| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lightweight concrete capable of increasing the amount of air without a fear of deterioration in development of concrete strength by including a partly or wholly dried lightweight aggregate and a water reducing agent excellent in dispersibility in the lightweight aggregate and using an air-entraining admixture and an antifoaming agent at the same time or in combination therewith. SOLUTION: This lightweight concrete is obtained by including a lightweight aggregate in a bone-dry state or the one absorbing water to about a half of the water absorptivity thereof, further the lightweight aggregate having <1.0 specific gravity as a part or all thereof, a water reducing agent excellent in dispersibility in the lightweight aggregate and an air- entraining(AE) admixture and an antifoaming agent at the same time or in combination. A polycarboxylic acid-based water reducing agent is preferably used as the water reducing agent and the AE admixture is used in an amount of preferably, e.g. 0.0012-0.006 L/m<3> . The antifoaming agent is used in the same amount as that of the AE admixture or preferably in a smaller amount. The lightweight concrete is preferably used at <=50% water-cement ratio. Thereby, the lightweight concrete is capable of saving the labor of compounding or placing operations of the lightweight concrete, reducing efforts required for the placing operations, shortening the operating time and in its turn shortening the term of works and reducing the cost. |
