Optimized Alkali-Activated Slag-Based Concrete Reinforced with Recycled Tire Steel Fiber

Abstract

This study employed Taguchi-Grey relational analysis to optimize the influences of binder content, the molarity of sodium hydroxide (SH) solution, alkaline solution to binder content (Al/Bi) ratio, water to alkali-activated solids (W/S) ratio, and sodium silicate to sodium hydroxide solution (SS/SH) ratio on the workability, setting time, and compressive strength of alkali-activated slag-based concrete (AASC). Then, the recycled tire steel fibers (RTSF) were introduced into the optimized mixture in different dosages, and the physical and mechanical properties of fiber-reinforced AASC (FR-AASC) were evaluated. RTSF inclusion negatively affected the workability and increased the density while slightly reducing the water absorption. Additionally, the compressive strength and flexural behavior of FR-AASC improved by increasing the RTSF content. The analysis of images taken from flexural specimens through the Digital Image Correlation technique (DIC) revealed that higher RTSF dosage caused a curved macro crack with several branches alongside, leading to a better post-cracking performance in terms of strength and toughness.

Sensitivity analysis and weather condition effects on hygrothermal performance of green roof models characterized by recycled and artificial materials’ properties

“…The reason is that the rainfall and, subsequently, water content of green roof layers for scenario 3 (0.015 Ltr/m 2 ) were averagely lower than those for scenarios 1 and 2 (0.022 Ltr/m 2 ). Similar to what other researchers [26,[52][53][54][55] reported, decreasing the amount of water content led to increasing air-voids and diffusion properties of artificial and recycled coarse aggregates with high porosity. That's why the substrate layer enhanced the thermal performance of buildings when combined with a drainage layer with a large pore volume, as revealed by Scharf and Zluwa [16].…”

Mixed Mode Fracture of the Geopolymer Composites Reinforced With Recycled Steel Fibers

“…Such an unexpected decrement in the fracture energy could be attributed to the heterogeneous distribution of the steel fibers. Eskandarinia et al (Eskandarinia et al, 2022) stated that the recycled steel fiber at high dosages (i.e., Vf > 0.6 vol%) may cause a balling effect due to its irregular shape. Despite the slight decrement in the fracture energy due to the uneven distribution of the fibers, recycled steel fibers significantly amended the fracture energy capacities of the plain geopolymers.…”

“…Within this perspective, researchers aim to substitute industrial steel fiber with recycled one. The scope of the research attempts could be divided into three categories: (i) fresh (Celik & Ozkilic, 2023;Eskandarinia et al, 2022;Zhong et al, 2019), (ii) mechanical (Celikten, 2022;Mucsi et al, 2018;Yolcu et al, 2022) and (iii) durability and transport properties (Althoey et al, 2023) of the recycled steel fiber reinforced geopolymers. In some cases, recycled steel fibers were hybridized with industrial steel fibers (Alsaif & Albidah, 2022) or polyvinyl alcohol (Wang et al, 2020) to benefit from the synergetic effect of fibers.…”

Experimental study on flexural mechanical properties of steel fiber reinforced alkali-activated slag concrete beams

“…Steel fibers, as the most common fiber material, possess excellent tensile, shear, crack resistance, and toughness properties. The addition of steel fibers in concrete matrix materials can enhance the concrete's resistance to permeability, shrinkage, and deformation, as well as reduce the width of cracks during normal structural usage [18]. Therefore, it is possible to incorporate steel fibers into alkali-activated slag concrete to mitigate its drying shrinkage behavior and improve post-cracking behavior, toughness, and ductility [19,20].…”