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Commissioned Reports - Wood Modification and Re-engineering


Date: 2008
Title: Maximising the potential of UK grown Scots pine falling boards.
Authors: Report commissioned from BRE
Full Report: PDF

Summary
The main objective of the project was to improve the utilisation of UK Scots pine falling boards (boards cut from the outer edge of the log) by using the process of re-engineering. At the present time, falling boards are used mainly in ‘lower value markets’ such as the pallet and fencing market. Although, there is clear evidence to demonstrate that engineered wood products can be successfully manufactured using pine falling boards and could form the feed stock for a new generation of engineered products to meet specific performance requirements. The project aim was to produce two laminated products with the capability of penetrating higher value markets. A batch of each selected product was manufactured and assessed for strength and stiffness and the recorded values compared to structural grade values in the relevant standards.


Date: 2007
Title: Review of existing bioresins and their applications.
Authors: Report commissioned from BRE
Full Report: PDF

Summary
A critical appraisal of the current potential for bioresins in the UK and how they might contribute to an enhanced sustainability profile for future re-engineered wood products made from UK timber. A new adhesive system in which all or part of the phenolic component is replaced by a bioresin is an attractive and real opportunity for the forest products industry. The need is to deliver this environmentally improved system without sacrificing high durability or ease of bonding. The movement away from synthetic resins made from petrochemicals, particularly in North America is happening and it is predicted for the UK that in 5 to 10 years the impact will be registering in UK markets and home production and manufacture will have commenced.

The work within this project will continue to appraise the status of bio resins worldwide and the drivers and barriers dictating commercial growth, their fitness for purpose and viability for use in re-engineered wood products.


Date: 2006
Title: Scoping study – Bio-resins (231932)
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version

Summary
DEFRA has been extremely supportive in developing new polymer resins to create fully bio-based composites. Considerable advances have been made over the past 5 years. A range of adhesives have been derived from natural oils such as Cashew Nut Shell Liquid (CNSL) and vegetable oils (rapeseed, soybean, sunflower). The cost was a significant barrier to the development of renewable materials, however, the production has become viable as technologies evolve, and economies of scale come on stream, along with price inflation of petroleum and increasing awareness relating to end of life disposal. Bio-resins provide a natural alternative to traditional petrochemical derived materials such as phenol-formaldehyde and isocyanate resins in the manufacture of composite products. Many of the synthetic resins are coming under increasing restrictions due to tightening environmental exposure regulations. The industry risks losing key familiar resins in the future; hence the need to critically assess the opportunity for bio-resins.

The development of a bio-resin system for replacement of synthetic resin become important for the present and future ‘green’ credibility of re-engineered wood products. No study has been carried out using bio-resin for re-engineering wood products except wood based composites.

This project aims to provide the platform upon which Forestry Commission can evaluate support for emerging bio-resins and their application in timber re-engineering industry in UK. The study will consist of an appraisal of the status of bio-resins worldwide and the drivers and barriers dictating commercial growth, their fitness for purpose and viability for the timber re-engineering products, industry and recognised experts in the field. The findings of the study shall then be developed into a series of recommendations and proposals, comprising a strategy for the further development of bio-resins in re-engineered UK timber products.


Date: 2005
Title: Technical evaluation of defect cutting to improve the timber strength and its effect upon mechanical (222188)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This project has demonstrated the potential of defect cutting and finger jointing of structural timber to significantly improve the yield of the C24 strength class over that which can normally be expected to be achieved for timbers such as Douglas fir and Sitka spruce.

For Douglas fir there is potential to increase the yields for the strength classes C27, C30 and C35 over that which can normally be achieved. This would make the us of UK grown Douglas fir more acceptable for end uses such as glulam, which, utilises the higher strength classes in its manufacture.

Unfortunately, there seems little potential to increase the range of the strength classes that Sitka spruce can be attributed to, as beyond the C24 strength class both stiffness and density become an issues with the ultimate limiting factor being density. In fact density was the limiting factor for all the higher strength classes regardless of species.


Date: 2005
Title: Evaluation of the potential to machine grade re-engineered UK grown softwood (222187)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This project has clearly shown that strength grading machine settings for the current BS 5268 strength classes and the proposed grading machine settings for EN 338 strength classes, both for use on solid timber; do not effectively grade reengineered laminated timber.

The results obtained for the strength classes C16 and C24 were in the main indistinguishable from each other, which is a clear indication that the settings are inappropriate for the nature of the reengineered timber. The main problem is believed to be a separation of the measured strength, which is increased by the laminating process, and the stiffness of the original material that is not significantly changed by the laminating process. As the machine settings are based on this relationship for solid timber the separation of the two parameters results in a total inability for the machine settings to correctly identify the strength classes.
It is believed that the future of timber may well lie in the development of such reengineered products and that machine grading in one of the best ways of making such products accessible the market place. Therefore, to go forward with future work will need a greater drive from the UK sawmilling industry to identify products and take ownership of designs agreed within the industry on which a data base can be constructed for the derivation of suitable strength grading machine settings.

It should be stressed that the results in this report are for bending type machines and there is the possibility that strength grading machines that do not have a bending component as the indicating parameter may return more favourable result with laminated timber. However, strength grading machines that rely on density as a major component of the machine indicating parameter may be affected in a similar manner to bending type machines as the relationship between measured strength and density will be affected in a similar manner to the relationship for measured strength to stiffness.


Date: 2005
Title: Maximising the potential of Scots pine falling boards (225822)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
In a recently completed study by BRE on the quality of Scots pine from the Grampian and Cairngorm regions of Scotland it was identified that the inherent qualities of the material being processed at the present time shows great potential for penetrating higher value markets. There is evidence to demonstrate that engineered wood products can be successfully manufactured from falling boards (boards cut from the outer edge of the log).  These products have been found to have enhanced strength characteristics over the basic properties of the starting material, and the present market for falling boards realise very low returns.
 
This project demonstrates the potential of Scots pine and discusses the most appropriate ways of introducing the selected products to the market place.  As a low value material, falling boards have the potential to produce value added components which could form the feed stock for a new generation of engineered products to meet specific performance requirements.

It is believed that due to the superior basic structural properties of Scots pine, there is far greater potential of improving the physical characteristics of this species compared to Sitka spruce.  Therefore, it should be possible to produce EWP’s from Scots pine that considerably exceed the performance of the C24 strength class, TR26 for truss rafters is more than possible along with the higher strength classes ,C30, C35 and C40 in significant yields.  Whilst the majority of the Sitka spruce falling boards can be visually graded to the C18 strength class, there is sufficient evidence that Scots pine falling boards will make the C22 strength class (based on BS5268: Part 2).  This, taken with the good stiffness and density properties of the species in relation to its strength, gives the material great promise.

The main objectives of this project are:

  • Identify two potential products which would utilise the various grades of Scots pine falling boards
  • Using identifiable material (material processed from participating estates), construct a significant number of products for
    • Strength and stiffness evaluation
    • Dimensional stability
    • Customer perception
    • Alternative markets

Trees selected from participating estates (Scotland and England) have been sawn and data collated on the quantities and dimensions of material produced. The material will then be appearance graded according to a relevant standard.  Using the board material, a quantity of products will be produced.  The products will then undergo evaluation for strength and stiffness, dimensional stability etc.

The main outcome of the project will be a full evaluation of the products constructed and identify the current constraints in using these products and the most appropriate ways of bringing the products to market.


Date: 2005
Title: Inside out beams the next phase (Star sawn beams) (225831)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This project is taking forward the encouraging results generated in the initial Forestry Commission project ‘Obtaining better utilisation of UK grown small diameter hardwood stems using a novel sawing pattern for the production of structural members’ (PPD 24/02).  The main objective of the initial project was to improve the utilisation of small diameter, low value, UK grown hardwood stems, to produce re-engineered components of standard dimensions using a novel cutting and jointing technique.  Using ‘Green’ gluing technology (bonding wood whilst the timber is ‘wet’) it is possible to convert smaller diameter hardwood stems using a ‘star’ sawing pattern (cut into four equal quarters), turn the quarters inside out and bond the sections using the ‘green’ gluing process.  This project focuses on refining the engineering process, construct beams which are longer than a single stem, produce engineering design values, optimise the drying process and identify key markets for this innovative product.


Date: 2001
Title: Wood modification -a Review (PPD100, CV7503)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This review is of the current state of the art for Wood Modification and identifies opportunities for UK grown timber. The study was funded jointly by DTI and the Forestry Commission. The DTI funding was part of the CD Framework project cc 2115 entitled "Best value from UK timber in construction" within Sub-project 3: Enhancing the performance of UK grown timber and improving its market opportunities through wood modification. The aim of Sub-project 3 is to develop new methods for exploiting a range of environmentally and socially acceptable techniques for enhancing the resistance of timber to deterioration due to moisture, while improving their performance and fitness for purpose, and their application to the UK timber resource. In many European countries there has been considerable investment in the development of wood modification.

Several of these processes have now been commercialised and the sale of imported modified timber has now begun. This represents both a threat to the use of home grown timber and a missed opportunity.