Paul R. Blankenhorn

Wood fiber surface treatment level effects on selected mechanical properties of wood fiber–cement composites

Abstract The objective of this study was to determine the effects of sodium (N) silicate, potassium (K) silicate, and silane (Si) treatment levels on newspaper and unbleached kraft fibers for enhancing selected mechanical properties of wood fiber–cement composites compared to untreated wood fiber–cement composites. Both wood fiber types were treated with selected aqueous solution strengths, air dried, and mixed with water and cement. The bending and compression properties of the specimens were determined after 28 days of hydration. Results of this study indicated that the aqueous chemical treatments of the wood fibers enhanced some of the mechanical properties of wood fiber–cement composites compared to the untreated wood fiber–cement composites. The enhancement depended on chemical treatment and wood fiber type. All three chemical treatments of newspaper fiber enhanced the normalized toughness values compared to the untreated newspaper fiber–cement composites. In addition, higher treatment levels using N silicate with newspaper fiber improved the compressive strength and bending modulus of the composites compared to the untreated newspaper fiber–cement composites. Kraft fiber treated with all three chemicals enhanced the compressive strength, bending modulus and bending strength compared to the untreated kraft fiber–cement composites. However, only silane-treated kraft fiber improved the normalized toughness values compared to the untreated kraft fiber–cement composites. The results of the study indicated that certain chemical treatments react better with different wood fiber types resulting in selected mechanical property enhancements.

Effects of fiber surface treatments on mechanical properties of wood fiber–cement composites

Abstract The purpose of this research was to determine the effects of treated and untreated hardwood, kraft softwood, and newsprint wood fibers on the 7- and 28-day bending strength, compressive strength, and toughness values for wood fiber–cement composites. Untreated and acrylic- or alkylalkoxysilane-treated hardwood, kraft softwood, and newsprint wood fibers used in wood fiber–cement composites resulted in different bending and compression properties. Fiber characteristics along with different chemical treatments influenced the composite properties. Compressive strength decreased for all fiber types and chemical treatments compared to the neat cement controls. Bending strength values for all wood fiber composites were higher than the neat cement control specimens. Both the acrylic emulsion and alkylalkoxysilane treatments provided improvements in the bending strength values compared to the untreated wood fiber–cement composites. Toughness improved for all untreated and treated wood fiber–cement composites compared to the neat cement control specimens. The toughness value results for the alkylalkoxysilane-treated fibers were similar to the acrylic-treated fibers in that the longer kraft softwood fiber–cement composites had the highest toughness values compared to the other fiber groups.

Temperature and moisture effects on selected properties of wood fiber-cement composites

The effects of moisture cycling on the dimensional stability and temperature cycling on the compressive strength of treated wood fiber-cement composites were investigated. The Kraft softwood fibers and the hardwood fibers were treated with an aqueous acrylic emulsion or alkylalkoxysilane prior to manufacturing into wood fiber-cement composites. Moisture cycling results indicated that the treated fiber-cement composites were more resistant to deterioration than the neat cement specimens. The alkylalkoxysilane-treated fiber-cement composites resisted deterioration more than the acrylic emulsion-treated fiber-cement composites. Treated hardwood fiber-cement composites were more resistant than the treated Kraft fiber-cement composites. The effects of temperature cycling on the compressive strength values produced similar results. The treated fibers were more resistant to deterioration than the neat cement. The alkylalkoxysilane-treated Kraft and hardwood fiber-cement composites had higher average compressive strength values than the acrylic emulsion-treated wood fiber-cement composites.

Approaches to improve the properties of wood fiber reinforced cementitious composites

Abstract In an attempt to improve the workability, stability, and physical and mechanical properties of wood fiber-reinforced cementitious composites (WFRCs), alkali-activated blended cements have been explored for their compatibility with various wood fibers such as hardwood fiber, recycled newspaper fiber and recycled kraft paper fiber. Methods including high shear mixing, modifying the cement matrix with silica fume, and molding pressure were evaluated as means for further strengthening the wood fiber-reinforced cement composites. Flexural strengths up to 40 MPa. along with enhanced toughness have been achieved.

Economic evaluations of multiple rotation sric biomass plantations

Abstract A series of short-rotation intensive culture (SRIC) Populus plantations involving four management strategies (control, fertilization, irrigation, and fertilization-irrigation) were evaluated in tandem with alternate harvesting and storage strategies to determine the least cost method for supplying biomass to an ethanol conversion facility. The plantations were based on Populus hydrid NE-388, a tree spacing of 0.6 m × 0.8 m, and a rotation length of four years. First rotation yields from the various strategies ranged from 33 to 42 oven-dry metric tonne per hectare (Mg(OD) ha−1). An average yield increase of 12% was realized from the second rotation coppice plantations. The control strategy had the lowest production costs for the two rotations, averaging 532 Mg−1 (OD). Harvesting and storage requirements nearly doubled the final costs, with the least cost system having an average total cost of

Short rotation woody biomass plantations: Technical requirements and costs for establishment

66 Mg−1 (OD). Over 50% of the total cost originated from equipment and material inputs, with labor costs representing nearly 30% of the total and land the final 20%.

Effect of hydration on the mechanical properties of epoxy impregnated concrete

Abstract The establishment of short rotation, intensive culture, (SRIC) woody biomass plantations using hybrid poplar was cost analyzed on a financial and energy input basis. Establishment operations were at a commercial scale and met the power requirements of each task in a cost-efficient manner. Total establishment costs amounted to

Production costs for first rotation biomass plantations

1249 ha−1 and, on an energy cost basis, 16205 MJ ha−1. The planting operation was the largest expense, involving 73% of the total financial and energy costs in establishment. The second largest expense was herbicide spraying, costing approximately 22% on a financial and energy basis. In turn, establishment represented 36% of the total production costs in the 4-year rotation of non-fertilized plantations.

Financial selection of rotation age for SRIC plantations

Abstract Following various hydration times (1 to 28 days) concrete was impregnated with an epoxy resin system. For a given impregnation condition (vacuum, pressure and time), it was found that higher polymer loadings were achieved in specimens having shorter hydration times. Compressive modulus and compressive strength values for impregnated specimens were higher than their corresponding control values. Compressive modulus values appear to be a function of hydration time (up to 14 days) for impregnated specimens, but the modulus of 1 day impregnated specimens is considerably higher than that of all the controls (1 to 28 day). Compressive strength values appear to be primarily a function of volume loading, and 1 day impregnated specimens displayed compressive strength values of greater than 10, 000 psi.

Cost parameters affecting multiple rotation SRIC biomass systems

Abstract A series of short rotation Populus plantations involving alternate management strategies were evaluated in terms of the financial and energy costs required in the production process. The plantations used hybrid poplar NE-388 ( Populus maximowiczii × trichocarpa ), a tree spacing of 0·6 m × 0·8 m and a rotation length of 4 years. Four production strategies (control, irrigation, fertilization, and fertilization-irrigation) were employed on sites representing favorable and unfavorable growing conditions. The production costs were based on a proposed commercial design involving a plantation unit of 924 hectares, with 4 such units providing a sustainable supply of biomass. The control strategy on the better site was least expensive, with base stumpage costs of