| 摘要 |
Ground, calcined natural aluminosilicate minerals are mixed at ca. 20% w/w with bitumen, are used for road-surfacing. A light-coloured surface, having better skid-, wear- and gelling-resistance, water absorption and economics than those known in prior art, results. Preferably the mineral is a white clay or state caly or quartz sand, having 50-90% SiO2, 10-25% Al2O3 and not more than 2% of iron compounds. It is calcined at 1000-1400 C, then ground to a particle size of ca. 2mm. Whiteness is ca. 75% of that of a standard white reflecting surface, and is reduced only to 49% on wettin. |
