Suitability of Casuarina equisetifolia as utility poles in Senegal
The use of Casuarina equisetifolia trees grown in Senegal as utility poles was investigated as follows: (1) to determine the longitudinal air permeability of the species with regard to its treatability; (2) to determine the treatability of the wood using a full-cell process; (3) to determine the mechanical properties of the species relative to its use as utility poles in Senegal.
The mean superficial longitudinal air permeability of 60 specimens was 4990 cm³(air)/cm s atm whereas the theoretical permeability was 4710 cm³/cm s atm. It was determined an average of 1830 vessels per cm² with a mean diameter of 117 microns and a volume fraction of 0.20 . The presence of tyloses was not observed during the anatomical measurements.
As expected, the most important variables influencing the effectiveness of the preservative treatment were the impregnation pressure and the permeability of the specimens. Retention increased as the impregnation pressure was increased; and at a given pressure, retention was positively correlated to permeability. Since the wood seems to be fairly permeable, it can therefore be satisfactorily treated by controlling the impregnation pressure.
The results of static bending tests were compared to the theoretical maximum stress at ground line (R) of the different classes of utility poles used in Senegal. With an average modulus of rupture (MOR) of 108 megaPascals, the ratio of MOR to R varied between 2.12 to 2.34. This ratio provides evidence that Casuarina's wood meets the mechanical requirements of the Standard NFC67-100, which sets the guidelines for utility poles in Senegal.