ALTERNATIVE MATERIALS FOR THE REINFORCEMENT AND PRESTRESSING OF CONCRETE. CHAPTER 8. ARAMID-BASED PRESTRESSING TENDONS

This chapter discusses the use of Aramid based prestressing tendons. The stress-strain behaviour of Aramid fibres is compared with that of other types of reinforcing materials. The structure, physical characteristics, and mechanical properties of various Aramid products are presented. These include Arapree and Fibrarod. The physical properties relevant to design with Arapree are discussed in more detail. These include: a) Poisson's Ratio; and b) radial coefficient of thermal expansion. Mechanical properties of especial importance include: a) strength; b) strain at failure; and c) stress-strain behaviour. The technological properties which should be given special attention include the influence of: a) time upon creep and relaxation; b) moist environments; and c) temperature. The effect of sustained load upon stress rupture, of fatigue, and bond behaviour are also illustrated and discussed. Methods to test durability are presented, with special attention to the effect of alkaline environments. The Arrhenius approach is used. Anchorage methods are also discussed. Applications include the prestressing of concrete motorway noise barrier posts near Rotterdam.