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

Authors: FERREIRA, SAULO - University Of Brazil; SILVA, LUIZ - University Of Brazil; McCaffrey, Zachariah - Zach; BALLSCHMIEDE, CONRAD - Technical University Of Darmstadt; KOENDERS, EDUARDOS - Technical University Of Darmstadt

Submitted to: Construction and Building Materials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2020
Publication Date: 11/20/2020
Citation: Ferreira, S., Silva, L., McCaffrey, Z., Ballschmiede, C., Koenders, E. 2020. Effect of elevated temperature on sisal fibers degradation and its interface to cement based systems. Construction and Building Materials. 272. Article 121613. https://doi.org/10.1016/j.conbuildmat.2020.121613.
DOI: https://doi.org/10.1016/j.conbuildmat.2020.121613

Interpretive Summary: Sustainable agriculture includes the use of biobased materials to replace petroleum-based fillers or reinforcing agents. Cement, used as a building material, generally contains fillers and/or additives in order to meet certain structural specifications. However, exposure to high temperatures can negatively impact the structural integrity of cement-based materials. The sisal plant, Agave sisalana, is easily cultivated and produces long, strong, flexible fibers. Sisal fibers were exposed to a range of temperatures to understand the modifications on structure, mechanical properties and adherence to cement. Developing an understanding of the behavior of new fillers in building material composites, such as sisal and cement, when exposed to adverse environmental conditions is critical for the design of safe building materials.

Technical 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 300°C. Sisal mechanical behavior was improved until 150°C. This may happen due the water evaporation and shrinkage, promoting a close and densified fiber structure. At 250°C a few microcracks were observed on fiber surface. Cement main components degradation was observed before natural fiber (around 250°C). Bonding to cement matrix decreased after 100°C. The better hypothesis is based on fiber shrinkage and the loss of chemical bonding.