The deflection of reinforced concrete beams containing recycled steel fibers

The annual entrance of billions of used tires into landfills has caused tremendous environmental concerns, while the recycled steel fibers from these tires can improve the mechanical characteristics of construction materials, including cement concrete. In this paper effect of the addition of recycled steel fibers on mechanical characteristics of ordinary cement concrete with different water to cement ratios are studied; to achieve that, compressive and flexural specimens are exanimated using standard test methods with four general mix designs. The range of recycled steel fibers is chosen as 0%, 1%, 2%, 3%, and 4% (per unit weight), and optimal fiber percentages based on water to cement ratios are also calculated. Results show that using recycled steel fibers positively affects all the mix designs, especially ductility, and postfracture energy absorption increases with the increase of fiber content. Fiber addition increases the compressive and flexural strength by about 25% and 58%, respectively. Depending on the water to cement ratio, the optimum percentage of recycled steel fiber for concretes with 0.6, 0.5, and 0.4 water to cement ratios are 3.0%, 2.3%, and 1.8% of unit weight, respectively. K E Y W O R D Scompressive and flexural strength, fiber-reinforced concrete, green environment, mix-design, recycled steel fiber

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of water to cement (W/C) ratio and age on mechanical behavior of tire‐recycled steel fiber reinforced concrete

Karimi

Ebneabbasi

Karamzadeh

et al. 2022

“…The behavior of fiber reinforced concrete (FRC) at the serviceability limit state has received much less research attention than at the strength limit state. Relative to RC, FRC members typically display reductions in crack spacings 1,2 and crack widths, 3,4 as well as improvements in member stiffness 5–7 and reductions in instantaneous 8,9 and long‐term (LT) deformations and crack widths 4,10,11 …”

Section: Introductionmentioning

confidence: 99%

Time‐dependent elongation and cracking behavior of fiber reinforced concrete tension chords

Watts

Amin

Gilbert

2022

The long-term (LT) tension stiffening effect in fiber reinforced concrete (FRC) tension chords is investigated in this paper. Six tension tie specimens with varying fiber types (either no fibers, polypropylene, or steel fibers) and reinforcement ratios were subjected to a sustained tensile in-service load for 560 days. The LT specimens were fitted with gauges to monitor their elongation over the test period. In addition, 12 specimens were subjected to instantaneous loading to capture the entire load-deformation response of the tension ties, up to and beyond the yielding of the reinforcement. A complete suite of material characterization tests were conducted in conjunction with the tension tie testing. The results from this investigation indicate that the inclusion of the fiber types and dosages adopted in this program improve the short-term performance with respect to stiffness, tension stiffening, and cracking. Steel fibers improved the LT behavior, while the polypropylene fibers used in this study led to mixed results. Models previously developed by the authors have been shown to describe the behavior with good accuracy.

“…Recent research revealed that steel fibers originating from the waste tire recycling industry could be a helpful reinforcement system to significantly reduce cementbased materials' brittle behavior. [31][32][33][34][35][36][37] Using recycled materials can help solve the pollution caused by industrial development, which has severe and irreparable consequences on the environment, in addition to reducing the production costs of fiber reinforced concrete. One of the originalities of this research is using the low-cost and eco-friendly tire-recycled steel fiber.…”

Section: Introductionmentioning

confidence: 99%

Structural and environmental performance of recycled steel fiber reinforced concrete segment under the thrust force of the tunnel boring machine jacks

Sharghi

Afshin

Chakeri

et al. 2022

The present study evaluates the structural and environmental performance of recycled fibers as a low-cost and eco-friendly reinforcement of segmental tunnel lining. In this research, the defect effects in the support area are investigated using three types of scaled panel samples. In addition to the fiber-only reinforced concrete, the performance of a new hybrid design is evaluated. The axial displacements, crack widths, crack lengths, and crack depths were monitored by displacement gauges and image processing. The experimental and numerical results show that the presence of defects, in addition to increasing at least five times the opening of the spalling crack, induces the appearance of new secondary cracks. Based on the results, it was observed that recycled fibers have a good ability to reduce the opening and growth of cracks. The hybrid reinforced design showed a significant performance compared to conventional reinforced segments, even in the most critical support conditions. According to several environmental parameters, the highest environmental compatibility in continuous support conditions is related to the fiber-only reinforced concrete design; however, with presence of defects in the support area, the new hybrid reinforced design has shown the highest environmental compatibility in most environmental parameters. It was finally concluded that the fiber-only reinforced concrete with recycled steel fibers and the new proposed hybrid reinforced concrete designs had high efficiencies in all cases in terms of structural, environmental, and economical performances. In addition to significantly reducing the crack openings in the hybrid reinforced design, the used rebars were reduced by about 40%.defect in support area, environmental, FE analysis, hybrid design, laboratory tests, recycled steel fiber, scaled panel sample, segmental lining Discussion on this paper must be submitted within two months of the print publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.