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Applicability of wood durability testing methods to bio-based building materials
2015 - IRG/WP 15-20561
It is well known that organic materials may be susceptible to attack from a range of fungal organisms and any bio-based material used in locations where there is the possibility of microbiological activity must be expected to be able to withstand or prevent such attack. There are a wide range of test methods and standards in place to test susceptibility although most of these test individual components such as wood or panel material. A wide range of old and new bio-based materials and novel construction techniques are showing an increase in use in new building and in the restoration of old buildings. These materials need to be assessed against microbial activity to determine if they are suitable for use in a particular area. Standard wood decay test methods are widely known and would seem applicable to many of the materials being used – especially where wood based products are used. However, due to their structure certain testing problems can arise. This paper seeks to test a variety of building materials, including sheep’s wool, mineral wool, hemp, wood fibre, cellulose flakes and assess the suitability of the testing regime on these materials. The method selected was the wood panel testing method DD ENV 12038, with some modifications to measure the extent of fungal growth as well as decay. The results show that although there was significant growth of the fungi through test samples only the lignocellulosic materials showed any appreciable decay. It was also noted that for some of the samples the structure of the material e.g. very thick or particulate fill, made the test sub-optimal.
S F Curling, B K Stefanowski, E Mansour, G A Ormondroyd

Performance of bio-based building materials – viewpoints from the first year of COST Action FP1303
2015 - IRG/WP 15-20572
Maintaining and expanding the market potential for bio-based building products in indoor and outdoor construction uses remains a key activity for industries in the forestry and biotechnological sector, particularly in Europe. Whilst there are ongoing activities within IRG for collecting and populating a database on performance on wood, the performance data for many other (i.e. non-wood) "environmental friendly" building materials are lacking as well as suitable comprehensive test methodologies to determine their resistance against mould, stain, and decay. The similarity in terms of decay hazard, resulting response on climatic loads and thus performance of different bio-based building materials has not yet been recognised adequately, and in order to overcome this problem within Europe, COST (Cooperation in Science and Technology) established the Action FP1303 entitled “Performance of biobased building materials”, which from 2013-2017 will provide a platform for networking and scientific exchange between different disciplines, such as material sciences, wood technology, biology, biotechnology, building physics and engineering. Through the activities in this Action, there will be a coordinated effort to put the issue of biodegradability of organic building products on the agenda, combined with consumer demands and preferences. These will help define service life prediction and performance models, will consider aesthetical aspects as well as the functionality of building assemblies. These will ultimately contribute to the control and prevention of any imminent threat to use bio-based building materials, which in turn could severely damage a pan-European low carbon building agenda. This paper outlines some of the activities undertaken within the first year of the Action, and describes some of the planned activities in the coming years.
D Jones

Laboratory test to determine the effect on durability of combining biobased building materials with timber in construction
2017 - IRG/WP 17-20604
The use of Structural Insulated panels is a construction approach that is seeing more abundant use and is becoming a widely available method. Preformed units are usually a composite structure which often include a range of bio-based materials such as timber, wool or straw. Traditional laboratory based wood decay tests do not take into account this combination of biobased materials and it may be possible that non wood materials such as plant or animal fibre insulation could influence the durability of adjacent wood elements by synergistic mechanisms. One method may involve the insulation material acting as a moisture reservoir or moisture buffer for wooden structural elements with a consequential effect on their durability. This paper details an experimental approach to determine if there could be such an effect, using a modified form of existing wood decay testing methods. The test utilises an agar jar approach with a pad of fibrous insulation e.g. wool or hemp placed between the inoculated agar and a wood block. Results show the effects of the type of insulation used on the moisture content and decay of the test blocks. It is shown that moisture was able to pass through the insulation to varying degrees to be absorbed by the wood blocks. Fungal mycelium was then able to grow through some of the insulation materials to attack the wood. The test show that wool for example appeared to hold water away from the wood samples and reduced subsequent decay. Hemp however, did not prevent water access to the wood blocks and in fact enhanced decay of the blocks.
S F Curling, G A Ormondroyd

Comparative study on the efficacy of biobased wood preservative over conventional wood preservatives against fungi and termites
2022 - IRG/WP 22-30761
The current focus of wood preservation research is on developing wood preservatives from natural and environmentally compatible compounds for industrial application. Liquefaction of wood is one of the promising approaches to utilize woody waste where the wood powder is converted into a chemically active liquid with the help of a liquefying agent like phenol, cresol, plant-based solvent as CNSL and Cardanol. These Liquefied wood polyols and conventional wood preservatives like CCA, CCB, and Chlorpyriphos as synthetic chemicals were in use for a long time and used in prescribed proportion. The efficacy and economic suitability of liquefied wood as a wood preservative and conventional wood preservative against termite and fungi have been studied. Wood samples were impregnated with both conventional and liquefied wood preservatives and evaluated as per Bureau of Indian Standards (BIS) in terms of its antifungal (IS 4873, Part I:2008) and termiticidal activities (IS 4833:1993) through accelerated termite graveyard test and fungal resistance test. The level of impregnation of liquefied wood in wood was estimated by determining the weight percent gain. In the graveyard test, samples were periodically observed weekly intervals. The results indicated that Samples treated with phenol, CNSL, Cardanol based liquefied wood polyols exhibited better results as compared to conventional synthetic wood preservatives both in visual observation and percentage weight loss as compared to initial condition and untreated control samples. The percentage weight loss of liquefied wood polyols (phenol, CNSL and cardanol individually) treated wood sample was ranging from only 5-20% of its initial weight; wood treated with preservatives (CCA, CCB, and chlorpyriphos) shows % weight loss varied from 40- 60% and did not exhibit better resistance against termite and fungi as compared to the untreated samples. The treated samples were also exposed to fungus for 16 weeks. The fungicidal traits of liquefied wood polyols (phenolated, CNSL, and cardanol individually) treated wood showed higher antifungal efficacy against both white rot and brown rot of wood, conventionally wood treated preservatives (CCA, CCB, and chlorpyriphos) shows low efficacy against termite and fungus. The utilization of liquefied wood polyols for timber protection against termite and fungi as one of suitable option for valorizations of wood waste which is being generated during primary & secondary processing of wood by wood-based industry in large scale. The liquefied wood polyols (CNSL & Cardanol) based proved as the best wood preservative among all categories and having potential for commercialization over conventional wood preservatives at large scale by wood-based industry.
A Kumar, A John, B N Hazarika