| 摘要 |
<p>A cementitious material comprises cellular granules of soluble anhydrite and/or calcium sulphate hemi-hydrate. An aggregate e.g. expanded perlite, exfoliated vermiculite, pumice, fly ash or their mixtures may be present, together with retarders and accelerators. The material is made by, in any order, comminuting, drying and calcining a foamed gypsum plaster, the calcining making the product cementitious. The foam may contain up to 3% of slaked or quick lime or up to 5% of Portland cement; up to 3% of alum, borax, calcium chloride, ammonium or aluminium sulphate, gum arabic, graphite, mica or sulphite lye or combinations thereof.</p> |
