Evaluation of hybrid steel fiber reinforcement in high performance geopolymer composites

Abstract

In this paper, cement free high performance alkali activated slag-fly ash composites are designed by applying the modified Andreasen and Andersen particle packing model, and steel fibers of two lengths are applied for strength reinforcement and shrinkage compensation. The influence of the fiber length, dosage and hybrid on the fresh behavior, compressive strength, stress-stain behavior under flexural load, porosity and drying shrinkage are evaluated, and the gel structure of this blended alkali system is also identified. The results show that by applying the hybrid fiber together with the particle packing design approach, a compressive strength of around 100 MPa can be achieved with a w/p ratio of 0.4. The addition of steel fiber slightly decreases the slump flow and increases the porosity, but effectively inhibits the drying shrinkage and improves the stressstain behavior. The hybrid usage of long and short fiber shows a synergetic effect and leads to the optimum strength. The steel fiber reinforcement is beneficial for the application of alkali activated materials.

Fiber-reinforced geopolymer composites: A review

“…Therefore, the fresh matrix requires more vibration to lose its harsh static mode and form the mold [27,101]. Some experiments showed that the critical value tends to decrease when the aspect ratio of fiber and filler volume is increased [126][127][128][129]. Furthermore, the high surface roughness and crimped or hook-end fibers result in a reduction in critical concentration and flowability [124,130].…”

Effect of Micro Polypropylene Fibre on the Performance of Fly Ash-Based Geopolymer Concrete

“…Davidovits (Davidovits, 2005;Davidovits, 1994;Davidovits, 1991) was the first to synthesize fibre reinforced geopolymer concrete for their use in the plastic processing industry. This was furthermore extended by various other researchers, utilizing particular sorts of fibres, for instance, carbon and glass (Natali et al, 2011), polyvinyl alcohol (PVA) (Yunsheng et al, 2008;Nematollahi et al, 2015) polypropylene (PP) (Li et al, 2016), polyethylene (PE) (Nematollahi et al, 2017;Ahmed and Ronnie, 2017) and steel fibers (Gao et al, 2017;Ranjbar et al, 2016b;Li et al, 2016;Bernal et al, 2010;Ranjbar et al, 2016c) in a diverse range of geopolymers containing different source materials and alkaline solutions (Shaikh, 2013b). Subsequent, reinforcement of geopolymers with different type of fibres were carried on through protein-based fibres (Alzeer and MacKenzie, 2012), basalt fibres (Dias and Thaumaturgo, 2005), organic fibres like cotton, flax, etc.…”

Hybrid fibre-reinforced geopolymer (HFRG) composites as an emerging material in retrofitting aging and seismically-deficient concrete and masonry structures

“…This finding was also observed in [15] and [16] whereby the higher the steel fibre volume used in a fixed (steel + PE) combination, the higher the workability found. Meanwhile, Gao et al [17] characterized the slump flows of samples with 1% fibre volume content at different long/short fibre ratios (i.e., 80/20, 60/40, 40/60 and 20/80) and reported that higher long/short fibre ratio exhibited a relatively low slump. The information on the effect of fibre hybridization on the flowability of fresh FRG composites is rather limited, and apparently additional studies in this aspect need to be conducted due to its complexity.…”

“…FA-based FRG composite is observed to be more workable than slag-based composite because of its inherently smooth spherical shape bringing a ball-bearing effect that reduces internal friction in the mixture. Other factors that influenced the workability condition of fresh FRG composites include fibre types and smoothness, fibre mechanical properties, alkaline activator properties, and other admixtures [7,17]. Tables 1 and 2) are the ones producing the highest strengths or toughness, nevertheless other combinations can be found in the individual concerned studies.…”

“…However, there is a tendency that hybridization becomes significant if the combination is on the length of fibres with same material type. For instance, Gao et al [17] found out that combining 60% of long steel fibre and 40% of short steel fibre (% by weight in total steel fibre combination) yields an increase in compressive strength of 5-9% compared when only using long or short steel fibre alone. Accordingly, hybridization presents a synergetic effect by constraining the cracks from both micro and macro intensities, resulting in the occurrence of an optimum compressive strength.…”