Engineering of ultra-high performance self-compacting mortar with recycled steel fibres extracted from waste tires

The main novelty of this study is producing Ultra High-Performance Self Compacting Mortar (UHPSCM) incorporated Recycled Steel Fibre (RSF) from waste tires. For this purpose, different mix compositions including 0%, 1%, and 3% RSF content in terms of volume were proposed. Self-compacting ability was assessed using mini-cone tests, while nondestructive testing has been used to evaluate the effect of RSF inclusion on the compaction of UHPSCM constituent materials. Mechanical performances were investigated using compression and unnotched flexural tests. Residual flexural strength in both service limit state (SLS), ultimate limit state (ULS), and two equivalent flexural strengths were evaluated under notched flexural tests and analysed using statistical approaches. Concrete Damage Plasticity (CDP) has been employed for the analysis behaviour of developed mortars under different loadings. Additionally, an element deletion approach was used to evaluate the fracture of UHPSCM under compression and flexural loadings. The experimental results showed that adding 1% and 3% of RSF resulted in decreasing workability by 3% and 22%, respectively. Improving compressive strength by 16% and 22% and flexural by 7% and 8% were noticed in the case of samples with 1% and 3% fiber, respectively, in 28 days. In spite of the significant improvement of post-cracking behaviour of samples with 3% of RSF, this behaviour was insignificant for the samples with 1% of RSF. However, with less amount of fibre inclusion, brittle failure can be altered to ductile failure. Moreover, the behaviour of the tested specimens under different loadings was successfully predicted using Finite Element (FE) simulations. Graphical abstract