The effects of fibre on the mechanical properties of aerated concrete

Abstract

Aerated concrete (AC) is lightweight concrete in which air voids are captured in the mortar by means of the addition of an aerating agent to meet specific requirements of density and strength. Aerated concrete displays brittle failure in tension, however, and thus an alternative solution to make the concrete more ductile and reduce the problem of cracking is to add steel bars or steel fibre. The aim of this study is thus to investigate the effect of steel fibres on the compressive strength, flexural strength, stress-strain relationship, modulus of elasticity, density, sorptivity, and water absorption of aerated concrete with such fibres as compared to plain aerated concrete. End-hooked steel fibres with lengths of 35 mm and 60 mm with aspect ratios of 64 and 67 respectively were used in this study, with a volume friction (Vf) of 1.5%. The results showed that the effect of the aspect ratio (Lf/df) on flexural strength was most prominent, and that the compressive strength of the fibre reinforced aerated concrete (SFRAC) increased significantly and the density increased slightly, while the water absorption was decreased. The sorptivity of the SFRAC with short fibres was similar to that of standard AC, with this being increased slightly with the longer fibres. However, the stress-strain relationship in tension increased most significantly. Overall, 1.5% of steel fibre of 60 mm length provided the highest flexural strength at 28 days.