The effect of sodium chloride treatment on bending strength of silver fir wood (Abies alba Mill.)

Abstract

Among properties which characterize the application of silver fir wood (Abies alba Mill.) in buildings is its static bending strength. In the framework of improvement of this mechanical property, a comparative experimental investigation was performed with sodium chloride (NaCl) treated and non-treated silver fir wood with regard to modulus of rupture and modulus of elasticity, based on mechanical tests performed according to norms ISO 3133 and 3349. From 48 samples with dimensions 20x20x300 mm, 24 of them were full covered with solid NaCl for a period of 60 days. The samples were sawn from boards produced from fir logs of the area of Librazhdi, in central Albania. After weight percent gain was calculated, the treated and non treated samples were conditioned and tested by means of mechanical testing machine, in the Faculty of Forestry Sciences of Tirana. The weight percent gain of treated wood resulted 9.56%. The static bending strength of non treated fir resulted 81 N/mm2, while for treated wood 16.32% higher. With regard to modulus of elasticity treated wood presented a value equal to 12493 N/mm2, 8.83% higher than non treated wood. In the framework of a quantitative and qualitative analysis, measured values of the rupture and elasticity modulus in static bending of non treated wood were compared with respective values of fir wood from the literature. No significant variations were noted. Although the complexity of factors that affect on the performance of wooden construction, NaCl treated fir wood appears to bring more security for use in buildings.