| abstract |
A PROCESS IS PROVIDED FOR THE PREPARATION OF AN EXPANDED INSOLUBLE AGGREGATE FROM A MIXTURE OF AQUEOUS AND ANHYDROUS ALKALI METAL SILICATES, HAVING WEIGHT RATIOS OF 1:3.0-7.0, WITH PRIMARY AND SECONDARY INSOLUBILIZERS. THE ANHYDROUS SILICATE IS ADDED TO OBTAIN A SILICATE SOLIDS CONTENT WITHIN THE RANGE OF 80-40 PERCENT. AFTER MIXING AND CURING, THE COMPOSITION IS GROUND TO A PARTICULATE FORM AND SUBSEQUENTLY EXPANDED AT TEMPERATURES IN EXCESS OF 800*F. THE PRIMARY INSOLUBILIZER, E.G., SODIUM SILICONFLUORIDE, SERVES TO REDUCE THE HYGROSCOPICITY OF THE GROUND PARTICULATE MATERIAL PRIOR TO EXPANSION, WHILE THE SECONDARY INSOLUBILIZER, E.G., CALCIUM CARBONATE, REACTS AT EXPANSION TEMPERATURES TO PROVIDE AN INSOLUBLE LIGHTWEIGHT AGGREGATE. |