This research approach focused on 2x8 and 2x10 lumber sizes, in lengths ranging from 12- to 16t. Lumber sample data collection included: growth rings per inch (RPI), specific gravity (SG) and presence of pith. The lumber was tested in static bending per ASTM D 198. Small clear samples were then cut and used for compression testing using ASTM D 143. Lumber for this project was collected from retail lumber stores across the Southeastern United States. The larger 'host' study focused on generating current material property data from over 2000 southern pine boards to help establish more accurate and up to date lumber standards. The sampling, dubbed the 'production-weighted sampling' procedure, utilized in this study mimics the requirements of ASTM 1990. Moreover, the findings from this study are beneficial for industry and research communities alike as several smaller projects, including this one, highlight advances ranging from new lumber design values to non-destructive testing technique innovations evaluating wood. All data were analyzed using IBM SPSS version 25 software. Bivariate correlations were run in conjunction with linear regressions. Compression parallel to grain (C?) and compression perpendicular to grain (C?) were statistically tested with RPI, SG and the presence/absence of pith as independent variables. Initially, the independent variables were tested across all data for each lumber size. Then, a series of data segmentation techniques were employed among each of the independent variables: RPI, SG and pith presence. For RPI, the segments were categorized: less than 3 RPI, 3 to 5 RPI, and more than 5 RPI. Secondly, SG segments were developed in groups: less than 0.4, 0.4 to 0.5, more than 0.5. Lastly, the pith data were segmented: no pith, pith one end and pith both ends. Compression parallel and perpendicular to grain were not predictable by RPI, although the SG values by RPI segments did exhibit a stronger statistical relationship. The SG segments themselves did not reveal statistical significance; however, the pith segments yielded higher r2 values. For compression parallel to grain, r2 values were almost double than perpendicular to grain r2 values, across all pith segments and both lumber sizes.

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.