Moisture Effects on Elastic and Viscoelastic Properties of CFRP Rebars and Vinylester Binder

The objective of the research was the evaluation of moisture effect on deformability of vinylester binder carbon-fiber- reinforced plastic (CFRP) rebars. Moisture sorption was investigated at different humid conditions. Maximal moisture content of the binder was about 1.86% by weight and for rebars 0.5%. For the CFRP rebars it was estimated that the degree of anisotropy of diffusion coefficient tensor is approximately 40. The elastic moduli of the materials were determined in stress–strain tests and compared with dynamic elastic and shear moduli. The moduli dropped about 10% for maximally moistened materials. The long-term deformability of the composite rebars and binder were examined in tensile creep tests. The principle of moisture–time equivalence was used for creep description of moistened specimen. Creep strain for the wet resin is approximately 5 times larger then for the dry one. Creep forecast was made for a period about 40 years