| 摘要 |
<p>Thermohydraulically bonded high-density concrete products such as building blocks and bricks are produced by intimately mixing, e.g. in an edge mill, cement e.g. Portland and/or lime with quartz flour in a ratio of 70/50 to 50/30 for cement and 50/50 to 30/70 for lime, and water in an amount by weight of 0.2-0.35 part of cement and/or 0.4-0.6 part of lime, with or without a coarse aggregate, such as sand with particle sizes up to 5 mm., in an amount by volume of up to 65% of the above total, forming the resultant moistened mixture into the required shaped product, compressing it by mechanical means such as by tamping or using a press or vibrating device, until the air volume is not more than 2% of the product, then steaming it under pressure e.g. in an autoclave at a temperature of at least 170 DEG C., e.g. for 10 to 12 hours, such that pressure X time = 120-170 atm. hrs. The shaped produce may be vacuum treated during or before compressing. Preferably the ratio by weight of lime as Ca(OH)2 to cement is 0.66 to 1.5. From 0.1 to 1% by volume of non-foaming wetting agent may be added to the mixture which may include fibres such as of glass, cotton, nylon or lava.</p> |
