Diagnostic testing in the natural and built environment

Engineers, environmental scientist, and geomorphologist require consistent, accurate and cost-effective methods for analyzing processes occurring in the natural environment and materials and products for the design of the built environment. This research evaluates diagnostic testing methods for both the natural and built environments. Riverbank, streambank and hillslope erosional processes have been studied for well over a century in the United States and the methods for the analysis and measurement of these processes has varied from direct measurement to indirect measurement methods such as remote sensing or indicators of event dating with sedimentary/biological evidence. Erosional processes contributing excess sediment that is above the background levels has been identified by the United States Environmental Protection Agency (US EPA) as one of three primary pollutants causing functional and biological impairment of the streams and rivers across the United States. Most methods to analyze these processes are costly and require timeframes that often inhibit the ability of scientist and practitioners to implement the study. Tree roots that were exposed by erosional processes are evaluated using dendrogeomorphic methods to determine the initial date of exposure and the resulting average annual erosion rates. Twelve species, primarily eastern hardwoods, were sampled and ten species were observed to have consistent identifiable responses to root exposure when compared to buried control samples of root-wood. Two species, Fagus grandifolia and Platinus occidentalis were not able to be analyzed due to degradation of the roots. Results of these studies indicated that exposed tree roots offer an accurate means of determining past and present erosion rates for more extensive study sites than would be available with most other methods. The year of first exposure (vs buried) of the tree root can be consistently determined using macroscopic and microscopic indicators including; changes in growth ring width, more pronounced growth ring boundary, ray widening and bending, stem-like vessel arrangement, eccentricity, reductions in size and number of vessels, reductions in the size of fibers and tracheids and an increase in fiber and tracheid cell thickness. Exposed roots were used to derive annual riverbank erosion rates on the Tittabawassee River in Michigan and related to the US EPA Bank Erosion Hazzard Index (BEHI). Results of the regression analysis between exposed tree roots and the BEHI indicated that more recently exposed roots (less than 7 years) provide a good prediction of riverbank erosion rates (R2 0. 67). Novel products made from natural resources are continually being developed. Cross Laminated Timber (CLT) panels and beams represent a relatively new product to multi-story building construction industry, especially in the U. S. Due to the outstanding dimensional stability, high strength and stiffness properties, fire resistance that is similar to “mass timber” products, rapid erection times of pre-manufactured components, and excellent acoustic properties, CLT offers a sustainable alternative to traditional steel and concrete construction methods for mid-rise and high-rise buildings. Yet, as with other wood products, the properties of CLT are highly variable depending on the species, size and configuration of the layup boards and adhesives used. CLT panels of southern pine (southern yellow pine) lumber and 3 adhesives; polyurethane (PUR), melamine formaldehyde (MF), and phenol-resorcinol formaldehyde (PRF) were tested for fire performance using a small-scale and intermediate scale panels. The ASTM PS-1 fire testing standard for plywood is evaluated for relevance to predict fire performance of CLT for a given species and adhesive combination. Fire testing results of small-scale panels indicated that polyurethane performs poorly for delamination when compared to the performance of both melamine formaldehyde and phenol-resorcinol formaldehyde small scale panels in the same test (ASTM PS-1). The findings of the small-sale f re test were in agreement with results of the intermediate-scale fire testing performed at the Forest Products Laboratory (FPL) for the same adhesive and species combinations as a part of the broader study of the research team. The ASTM PS-1 fire testing procedure represents a viable means for cost effective analyses, easier panel production and replication of adhesive formulation/species testing when compared to intermediate or large scale CLT panels.