Effects of pilot hole diameter and depth on screw driving torques in plywood

Factors affecting screw driving torques in plywood were investigated in this work. The factors were number of layers (7 and 9), pilot hole diameter (3.0 and 3.5 mm), pilot hole depth (60 and 80% of the thickness of specimen), and thickness of the metal plate (7.5 and 10 mm). Screw driving torques were studied in oriented strandboard, medium-density fiberboard, particleboard, and some wood-plastic composites. There is no such information about screw driving torques in plywood (PW). Therefore, this study focused on the plywood made of aspen (Populus tremula L.). The mean seating torque (SET) values ranged from 0.31 to 0.69 N∙m, whereas mean stripping torque (STT) values ranged from 0.50 to 4.7 N∙m. The ratios of STT/SET were between 2 and 5 in PW with seven layers, whereas the ratios were between 4 and 7 in PW with nine layers. The results indicated that the four main effects of SET and STT were statistically significant with p-values of ˂ 0.0001.

Properties of Oriented Strandboard Produced Using Phenol-Formaldehyde Resin Synthesized with Bio-Oil of Lignocellulosic Wastes

The main objective of the present study was to modify phenol-formaldehyde (PF) resin by using bio-oil obtained by pyrolysis with and without alkali catalyst (potassium carbonate: K2CO3) (10 to 50 weight %) and determine technological properties oriented strandboard (OSB) panels produced using the modified PF resin formulations. The pine sawdust was used as a raw material of bio-oil. The chemical characterization of bio-oils was determined by GC-MS analysis. The OSB panels were produced with the bio-based PF resins and then their technological properties were determined. As the amount of potassium carbonate catalyst increased up to 20 wt% in the PF resin, 24-h thickness swelling of OSB panels decreased from 15.4 to 14.3%, but further increment in the potassium carbonate catalyst content increased the thickness swelling (22.8%). The IB strength of the OSB specimens with PF resin with 10 wt% bio-oil produced with catalyst or pyrolysis process was found the same (2.18 N/mm2) and it was higher than the reference value (1.97 N/mm2). As the amount of bio-oil was increased to 20 wt%, the difference in the IB values between treated OSB and reference OSB was negligible. However, above the 20 wt% bio oil, it was observed a decreasing trend in the IB values. The bending strength and bending modulus of the OSB specimens containing 20 wt% bio-oil were also found to be higher than those of the reference OSB specimens. It was concluded that the PF resin synthesized using bio-oil of (20 wt%) produced with and without alkali catalyst could be successfully used in the production of the OSB.

Analysis of properties of boards for concrete formwork

The paper summarizes results of the analysis of properties of large-area materials usable for the manufacture of concrete formwork and available on our market. The materials were compared from the viewpoint of physical and mechanical properties including economic evaluations. Materials were assessed manufactured by DOKA company dealing with the production of shuttering systems, viz. Doka 3-SO, Dokadur and Dokaplex. The materials were compared with following boards available on our market: bioboard Agrop, water-resistant (exterior) surface-treated plywood and oriented strandboard (OSB). Results of the paper consist in the comparison of cost/physical-mechanical properties.

A Probabilistic Approach to the Simulation of Non-Linear Stress-Strain Relationships for Oriented Strandboard Subject to In-Plane Tension

This paper presents the results from an experimental test program conducted on commercially available oriented strandboard (OSB) panels and statistical analyses of the results. Standardised testing was used to determine the short-term behaviour of OSB/3 panels subjected to tension loading. A variety of thicknesses sourced from three different producers were used. Analysis of the results indicate that a quadratic expression in the form of  = a2 + b provides the best description of the relationship between stress (and strain ( up to the point of failure. It has also been shown that the coefficients a and b of the quadratic regression equations are negatively correlated to each other. Anderson-Darling goodness-of-fit tests were conducted on the results for tension strength and modulus of elasticity (MOE). The results indicate that the tension strength and MOE come from populations that follow either normal or lognormal probability distributions.

Dimensional stability performance of fire retardant treated veneer-oriented strandboard composites

This study investigated dimensional stability properties of oriented strandboard (OSB) panels faced with fire retardant treated (FRT) veneers. The beech (Fagus orientalis Lipsky) veneers were treated with monoammonium phosphate (MAP), diammonium phosphate (DAP), lime water (LW), and a borax/boric acid (BX/BA) (1:1) mixture. Dimensional stability tests were performed according to ASTM D-1037. The results revealed that facing veneers impregnated with fire-retardant chemicals had significant effects on the linear expansion (LE) properties. The lowest LE value was obtained from the panels faced with MAP treated veneers, while the highest LE value was found in the panels faced with BX/BA treated veneers. The FRT treated veneer facing technique also affected the thickness swelling (TS) properties of the OSB panels. The panels faced with LW treated veneers had the highest TS, whereas the panels faced with MAP treated veneers had the lowest TS values.