水中自充填混凝土

Abstract

土木工程在施工過程常需要於水中澆置混凝土，諸如橋墩、基樁等，在過去多使用坍度較低、富配比之混凝土，使混凝土具有較好的工作度及黏滯性，此時工程人員最關心的是混凝土離開特密管後，水泥砂漿是否隨者水流失，或者混凝土與水混合而增加水灰比導致強度因而減少。此外，由於921地震後地震力之提升，鋼筋用量增加、間隙越來越密，傳統混凝土在水中澆置後，填充性不佳搗實也困難，造成容易發生施工品質不良之缺陷；而自充填混凝土優越的特性正可克服此困難點。 所以本研究以SCC之性能為導向，開發出數種適用於水中結構物之自充填混凝土配比，除了測試其工作性能符合SCC規定標準外，在混凝土硬固後之工程力學性質、耐久性與體積穩定性上，也以一系列試驗方法確保混凝土之品質。更重要證明了水中自充填混凝土達到水中不分離目標，並確實改善了一般水中混凝土所常見的弊病；對我國在混凝土方面上的研究、創新與開發新的技術有所貢獻。

For a civil engineering project, such as pier or foundation piles, it usually requires pouring concrete in water. In the past, engineers often used low slump, rich mix proportion concrete in order to increase the viscosity of the concrete. What the engineers concern most is after the concrete leaves from the tremie, if the cement is washed away by water or if the exterior water is mixed with concrete, the quality of concrete is reduced. In addition, due to the change of design code, the reinforcement is increased remarkably; the structural reinforcing bars are congested. The traditional construction method makes it difficult to complete the pouring process and the compactness of the concrete is not reached; therefore, it is apt to result in a low quality construction. However, this is what self-compacting concrete for underwater construction can overcome. Based on the SCC requirement, this research has developed several self-compacting concretes for underwater construction and can also be applied in traditional work. The properties tested include workability to fit in the SCC scale, the mechanics characteristic, durability and stability of the volume after the solidification of the concrete. The quality of the concrete is confirmed by these series of tests. Most of all, this research has proved that self-compacting concrete for underwater construction has reached the goal of inseparability in water, and it does overcome the common disadvantages that ordinary concrete might encounter and thus can contribute to the related researches in this area for any other inspiring new ideas or opening up new technologies.