Polymer Binder, Impact on the Pull-Out Force of Macro Fibers in Sprayed Concrete

Macro-fibers have been used in sprayed concrete for many years now, particularly to prevent cracks from developing in the concrete due to deformation energy. These fibers can be made of steel or plastics and are provided for the Application. The type of fiber to be used is selected based on the building project’s requirements. Usually, the fibers are added to the sprayed concrete in the standard application’s mixture, regardless of whether the concrete is wet or dry (fiber-reinforced concrete or FRC). FRC’s functional principle is to mechanically anchor the steel or polymer fibers in the dense matrix of the binder or concrete. Steel fibers are available in various forms, depending on the manner in which they are bent. The shaping process aims to impede or prevent them from sliding out of the concrete. This test method was used to study the interaction of the polymer binder with the fiber (the interface of the distinct materials, concrete and fiber) and to determine whether polymer-containing concrete demonstrates better adhesion to the fiber, thus increasing the pull-out force. The study showed that there was very strong interaction between the polymer fibers and the VAE polymer used. It was possible to increase the relative pull-out force from 1 for the reference concrete to 1.48 (+50%) for the polymer concrete.