Publication

Abstract : Rheology deals with flow and deformation of matter under applied force. The study of rheological response of superplasticised portland pozzolana cement pastes subjected to a stepwise loading at three levels of temperature using Herschel-Bulkley and Bingham flow model is presented here. Rheological tests were done in a temperature controlled coaxial cylinder viscometer (Brookfield DV-II). Cement pastes prepared at water-cement ratio of 0.37 using four types of portland pozzolana cement (PPC) and 2 superplasticisers (SP) of four different families were used for the study. Saturation dosages of the superplasticizers were obtained through marsh cone and mini slump tests. Rheological tests were done on superplasticized cement paste mixes for three levels of dosages viz., lower than saturation dosage, saturation dosage and higher than the saturation dosage. Cement paste samples were subjected to shear rate ranging from 30 S-1 to 65 S-1 in the viscometer and the resultant shear stress was measured. Rheological parameters obtained at three test temperatures (15ºC, 27ºC and 35ºC) by fitting the second cycle downward flow curves using Bingham model and Herschel Bulkley model were analysed and utilised for modeling through random kitchen sink algorithm. The variation of predicted and measured values of the rheological parameters were compared and validated. It was observed that, the model could effectively predict the rheological parameters within the experimental domain.