Beneficial effect of recycled tire powder incorporation on the tensile performance of strain-hardening alkali-activated concrete

초록

The cement industry is a significant contributor to global CO2 emissions, generating approximately 0.9 tons of CO2 per ton of cement produced. To address this environmental impact, this study explores the potential of alkali-activated concrete (AAC) utilizing supplementary cementitious materials (SCMs) such as waste liquid crystal display glass powder (LCDGP) and ground granulated blast furnace slag (BFS). The study aims to enhance the performance of AAC by incorporating recycled tire powder (RTP). This research investigates the mechanical properties and microstructure of strain-hardening alkali-activated concrete (SH-AAC), incorporating polyethylene fibers and varying RTP contents. The SH-AAC mixtures, which include BFS, LCDGP, silica sand, and RTP, were analyzed for compressive strength, tensile behavior, and crack patterns using digital image correlation (DIC). The research results indicate that the addition of RTP improves compressive strength, with a significant increase observed at 74.55 MPa with a replacement ratio of up to 10 %. Moreover, the tensile strength, tensile strain, and energy absorption capacity, which indicate tensile performance, increased by 13 %, 40 %, and 34 % compared to the control group, reaching 5.15 MPa, 5.15 %, and 175.9 kJ/m3 at 70 % RTP, respectively. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) confirm the formation of C-(N-)A-S-H phases, indicating successful alkali activation. Additionally, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses demonstrate that NaOH pretreatment of RTP enhances interfacial adhesion, contributing to the improved mechanical performance. This study demonstrates that incorporating RTP and LCDGP in SH-AAC not only offers a sustainable alternative to traditional concrete but also provides enhanced mechanical properties with a reduced environmental impact.

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