Effect of Urea Usage Rate on Thixotropic Behavior of Cementitious Systems

Abstract

It was understood that studies investigating the use of alternative materials have increased in order to develop concrete technology, to expand sustainability and to improve the fresh and hardened state properties of cementitious systems. It was reported that one of these alternative materials is urea, which can increase both the flow performance of the mixture and the freeze-thaw resistance. In this study, the effect of the use of urea on the thixotropic behavior of Portland cement systems was investigated. In addition to the urea-free control mix, 4 different batches of paste mixes were prepared by replacing the cement with urea at a rate of 2.5%, 5% and 10% by weight. The thixotropic behavior of the mixtures was evaluated by comparing the hysteresis area values obtained from the viscosity-shear rate graphs. It was determined that the structural recovery area measured at the initial and the structural breakdown area measured at the end of the 180 second rest period decreased with the use of urea. It was determined that the optimum urea utilization rate was 2.5% in terms of the thixotropic area value of the mixtures.