Behaviour and damage assessment of a new hybrid-fibre-reinforced mortar under impact load

An innovative hybrid fibre system of steel fibres, polyvinyl alcohol (PVA) fibres and inexpensive (approximately US$230/t) calcium carbonate whiskers (CW) was assessed as a way of improving the mechanical behaviour of fibre-reinforced concrete under static and impact loads and reducing production costs. Static mechanical properties and repeated drop-weight impact tests of the designed hybrid-fibre-reinforced cementitious composites (HyFRCCs) are presented in this paper. The reinforcing effect of the new hybrid fibre system was found to be very close to that of conventional HyFRCCs (incorporating only steel and PVA fibres) under both static and impact loads. It is thus suggested that steel and PVA fibres can be partly replaced with CW to reduce production costs in large-scale construction applications. Ultrasonic pulse velocity, dynamic elastic modulus and crack width assessments were carried out to quantify the degree of damage in samples during mechanical testing. The impact energy absorbed by the specimens could be predicted using linear modelling. There is therefore potential for using such tools to evaluate the in situ structural damage under dynamic loads.