Effect of moisture movement on the tensile stress–strain behavior of SHCC with alkali treated curauá fiber

Abstract

This work presents the influence of the wetting and drying cycles on the tensile behavior of the strain-hardening cement-based composites reinforced with natural curaua fiber. The 3 sets of 10 dog bone shape specimens were prepared and submitted to the cycles. After 15, 30 and 45 cycles the composites were tested under tensile load in wet (5 specimens) and dry conditions (5 specimens) and compared to the reference specimens. After the cycles, composites presented strain-softening behavior. The residual fiber stress and strain at rupture were verified on fibers extracted from the composites submitted to the tensile test. This procedure was applied to the determination of the matrix environment influence on fiber properties after accelerated aging cycles. The strain-softening behavior of the composites submitted to the wetting and drying cycles was correlated with the fiber-matrix interfacial observations under a microscope and highlighted by fiber pull-out work indicators. The strain-softening behavior is strongly related to the natural fiber volume change and defibrillation induced by the moisture movement during aging.