Engineering properties of crumb rubber alkali-activated mortar reinforced with recycled steel fibres

Abstract

To mitigate the potential problems of waste tyres and Portland cement greenhouse gas emissions while further promote the sustainable development of construction industry, this paper, for the first time, explores the workability and mechanical properties of crumb rubber alkali-activated fly ash-slag mortar reinforced with recycled tyre steel fibre (RSFRAM) considering different contents of crumb rubber (CR, i.e. 5%, 10% and 15% replacement by volume of fine aggregate) and recycled tyre steel fibre (RTSF, i.e. 0.5% and 1.0% by volume). The results indicate that the inclusion of CR led to a 4.7% to 26.7% improvement in workability of RSFRAM when the RTSF content was low, while the addition of RTSF compensated the strength loss caused by the addition of CR. The combination of CR and RTSF created a synergistic effect on the flexural behaviour of RSFRAM. The optimal mixture was regarded as R5F1.0 (5% CR replacement and 1.0 vol.% RTSF) exhibiting comparable compressive strength, and superior flexural strength (around 171.1% higher), toughness indices (highest among all RSFRAMs) and residual strength factors (higher than 100) compared to the reference mixture without CR and RTSF. In addition, R5F1.0 can meet the strength requirement of concrete (i.e. 28 MPa for basic construction application) and thus suitable for structural applications as a sustainable material.

Experimental study on engineering properties of concrete reinforced with hybrid recycled tyre steel and polypropylene fibres

“…RTSF (see Fig. 1a and b) (Zhong et al, 2019) and PPF (see Fig. 1c and d) were used as reinforcing fibres in this study.…”

“…Four-point bending tests on three prismatic samples (100 Â 100 Â 500 mm) at 28 d were conducted as per ASTM C1018 (1997) to determine the flexural behaviour of all mixtures, where the previous work (Zhong et al, 2019) found that this standard was more suitable for describing the flexural behaviour of FRC with deflection-hardening feature. A controlled displacement rate of 1 mm/min was adopted for all flexural testing in this study.…”

“…It was reported that more than 500 million waste tyres are landfilled (Thomas and Gupta, 2016) while limited land disposal sites would become one of the serious threats to human society (Wang et al, 2019). The accumulated solid tyre waste could also pose several challenges to the environment as it may induce fire or disease (Ramarad et al, 2015;Zhong et al, 2019). However, through certain processing stages, rubber particles, steel and polymer fibres can be recovered (Gigli et al, 2019), which provides a potential way to effectively recycle a majority of waste tyres around the world.…”

Flexural fatigue behaviour of recycled tyre polymer fibre reinforced concrete

“…Nevertheless, the increasing energy consumption (about 15% of the total building energy) and generated environmental pollution by manufacturing the aforementioned fibres [30][31][32] motivated researchers to explore the possibility of utilizing end-of-life materials (e.g. waste tyres) as fibre reinforcement constituents.…”

The The Effects of Recycled Tire Rubbers and Steel Fibers on the Performance of Self-compacting Alkali Activated Concrete

“…This improvement may be due to the hydrophilic nature of SF [36], improving the bond between SF and matrix. Also, high elastic modulus of SF facilitates stress distribution so that tensile crack formation is restrained, improving the mechanical strengths [37].…”