Studies of Mineral Particles Grading Effects on Cement-based Compound Cementitious Materials

In this paper, compressible bulk density (CPM) model dense packing effect of fine mineral admixture to study the rheological properties of the mineral powder gradation effect of low water cement ratio cement-based composite cementitious materials and hardened paste the impact of the performance. This paper first discusses the theoretical basis of the CPM model, calculation methods, procedures, as well as the CPM model is applied to the the powder particle system accumulation of problems and solutions encountered in the calculation of the density. The Toufar model of two packing density model CPM models and by minimizing water demand method of Test results showed that the CPM model has significant advantages. Then we use the CPM model to analyze the impact of particles of different particle size and different contents of the of particle mixtures accumulation density. On this basis, the paper through the experimental study of mineral powder dosage fineness and water glue slurry rheological properties of fresh and hardened slurry performance ratio, and combined with CPM model density calculations explore mineral gradation effects of micronized slurry rheological properties of fresh and hardened slurry compressive strength and drying shrinkage. The study results show that: 1) the CPM model can effectively predict the packing density of the powder particle system; 2) has an important effect on the particle size distribution of the better gradation of mineral powder and cement the packing density of the solid particles in the mixture system of solid particles system packing density is higher. 3) particle size distribution is closely linked with the fresh slurry rheological properties and changes in In the same amount of water conditions, with the bulk density of the solid particle system improve, the improvement of the particle size distribution of fresh slurry yield shear stress and plastic viscosity have different degrees of reduction, the loss of slurry with time is also reduced . 4) particle size distribution of the compressive strength of the hardened cement paste have a close relationship. The particle size distribution of the better, the higher packing density of the solid particle system, low water consumption, the particles are more tightly packed structure, so as to increase the compressive strength of the slurry. 5) the smaller the water-cement ratio, particle gradation of fresh slurry and hardened paste dense packing effect more significantly, the dense packing of mineral powder effect only in low water cement ratio only 'can give full play to. 6) the particle size distribution of hardened cement paste shrinkage has a certain relationship. When the particle size of the mineral powder is within a certain range, the compacting degree of improvement with the accumulation of the solid particulate system, the shrinkage rate of the hardened paste have different degrees of decrease. When the particle size is too small, the cement slurry will consume a lot of free water, but will also increase the drying shrinkage of hardened paste. 7) the use of the the CPM model calculation analysis of the packing density of the solid particles is optimized composite cementitious materials with effective means than design.