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Hypertufa is an anthropic rock made from various aggregates bonded together using Portland cement. Hypertufa is intended as a manufactured substitute for natural tufa, which is a slowly precipitated limestone rock; being very porous, it is favorable for plant growth. Hypertufa is popular for making garden ornaments, pots and land forms. Hypertufa is relatively light compared with terracotta or traditional concrete and can withstand harsh winters, at least down to . Hypertufa was invented for use in alpine gardens. Alpine gardeners formerly used antique animal watering troughs, which became rare and expensive. == Composition == Aggregates are generally ''Sphagnum'' (peat moss), sand, and perlite or vermiculite. Hypertufa made with the classic proportions for mortar (1 part cement: 3 parts aggregate) has a composition of *3 parts Type I Portland cement *4 parts ''Sphagnum'' *5 parts perlite or 3 parts cement: 9 parts aggregate To increase structural strength and longevity, polymer fibers, liquid acrylic,〔 and fiberglass may be incorporated into the mixture, along with various grades of sand, pebbles, and crushed rock which add to the final object's overall strength and stone-like appearance though they increase its weight. Powdered concrete dyes (in small amounts) also tint the hypertufa to resemble natural rock.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hypertufa」の詳細全文を読む スポンサード リンク
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