自充填混凝土、流動化混凝土與一般混凝土之質流行為

Abstract

目前SCC的檢定方法為新拌之混凝土必須通過坍流度試驗、V漏斗流出試驗、箱型充填試驗，並於澆置前通過全量通過試驗才能稱為SCC。但採用上述的試驗法來評估其工作性，不但相當麻煩而且其可信度及敏感度方面均不甚理想。究其原因可知，這些測試法均屬單點試驗法(Single-point Test)，其量測結果無法代表混凝土本身內部的特性。為避兔此缺陷，採用質流試驗可達到此目的，因為透過質流理論，模擬混凝土之流變行為，解析其降伏應力ty(Yield stress)與塑性黏度m(Plastic viscosity)，藉透過此兩者之關係，可以推求出SCC的工作性優良與否。本文預期測試之項目包括： (1)自充填混凝土(SCC)：在相同的水灰比和相同的骨材含量下，僅改變粉體量中水泥及卜作嵐材料(飛灰、爐石)的比例，探討其對質流行為的影響。並藉由SCC所求得的降伏剪應力(ty)和黏滯性(m)得到一個符合自充填混凝土的範圍。 (2)水泥砂漿(Mortar)：探討水泥砂漿對於不同比例的水泥、飛灰和爐石對降伏剪應力和黏度有何影響。 (3)水泥漿(Paste)：改變粉體中水泥、飛灰、爐石的比例，探討不同比例下，其質流行為。並討論自充填混凝土、水泥砂漿和水泥漿三者之間的關係。 (4)流動化混凝土(Flowing Concrete)：以粉體量當變數，探討不同粉體量對質流行為的影響。 (5)一般混凝土(OPC)：以坍度和砂率當變數，探討其質流行為。

The current workability test for SCC is Slump-Flowing-test, V-test and U-test. These methods are very troublesome and the result is only “Single-point Test”. The results can’t represent the characteristic of concrete. In order to avoid this disadvantages; rheological tests are utilized. Rheological test can give two parameters; yield stress (ty) and plastic viscosity (m). By using the relationship of yield stress and plastic viscosity we may better represent the concrete’s workability. The test expected program is to investigate the following： (1)Self-Compacting Concrete (SCC)：The W/B and aggregates content are the same, but change the proportion of cement and pozzollans (fly ash、slag ) to determine the effect of the W/B ＆ aggregate content on the rheological behavior. (2)Mortar：Examining the change of the proportion of cement and pozzollans (fly ash、slag ) on yielding stress and viscosity. (3)Paste：Studying the effect of the proportion of cement and pozzollans (fly ash、slag ) on the rheological behavior, and discusses the relationship among SCC、mortar and paste. (4)Flowing Concrete(FC)：Determining effect of amount of the mineral admixtures on the rheological behavior. (5)Ordinary Property Concrete (OPC): The effect of S/A and the slump on the rheological behavior.