| 摘要 |
PURPOSE:To cast concrete having good quality by suppressing a rise in the temp. of concrete due to heat of hydration, by supplying aggregate before the kneading of concrete to the continuous moving body provided in a vacuum tank in predetermined moisture content and removing evaporation heat to lower the temp. of the aggregate. CONSTITUTION:Aggregate S such as fine aggregate, coarse aggregate or a mixture thereof having about 15% of surface moisture supplied to a hopper 1 falls on the belts 4 of belt conveyors synchronously driven of respective stages through a vacuum valve 2 on a supply side. When the aggregate S is successively supplied so that the supply amount thereof does not exceed the skirts 6 attached on both sides of the belts 4, the aggregate S becomes the same thickness up to the belt 4 of the lowermost stage over the respective stages. The supply of the aggregate S is stopped and a vacuum valve 8 is opened to drive a vacuum pump 14. The surface water of the aggregate S is evaporated and the temp. of the aggregate is lowered to temp. 3-4 deg.C higher than the surface temp. of the cooler 10 in a cold trap 9. The cooled aggregate S can be discharged while the total amount thereof is cooled by bringing a vacuum tank 3 to atmospheric pressure by opening a vacuum breaking valve 16 and opening a vacuum valve 7 on a discharge side to drive the drive pulleys 5 of the respective stages. |
