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液态氮是一种有效的冷却剂。据报导,美国北卡罗来纳州威尔明顿市的一位承包商最近在建造一座桥梁工程中,将液态氮注入混凝土拌和物中以保证得到混凝土的浇筑温度不超过75°F。该工程不大,没有必要建造冷却罐。如果用冰片冷却,则用冰量是相当可观的。况且,冰片还会破坏设定的水灰比。采用液态氮冷却混凝土有四种方法:冷冻混凝土拌和水;将冷冻水转化为冰水;混凝土拌和前预冷骨料;在拌和料内直接喷注液态氮。在北卡罗来纳大桥施工中表明,直接喷注液态氮是最佳方法。在搅拌机的背面配置了一个温度计,用来测定所需要的冷却温度。卸下该温度计,可插入一个喷枪,喷入适当的液态氮量。可由一个计时器来控制
Liquid nitrogen is an effective coolant. According to reports, a contractor in Wilmington, North Carolina, recently built a bridge project to inject liquid nitrogen into the concrete mix to ensure that the pouring temperature of the concrete does not exceed 75°F. The project is not large and there is no need to build a cooling tank. If ice flakes are used for cooling, the amount of ice used is considerable. Moreover, borneol will also destroy the set water-cement ratio. There are four methods of using liquid nitrogen to cool concrete: freezing concrete to mix water; converting chilled water to ice water; pre-cooling the aggregate before mixing concrete; and spraying liquid nitrogen directly into the mix. The construction of the North Carolina Bridge shows that direct injection of liquid nitrogen is the best method. A thermometer is provided on the back of the mixer to determine the required cooling temperature. Remove the thermometer and insert a spray gun into the appropriate amount of liquid nitrogen. Can be controlled by a timer