Effect of short glass fibre on dilated concrete in compression and tension

Glass fibres are fundamentally different from their host matrix, and their strength in tension is significantly higher. The fine size of the fibres also allows large volume fractions to be easily mixed and uniformly dispersed in the matrix. Closely spaced fibres can then provide effective reinforcement at the micro-cracking level, prevent the coalescence of micro-cracks into unstable macro-cracks and increase the strength. The present research work is carried out with 3 mm micro glass fibre at 0·1 to 0·5% volume fractions for normal strength concrete (M30) in uniaxial compression and uniaxial tension. The stress–strain behaviour in tension and compression is studied. Strain softening in compression and strain hardening in tension is observed. Fibre dispersion and fibre orientation at the fracture plane of specimens is examined through an optical microscope. The fibre efficiency and bond strength are calculated. The strength of the fibre-reinforced composite is influenced by the fibre length coefficient (η_l), fibre orientation coefficient (η_θ) and fibre dispersion coefficient (η_d). The higher the fibre dispersion coefficient and fibre orientation coefficient, the higher is the strength of the composite, owing to the homogeneity of fibre dispersion and because the fibres perform efficiently across the fracture plane.