Fire Retardancy of Cementitious Panels with Larch and Spruce Bark as Bio-Admixtures

Abstract

The aim of this study is to investigate the production of fire-resistant panels made out of bark from spruce (Picea abies), larch (Larix decidua Mill.) and cement. This research included test panels produced from bark, cement, water and cement-bonded recycling material aiming for the target density of 750 kg/m3. The physical (density, dimension stability, thickness swelling) and mechanical properties such as tensile strength and compressive strength together with fire resistance were tested. Considering the results, appealing values have been achieved: max. compressive strength: 3.42 N/mm2; max. thickness swelling: 5.48%; and density: 515 to 791 kg/m3. In principle, the properties of the produced panels depend not only on the density, but also on the hydration and, above all, on the compaction and the composition of the boards. The fire tests demonstrated that the produced panels have an enormous potential in terms of fire resistance and could be utilized for fire-retardant applications.

Environment-friendly waterborne fire retardants for protection of wood and bark against fire flames

“…According to their findings, a mineral-enriched matrix in the composites was the main reason for their flame retardancy. Cement as a non-combustible building material and bark as a natural barrier of tree against fire plays an important role in flame retardancy (Pacher et al 2022). Tree bark contains the phenolic compounds that provide fire-retardant properties to such composites, together with the protective role of bark as fire-stopping, is found in many species (Bauer et al 2010).…”

“…Furthermore, tannins are high molecular weight (up to 20,000) compounds that form complexes with proteins and alkaloids, which precipitate. The likely mechanism of action is as follows: The tannins are able to neutralize radicals due to their endowment to donate electrons (Hemingway and Lacks 1992) and via electron donation, as well as through forming a protective layer against the heat and against diffusion to the flame of combustible volatile compounds (Pacher et al 2022). Tannins determine reduction of heat power, which could retard and slow down the fire.…”