Lightweight calcium silicate moulding and prodn. using expansion agent - forming ettringite on reaction with water, giving strong prod. similar to wood

摘要

Prodn. of a lightweight Ca silicate article involves mixing 100 (wt.) pts. Ca silicate (I), 1-15 pts. of a material (II), which can form ettringite on reaction with water, 1-30 pts. reinforcing fibres (III) and 1-40 pts. binder (IV) in water to form an aq. mix., moulding this as reqd. and drying the moulded mix. A new lightweight Ca silicate article contains 100 pts. (I), 1-20 pts. EVA contg. 0.01-20% water retention aid (V) and 1-30 pts. (III). (II) is pref. an expansion agent of type K, M or S, as defined in the ACI classification; Ca sulphoaluminate clinker, pref. contg. 3CaO.3Al2O3.CaSO4, opt. mixed with gypsum; a mixt. of aluminate clinker and gypsum; or a mixt. of material contg. blast furnace slag or Al(OH)3, gypsum and quicklime or slaked lime. (V) is a water-absorbing polymer, pref. methylcellulose, CMC, PVA, Na polyacrylate or polyethylene oxide. USE/ADVANTAGE - The prod. is lightweight (bulk density 0.3-0.7 g/cc, i.e. almost the same as natural wood) and has high mechanical strength, high heat resistance and high dimensional stability. It can be processed easily, like wood. It is useful as a heat-resistant building material or synthetic wood.