Análise do comportamento mecânico e biológico do bambu gigante (Dendrocalamus asper) tratado com cobre e boro

Abstract

With the increasing demands for constructive materials, alternatives are necessary to ensure sustainability in the exploitation of natural resources. In this environment, by presenting itself in abundance in nature, adding good mechanical behavior and extensive applicability, bamboo has attracted interest. However, it does not have good resistance against the attacks of xylophagous organisms, which limits and harms its use. Therefore, preservative treatments are performed usually running counter to the inefficiency or the high environmental impact in the disposal of substances used. Currently, boron treatments based on boron are the most used, with the greatest relevance being sodium octaborate and CCB, a compound based on the action of boron with cooper and chromium. In this work, the treatment of giant bamboo under immersion in “CB” was studied, which works with cooper and boron, without chromium. The stems were treated by immersion for 7 days with CB, Boric acid at 1% and cooper sulphate at 0,5%, CB Boric acid at 2% and cooper sulphate at 1% and Sodium octaborate at 5%. Resistance to accelerated attack by white rot fungus - Trametes versicolor, brown rot fungus - Gloeophyllum trabeum and Postia placenta was evaluated by loss of mechanical resistance and loss of mass for treated and untreated groups (N). In addition, tests of seeds of lettuce (Lactuta sativa) germination were carried out against CB, CCB and O solutions under different dilutions, in order to simulate the phytotoxicity of these compounds’ disposal after treatment in the soil. The results of mass loss showed small variation from group to group, being all classified as “highly resistant”. However, the values of the CB and O groups were similar compared to T. versicolor and G. trabeum; against P. placenta, O offered less resistance than N and CB. In the loss o mechanical strength test, evaluated by static bending tests, CB showed greater rupture modules than N and O in the face of T. versicolor and greater than O in the case of G. trabeum; the deflection capacity of O was less than N and CB in the three fungi. Thus, it was possible to notice that boric acid with copper sulphate has potential efficacy in the treatment of bamboo, requiring more tests to prove it with greater sufficiency. In the phytotoxicity test, all groups tested proved to be very phytotoxic, requiring high dilutions or even a post-treatment of the effluent to minimize the environmental impact of the disposal.