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Eignung von Einjahrespflanzen als Zuschlagstoffe für Gipsspanplatten

WKI-Mitteilung 551/1992.
Suitability of annual plants as additives for gypsum-bonded particleboards
: Thole, V.


Holz als Roh- und Werkstoff 50 (1992), S.241-252
ISSN: 0018-3768
Fraunhofer WKI ()
annual plant; Einjahrespflanze; Gipsbindemittel; Gipsspanplatte; gypsum-bonded particleboard; gypsum plaster; hydration

The semi-dry process for the manufacture of gypsum-bonded particleboards was suggested by Kossatz. This process offers besides the use of wood particles as additives the possibility of employing annual plants. Using a Chinese and a German Beta-hemihydrate gypsum plaster the suitability of bagasse, bamboo, cotton stalks, rice straw and wheat was investigated. Besides phase-analytical investigations regarding the characterization of the binders also the efficacy of various retardants as well as the influence of the different plant substances on the hydration were determined. Test boards of varying formulas and density were manufactured from annual plants in order to evaluate the suitability of same. The considerably retarded hydration of the gypsum plaster induced by different extracellular substances does not necessarily lead to boards with low strength properties as well as a moderate impairment compulsorily leads to boards with high strength properties. As far as the board strength is concerned, equal importance has to be attached to the surface condition of the particles, their spraying behaviour and pore structure, as well as to the fineness ratio of the particles and the portion of plant parts which cannot be broken up to particle-shape structures.