Effect of thermal modification in the natural resistance of Eucalyptus grandis and Pinus taeda woods

The aim of the study was to evaluate the natural durability of wood submitted to heat treatments and exposed in a field environment. Were used Eucalyptus grandis and Pinus taeda species, being selected five trees selected for each species studied, which were unfolded, dried in a conventional drying kiln, and later submitted to the heat treatments using temperatures of 140 and 160 degrees C. Subsequently 75 specimens of each species were prepared, which were tested in the field during six months of exposure, and the evaluations of the samples occurring every 40 days. The evaluation included the analysis of climatic variables, potential of fungal attack and the mass loss (%) of the woods, being the statistical analysis of the data by ANOVA for mass loss (%), in a completely randomized design with triple factorial arrangement, for the factor specie in two levels, factor thermal treatment in tree levels (control, 140 and 160 degrees C) and time of exposure in five levels (40, 80, 120, 160 and 200 days of exposure). Eucalyptus and pine treated at 160 degrees C presented respectively the highest and lowest resistance to mass loss. All woods are classified by the average values as very resistant.