Untreated Timber Research Articles

Bark beetle-associated fungi in Fennoscandia with special emphasis on species of Ophiostoma and Grosmannia

Global trade in untreated timber and wood products raises the risk of accidentally introducing forest pests and pathogens into new environments. Bark beetles (Coleoptera: Scolytinae) include several species that are regarded as forest pests. These insects are known to live in close association with fungi, especially species of ophiostomatoid fungi (Ascomycota). Several of these fungi are agents of blue stain in timber, and some are serious plant pathogens. However, only little is known regarding the fungal associates of bark beetles, or the interactions between the fungus, the bark beetle and the host tree in the boreal forests of Fennoscandia. The aim of this study was to increase the knowledge regarding bark beetle-associated fungi in Fennoscandia, with special emphasis on the genera Ophiostoma Syd. & P. Syd. and Grosmannia Goid. Fungi associated with 13 different bark beetle species, infesting Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and birches (Betula L. spp.) in the eastern parts of Finland and neighboring Russia, as well as southern Norway, were isolated and identified. The fungal identifications were based on morphological characteristics and DNA sequence comparisons. The survey revealed the occurrence of at least 29 species of Ophiostoma and Grosmannia. All the bark beetle species considered in this study were frequently associated with a complex of ophiostomatoid fungi. Several species were recorded for the first time in the countries in the study. A surprisingly high number of previously undescribed fungal species were discovered. During the survey, eight of these species were described as new taxa. In addition, the study revealed new insect-fungus relationships. The number of taxa encountered, covering a relatively small geographical area, indicates that there are many more ophiostomatoid fungi occurring in the boreal forests of Fennoscandia than has previously been recognized. The study emphasizes the importance of developing a clear understanding of the possible threats of moving timber and wood products without knowledge of the micro-organisms that might also be moved.

Service Life Design for Timber Piles Attacked by Marine Borers

This paper presents a proposed procedure for the design of timber piles or posts used in marine structures subjected to marine borer attack. It is assumed that the most severe borer attack, regardless of borer species, can be represented by a narrow front along the perimeter of the timber pile cross-section within the tidal zone. The parameters chosen for engineering design relate to timber properties, environment parameters and structural configurations. For practical purposes, untreated timber species are grouped into four marine durability classes, and treated timber sapwood is classified according to the preservative retention. The environment effects are considered in terms of seven coastal zones and three salinity classes of seawater. Using the proposed procedure, the design attack depth and hence the loss of cross-section can be computed, from which the load capacity can be evaluated for a design service life.

Evaluation of the potential of applying composting/bioremediation techniques to wastes generated within the construction industry

The objective of the present study was to evaluate the viability of reducing landfill requirements to satisfy EC Landfill Directive requirements by applying composting/bioremediation techniques to the construction and demolition (C&D) industry waste stream at laboratory scale. The experimental study was carried out in nine test rigs to examine different wood mixtures; untreated timber, creosote treated timber and chromated copper arsenate (CCA) treated timber. Several experimental variables affecting the process were characterised and optimised. These include the best nitrogen additive and optimum moisture content required for composting. Poultry manure was found to be the best nitrogen additive. The optimum moisture content was decreased after the addition of poultry manure. The composting/bioremediation process was evaluated through monitoring the microbial activity, carbon dioxide emissions and toxicity examination of the composted product. A typical temperature profile suggested that untreated and CCA treated mix could be classified as hot composting whereas creosote treated mix could be classified as cold composting. The paper reports on the results obtained during this investigation.

Biegekriechverhalten von modifiziertem Holz

The present study is a supplement to Epmeier and Kliger (2005), which investigated the effect of three different modification methods (acetylation, modification with methylated melamine resin and heat treatment in vegetable oil) on four material properties (density, modulus of elasticity (MOE), creep deflection and relative creep) and their inter-relations. In this study, another modification method (furfurylation) and four additional material parameters (“relative stiffness”, i.e. MOE/density, moisture content, change in moisture content and anti-creep efficiency) and their correlations are included. In addition, the creep curves were analysed to assess the development of bending creep performance. The properties were assessed by experimental work on 132 specimens of Scots pine sapwood with dimensions of 45×70×1100 mm3. It was found that modification leads to significant changes in material properties. Furfurylation increases density and reduces creep deflection, relative creep and moisture content. Modified timber tends to deflect and creep significantly less than untreated timber. However, the extent of reduction in relative creep appears not to be related to the extent of reduction in creep deflection. Initial deflection and/or modulus of elasticity are suitable for predicting the creep deflection of untreated and modified timber.

The effectiveness of silica treatments against wood-boring invertebrates

Abstract Timber specimens were impregnated with the organo-silicate tetraethyl orthosilicate (TEOS) in an effort to deposit hard silica granules and improve resistance to wood-borers. Trials were conducted against marine borers (teredinids and Limnoria), the termite Coptotermes acinaciformis, and the wood-boring beetle Lyctus brunneus. A 14-week laboratory bioassay against C. acinaciformis showed that treated Pinus radiata containing 16.7 wt.% silica was as readily attacked as untreated timber. However, a 3-year laboratory trial of treated Castanospermum australe showed that attack by L. brunneus was prevented by 10.3 wt.% silica, and reduced by 0.7 and 3.4 wt.% silica. A trial of wood treated with copper-chromium-arsenic followed by silicon was conducted in the sea at Townsville, Australia for 7 years. Double treatment with 6.7 or 19.2 wt.% silica prevented attack in P. radiata by teredinids, while for CCA alone some replicates failed. In the same trial, double-treated Corymbia maculata with lower silica retention failed. Silica granules may overwhelm the food and waste-sorting mechanisms in teredinids and lyctine larvae, whereas borers, requiring less intimate contact with granules (Limnoria and termites), or those that do not ingest wood for food (Sphaeroma and Martesia), are little affected.

Probabilistic procedure for design of untreated timber poles in-ground under attack of decay fungi

Based on first-order probability theory, this paper presents a probabilistic procedure for design of timber poles in ground contact under attack of decay fungi. Fungal attack prediction model developed in a multi-disciplinary national project in Australia, sponsored by the Forestry and Wood Products Research and Development Corporation, is used in this study for decay progress modelling. A durability design factor, k D, is derived and proposed for consideration in practical design of timber construction. Examples for computation of k D for untreated timber poles installed at two sites in Australia are given.

Probabilistic procedure for design of untreated timber piles under marine borer attack

This paper presents a probabilistic design procedure for untreated timber piles under attack of marine borers, in which a new probabilistic-based durability factor is derived and introduced into the current Australian engineering design procedure. In evaluating this durability factor, a prediction model of marine borer attack on timber piles, which was developed in a national project in Australia is used for modeling the attack progress. Examples of the durability factor computed for untreated timber piles with different diameters or located at different coastal zones are provided.

Surface finishes by mechanically induced wood surface fusion

Mechanically induced vibration wood fusion welding techniques can also be used to obtain wood surface finishes of increased surface hardness and performance in presence of polymerizing unsaturated oils such as sunflower oil, or other polymerizing finishes. Wood surface hardness values more than double than those for the untreated control timber can be obtained by this method. This result is obtained due to two effects induced by the sharp increase in temperature induced by the mechanical welding vibration (i) the polymerization to a hardened network of the unsaturated oil and (ii) the densification proven to occur in the surface layer of the timber during mechanically-induced vibration-welding. The first of these effects predominates at shorter welding times while at slightly longer welding times both effects occur with the second one progressively becoming the bigger contributor. In the latter case the some μm thin densified surface is a surface composite formed by the networked unsaturated oil permeating the wood fibre/fused lignin composite.

Increased PCDD/F formation in the bottom ash from fires of CCA-treated wood

Bottom ash that was the result of the combustion of chromated copper arsenate (CCA) treated wood under controlled fire conditions showed an increase of several orders of magnitude in the levels of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs), compared to that of untreated timber. Wood that has been pressure treated with CCA contains copper (II), which is known to catalyse the so-called de novo formation of PCDD/Fs. Comparable levels of PCDD/Fs would be expected in residual ash from burning CCA-treated wood in backyard fires, stoves and wood heaters, as a consequence of similar combustion conditions.

Using Simulation to Evaluate Rail Sleeper Replacement Alternatives

A simulation model developed to enable a cost-benefit analysis of sleeper-replacement strategies, using the Weibull distribution, has been updated from a previous version to include up to four different types of sleepers within the track section: steel, concrete, treated timber, and untreated timber. In addition, several changes have greatly increased the number of strategies that can be simulated. The creation of a replacement strategy has been substantially developed to include two separate components, many new frequency and policy options, and the option of continuing a completed simulation with a modified replacement strategy. The model output is designed to give adequate information to the operator to determine the best course of action to take when comparing various possible replacement strategies. The results include the track condition, with the clusters of failed sleepers, and the cost of the replacement strategy. Five distinctly different replacement strategies were simulated for 20 years on a track section with 50,000 mature sleepers. These simulations showed that the nature of the strategy can have very significant effects on the cash flow required from year to year and on the annual demand for replacement materials. Careful investigation is needed to establish compromise strategies that produce acceptable numbers and sizes of clusters of failed sleepers and sleeper life in track while not exceeding available funding and materials.

Effects of Chromated Copper Arsenate (CCA) Wood Preservative on Early Fouling Community Formation

The effects of the anti-marine-borer timber preservative CCA (a pressure impregnated solution of copper, chromium and arsenic compounds) on early fouling community formation were investigated during a number of field trials. The formation of a biofilm on the surface of CCA-treated and untreated timber panels of Scots pine was examined by scanning electron microscopy following submersion in Langstone Harbour, Portsmouth, UK for periods of 2, 7, 14 and 28 days. Results indicated a slightly faster rate of biofilm formation after 2 and 7 days of exposure on untreated timber compared to CCA-treated timber, although no differences were visible between panels after 14 and 28 days exposure, or between panels treated to different CCA loadings after all exposure periods. Settlement of the serpulid Ficopomatus enigmaticus and two species of barnacles ( Elminius modestus and Balanus crenatus) onto the surface of untreated and CCA-treated panels of Scots pine was examined following 4 weeks exposure in a brackish water millpond at Emsworth, West Sussex. Numbers of individuals were higher on CCA-treated panels than on untreated panels, and in the case of F. enigmaticus abundance of individuals increased with increasing preservative loadings. Early colonization by macroalgal species on the surface of CCA-treated and untreated panels of Scots pine was examined following submersion of panels in Langstone Harbour for a period of 4 weeks. Percentage cover of most species of algae was similar on the surface of CCA-treated and untreated panels, with the exception of Hincksia granulosa and Ceramium nodulosum which had significantly higher percentage cover on untreated panels. Possible explanations for the recruitment patterns are discussed.

Assessment of 100-Year-Old Foundation System to Meet Current Retrofit Load Demands

Results are presented of a geotechnical investigation and foundation analysis as a component of the seismic retrofit to the Amtrak King Street Station in Seattle, Washington. The purpose of this effort was to assess the condition of the existing pile foundation, to quantify the foundation response to revised seismic loads, and to provide recommendations for retrofitting of the foundation. King Street Station is a one- to three-story brick masonry structure with a 12-story clock tower. The building was constructed in 1906 in the area of a reclaimed tide flat. The foundation for the structure consists of timber piles; however, no information was available on the length of the piles or whether they were treated with a preservative. The approximate length of the piles was established at 9.7 m using ground-penetrating radar. A core sample obtained from one of the timber piles showed them to be untreated timber and in good condition. The subsurface investigation revealed a liquefiable granular fill soil in the upper 6 m underlain by medium-dense marine sands overlying dense glacial soils. An engineering analysis of the expected performance of the piles during the design seismic event showed that the piles could settle approximately 100 to 355 mm because of liquefaction of the marine sand layer and that the deflection of the piles under lateral loading was substantially in excess of the static loads. Steel pipe minipiles were recommended as a mitigation measure.

Natural finishes for exterior timber

Untreated timber exposed to the weather will discolour and degrade under the influence of physical and biological agencies. If the natural appearance of exposed timber is to be preserved, it is necessary to apply some form of surface treatment. This digest discusses the selection, use and maintenance of exterior wood stains, varnishes and other types of external natural finish. Before considering the different types of natural finish in detail, it first deals with the characteristics of the wood substrate that have a significant influence on their performance. The digest brings up to date the information contained in an earlier (now withdrawn) digest, No. 182.

Iglesia de San Francisco, en Hüttwilen, Suiza

This church is beautifully integrated in the landscape, including the villalle which has retained its old time style. The building has room for 200 worshippers on the higher level, and below there are facilities for meetings, classrooms, a sacristy, coatroom, services, etc. The spectator is attracted by the shape of the tower and the roof. Fibrocement has been used as roofing material, and also as surfacing for some of the outer walls. Untreated concrete, timber and subtle illumination have contributed to create a suitable atmosphere for meditation inside the church.

Transformation of Copper Salt by Wood Decaying Fungi

When effective preservation tests are performed using wood specimens to which Coriolellus palustris, one of the oxalic acid producing fungi, is cultured, it has often been found that decay is limited to a particular portion where tissue is completely destroyed to make a hole, in the case of the specimen treated with preservatives containing copper salt. Under the microscopic observation of the decayed wood tissue light green colored, minutely crystalized substance is observed. Copper concentration is apt to be high around the hole. Accordingly, oxalic acid which is metabolized by the fungi is assumed to react on copper salts to form copper oxalate, and it is pressumed that there is a certain relation between the partially serious decay phenomenon and copper oxalate accumulation by fungi. In order to test these hypotheses a fundamental experiment was carried out by culturing the fungi in solution, agar and filter paper each of which contained copper salt with various concentration. Light green colored precipitate was obtained from the former two, and the surface of the filter paper was colored light blue. The substance precipitated by the fungi was identified to be copper oxalate by means of infrared absorption and X-ray diffraction methods. The surface of the filter paper colored light green was found to be remarkably rich in copper concentration by fluorescent X-ray analysis. It was found also that whereas the fungi cultured in water without any copper salt ingredient grew dispersed in the whole expanse of water, those in a solution containing copper salt grew concentrated like a concentric circle. The higher the concentration, the more distinct the denser, the smaller was the colony. It is noticed that untreated timber decays altogether shrunk. It is assumed that this is similar to the growth of fungi in water without copper salt ingredient. Timber treated with copper salt dacays partially but seriously. It appears that this is similar to the growth of fungi in copper salt solution.So it is only assumed, and so it only appears. It requires further studies to account for the decay of timber treated with copper salts.