High strength concrete innovations: hybrid blends with silica fume, nano-coated aggregates, and steel fibres – experimental and fea-based performance insights

ABSTRACT

This research assesses the improvement in concrete properties through the application of silica fume, nano-coated coarse aggregates, and steel fibres in 14 mixes. Mechanical tests were conducted at 7, 14, 28, and 90 days. Optimum mix M13, 85% cement, 15% silica fume, 80% coarse aggregates, 20% nano-coated aggregates, and 1.5% steel fibers, recorded the highest value of 103.25 MPa compressive, 9.305 MPa split tensile, and 10.433 MPa flexural strength at 28 days. Compared to normal concrete (M1), with values of 87.14 MPa, 7.853 MPa, and 8.805 MPa, respectively, M13 exhibited enhancement in strengths of more than 18% compressive, 18.5% tensile, and 18.5% flexural strength. Flexural response from experiment of the beams under load also exhibited less deflection in M13 (10.39 mm at 300 kN) than in M1 (11.38 mm), warranting enhanced ductility. Finite Element Analysis using ANSYS agreed with experimental trends with almost the same deflection values. X-ray Diffraction (XRD) analysis validated increased crystallinity and hydration of M13 with sharp peaks pointing to increased pozzolanic activity and greater microstructure than regular concrete. These results validate the efficiency of the combined application of silica fume, nano-modified aggregates, and steel fibres in the production of long-lasting, high-performance concrete for structural use.

Keywords:
Silica fume; nano coated aggregates; steel fibres; flexural behaviour; FEA