Studying the impact of admixtures chemical structure on the rheological properties of silica-fume blended cement pastes using various rheological models

In this study, the influence of various types superplasticizers namely; sikament-TG (TG), phenolformaldehyde-sulfonilate (SI) and low phenol phenol-formaldehyde-sulfonilate (SII) on the rheological properties of silica fume-blended cement pastes (SF-BCPs) were studied. The mini slump and rheometer tests were used to examine the rheological properties of SF-cement blended pastes (SF-BCPs). The obtained results showed that, laboratory prepared admixtures (SI and SII) have a high efficiency than the commercial one (TG) in improving the rheological properties of SF-BCPs. Also, it is concluded that fresh control and admixed C-Ps exhibit a nonlinear behavior (shear-thin/thick). Therefore, Bingham-model cannot be applied for these C-Ps. Herschel-Bulkley-model and modified-Bingham- model can be used for shear-thick only as it is found that at tau=infinity when gamma degrees=infinity, while Hyperbolic-model can be applied for shear-thin only. The hyperbolic-model better than other models according to R-2 and RMSE values; thus, the obtained hyperbolic-model YS values tend to be more reliable. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of Faculty of Engineering, AM Shams University.