Efeito da umidade dos moirões e da concentração de ingrediente ativo na retenção de CCA-C

Abstract

The CCA is the most used preservative product in Brazil. It reacts fast, presents good resistance to leaching and presents excellent results in the protection of xylophagous agents. The strategy of wood treatment companies is to control factors that influence retention, such as preservative solution concentration and moisture of wood, to reach higher values and closer to the normalized minimum. The objective of this study was to reduce CCA-C consumption without harm the quality of the treatment, by determining the most efficient interval of moisture of the wood for two genotypes of Eucalyptus sp. in different concentrations of active ingredients. 72 posts of E. cloeziana and E. camaldulensis x E.urophylla, 150 cm long and 8 to 10 cm in diameter were treated. The posts were randomly selected in three storage stacks with different storage times in the yard (long, intermediate and short). The active ingredient concentrations tested were 1.2; 1.4 and 1.6%. The experiment was performed according to a completely randomized design, arranged in a 3x3 factorial arrangement. The factors were the storage times in the yard, as a function of the moisture of the wood, and the concentrations of active ingredient. The response variable was retention. The joint analysis of these two factors on CCA-C retention was performed using the Scott Knott's Test at 5% significance. In the hybrid, it was observed that the increase in concentration generated an increase in retention and for E. cloeziana, it was observed that only the 1.4 and 1.6% concentrations were different. In E. cloeziana the retention observed in the long storage time was higher than the short storage time. The intermediate storage time did not differ from the others. For the hybrid, the retentions observed in the times of long and intermediate stocks did not differ among them. Retention in the short storage time was lower than in the others. For the hybrid, the long storage time and the concentrations of 1.4 and 1.6% provided satisfactory retention averages for ground contact posts, according to NBR 9480 (ABNT, 2009). The pressure of 12.5 kgf*cm -2 , the time of 45 minutes, the concentration of 1.4 and 1.6% and the moisture of the posts between 13 and 24% were the parameters that provided satisfactory retentions according to (NBR 9480 - ABNT, 2009). Regarding to E. cloeziana, the concentration of 1.6% and the long storage time provided higher retentions. However, a satisfactory retention average was observed only for indoor or outdoor use without contact with ground (NBR 9480 - ABNT, 2009).