| 摘要 |
<p>Cementitious building, structural and paving products are made in a process comprising shaping a mixture of calcareous material such as lime, hydrated lime, Portland cement or a mixture thereof, siliceous material such as ground sand, quartz, sandstone, soil, diatomite, clay, fly ash, mine tailings or furnace slag, and water, optionally with the addition of reinforcing material, subjecting the shapes to curing at superatmospheric pressure and a temperature at least 250 DEG C. to form a calcium silicate hydrate coating on the siliceous material, and reducing the shapes to ambient temperature and atmospheric pressure, characterized in that the total curing period is less than 30 minutes. A pressure of 1250 p.s.i. and a temperature of 300 DEG C. may be used in the curing. Both forming and curing may be conducted in a heated hydraulic platen press or in an extrusion die, either sequentially or simultaneously. Reinforcing material may be asbestos, mineral wool, metal mesh, gauze, steel rods or fibres of silica, glass, silicon nitride, cellulose or synthetic organics. Sulphonated petroleum surfactants, hydrated starch or carboxymethyl cellulose plasticizers and calcium chloride or sodium hydroxide as accelerator may be included in the mix.</p> |
