2017 Volume 71 Issue 1 Pages 17-23
High-strength high-durability cement is used these days, and it consists of low heat Portland cement（LHC）and silica fume（SF）. However, LHC-SF system is uneconomical and utilizes a small amount of industrial wastes. In contrast, moderate-heat Portland cement（MPC）utilizes more industrial wastes, and the limestone powder（LSP）is an economical material. Therefore, MPC-LSP system is expected as the new high-durability cement. This paper investigates the fluidity of low water-to-powder ratio MPC-LSP paste with superplasticizer from the point of the packing fraction and the initial hydration. To make the fluidity higher, the authors used the packing simulation, and the LSP mass ratio to MPC was configured to make the highest packing fraction. The fluidity of configured MPC-LSP paste was higher than that of LHC-SF paste. In addition, the increase in the LSP ratio to MPC increased the fluidity of MPC-LSP paste, and this tendency was stronger at low water-to-powder ratio. On the other hand, the cumulative heat liberation of MPC-LSP paste was lower than that of LHC-SF paste. In addition, the increase in the LSP ratio to MPC decreased the cumulative heat liberation of MPC-LSP paste, and this tendency corresponded with the fluidity. It is considered that LSP influenced on the initial hydration of calcium-aluminate phase in cement, resulting in the higher fluidity. The initial hydration is an important factor in the fluidity of cement paste.
