Fire behavior of bio-based earth products for sustainable buildings

  • A. Laborel-Préneron
  • J. E. Aubert
  • C. Magniont
  • A. Lacasta
  • L. Haurie
Keywords: Bio-based building material, Earth bricks, Fire resistance, Barley straw, Hemp shiv

Abstract

Construction is one of the most polluting industrial sectors. For this reason, developing sustainable building materials is a world-wide interest. Earth as a building material is thus increasingly studied because of its low environmental impact and its ability to regulate indoor moisture and to improve occupant’s comfort. Moreover, earth is a well-known non-combustible material. Recent studies deal with unfired earth bricks with plant aggregates incorporated to the earth matrix in order to lighten and improve various properties of the composite materials. However, these vegetal additions, of combustible nature, raise questions about the fire-behavior of the bio-based material. To our knowledge, the fire-behavior of this kind of materials has been little investigated in the literature. The present paper constitutes a preliminary study about the fire reaction of earth bricks containing 0%, 3% and 6% weight content of barley straw or hemp shiv. A pyrolysis combustion flow calorimetry (PCFC) was done to predict the fire-behavior of the plant aggregates. Other tests were performed on the composites to determine their flammability, their thermal insulation and their mechanical strength after high temperature exposure. The following conclusions were reached. The PCFC test has shown a peak of heat release rate around 350°C for the plant aggregates, which corresponds to the degradation of the cellulose. The ignition-extinction test has proved that the material is still non-flammable even with vegetal additions. Thermal conductivity of the composites decreased when the experienced temperature increased (until 800°C) due to the higher porosity. The higher the plant aggregates content, the more fire resistant was the material, meaning that the rise of temperature was delayed. Concerning mechanical performance, a strength drop was observed for composites around 400°C before a slight increase until 800°C thanks to the firing of the earth.

Published
2017-06-21
How to Cite
Laborel-Préneron, A., Aubert, J. E., Magniont, C., Lacasta, A., & Haurie, L. (2017). Fire behavior of bio-based earth products for sustainable buildings. Academic Journal of Civil Engineering, 35(2), 160-165. https://doi.org/10.26168/icbbm2017.24