Effect of elevated temperature on sisal fibers degradation and its interface to cement based systems

Abstract

This experimental investigation aims to study the influence of temperature on natural fibers mechanical performance and on its interface to cement based systems. Natural sisal fiber was used on this study. Temperatures of 20, 100, 150, 200, 250 and 300 °C were used as conditions for this research. The influence of temperature on this fiber was evaluated by scanning electron microscopy (SEM), x-ray diffraction patterns (XRD), thermogravimetric analysis (TGA). The mechanical properties were evaluated by tensile test. Pullout test were performed in order to evaluate bonding on cement-based matrix after exposition to higher temperatures. The results indicate a minor modification on sisal morphology after temperature exposition until 200 °C. At 250 °C a few microcracks were observed on fiber surface, indicating a debonding of sisal fibercells and microfibrils. Sisal mechanical behavior was improved until 150 °C. This may happen due the water evaporation and shrinkage, promoting a closed and densified fiber structure. Cement main component degradation was observed before degradation of the natural fiber (around 250 °C). Bonding to cement matrix decreased after 100 °C and was maintained stable until 150 °C, and resulted in pullout forces reduction of 75% in comparison to fiber tested at 20 °C.