CCA preservative treatment and redrying effects on the bending properties of 2 by 4 southern pine

Loblolly pine 2 by 4 lumber was treated with chromated copper arsenate (CCA) preservative (0.4 or 0.6 pcf) and then air-dried or kiln-dried at 240?F. For commercially graded No. 2 lumber, average bending strength was consistently reduced from 6 to 23 percent depending on the treatment and redrying level. The effect of CCA treatment and redrying throughout the rest of the bending strength distribution was shown to be a function of rank order or percentile level within the distribution. Air-drying after treatment affected strength only above the 20th to 40th percentile depending on the level of treatment. Kiln-drying after treatment at 240?F affected the entire bending strength distribution. The effects of CCA treatment and redrying were highly interactive with quality level based on strength ratio and the presence or absence of pith. Results indicated that CCA treatment and redrying reduced the strength of 2 by 4 loblolly pine lumber having higher strength ratios more than 2 by 4 lumber having lower strength ratios. The presence of pith tended to lessen the effect of CCA treatments on strength.

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