Strength Investigation of Fly Ash Based Concrete Waste Steel Fibre and Polypropylene Fibre as Reinforcing Materials

The improper management of waste steel fibres causes a huge environmental damage. Proper utilization of these waste steel fibres can be done in civil engineering. Concrete obtained by adding these fibres is considered to show a good mechanical improvement of brittle matrix, moreover it is a promising candidate for both structural and non-structural applications. In the present work, as a continuation of research already performed in this field by the other authors, the post cracking performances of FRC (fibre reinforced concrete) were evaluated by means tests on flexural elements and slabs. All fresh and hardened concrete properties are estimated experimentally. By the means of flexural test the post-cracking behavior of SFRC is obtained. These specimens showed a good energy absorption and good residual strength after cracking. Moreover, cracks have an important role in concrete structures as they are the permeable components and have high risk of corrosion. Cracks make the structure aesthetically unacceptable and make structure weak. Cracks are considered to be neither harmful to structure nor affects its serviceability if they are in limited width. Hence it is important that crack width must be less and this is achieved by adding polypropylene fibres to concrete.

This work examines the mechanical properties of concrete by using waste steel fibres from mechanical labs and recronS polypropylene fibres and flyash as replacement of cement. In this work cement was replaced by flyash by 20% of cement by weight in each mix, waste steel fibres with varying percentages like 1, 2, 3, 4, 5, 6 in the mix, and the combinations were tested and in the second case with same combinations 1% of polypropylene fibre is added and tested for workability, compressive strength, tensile strength, flexural strength. In this study we observed that the strength was increased with increase in fibre content but workability decreased and optimum percentage of steel fibre was observed at 5% so super plasticizer has been used to increase workability and the effect of polypropylene was not on the strength but crack width reduced and observed controlled brittle failure.