Development of Southern Pine Lumber Based Engineered Products and Evaluation Technology

Southern pine (SP) lumber, the primary softwood lumber in the United States, has been popular since early colonization of the U.S.A. and remains a preferred choice for today’s lumber construction professionals. SP trees, as the major commercial softwood forest in South region, are largely grown, managed, and harvested on privately owned plantation forests. In the United States, softwood lumber consumption as a percentage of total lumber consumption has remained around 83% since the 1960s. Most softwood lumber is used for housing construction. SP comprises the primary softwood lumber products in the United States due to its superior mechanical properties, rapid drying capability, versatility, and availability. SP lumber also has long been the preferred species for pressure treatment because of its unique cellular structure that permits deep, uniform penetration of preservatives. However, as a natural material, the mechanical and physical performance of SP lumber has changed over the past decades according to the intensive lumber plantation management and dynamic market consumption. As a result, visually graded lumber products contain a large portion of juvenile wood and a lack of large cross section became two main issues in the most recent SP lumber marketing activities. According to the recent United States timber production statistic report, the South has given up its position as the largest softwood lumber-producing position in 2011. The total U.S. softwood lumber production in 2011 was about 26.8 × 109 bf, with 13.3 × 109 bf produced from West region and 12.0 × 109 bf produced from South region (Howard and Westby 2013). In this study, research that attempts to develop better and higher value SP lumber has been conducted for lumber construction marketing purpose. Five chapters are included in this study to fulfill the research purposes. Two lumber composite products made with low grade SP lumber were fabricated and evaluated for market purpose. A prototype in-grade testing plan to assess the actual design values of visually graded southern pine lumber from the gulf south region in the USA was developed. For comparison purpose, nondestructive tests (NDT) with four commercial techniques on on-grade No.2 SP lumber were conducted