In the last decades, fiber reinforced concrete have emerged as the possible key to revolutionize civil engineering. Among different types of fibers employed in concrete technology to date, the application of recycled steel fibers produced from end-of-life car tires appears to be a viable approach towards environmentally friendly construction. In this study, we demonstrate the laboratory research and numerical analysis of concrete reinforced with waste steel fibers recovered during the recycling process of end-of-life car tires. Concrete mixes with the following fiber contents: 0.5%, 0.75%, 1.0%, 1.25%, and 1.5% per volume were prepared and then tested in three-point bending conditions. The laboratory investigation revealed highly boosted properties of concrete under flexure. We further performed the finite element method (FEM) analysis of 2D models using Atena software in order to develop a material model allowing the numerical modelling of recycled steel fibers reinforced concrete (RSFRC) behavior. The parameters of RSFRC material model have been modified using the inverse analysis until matching the experimental performance of the material. The results, being in good agreement with the laboratory investigation, have indicated a high potential of RSFRC for real scale construction applications.

The importance of sustainability and recycling has become increasingly recognized and understood in academia and industry over the last several decades. Recycling of construction and debris waste is one of many avenues that provide a great opportunity to prevent waste material from entering landfills and reduce the construction industry reliance on decreasing natural resource supplies. The research program focused on fracture parameters of cement based composites with various amount of waste aggregate was conducted. There were prepared composites based on specifically composed aggregates (mixture of natural sand and red waste ceramic aggregate). There was utilized simplex experiment design. Altogether, 6 mixtures of aggregates were prepared. The aim of this contribution is to present and compared basic fracture parameter values. Flexural and compressive strength and fracture toughness were of special interest. All of these tests are important for a practical application of concrete with ceramic aggregates for structures