Abstract
The effects of powder packing fraction on the fluidity of low heat Portland cement（LHC）paste for the development of a new type high strength cement without silica fume are describes in this paper. The packing fraction of powder particles can be improved controlling the particle size distribution of powders. The relationship between suspension fluidity and the packing fraction of powder was studied. A high packing fraction results in increased fluidity of suspension. A computer program for determining the packing fraction of powder particles directly from a particle size distribution was written and the packing fraction was calculated. Based on this calculation, the packing fraction of LHC improved in bimodal particle size distribution was confirmed. LHC having different particle size distribution was produced by ball mill. The packing fraction of mixture of fine LHC（mean particle size；8μm）and coarse LHC（mean particle size；40μm）is obtained highest packing fraction compared with all other cases by computer simulation. By using of this LHC adjusting particle size distribution, the fluidity of cement paste and mortar can be improved at low water to cement ratio. When the water to cement ratio of mortar with this cement is 0.17 to 0.21, mortar flow is over 30cm. The compressive strength of mortar with this cement is over 150 N/mm2 at 91 days.
