Dovetailed and hybrid synthetic fibre concrete - Impact, toughness and strength performance

Concrete is a widely used material within the civil engineering environment, having many varied applications that utilise its inherent qualities. When concrete is subject to rapid or impact loading it can suffer failure as it is inherently weak in tension. The inclusion of fibres may go some way to mitigate this weakness. This paper investigates a new synthetic dove tailed (DT) cross section fibre with regard to energy absorption and builds upon previous pull out testing by the authors. The test examines polypropylene DT fibres and hybrid blends of DT and other structural synthetic fibres to evaluate the best performing hybrid mix. The parameters of the test are: compressive strength, flexural strength, energy absorption (toughness) measured with load and deflection and time dependant absorbed energy using a drop hammer impact test and high velocity ballistic rifle fire. The findings showed a 50%/50% mix of DT and Type A polyethylene fibre of a smaller diameter outperformed the other DT and hybrid fibres tested. The single size prototype DT fibre is in its development stage and the results suggest a smaller diameter fibre may be more effective at coping with post crack forces. This specification change may prove beneficial with regard to enhanced energy absorption and will have many practical applications ranging from blast and projectile protection, motorway barriers, pre cast concrete impact damage, airport runway, rail system infrastructure and earthquake design. (C) 2015 Elsevier Ltd. All rights reserved.