Investigation of rheological properties of fresh cement paste containing ultrafine circulating fluidized bed fly ash

Abstract The rheological properties of fresh cement paste with different amount of ultrafine circulating fluidized bed (UCFB) fly ash was fitted through the rheological models. The results show that the fresh cement paste containing different content of UCFB is always Bingham fluid. When the content of UCFB fly ash was lower than 30 wt%, the rheological properties of cement-UCFB fly ash were better than that of pure cement paste. In addition, when the amount of UCFB fly ash was 10 wt%, the fresh cement-UCFB paste has the best rheological properties. The effects of particle size distribution on the rheological properties of cement-UCFB paste were also analyzed through Rosin-Rammler fitting analysis. The packing density and particle size distribution are the main factors affecting rheological properties of the system. When n value is smaller, in other words, the particle size distribution range is wider, the fluidity of cement-UCFB fly ash system is better than that of pure cement. The morphology of the particles also affect the rheological of the fresh cement paste.