Accelerated Aging of Low-Density Cement-Bonded Wood Composites Made Conventionally and With Carbon Dioxide Injection

The purpose of this study was to evaluate the durability of low-density cementbonded wood composites using an accelerated aging process. Low-density cement-bonded wood composites were made with two types of wood particles (excelsior and splinter) and pressed either conventionally or with carbon dioxide injection. In the conventional boards, calcium chloride and sodium silicate were tested as additives to improve wood to cement bonding. Calcium hydroxide and a mixture of calcium hydroxide and sodium silicate were added to portions of the CO2-injected boards. All the boards were tested before and after 10 cycles of a 3-day soak/freeze/thaw/dry cycle. Boards injected with carbon dioxide showed better initial physical and mechanical properties and also better performance after accelerated aging than did conventionally pressed boards. Excelsior board outperformed splinter board in all conditions tested. No difference could be attributed to additives in either the conventional or the CO2-injected boards. In all treatments, flexural modulus of elasticity retention was less than 50% after 10 czcles of aging, and modulus of rupture was less than 75%. The analysis indicated that freezing had no effect on aging.