Caracterização de postes de madeira para uso na rede elétrica

Abstract

Wood poles used in electrical lines were from Eucalyptus species. These poles should present adequate mechanical characteristics in order to ensure the security and structure of electrical lines. Wood poles should be treated with products able to protect the wood against insects and fungus to increase service life. Taking these into account, this study aims to evaluate mechanical properties of wood poles and qualify preservative treatment used in the wood poles. Mechanical evaluation of wood poles was performed through nondestructive tests of ultrasonic wave propagation and destructive tests according to NBR 6231 (ABNT, 1980) in order to establish a method to estimate mechanical properties through nondestructive tests. Preservative treatments through full-cell method were carried out for 60, 90 and 120 minutes with pressure of 10 and 12 kgf/cm2 using a CCA-C preservative solution. Tests of penetration and retention of the solution were performed to evaluating the preservative treatments. Chemical analysis of wood was done through extractives content, Klason lignin content and infrared spectroscopy (ATR-IR). The evaluation of mechanical properties showed not significant correlation coefficients between MOEeng. and dynamic modulus of elasticity, proving the inefficiency of nondestructive method in this study. The results of preservative treatments showed that CCA-C penetration on wood was deep and irregular in 50-70% of poles for both species. On the other hand, retention did not present the minimum value required by NBR 8456 (ABNT, 1984). This analysis showed that higher pressure and time of treatment, higher is CCA-C retention. Wood from both species presented similar results for extractives content and Klason lignin content. Infrared spectroscopy (ATR-IR) technique did not show a efficiency to predict the chemical modification in treated wood.