Impact of surface plasma treatment on the performance of PET fiber reinforcement in cementitious composites

The purpose of this study is to demonstrate the influence of plasma treatment on the surface properties of PET fibers used as micro reinforcement in cementitious composites. The stress transfer across cracks that untreated fibers are able to accomplish can be enhanced via plasma treatment. The increase in surface roughness and the activation of polar groups result in the reduction of surface energy as observed during wetting angle measurements. The improvement in adhesion between primary (non-recycled) fibers and the surrounding matrix brought about a more pronounced strain hardening of the specimens tested in four-point bending. Plasma treatment of thinner fibers from recycled PET led to a lower capacity for transferring tensile stresses due to the reduced cross-sectional area of the fibers. The considerable bridging force provided by the plasma treated primary PET fibers resulted in the prevention of excessive and abrupt cracking, and limited crack openings.