Mode II Fracture Toughness of Hybrid FRCs

Abstract

Mode II fracture toughness (K IIc ) of fiber reinforced concrete (FRC) has been widely investigated under various patterns of test specimen geometries. Most of these studies were focused on single type fiber reinforced concrete. There is a lack in such studies for hybrid fiber reinforced concrete. In the current study, an experimental investigation of evaluating mode II fracture toughness (K IIc ) of hybrid fiber embedded in high strength concrete matrix has been reported. Three different types of fibers; namely steel (S), glass (G), and polypropylene (PP) fibers were mixed together in four hybridization patterns (S/G), (S/PP), (G/PP), (S/G/PP) with constant cumulative volume fraction (V f ) of 1.5 %. The concrete matrix properties were kept the same for all hybrid FRC patterns. In an attempt to estimate a fairly accepted value of fracture toughness K IIc , four testing geometries and loading types are employed in this investigation. Three different ratios of notch depth to specimen width (a/w) 0.3, 0.4, and 0.5 were implemented in this study. Mode II fracture toughness of concrete K IIc was found to decrease with the increment of a/w ratio for all concretes and test geometries. Mode II fracture toughness K IIc was sensitive to the hybridization patterns of fiber. The (S/PP) hybridization pattern showed higher values than all other patterns, while the (S/G/PP) showed insignificant enhancement on mode II fracture toughness (K IIc ). The four point shear test set up reflected the lowest values of mode II fracture toughness K IIc of concrete. The non damage defect concept proved that, double edge notch prism test setup is the most reliable test to measure pure mode II of concrete.

Modified Disk-Shaped Compact Tension Test for Measuring Concrete Fracture Properties

“…However, when the mechanical and fracture behavior of a concrete in an already built structure is required, cylindrical drilled cores are extracted from the concrete structure allowing the compressive strength, the splitting tensile strength and the Young's modulus of concrete to be easily determined (Abou El-Mal et al 2015;Harkouss and Hamad 2015). In this case, the CT test seems to be the suitable test for measurement of the specific fracture energy by using slice shaped specimens cut off from the cylindrical cores, in particular if the above mentioned disadvantages in testing such specimen type are surmounted.…”

Effect of Fiber Hybridization on Durability Related Properties of Ultra-High Performance Concrete

“…Workability can be ensured by applying large amounts of superplasticizer (2009). Fibers are added to the matrix as reinforcement to control cracking and to increase material ductility (Dinh et al 2016;Abdallah et al 2016;Bencardino et al 2010;Abou El-Mal et al 2015;Sorensen et al 2014). The cracks in concrete generally occur over time due to a number of reasons.…”

Strain Rate Dependent Behavior and Modeling for Compression Response of Hybrid Fiber Reinforced Concrete

“…However, to ensure a balance between ultimate strength and strain capacity, optimum volume/weight proportion of different fibers is desired (Ahmed et al, 2007). For static loading conditions, HFRC composites result in better energy absorbing properties compared with that of mono-fiber concrete composites (Chen et al, 1996;Abou El-Mal et al, 2015;Li, 2012). A new type of steel fiber with spiral shape, proposed recently (Xu et al, 2012a(Xu et al, , 2012b, has been found to demonstrate larger displacement capacity and provide better bonding compared to hookedend, deformed and corrugated fibers (Hao and Hao, 2013;Hao et al, 2016).…”