Abstract
The effect of polycarboxylate superplasticizer on the fluidity and rheology of cement - silica fume - water paste was investigated. The changes of dispersion degree, yield stress and plastic viscosity of paste with different superplasticizer content were analyzed. The results show that the rheological properties of paste with different superplasticizer content conform to Herschel-Bulkley model. The shear thinning of the slurry is manifested as a typical yielding pseudoplastic fluid characteristic. When the content of superplasticizer is less than 1.0%, the plastic viscosity and yield stress decrease and the fluidity increase with the increase of plasticizer content. When the content of superplasticizer is more than 1.0%, the yield stress decreases slightly and the plastic viscosity increases with the increase of plasticizer content. The fluidity decreases with the increase of yield stress, and there is a good correlation between them.
Highlights
High cement content, low water binder ratio and the use of silica fume(SF) give RPC a very dense microstructure
Polycarboxylate superplasticizer has strong electrostatic repulsion force and steric repulsion force[3], which can disperse flocculation structure, and form hydration film on the surface of silica fume and cement to reduce the friction between particles
2.2 Mix design In order to grasp the influence of polycarboxylate superplasticizer on the fluidity and rheology of cement paste containing silica fume, six mix proportions with different superplasticizer agent contents were prepared by keeping the silica fume content and water binder ratio unchanged
Summary
Low water binder ratio and the use of silica fume(SF) give RPC a very dense microstructure. The ball effect, activity effect and microaggregate filling effect of silica fume are used to optimize the rheological properties of cement paste, and the macro defect free structure of cement matrix is formed. Polycarboxylate superplasticizer has strong electrostatic repulsion force and steric repulsion force[3], which can disperse flocculation structure, and form hydration film on the surface of silica fume and cement to reduce the friction between particles. The influence of polycarboxylate superplasticizer on the dispersion degree, yield stress and plastic viscosity of cement-silica fume-water slurry was determined, and the influence law of its content on the fluidity and rheology of cement-silica fume-water system was grasped
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