Resumen de Correlations between drying defects, their parameters and moisture gradient kiln-dried, south african growth "Eucalyptus grandis" poles
P. Mugabi, T. Rypstra, H.F. Vermaas, D.G. Nel
on-destructive testing for drying defects in Eucalyptus grandis utility poles would be highlyadvantageous. These defects can negatively affect creosote preservative treatment and in-serviceperformance. The objective of this study was to assess correlations between drying defects such assurface checking, honeycombing, collapse, their parameters and moisture content (MC) gradient inpoles, to possibly find a simple and quick but reliable method to assess internal and external dryingdefects. Defects and moisture content gradients were measured in 39 kiln-dried E. grandis poles. Aftermeasuring surface check length, width and depth using a measuring tape, a ruler and a depth gauge,destructive sampling at the theoretical ground line (TGL) was done to measure the MC gradientbetween the shell and core of poles. Digital image analysis of cross-sections of discs cut at TGLwas used to measure honeycomb check width, length and area, as well as counting individual closedsurface checks. Collapse was assessed using qualitative methods. Results showed that honeycombingand collapse were positively, and surface checking and MC gradient were negatively correlated.Surface check width, length and depth were also correlated. Honeycomb count, check width, lengthand area were strongly correlated. It was concluded that measuring any of these surface check and/or honeycomb parameters may give meaningful deductions about the extent of surface checking andhoneycombing respectively.
