Search

The impregnability of Portuguese maritime pine (Pinus pinaster Ait.) subjected to microwave (MW) drying was tested, and the hydrophobicity, anti-swelling efficiency (ASE), and water repellence efficiency (WRE) were evaluated. Small wood heartwood samples of Portuguese maritime pine and two distinct MW treatment settings were employed. The levels of ASE and WRE of the wood elements were evaluated throughout four cycles of drying in an oven and soaking in water. Because of MW applied energy, the wood pine samples were satisfactorily impregnated with the preservative product. Regarding the absolutely dry densities of the samples, very subtle reductions were measured, and they were statistically equivalent to the average density of the non-MW-treated group. Slight improvements were identified in the WRE values of wood samples dried in the microwave. In terms of ASE, both MW-treated groups had a statistically significant increase. The MW treatment decreased the volumetric swelling of the maritime pine wood specimens. Hence, this study raises new insights and previously unexplored paths that can contribute to the expansion and greater application of MW technology in maritime pine and other species. [ABSTRACT FROM AUTHOR]

The impregnability of Portuguese maritime pine (Pinus pinaster Ait.) subjected to microwave (MW) drying was tested, and the hydrophobicity, anti-swelling efficiency (ASE), and water repellence efficiency (WRE) were evaluated. Small wood heartwood samples of Portuguese maritime pine and two distinct MW treatment settings were employed. The levels of ASE and WRE of the wood elements were evaluated throughout four cycles of drying in an oven and soaking in water. Because of MW applied energy, the wood pine samples were satisfactorily impregnated with the preservative product. Regarding the absolutely dry densities of the samples, very subtle reductions were measured, and they were statistically equivalent to the average density of the non-MW-treated group. Slight improvements were identified in the WRE values of wood samples dried in the microwave. In terms of ASE, both MW-treated groups had a statistically significant increase. The MW treatment decreased the volumetric swelling of the maritime pine wood specimens. Hence, this study raises new insights and previously unexplored paths that can contribute to the expansion and greater application of MW technology in maritime pine and other species.

Wooden utility poles are crucial in supporting overhead telecommunication lines in Portugal. Maritime pine (Pinus pinaster Aiton) is the most common wood species used for this purpose. The durability of the poles is typically determined by the deterioration observed in their ground line. Aiming to reduce the use of new sound wooden poles, reducing the economic costs involved, and the environmental impacts, the reuse of those old wooden poles by removing the degraded part is one possible solution. This study aimed to develop and validate solutions with composed poles, specifically for the connections between the wood members, so that it is possible to more efficiently incorporate used parts into the remanufactured poles. Two types of connections were used: members joined by a cylindrical steel tube, and members joined by finger joints. The static bending moduli of elastic and rupture were tested. The mechanical properties of the reused wooden utility poles showed to be in line with the values of new sound wooden poles made of different wood species. Finally, both proposed solutions proved to be practical for use in the production of reused utility poles, which are mostly made from old timber poles.

The application of non-destructive technologies for the assessment of mechanical properties has been increasingly used due to its reliable assessment of the condition of timber elements. The application of such methods is well established for sawn timber and small-diameter roundwood. However, regarding the assessment of the mechanical properties for roundwood with larger diameters, which are usually used for new utility poles, a fewer number of studies are available. This research considered three different methodologies for application in Maritime Pine utility poles: i) longitudinal vibration, ii) transverse vibration, and iii) ultrasound. The methodology with better results was chosen for use in the second stage of testing. Furthermore, mechanical tests were performed to compare and validate the results from the non-destructive tests. The moisture contents and densities were also determined. Simple and multiple linear regression analyses were performed between the visual, dynamic, and mechanical properties. The longitudinal vibration method achieved the best correlation within the non-destructive methods, while the ultrasound method had no noticeable correlation. The vibration frequency (f) (r = 0.51) showed a better correlation with the bending strength (MOR) than the dynamic modulus of elasticity (MOEdyn) (r = 0.45). The static modulus of elasticity (MOE) was the best property used to predict MOR because it presented the highest correlation (r = 0.79).

There has been a strong recent effort to develop procedures that prevent the unnecessary replacement of timber utility poles. Even when assessments show that the utility pole needs to be replaced, there are many cases in which the removed utility poles can be reused. The aim of this study was to determine the mechanical properties of Maritime Pine (Pinus pinaster (Ait.)) utility poles removed from service (UPRFS) in order to assess their ability to be reused in structural applications. A sample of 51 UPRFS in Portugal was selected, and visual and mechanical properties were evaluated through non-destructive and destructive tests. Dynamic modulus of elasticity (MOEdyn) was correlated with bending strength (MOR) (r = 0.43) and modulus of elasticity (MOE) (r = 0.71). UPRFS showed a decrease of 14% and 6% in the mean values of MOR and MOE, respectively, when compared with new utility poles. A high variability and low values were obtained for MOR. These results highlight the reuse potential of the maritime pine utility poles for structural applications. Furthermore, the determined properties of UPRFS could be improved with a more stringent selection process that discards utility poles showing severe damage or by removing damaged areas in the utility poles.

The application of non-destructive technologies for the assessment of mechanical properties has been increasingly used due to its reliable assessment of the condition of timber elements. The application of such methods is well established for sawn timber and small-diameter roundwood. However, regarding the assessment of the mechanical properties for roundwood with larger diameters, which are usually used for new utility poles, a fewer number of studies are available. This research considered three different methodologies for application in Maritime Pine utility poles: i) longitudinal vibration, ii) transverse vibration, and iii) ultrasound. The methodology with better results was chosen for use in the second stage of testing. Furthermore, mechanical tests were performed to compare and validate the results from the non-destructive tests. The moisture contents and densities were also determined. Simple and multiple linear regression analyses were performed between the visual, dynamic, and mechanical properties. The longitudinal vibration method achieved the best correlation within the non-destructive methods, while the ultrasound method had no noticeable correlation. The vibration frequency (f) (r = 0.51) showed a better correlation with the bending strength (MOR) than the dynamic modulus of elasticity (MOEdyn) (r = 0.45). The static modulus of elasticity (MOE) was the best property used to predict MOR because it presented the highest correlation (r = 0.79). [ABSTRACT FROM AUTHOR]