Corrugated wood composite panels for structural decking

High flexural strength and stiffness can be achieved by forming a thin panel into a wave shape perpendicular to the bending direction. The use of corrugated shapes to gain flexural strength and stiffness is common in metal and reinforced plastic products. However, there is no commercial production of corrugated wood composite panels. This research focuses on the application of corrugated shapes to wood strand composite panels. Beam theory, classical plate theory and finite element models were used to analyze the bending behavior of corrugated panels. The most promising shallow corrugated panel configuration was identified based on structural performance and compatibility with construction practices. The corrugation profile selected has a wavelength equal to 8”, a channel depth equal to ¾”, a sidewall angle equal to 45 degrees and a panel thickness equal to 3/8”. 16”x16” panels were produced using random mats and 3-layer aligned mats with surface flakes parallel to the channels. Strong axis and weak axis bending tests were conducted. The test results indicate that flake orientation has little effect on the strong axis bending stiffness. The 3/8” thick random mat corrugated panels exhibit bending stiffness (400,000 lbs-in2/ft) and bending strength (3,000 in-lbs/ft) higher than 23/32” or 3/4” thick APA Rated Sturd-I-Floor with a 24” o.c. span rating. Shear and bearing test results show that the corrugated panel can withstand more than 50 psf of uniform load at 48” joist spacings. Molding trials on 16”x16” panels provided data for full size panel production. Full size 4’x8’ shallow corrugated panels were produced with only minor changes to the current oriented strandboard manufacturing process. Panel testing was done to simulate floor loading during construction, without a top underlayment layer, and during occupancy, with an underlayment over the panel to form a composite deck. Flexural tests were performed in single-span and two-span bending with line loads applied at mid-span. The average strong axis bending stiffness and bending strength of the full size corrugated panels (without the underlayment) were over 400,000 lbs-in2/ft and 3,000 in-lbs/ft, respectively. The composite deck system, which consisted of an OSB sheathing (15/32” thick) nailed-glued (using 3d ringshank nails and AFG-01 subfloor adhesive) to the corrugated subfloor achieved about 60% of the full composite stiffness resulting in about 3 times the bending stiffness of the corrugated subfloor (1,250,000 lbs-in2/ft). Based on the LRFD design criteria, the corrugated composite floor system can carry 40 psf of unfactored uniform loads, limited by the L/480 deflection limit state, at 48” joist spacings. Four 10-ft long composite T-beam specimens were built and tested for the composite action and the load sharing between a 24” wide corrugated deck system and the supporting I-joist. The average bending stiffness of the composite T-beam was 1.6 times higher than the bending stiffness of the I-joist. A 8-ft x 12-ft mock up floor was built to evaluate construction procedures. The assembly of the composite floor system is relatively simple. The corrugated composite floor system might be able to offset the cheaper labor costs of the single-layer Sturd-IFloor through the material savings. However, no conclusive result can be drawn, in terms of the construction costs, at this point without an in depth cost analysis of the two systems. The shallow corrugated composite floor system might be a potential alternative to the Sturd-I-Floor in the near future because of the excellent flexural stiffness provided.

Photodegradation and photostabilization of weathered wood flour filled polyethylene composites

Wood plastic composites (WPCs) have gained popularity as building materials because of their usefulness in replacing solid wood in a variety of applications. These composites are promoted as being low-maintenance, high-durability products. However, it has been shown that WPCs exposed to weathering may experience a color change and/or loss in mechanical properties. An important requirement for building materials used in outdoor applications is the retention of their aesthetic qualities and mechanical properties during service life. Therefore, it is critical to understand the photodegradation mechanisms of WPCs exposed to UV radiation and to develop approaches to stabilize these composites (both unstabilized and stabilized) as well as the effect of weathering on the color fade and the retention of mechanical properties were characterized. Since different methods of manufacturing WPCs lead to different surface characteristics, which can influence weathering, the effect of manufacturing method on the photodegradation of WPCs was investigated first. Wood flour (WF) filled high-density polyethylene (HDPE) composite samples were either injection molded, extruded, or extruded and then planed. Fourier transform infrared (FTIR) spectroscopy was used to monitor the surface chemistry of the manufactured composites. The spectra showed that the surface of planed samples had more wood component than extruded and injection molded samples, respectively. After weathering, the samples were analyzed for color fade, and loss of flexural properties. The final lightness of the composites was not dependent upon the manufacturing method. However the mechanical property loss was dependent upon manufacturing method. The samples with more wood component at the surface (planed samples) experienced a larger percentage of total loss in flexural properties after weathering due to a greater effect of moisture on the samples. The change in surface chemistry of HDPE and WF/HDPE composites after weathering was studied using spectroscopic techniques. X-ray photoelectron spectroscopy (XPS) was used to characterize the occurrence of surface oxidation whereas FTIR spectroscopy was used to monitor the development of degradation products, such as carbonyl groups and vinyl groups, and to determine changes in HDPE crystallinity. Surface oxidation occurred immediately after exposure for both the neat HDPE and WF/HDPE composites. After weathering, the surface of the WF/HDPE composites was oxidized to a greater extent than the neat HDPE after weathering. This suggests that photodegradation is exacerbated by the addition of the carbonyl functional groups of the wood fibers within the HDPE atrix during composite manufacturing. While neat HDPE may undergo cross-linking in the initial stages of accelerated weathering, the WF may physically hinder the ability of the HDPE to cross-link resulting in the potential for HDPE chain scission to dominate in the initial weathering stages of the WF/HDPE composites. To determine which photostabilizers are most effective for WF/HDPE composites, factorial experimental designes were used to determine the effects of adding two hindered amine light stabilizers, an ultraviolet absorber, and a pigment on the color made and mechanical properties of both unweathered and UV weathered samples. Both the pigment and ultraviolet absorber were more effective photostabilizers for WF/HDPE composites than hinder amine light stabilizers. The ineffectiveness of hindered amine light stabilizers in protecting WPCs against UV radiation was attribuated to the acid/base reactions occurring between the WF and hindered amine light stabilizer. The efficiency of an ultraviolet absorber and/or pigment was also examined by incorporating different concentration of an ultraviolet absorber and/or pigment into WF/HDPE composites. Color change and flexural properties were determined after accelerated UV weathering. The lightness of the composite after weathering was influenced by the concentration of both the ultraviolet absorber by masking the bleaching wood component as well as blocking UV light. Flexural MOE loss was influenced by an increase in ultraviolet absorber concentration, but increasing pigment concentration from 1 to 2% had little influence on MOE loss. However, increasing both ultraviolet absorber and pigment concentration resulted in improved strength properties over the unstabilized composites after 3000 h of weather. Finally, the change in surface chemistry due to weathering of WF/HDPE composites that were either unstabilized or stabilized with an ultraviolet absorber and/or pigment was analyzed using FTIR spectroscopy. The samples were tested for loss in modulus of elasticity, carbonyl and vinyl group formation at the surface, and change in HDPE crystallinity. It was concluded that structural changes in the samples; carbonyl group formation, terminal vinyl group formation, and crystallinity changes cannot reliably be used to predict changes in modulus of elasticity using a simple linear relationship. The effect of cross-linking, chain scission, and crystallinity changes due to ultraviolet exposure as well as the interfacial degradation due to moisture exposure are inter-related factors when weathering HDPE and WF/HDPE composites.

Risk analysis of light-frame wood construction due to multiple hazards

Light-frame wood buildings are widely built in the United States (U.S.). Natural hazards cause huge losses to light-frame wood construction. This study proposes methodologies and a framework to evaluate the performance and risk of light-frame wood construction. Performance-based engineering (PBE) aims to ensure that a building achieves the desired performance objectives when subjected to hazard loads. In this study, the collapse risk of a typical one-story light-frame wood building is determined using the Incremental Dynamic Analysis method. The collapse risks of buildings at four sites in the Eastern, Western, and Central regions of U.S. are evaluated. Various sources of uncertainties are considered in the collapse risk assessment so that the influence of uncertainties on the collapse risk of lightframe wood construction is evaluated. The collapse risks of the same building subjected to maximum considered earthquakes at different seismic zones are found to be non-uniform. In certain areas in the U.S., the snow accumulation is significant and causes huge economic losses and threatens life safety. Limited study has been performed to investigate the snow hazard when combined with a seismic hazard. A Filtered Poisson Process (FPP) model is developed in this study, overcoming the shortcomings of the typically used Bernoulli model. The FPP model is validated by comparing the simulation results to weather records obtained from the National Climatic Data Center. The FPP model is applied in the proposed framework to assess the risk of a light-frame wood building subjected to combined snow and earthquake loads. The snow accumulation has a significant influence on the seismic losses of the building. The Bernoulli snow model underestimates the seismic loss of buildings in areas with snow accumulation. An object-oriented framework is proposed in this study to performrisk assessment for lightframe wood construction. For home owners and stake holders, risks in terms of economic losses is much easier to understand than engineering parameters (e.g., inter story drift). The proposed framework is used in two applications. One is to assess the loss of the building subjected to mainshock-aftershock sequences. Aftershock and downtime costs are found to be important factors in the assessment of seismic losses. The framework is also applied to a wood building in the state of Washington to assess the loss of the building subjected to combined earthquake and snow loads. The proposed framework is proven to be an appropriate tool for risk assessment of buildings subjected to multiple hazards. Limitations and future works are also identified.

CHARACTERIZATION OF ASPHALT MATERIALS CONTAINING BIO OIL FROM MICHIGAN WOOD

The objective of this research is to develop sustainable wood-blend bioasphalt and characterize the atomic, molecular and bulk-scale behavior necessary to produce advanced asphalt paving mixtures. Bioasphalt was manufactured from Aspen, Basswood, Red Maple, Balsam, Maple, Pine, Beech and Magnolia wood via a 25 KWt fast-pyrolysis plant at 500 °C and refined into two distinct end forms - non-treated (5.54% moisture) and treated bioasphalt (1% moisture). Michigan petroleum-based asphalt, Performance Grade (PG) 58-28 was modified with 2, 5 and 10% of the bioasphalt by weight of base asphalt and characterized with the gas chromatography-mass spectroscopy (GC-MS), Fourier Transform Infra-red (FTIR) spectroscopy and the automated flocculation titrimetry techniques. The GC-MS method was used to characterize the Carbon-Hydrogen-Nitrogen (CHN) elemental ratio whiles the FTIR and the AFT were used to characterize the oxidative aging performance and the solubility parameters, respectively. For rheological characterization, the rotational viscosity, dynamic shear modulus and flexural bending methods are used in evaluating the low, intermediate and high temperature performance of the bio-modified asphalt materials. 54 5E3 (maximum of 3 million expected equivalent standard axle traffic loads) asphalt paving mixes were then prepared and characterized to investigate their laboratory permanent deformation, dynamic mix stiffness, moisture susceptibility, workability and constructability performance. From the research investigations, it was concluded that: 1) levo, 2, 6 dimethoxyphenol, 2 methoxy 4 vinylphenol, 2 methyl 1-2 cyclopentandione and 4-allyl-2, 6 dimetoxyphenol are the dominant chemical functional groups; 2) bioasphalt increases the viscosity and dynamic shear modulus of traditional asphalt binders; 3) Bio-modified petroleum asphalt can provide low-temperature cracking resistance benefits at -18 °C but is susceptible to cracking at -24 °C; 3) Carbonyl and sulphoxide oxidation in petroleum-based asphalt increases with increasing bioasphalt modifiers; 4) bioasphalt causes the asphaltene fractions in petroleum-based asphalt to precipitate out of the solvent maltene fractions; 5) there is no definite improvement or decline in the dynamic mix behavior of bio-modified mixes at low temperatures; 6) bio-modified asphalt mixes exhibit better rutting performance than traditional asphalt mixes; 7) bio-modified asphalt mixes have lower susceptibility to moisture damage; 8) more field compaction energy is needed to compact bio-modified mixes.

Dynamic properties of wood using the Split-Hopkinson Pressure Bar

Strain rate significantly affects the strength of a material. The Split-Hopkinson Pressure Bar (SHPB) was initially used to study the effects of high strain rate (~103 1/s) testing of metals. Later modifications to the original technique allowed for the study of brittle materials such as ceramics, concrete, and rock. While material properties of wood for static and creep strain rates are readily available, data on the dynamic properties of wood are sparse. Previous work using the SHPB technique with wood has been limited in scope to variability of only a few conditions and tests of the applicability of the SHPB theory on wood have not been performed. Tests were conducted using a large diameter (3.0 inch (75 mm)) SHPB. The strain rate and total strain applied to a specimen are dependent on the striker bar length and velocity at impact. Pulse shapers are used to further modify the strain rate and change the shape of the strain pulse. A series of tests were used to determine test conditions necessary to produce a strain rate, total strain, and pulse shape appropriate for testing wood specimens. Hard maple, consisting of sugar maple (Acer saccharum) and black maple (Acer nigrum), and eastern white pine (Pinus strobus) specimens were used to represent a dense hardwood and a low-density soft wood. Specimens were machined to diameters of 2.5 and 3.0 inches and an assortment of lengths were tested to determine the appropriate specimen dimensions. Longitudinal specimens of 1.5 inch length and radial and tangential specimens of 0.5 inch length were found to be most applicable to SHPB testing. Stress/strain curves were generated from the SHPB data and validated with 6061-T6 aluminum and wood specimens. Stress was indirectly corroborated with gaged aluminum specimens. Specimen strain was assessed with strain gages, digital image analysis, and measurement of residual strain to confirm the strain calculated from SHPB data. The SHPB was found to be a useful tool in accurately assessing the material properties of wood under high strain rates (70 to 340 1/s) and short load durations (70 to 150 μs to compressive failure).

Fossil bubble in porphyritic basaltic pyroclasts produced by small and large strombolian eruption at Pacaya, Guatemala

We investigate compositionally monotonous, but energetically diverse, tephra samples from Pacaya to see if fossil bubbles in pyroclasts could reflect eruptive style. Bubble size distributions (BSD) were determined for four ash to lapilli size tephra samples using an adapted version of stereology conversion by Sahagian and Proussevitch (1998). Eruptions range from very weak to very energetic. Hundreds of ESEM BSEs images were processed throughout ImageJ software for a robust and statistically correct data set of vesicles (minimum 700 bubbles per sample). Qualitative textural analysis and major element chemical compositions were also executed. There is higher vesicularity for explosive pyroclasts and an inverse correlation between bubble number density (NV) and explosivity.

DEVELOPMENT OF AN OPTIMIZATION MODEL FOR BIOFUEL FACILITY SIZE AND LOCATION AND A SIMULATION MODEL FOR DESIGN OF A BIOFUEL SUPPLY CHAIN

A range of societal issues have been caused by fossil fuel consumption in the transportation sector in the United States (U.S.), including health related air pollution, climate change, the dependence on imported oil, and other oil related national security concerns. Biofuels production from various lignocellulosic biomass types such as wood, forest residues, and agriculture residues have the potential to replace a substantial portion of the total fossil fuel consumption. This research focuses on locating biofuel facilities and designing the biofuel supply chain to minimize the overall cost. For this purpose an integrated methodology was proposed by combining the GIS technology with simulation and optimization modeling methods. The GIS based methodology was used as a precursor for selecting biofuel facility locations by employing a series of decision factors. The resulted candidate sites for biofuel production served as inputs for simulation and optimization modeling. As a precursor to simulation or optimization modeling, the GIS-based methodology was used to preselect potential biofuel facility locations for biofuel production from forest biomass. Candidate locations were selected based on a set of evaluation criteria, including: county boundaries, a railroad transportation network, a state/federal road transportation network, water body (rivers, lakes, etc.) dispersion, city and village dispersion, a population census, biomass production, and no co-location with co-fired power plants. The simulation and optimization models were built around key supply activities including biomass harvesting/forwarding, transportation and storage. The built onsite storage served for spring breakup period where road restrictions were in place and truck transportation on certain roads was limited. Both models were evaluated using multiple performance indicators, including cost (consisting of the delivered feedstock cost, and inventory holding cost), energy consumption, and GHG emissions. The impact of energy consumption and GHG emissions were expressed in monetary terms to keep consistent with cost. Compared with the optimization model, the simulation model represents a more dynamic look at a 20-year operation by considering the impacts associated with building inventory at the biorefinery to address the limited availability of biomass feedstock during the spring breakup period. The number of trucks required per day was estimated and the inventory level all year around was tracked. Through the exchange of information across different procedures (harvesting, transportation, and biomass feedstock processing procedures), a smooth flow of biomass from harvesting areas to a biofuel facility was implemented. The optimization model was developed to address issues related to locating multiple biofuel facilities simultaneously. The size of the potential biofuel facility is set up with an upper bound of 50 MGY and a lower bound of 30 MGY. The optimization model is a static, Mathematical Programming Language (MPL)-based application which allows for sensitivity analysis by changing inputs to evaluate different scenarios. It was found that annual biofuel demand and biomass availability impacts the optimal results of biofuel facility locations and sizes.

FOSSIL PLANTS AND PALYNOMORPHS FROM THE LATE PALEOZOIC CUTLER FORMATION, EASTERN PARADOX BASIN

The late Paleozoic Cutler Formation, where exposed near the modern-day town of Gateway, Colorado, has traditionally been interpreted as the product of alluvial fan deposition within the easternmost portion of the Paradox Basin. The Paradox Basin formed between the western margin of the Uncompahgre Uplift segment of the Ancestral Rocky Mountains and the western paleoshoreline of the North American portion of Pangea. The Paradox Basin region is commonly thought to have experienced semi-arid to arid conditions and warm temperatures during the Pennsylvanian and Permian. Evidence described in this paper support prior interpretations regarding paleoclimate conditions and the inferred depositional environment for the Cutler Formation near Gateway, Colorado. Plant fossils collected from the late Paleozoic Cutler Formation in The Palisade Wilderness Study Area (managed by the U.S. Department of the Interior, Bureau of Land Management) of western Colorado include Calamites, Walchia, Pecopteris, and many calamitean fragments. The flora collected is interpreted to have lived in an arid or semi-arid environment that included wet areas of limited areal extent located near the apex of an alluvial fan system. Palynological analysis of samples collected revealed the presence of the common Pennsylvanian palynomorphs Thymospora pseudothiessenii and Lophotriletes microsaetosus. These fossils suggest that warm and at least seasonally and locally wet conditions existed in the area during the time that the plants were growing. All evidence of late Paleozoic plant life collected during this study was found along the western margin of the Uncompahgre Uplift segment of the Ancestral Rocky Mountains. During the late Paleozoic, sediment was eroded from the Uncompahgre Uplift and deposited in the adjacent Paradox Basin. The preservation of plant fossils in the most proximal parts of the Paradox Basin is remarkable due to the fact that much of the proximal Cutler Formation consists of conglomerates and sandstones deposited as debris flow and by fluvial systems. The plants must have grown in a protected setting, possibly an abandoned channel on the alluvial fan, and been rapidly buried in the subsiding Paradox Basin. It is likely that there was abundant vegetation in and adjacent to low-lying wet areas at the time the Cutler Formation was deposited.

Evaluating the Effectiveness of a Commercial Portable Air Purifier in Homes with Wood Burning Stoves: A Preliminary Study

Wood burning for residential heating is prevalent in the Rocky Mountain regions of the United States. Studies have shown that wood stoves can be a significant source of PM2.5 within homes. In this study, the effectiveness of an electrostatic filter portable air purifier was evaluated (1) in a home where a wood stove was the sole heat source and (2) in a home where a wood stove was used as a supplemental heat source. Particle count concentrations in six particle sizes and particle mass concentrations in two particle sizes weremeasured for ten 12-hour purifier on and ten purifier off trials in each home. Particle count concentrations were reduced by 61–85 percent. Similar reductions were observed in particle mass concentrations. These findings, although limited to one season, suggest that a portable air purifier may effectively reduce indoor particulate matter concentrations associated with wood combustion during home heating.

Geological Report of Conrow Wood Creek Area 8 Miles N.E. of Whitehall, Montana

Plane table and pacing methods were used in the mapping of the individual areas, but an automobile traverse was used to tie the independent areas into a composite group that would be useful for the entire zone. All land marks, section corners, roads, fence lines, drainage, and geologic features were plotted in the field and later transferred to a master map.