Experimental Analysis of Bonding in Steel Glued into Pine Timber.

Combining steel with wood has been practised for many years. The issue is related to two main areas, i.e., bonding steel elements with wood so that they serve as connectors facilitating the assembly of wood elements and bonding steel elements to wood beams to improve their load-bearing capacity. In the first case, the adhesives used may be relatively expensive and more difficult to apply, whereas in the second one, especially when steel elements are glued inside the glulam (GL) beams, it is better if the adhesives used are more accessible to apply and cheaper. As it seems rational to reinforce wood with high-modulus ties, research has been carried out to compare the connection quality of commercially available adhesives that can be used for this purpose. Moreover, thermosetting adhesives have been applied as an alternative and cheaper solution. Thermostat adhesives also have a high pH of the bond, which prevents the steel from rusting. The research shows that the load-bearing capacity of the bond depends on whether the bars are ribbed or sheet metal. Moreover, among thermosetting adhesives, the most favourable load-bearing values were obtained using a mixture of PF/pMDI (phenol formaldehyde resin/polymeric diphenylmethane diisocyanate) and powder from recycled tyres. The shear strength of these joints was 1.63 N/mm2 and 3.14 N/mm2 for flat specimens and specimens with ribbed bars, respectively.

Possibility of Using Wind Turbine Waste in Particleboard Manufacturing.

Recent reports indicate that the development of electricity generation using wind turbines will continue to grow. Despite the long service life of wind turbine blades, their technological life comes to an end at a certain point. Currently, there is no industrial method for recycling them, and the proposed solutions need to consider a complete and comprehensive approach to this material. In many countries, these blades are stored in special landfills and await proposals for rational recycling. It has been proposed that this recyclable yet still troublesome raw material be used in building sheathing boards. Sheathing boards used in the construction industry have a relatively long lifecycle. Three types of polymer chips and two resins, i.e., PF and MUF, were used in the study. The boards' quality was assessed per the standards specified for particle boards. The resulting boards were characterized by strengths above 20 N/mm2 and an elastic modulus close to 4000 N/mm2. Slightly better results were obtained with the MUF resin.

Influence of the Structure of Lattice Beams on Their Strength Properties.

This paper presents the strength properties of wooden trusses. The proposed solutions may constitute an alternative to currently produced trusses, in cases when posts and cross braces are joined with flanges using punched metal plate fasteners. Glued carpentry joints, although requiring a more complicated manufacturing process, on the one hand promote a more rational utilisation of available structural timber resources, while on the other hand they restrict the use of metal fasteners. The results of the conducted analyses show that the proposed solutions at the current stage of research are characterised by an approx. 30% lower static bending strength compared to trusses manufactured using punched metal plate fasteners. However, these solutions make it possible to produce trusses with load-bearing capacities comparable to that of structural timber of grade C24 and stiffness slightly higher than that of lattice beams manufactured using punched metal plate fasteners. The strength of wooden trusses manufactured in the laboratory ranged from nearly 20 N/mm2 to over 32 N/mm2. Thus, satisfactory primary values for further work were obtained.

The Usefulness of Pine Timber (Pinus sylvestris L.) for the Production of Structural Elements. Part II: Strength Properties of Glued Laminated Timber.

The paper assessed the feasibility of manufacturing glued structural elements made of pine wood after grading it mechanically in a horizontal arrangement. It was assumed that the pine wood was not free of defects and that the outer lamellas would also be visually inspected. This would result in only rejecting items with large, rotten knots. Beams of the assumed grades GL32c, GL28c and GL24c were made of the examined pine wood. Our study indicated that the expected modulus of elasticity in bending was largely maintained by the designed beam models but that their strength was connected with the quality of the respective lamellas, rather than with their modulus of elasticity. On average, the bending strength of the beams was 44.6 MPa. The cause of their destruction was the individual technical quality of a given item of timber, which was loosely related to its modulus of elasticity, assessed in a bending test. Although the modulus of elasticity of the manufactured beam types differed quite significantly (11.45-14.08 kN/mm2), the bending strength for all types was similar. Significant differences occurred only during a more detailed analysis because lower classes were characterized by a greater variation of the bending strength. In this case, beams with a strength of 24 MPa to 50 MPa appeared.

The Usefulness of Pine Timber (Pinus sylvestris L.) for the Production of Structural Elements. Part I: Evaluation of the Quality of the Pine Timber in the Bending Test.

The study assessed the quality of pine lumber by marking the modulus of elasticity in the horizontal system. The research material was a plank with the following dimensions: 137 mm wide × 39.50 mm thick × 3485 mm long. The pine wood was obtained by sawing timber in the form of logs with round cross sections and originating from the Forest Division Olesno (50°52'30″ N, 18°25'00″ E). Each long log was sawn to provide four logs of about 3.5 m, which were marked as butt-end logs (O), middle logs (S)-2 items, and top logs (W). The origin of the logs from the trunk (Pinus sylvestris L.) has a significant impact on the physical and mechanical properties of the wood from which they are made. Only butt-end logs (log type O) allows for the production of high-quality timber elements. The pine timber that was evaluated in this paper had a high density of about 570 kg/m3 and a high percentage of timber items were assigned to class C24 and higher (above 50%). The adopted horizontal model of evaluation of the modulus of elasticity gave similar results to those obtained in an evaluation according to the EN-408.