Fracture Properties and Restrained Shrinkage Cracking Resistance of Cement Mortar Reinforced by Recycled Steel Fiber from Scrap Tires

Abstract

Thanks to better processing technology, quality recycled steel fiber (RSF) is routinely extracted from scrap tires, offering opportunities to reinforce cementitious materials in a more economical and sustainable manner. In this study, a detailed experimental program on cement mortar reinforced by up to 2 vol. % RSF was carried out. The work involved conventional tests to characterize cement mortar mechanical properties including compressive strength, elastic modulus, and splitting tensile strength. It also featured an innovative semi-circular bending (SCB) fracture test to characterize fracture-related properties, and a customized ring test to study the cracking resistance under restrained drying shrinkage of the studied mortars. The combined use of the fracture and ring tests is believed to lead to a better assessment of concrete structure behaviors in the field. Based on the test results, the addition of up to 2% RSF shows noticeable improvement on the splitting tensile strength, but it has marginal effects on the cement mortar compressive strength and elastic modulus. The improved fracture properties of the cement mortar reinforced by 2% RSF from the SCB fracture test demonstrate that the RSF-reinforced mortar not only has a better resistance to the initiation of major cracks but also exhibits an enhanced post-cracking performance. Based on the ring test results, the longer cracking time and higher residual strain level of the 2% RSF mortar samples clearly reveal that the RSF could effectively delay and bridge cracks.

Performance evaluation of fiber-reinforced concrete produced with steel fibers extracted from waste tire

“…In this part of the study, compressive strength and split tensile strength values for plain concrete (normal concrete without fibers) and reinforced concrete with steel fibers (either industrial, recycled, or hybrid) were collected from the Frontiers in Materials frontiersin.org literature. Experimental results obtained from these existing studies conducted by many researchers (Leone et al, 2016;Aghaee et al, 2015;Gul et al, 2021;Mastali et al, 2018;Groli et al, 2014;Köroğlu, 2018;Saatçi and Batarlar, 2017;Samarakoon et al, 2019;Zhang and Gao, 2020;Centonze et al, 2012;Dehghanpour and Yılmaz, 2018;Al-Tikrite and Hadi, 2017;Vistos et al, 2018;Nataraja et al, 1999;Dorr et al, 2019;Sengul, 2018;Ł and Suchorzewski, 2018;Awal et al, 2013;Chern and Young, 1989;Najim et al, 2018;Shi et al, 2020;Rossli and Ibrahim, 2012) were presented in Figures 11, 12. Industrial fiber reinforced concrete (IFRC), recycled fiber reinforced concrete (RFRC) and hybrid fiber reinforced concrete (HFRC) cases were shown in these figures.…”

A Comprehensive Review of Incorporating Steel Fibers of Waste Tires in Cement Composites and Its Applications

“…Moreover, contradictory results were reported for specimen numbers 12, 13, and 14, incorporating the same amount of 0.46% RSF. The possible reason is that for specimens 13 and 14, the authors used a planetary concrete mixer; thus, good fiber dispersion and better mixing were obtained [ 48 , 66 ]. On the other hand, better mixing was not achieved for specimen 12 due to the traditional mixing method [ 41 ] used.…”

“…Employing a planetary mixer for specimen preparation resulted in a considerable increase in the percentage of fibers supplied to the concrete mix and the dispersion of those fibers, thus significantly improving mix homogeneity. As a result, the blends were more workable for the same amount of water for specimens 6 and 7 [ 48 , 66 ]. On the other hand, Rossli and Ibrahim [ 37 ] reported an increase of 13% in the CS of the concrete at 0.20% RSF.…”

“…No significant change in compressive strength was reported for mortar specimen one at 0.01% for 14.9 mm long and 0.32 mm thick RSF. However, when RSF was increased in specimen two from 0.01% to 0.02% for the same-size (14.9 mm long and 0.32 mm thick) RSF, 10.3% was observed [ 66 ].…”

Una revisión del comportamiento mecánico del concreto con adición de fibras de acero de neumáticos reciclados

“…El reciclaje de neumáticos desechados permite darles un uso diferente como, combustible para hornos de cemento o también, al triturar el caucho y formar partículas se puede usar en mezcla asfáltica o como agregado para el concreto, en cuanto a las fibras de acero se pueden separar mediante procesos de magnetismo (12) , es importante que se reutilice la mayor cantidad posible de neumáticos ya que estos no son biodegradables son inflamables y expulsan sustancias toxicas (13) , estas fibras sacadas de las llantas pueden tener el mismo efecto que las fibras industriales en el concreto de repente en mayor dosificación pero el rendimiento será el mismo (14) . Reciclar es una manera de aportar contra la contaminación ambiental y de encontrar soluciones económicas, en diferentes países han apostado por reciclar los neumáticos para extraer el caucho y usarlo para recauchutar llantas o para convertirlo en polvo, pero muy pocos son los que se interesan por las fibras de acero que tiene los neumáticos.…”