Fundamental understanding of the mechanical and post- cracking behaviour of ultra-high performance mortar with recycled steel fibers

• Published in: Construction & building materials 2023-04, Vol.374, p.130918, Article 130918
• Main Authors: Abdolpour, Hassan, Niewiadomski, Paweł, Kwiecień, Arkadiusz, Tekieli, Marcin, Sadowski, Łukasz
• Format: Article
• Language: English
• Subjects: Finite element simulation; Post-cracking behaviour; Recycled steel fibre; Residual flexural strength; Ultra-high performance mortar
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.130918

[Display omitted] •Ultra high performance self compacting mortar was developed and characterized using recycled steel fiber.•A relation between amount of recycled fiber and followability was obtained.•Addition of 1%, 2% and 3% of recycled fiber resulted in increasing 8%, 14% and 21% of flexural strength.•A linear trend between dosage of fiber and two residual flexural strengths in the service limit state and ultimate limit state was obtained.•A new model was proposed for predicting width of cracks and vertical deflections.•Numerical simulations were proposed to understand fracture mechanism of developed mortars. The main goal of this paper was to assess the influence of recycled steel fibers sourced from end-life tires on the mechanical performance of self-compacting ultra-high performance mortars. For this purpose, mortars with different amounts of fibers, ranging from 1 to 3%, were prepared. Experimental, analytical and numerical studies were carried out in order to understand the brittle and post-cracking behaviour of the prepared mortar samples. The inspections of the fresh mortars revealed that there was a strong linear relationship between the relative slump flow and the dosage of the fibres. It was observed that mortars keep their self-compatibility when there is an addition of up to 3 % of fibre. In the mortars’ hardened state, there was an increase of their mechanical properties i.e. compressive strength and flexural strength, with an increasing content of fibres. Compared to the reference mix, the compressive strength of reinforced mortars increased by 7%, 14% and 32% (7 days) and 7%, 14% and 40% (28 days) when 1%, 2% and 3% of fiber were utilised. Moreover, it was observed that by 1%, 2% and 3% addition of fibres the flexural strength increased by 7%, 14% and 17% (7 days) and 8%, 14% and 21% (28 days). Post-cracking behaviour of mortars was evaluated using residual flexural strengths in service limit state and ultimate limit state. Statistical analysis revealed a linear trend between those strengths and dosage of fibres. Regarding to the post-cracking behaviour, it was obtained that, the mortars with the addition of 1% of fibres did not show any post-cracking responses. However, the behavior of their matrix during failure can change from being brittle to being ductile. It was observed that, the proposed models in RILEM and EN 14651 overestimated the crack mouth opening displacement responses. Accordingly, a new model was proposed in this study.