Flexural Behavior of Hybrid Fiber-Reinforced Cement Composites Containing High-Volume Fly Ash

Abstract

In recent years, there has been a growing interest in the development of thin walled fiber reinforced cement composites for structural applications. In these composites, the discrete fibers used may be made of metallic, mineral, polymeric or naturally occurring materials. Each type of fibers is unique in geometrical shape, size, surface characteristics, strength, stiffness and ductility. As a result, different fibers offer different extent of improvement to the matrix mechanical properties. However, the most sought-after property in a cement-based composite is the strain-hardening response that is associated with multiple cracking. In order to achieve this property, different types of fibers may be suitably combined to exploit their unique properties. In addition, partial replacement of cement by fly ash which has much finer particles than ordinary cement, is likely to modify the properties of the composite by reducing the matrix fracture toughness and enhancing the interfacial bond strength between the fiber and the matrix, thus promoting a strain-hardening response of the composite material. It would also support the recent emphasis on environmental awareness by reducing the cement content in the composite. The present investigation is therefore undertaken with the main objective of developing a strain-hardening composite using hybrid fibers and high volume fly ash.