Compression Strength of Fir and Beech Wood Modified by Citric Acid

Abstract

Fir wood (Abies alba Mill.) and beech wood (Fagus sylvatica L.) were impregnated by citric acid (CA) with natrium-dihidrogen-hipofosfit (NaH2PO2) as a catalyst. Part of the impregnated samples together with control samples were cured at the temperature of 140 °C for 10 hours, other part of samples was cured in microwaves for 35 minutes. Average compression strength parallel to the grain of wood modified using different regimes of curing was compared to the strength of the recent wood. Average compression strength parallel to the grain of wood retained after modification. In the case of fir wood average compression strength was even improved after modification. The results indicate that wood modified by citric acid may be considered for the purposes where compression strength properties are equally important as improved durability and dimensional stability of wood.