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Chemical corrosion wood
Holan, J. ; Kloiber, Michal
Chemical corrosion of wood is caused by acids, bases, and salts. Primary manifestations are changes color, next stage is defiberation of wood surface (into a few centimeters). It causes decrease of mechanical properties. Damaged structures (i.e. roof frame) are not capable enough to bear required loads and there is a threat of crash down. Improper use of preservatives on wood can induced process of corrosion what is apparent on some Czech monuments.
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Impact of the orientation and width of wood rings on the spreading of ultrasound in the wood structure
Kloiber, Michal ; Kotlínová, M.
The subject of the paper is the relationship between ultrasound wave velocity in wood, tree rings orientation and width, and wood mechanical properties (MOE in our case). For measuring, the Arborsonic Decay Detector has been chosen. Sound velocity decreased from radial to tangential direction of measurement. In groups with radial (3) and diagonal (2) position of tree ring, increasing of tree ring width has increased sound velocity. In group with tangential tree ring position no significant influence of tree ring width has been found.
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Comparison of the dynamic and static elasticity modules in damaged wood
Kloiber, Michal ; Kotlínová, M.
This work deals with evaluation of wood properties, that are obtained on the base of ultrasound testing with defectoscopic Arborsonic Decay Detector. Ultrasound waves expand with speed, that depends on wood quality. From time of stress wave propagation and wood density dynamic modulus of elasticity was calculated. The same test specimens were statically loaded afterwards, and dynamic and static modulus of elasticity were compared. These characteristics of wood according to damage by biotic factors change rapidly. This work proofs possibility of non-destructive wood properties by constructive-technical research of wood constructions.
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Ultrasonic testing of the structural timber within historic buildings - preview of elaborated methodics
Kloiber, Michal ; Bláha, Jiří ; Kotlínová, M.
The authors are engaged in interdisciplinary research and non-destructive testing of historic timber structures both in situ and in the lab. Therefore they take advantage of combining the approaches inherent to technical, historical and craft analyses of timberwork. To facilitate the spreading of knowledge of up-to-date diagnostic methods they are preparing an overview guidebook now which is supposed to help the heritage workers, owners, designers or contractors to choose among the possible testing tools and techniques the most proper one. The chapter which is devoted to the applying of ultrasonic methods for the timber non-destructive testing is shown as a sample here.
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Advanced detection methods used for on-site inspections of historic timber structures
Bláha, Jiří ; Drdácký, Miloš ; Kloiber, Michal
Research and evaluation of timber structures used within historic buildings should have consideration for an authentic substance bearing the most of specific heritage values. Modern technologies have brought new tools for a detection of the subsurface biogradation. Among the non-invasive techniques the ultrasonic testing, portable X-ray scanning and thermo-vision belong to most promising ones. There are also sophisticated semidestructive methods like microdrilling or video scope available.
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