| 摘要 |
<p>A porous lightweight particulate aggregate for use in concretes, mortars, building blocks and other building elements, comprises expanded and vitrified low alkalinity particles of a material composed of an alkali metal silicate having an M2O/SiO2 ratio of from about 1:2 to 1:4 wherein M is an alkali metal; silica in an amount of from about 0.1 to about 50% by weight of said alkali metal silicate; and an alkaline earth metal silicate in an amount of from 0.1 to 200% by weight of said alkali metal silicate, said particles having a density of not more than about 60 g/dm3 and a compression strength of up to about 275 kg/cm2 and having an expansion ratio of up to 15 times their original collapsed volume. Suitable fillers and additives may be added to said aggregate to provide specific and useful properties for a variety of uses thereof. A process of manufacturing a porous lightweight particulate aggregate comprises kneading an aqueous slurry of an alkali metal silicate, finely divided silica and a finely divided alkaline earth metal silicate, in order to form a homogeneous mixture, reducing said slurry to particles of a preselected size depending on the desired size of the finished aggregate, gradually raising the temperature of said particles to from about 110 to about 700.degree.C, and then firing until a temperature of from about 700 to about 1500.degree.C is achieved and vitrification of the silicates is completed. Potassium nitrate may be added to provide for the formation of a large central pore to produce a hollow particle structure on heating the mixture. The gradual increase in the temperature may be partially carried out in the presence of saturated steam in order to humidify and to therefore render the surfaces of the particles sufficiently plastic, whereby a hollow structure having a central large pore surrounded by a shell of highly porous material is obtained.</p> |
