| 摘要 |
<p>A gritting medium, for ice and snow covered roads, pavements and other traffic surfaces, consists of porous concrete granules (preferably of 5-15 mm. particle size) made by granulating a mixture of more than 10% quartz sand, more than 10% lime, 1-10% cement, 1-10% natural gypsum, less than 1% aluminium powder and more than 10% water, allowing the mixture to set and then steam hardening.</p> |
