Performance and life cycle of ultra-high performance concrete mixes containing oil refinery waste catalyst and steel fibre recovered from scrap tyre

Abstract

An economic solution to recycle spent equilibrium catalyst (Ecat) disposed of by petrochemical manufacturers and steel fibre recovered from scrap tyre would be their use in the production of structural concrete. In this study, the performance and life cycle of ultra-high performance concrete (UHPC) mixes containing these waste materials was examined. They were made using a total binder content of 1160 kg/m3 and also contained fly ash and silica fume in addition to Ecat and cement. Their average compressive strength at the end of 28 days was found to be above 150 MPa. The replacement of cement with Ecat reduced the CO2 emission and material cost of recycled steel fibre (RSF) reinforced UHPC samples by 15% and 6%, but there is no significant change in their compressive, flexural and split tensile strengths at the end of 28 days. Only 2% of the elastic modulus of these samples increased as a result of the addition of Ecat by weight of the binder. Ecat, an aluminosilicate material, is generally classified as a pozzolanic material, but its addition together with fly ash and silica fume in the UHPC mixture did not affect the strength gain properties. Based on our experimental findings, the use of waste materials including Ecat and RSF in the preparation of precast UHPC elements for explosion and earthquake resistant structures is recommended.