In ready-mixed mortar, an appropriate water-retaining and thickening material is usually added, but the water-retaining and thickening material has a stronger water requirement, thus increasing the unit water consumption, also affecting the mechanical properties and durability of mortar, so an appropriate amount of water-reducing agent should be used for the dispersion of cement slurry system. There is a wide variety of water-reducing agents. Theoretically, lignin, naphthalene sulfonate, melamine sulphamate, aliphatic and polycarboxylate water-reducing agents can be used as the dispersing agents in the cement slurry system. But these water-reducing agents differ greatly in their own dispersing, plasticizing and enhancing effects, but also have certain adaptability with cement, fly ash and slag powder used. More importantly, ready-mixed mortar is a multi-component mixture with significant differences in the proportions of each component, especially in the presence of thickening and water-retaining agents, greatly affecting the plasticizing and dispersing effects of water-reducing agents. When the thickening or water-retaining agent of a certain component exists in the aqueous solution, some types of water-reducing agents cannot play its due plasticizing effect, and sometimes even make the fluidity of mortar worse.
Therefore, in the production of high fluidity mortar and selection of water-reducing agents, a lot of tests must be passed to select the most appropriate water-reducing agent and determine the optimal dosage.