The effect of matrix composition on fibre/matrix interfacial bond shear strength in fibre-reinforced mortar

The effects of factors associated with the composition of the matrix, i.e. curing conditions and time and mix proportions, on the shear strength of the interfacial bond between steel fibres and a cementitious mortar matrix have been examined experimentally using a single-fibre pull-out test technique. The experimental results indicate that bond shear strength increases significantly with an increase in matrix curing time and, for specimens with the fibre axis perpendicular to the direction of casting and compaction of the matrix, with a decrease in the proportion of water by weight in the matrix mortar. This latter effect is attributed to bleed water gain under the embedded fibre, as it is not observed in specimens with the fibre axis parallel to the direction of casting and compaction of the matrix. Furthermore, the results indicate that there is no correlation between interfacial bond shear strength and matrix mortar compressive strength.