Optimization of Fibre Combination Using Latest Generation of Steel and Polyolefin Fibres

Abstract

Concrete has certain limitations like its low ratio tensile-compressive strength and its low fracture energy, behaving as a quasi-brittle material. Hence, in the last decades a significant number of researchers have carried out a wide range of campaigns, models as well as modifications and combinations with other materials with the only aim of improving concrete tensile characteristics. Among the various alternatives proposed in literature, the incorporation of randomly distributed fibres into the concrete matrix has enabled to reach residual load-bearing capacities that can be considered in the structural design. These structural fibres can be synthetic or made of steel. The presence of fibres improves the response of concrete under tensile and flexural stresses and can replace the use of rebars to reinforce concrete. Fibres suppose not only an increase of toughness but also they can control the development and propagation of cracks and therefore enhance its durability. This study aimed to characterize a high-performance self-compacting concrete reinforced with the latest generation steel fibres and the combination of these with polyolefin fibres through a series of fracture tests. Three-point bending tests followed EN-14651 and permitted assessing the post-cracking behaviour and, thus, the structural contributions of these types of fibres. The significance of this research relies in the optimization of several fibre cocktails that combined three steel fibres types and polyolefin fibres. The results showed that it is possible to achieve a fibre combination that can take advantage of the best performance of each fibre type.