Journals Proceedings

Abstract

This paper examined how the strength properties of plain concrete performance can be improved by the introduction of hooked-ends steel fibres by volume fraction and fly ash as replacement for cement into concrete batch with the objective of bridging the inherent brittle nature and dramatic disadvantages such as poor deformability and weak crack resistance of plain concrete in practical usage. Compressive and flexural strengths of concrete cubes and prisms produced with fly ash as partial replacement for cement at 0, 10, 20, 30 and 40%, with incorporation of steel fibres at 0%, 0.50%, 0.75% and 1.00% by volume fraction of concrete were determined. Seventy five (75) concrete cubes of size 150x150x150 mm were cast. Compressive strength of concrete cube specimens was evaluated 7, 14, 21, 28 and 56 days. Compressive strength results indicated that 10% fly ash replacement outperformed all other percentage replacements including the control mix replacement of 0% fly ash. The strength development of concrete cubes at 56 days fly ash replacement of 20%, 30% and 40% indicated faster rate of strength development than those of 0% and 10% fly ash replacement. Sixty (60) concrete prisms of size 100x100x400 mm were produced with steel fibres incorporation at 0%, 0.50%, 0.75% and 1.00% by volume fraction of concrete and fly ash partial replacement for cement at 10%, 20% and 30%. The flexural strength of concrete prisms was evaluated. Addition of hooked-ends steel fibres 0.55mm diameter and 33mm length to concrete cylinders and prisms slightly improved both split tensile and flexural strength of concrete. The results at 28 and 56 days indicated that concrete prism specimens reinforced with steel fibres have their strengths slightly greater than that of concrete cylinder and prism specimens with no steel fibre added.