative to structural material is provided. Fresh properties are evaluated by using flow, T₅₀₀ time, V-funnel, and J-ring methods. The mechanical behavior is evaluated in terms of compressive strength, tensile strength, static and dynamic modulus of elasticity, and damping ratio. Experimental results of the water absorption, porosity, and density are also attained. It is also found that an SCC mixture containing steel fiber, marble/granite residue, and rubber content is a potential mixture to be considered when designing in SCC associated with an improved damping ratio. Although the rubber content decreases the mechanical behavior and slump flow, the concatenated utilization of marble/granite residues and steel fiber contents provides a slight improvement in the damping result. An environmental benefit can also be associated since cement consumption is decreased with marble additions.

Keywords: composite material; mechanical properties; microstructural array; rubber content; self-compacting concrete; waste residues.

Figure 3

(a) Photograph representing the dynamic testing by impulse stimulus (damping and dynamic elastic modulus) and (b) response to the impulse of a damped system with a degree of freedom 0 < ζ < 1 at time t = 0, adapted from [58,59].

Figure 1

Rubber residues (a) macroscopic scale and (b) secondary electron microscope (SEM) image using the secondary electron (SE) technique to characterize rubber particles.

Figure 2

(a) Hooked-end steel fibers (HESF) designated as Dramix^® RC65/35B and (b) typical SEM/SE image evidencing steel fiber reinforced concrete sample.

Figure 4

(a) Relation between dynamic modulus and static modulus of the SCC samples, (b) considering some empiricals concerning static modulus and dynamic modulus, and (c) tensile-to-compressive strength ratios.

Figure 5

Ryshkewitch’s equation describes the compressive strength (CS) as a function of porosity (P), considering 28 days of curing.

Figure 6

(a) Experimental damping ratio as a function of the porosity level, and (b) reveals damping ratio and slump flow variations with compressive strengths for all examined concrete samples.

Figure 6

(a) Experimental damping ratio as a function of the porosity level, and (b) reveals damping ratio and slump flow variations with compressive strengths for all examined concrete samples.

Figure 7

SEM (SE technique) images of concrete mixes with distinct steel fiber contents and MGR: (a) the SCC/10SF, (b) the SCC/10SF/30MGR, (c) the SCC/20SF, and (d) the SCC/20SF/30MGR samples.

Figure 8

SEM (SE technique) images of concrete mixes with distinct steel fiber contents, MGR, and rubber: (a) the SCC/10SF/30MGR/2.5R sample and (b) the SCC/20SF/30MGR/5R sample.