Institute for Transportation

The development of additional preservative treatments for underutilized eastern hardwoods, such as red maple, is critical to the development of new market opportunities
that require long-term utilization of hardwoods in exterior structures. This project investigated the treatability of red maple sapwood and heartwood with water, toluene, CCA (chromated copper arsenate), ACQ (ammonium copper decyldimethylammonium chloride), creosote, and toulene- and waterborne copper naphthenate. The efficacy of CCA, and of water- and oilborne copper naphthenate against a brown-rot
fungus (Postia placenta), a white-rot fungus (Tratnetes versicolor), and a soft-rot fungus (Chaetomium globosum) was also determined using sapwood blocks in agar block decay
tests. Substantial differences were found between heartwood and sapwood treatability. Full-cell impregnation resulted in sapwood samples being thoroughly penetrated and
consistently treated to retentions of 30 to 40 pcf (lb. solution/ft.3 wood). Preservatives penetrated heartwood only about 3 mm transversely and 15 mm longitudinally. Retentions ranged from 5 to 15 pcf. On an equivalent copper loading basis, the oilborne copper naphthenate was more effective than the waterborne formulation against white- and soft-rot fungi. CCA protected maple sapwood against brown- and white-rot fungi at low
retentions, 0.1 percent copper weightlweight. Similar to past work, however, higher loadings were needed for soft-rot protection.