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Investigation of microwave as a means of eradicating dry rot attack in buildings
1992 - IRG/WP 92-1545
A microwave-apparatus developed for treatment of building-structures infested by dry rot was tested in the laboratory. The test-conditions simulated treatment of either infested timber or infested brickwork. Sawdust samples, both wet and dry, infested by viable mycelium of Serpula lacrymans were packed in glass-tubes. The tubes were then placed in the middle of either 20 cm thick wooden beams or 35 cm brickwork. The temperature during microwave-treatment was measured both in the tubes using toluene thermometers and in the "construction" using thermo-couples of the copper-constantine-type. The viability after treatment was tested by growth-ability on malt-agar, by ATP-content and by nucleus-staining. The lethal temperature with this specific apparatus was 37-39°C in brickwork and 40-50°C in wood. In comparison with more conventional methods of heat transfer microwaves seem to be more efficient. The variation in temperature within the treated area was undesirably high and in situ treatment above lethal temperature with this specific apparatus would lead to an unacceptably high risk of damage.
C Kjerulf-Jensen, A P Koch


Compatibility of deltamethrin with wood-finishing and construction materials
1993 - IRG/WP 93-30010
Under normal use conditions, treated wood comes to close contact with the structural components of a buiLding, and/or receives finishing, forming a new interface, which can affect the performance of a new product such as deltamethrin. To study this possibility, block-tests of Parana-Pine (Araucaria angustifolia), measuring 12 x 24 x 0.5 cm³ (with the largest dimension parallel to the wood-grain), received brushing treatment with deltamethrin and kerosene in two different concentrations: 0.02% (w/w) and 0.04% (w/w). After 20 days under laboratory conditions, the block-tests received a superficial finishing with poliurethan varnish, enamel paint, oil paint (alkidic) and latex paint and were fastened in close contact, through rubber band, with bricks, building cement, concrete blocks and plaster. A set of pieces made up of these construction materials was treated with deltamethrin in the same concentration as mentioned above, forming a reference series. The test against dry-wood termites (Cryptotermes brevis) was carried out 21 months after the treatment. The deltamethrin proved to be very effective in wood protection, independently of the finish used and the type of construction material in contact with the wood.
E S Lepage