Rheological and stability analysis of cement pastes incorporating silica-based wastes

This study investigates the influence of waste characteristics,especially zeta potential,on the properties of cement pastes and solutions.The focus is to evaluate the impact of the zeta potential of cement particles and waste materials on the sedimentation speed,rheology,and hardening time of stabilized cement pastes.Portland Cement II F 40,retarder additive,silica,and fly ash were used in the research.The pastes were prepared,and during the stabilization period,their rheological properties and pH were evaluated.The zeta potential and sedimentation speed of the cement and waste particles were measured at the pH that the pastes presented during the entire stabilization period.After the stabilization period,the pastes were subjected to the hardening time test.The zeta potential analyses revealed diverse values for the different powder types,with the cement particles exhibiting a zeta potential of−3.0 mV,the silica particles exhibiting−10.5 mV,and the fly ash particles exhibiting−20.3 mV.The influence of the high zeta potential modulus was observed on the sedimentation speed,with the solution containing fly ash exhibiting a speed of 40.01μm/s,whereas the solution containing only cement exhibited a speed of 99.38μm/s.In the pastes,the results indicate that the presence of fly ash particles with a significantly negative zeta potential led to a 16%reduction in hardening time compared to particles with a lower modulus of zeta potential.Rheometry tests showed that the inclusion of fly ash particles prevented the formation of agglomerates.Although the zeta potential influenced agglomerate formation and hardening time,it was found to have no effect on yield stress or viscosity.