Potencial tecnológico da madeira de Quercus faginea Lam. para revestimento de superficies

O carvalho-português (Quercus faginea Lam.) é uma espécie autóctone, cuja madeira actualmente não é utilizada e sobre a qual pouco se sabe. No entanto, dado que a sua madeira foi outrora utilizada na construção de naus e de caravelas, é de crer que tenha um potencial elevado para a produção de produtos nobres, como é o caso dos pavimentos. Com o objectivo de averiguar o potencial tecnológico da madeira de Carvalho português para revestimento de superfícies, foi realizada a caracterização das suas propriedades físico-mecânicas e avaliada a sua durabilidade natural face a térmitas subterrâneas, utilizando metodologias normalizadas. Foram utilizadas dez árvores provenientes de duas regiões de Trás-os-Montes. Os resultados mostraram que a madeira de Q. faginea é de dureza muito alta para o cerne (101 N/mm2) e possui resistência fraca quanto à tensão de ruptura à flexão estática (99 N/mm2) e média quanto à compressão (47 N/mm2) para uma massa volúmica média de 870 kg/m3. De modo a avaliar o comportamento em produtos compósitos, produziram-se também 20 peças com duas espessuras de madeira de Carvalho, coladas a madeira de Espruce (Picea abies H. Karsten), que foram submetidas a uma carga estática de 1kN. Os resultados demonstram que a dureza do pavimento diminui com a redução da espessura da lâmina de carvalho

Origins of the Sustainability Concept and Its Application to the Construction Sector in the EU

Sustainability aims to integrate environmental and social considerations into decision-making, alongside purely economic factors, in a balanced manner. Here, a concise critical review of policy instruments concerning the definition and implementation of this concept is presented. The sources were selected as the most relevant to capturing the origins and evolution of the idea of sustainability from the 1960s to the present day. The analysis narrows down to the construction sector within the European Union (EU), of which the perspective guides the work. As it emerges, the historical path led to the materialization of the sustainability concept into the UN’s 17 Sustainable Development Goals (SDGs). Despite interpretative discussions around the concept, these SDGs became the relevant sustainability model for sectors like construction. Its application to practice, however, faces three major challenges that must be acknowledged and addressed to allow defining robust and genuinely sustainable decision-making strategies: greenwashing, commodification, and “cherry picking”

Feasibility of creosote treatment for glued-laminated pine-timber railway sleepers

This article studies the possibility of using market available glued-laminated timber (GLT) based on melamine-urea-formaldehyde (MUF) adhesives as an alternative to traditional solid timber sleepers. The study comprised an examination of the effect of creosote treatment on the short-term and durability after accelerated aging of the glue lines (delamination and shear strength) and the potential for full sapwood penetration by the creosote. Creosote treatment showed a negative effect on shear strength and delamination, more severe in the nonstructural than the structural GLT specimens tested. Full penetration of creosote into the sapwood was not achieved. GLT elements based on MUF adhesives can be considered an alternative to solid wood sleepers if specific grading of lamellas, proper treatment schedule, and highly controlled factory production are implemented

A semi-destructive assessment method to estimate the residual strength of maritime pine structural elements degraded by anobiids

In this article, an assessment method to estimate the residual strength of pine structural elements degraded by anobiids is presented. This novel method was developed in the laboratory to be used in situ and is based on the strength required to withdraw a screw on the surface of degraded timber. Samples of degraded maritime pine (Pinus pinaster Ait.) were submitted to micro-computed tomography (μ-XCT) to quantify density loss. This parameter is highly correlated with mechanical properties thus central for the assessment of timber structural capacity. Density loss values have been correlated with both screw withdrawal force and shear parallel to the grain strength showing significant relationships between these parameters. Using these correlations, the density loss of a degraded element and its shear strength parallel to the grain via the screw withdrawal force can be estimated enabling a valid quantitative assessment of the timber elements residual strength and, therefore, contributing to reduce unnecessary replacement, to boost eco-efficient interventions and to provide foundations required to perform experimental modelling tests.authorsversionpublishe

Reuse of wooden utility poles through the combination of new and old elements

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