Abstract
Alkali-activated/geopolymer composites have attracted interest of the research community in recent years. The popularity of alkali-activated composites is backed by the global pressure towards producing environmentally friendly construction materials and contributing to the effort of reducing the carbon dioxide footprint associated with ordinary Portland cement production. Various by-product materials (e.g., slag, fly ash and red mud) or natural resources (e.g., metakaolin) were utilized for producing alkali-activated concrete. Previous research conducted on various alkali-activated composites have shown satisfactory mechan-ical properties. The addition of manufactured steel fibers (MSF) to alkali-activated concrete mixtures have also been commonly used for improving its mechanical properties. Utilizing recycled tire steel fibers (RSF) from post-consumer tires, instead of MSF, have the potential to reduce costs and positively con-tribute to sustainability by reducing the CO2 emissions generated from manufacturing industrial steel fibers. Therefore, this research is investigating the role of RSF dosage on alkali-activated concretes mechanical properties. The experimental program included synthesis of metakaolin-fly ash based alkali-activated concrete specimens with various percentages of RSF. The performance of the RSF mixes was also com-pared against a mix with MSF. The prepared specimens were tested for the compressive stress-strain behavior, bond-slip relationship and residual compressive strength after exposure to elevated tempera-tures. Although the addition of RSF slightly influenced the compressive strength, it significantly enhanced the strain capacity at peak strength. The addition of RSF also reduced the deterioration in compressive strength after exposure to elevated temperatures. Copyright (c) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Confer-ence on Advances in Construction Materials and Structures.