The influence of non-metallic and metallic fibres on the mechanical properties of cement mortars

Abstract

Compared to concrete, the compressive strength is not a very important property of cement mortar. It is very important that mortar forms a complete, strong, and durable bond with the building material elements, because it is used as an adhesive and sealant material. The physical and mechanical properties of cement mortar, especially flexural strength, toughness, tensile strength, reduction of plastic as well as drying shrinkage, can be enhanced by the use of randomly dispersed fibres, such as steel, carbon or polymer. In the present research there were investigated cement mortars modified with randomly dispersed polypropylene and steel fibres in different volume fraction used both separately and in a hybrid system. The conducted research proved that the low modulus polypropylene fibres with good flexibility added to cement matrix resulted in good properties of fresh mortar and caused the reduction of early age cracking. The beneficial effects of flexible fibres could be attributed to their high aspect ratio and increased fibre availability at a given volume fraction due to their low density. Because of low stiffness, these fibres are particularly effective in controlling the propagation of micro-cracks. It was found that the hybrid combination of metallic and nonmetallic fibres can offer potential advantages in improving cement matrix properties, such as the ultimate strength and toughness of composites.