Effect . . MIXI: of Types of Superplasticizers and ng Methods on the Properties of Cementitious Systems

This paper reports the properties of cement paste, mortar and fresh and hardened concrete using superplasticizers with electric repulsion, steric barrier and those possessing both dispersing mechanisms and their interaction with cementitious materials having pozzolanic properties and those without pozzolanic properties prepared by different mixing methods. It was found that there is an optimum W/C for the primary water (W1/C) where bleeding is minimum and thus dispersion state is optimum. The fresh properties of concrete prepared by double mixing method are different from those by conventional mixing method (Single mixing). Also, when superplasticizers are added in primary water (W1), fresh properties of concrete are different from those when added in secondary water (W2). The effect of dosing method of superplasticizers and replacement of cement with different cementitious materials, varies greatly with the type of superplasticizers.