The additive is a generic term for a few materials which could change some properties of mortar, such as redispersible polymer powders (or emulsion), fibers, retarding agents, fluidizing agents, deformation agents for adjusting the volume of mortar, and water-repellent agents. The special performance that additives give dry-mixed mortar is the key to distinguish it from traditional building mortar.
The most crucial raw material in dry-mixed mortar is the additive. Although the amount added is very small, its role is great. It can significantly improve the performance of mortar. For example, it enables mortar with flexibility by adding redispersible polymer powder; enables floor mortar to flow freely by increasing the addition amount of fluidizing agents; and enables the surface cracks of mortar significantly reduced by adding fibers, and so on. Therefore, the development of modern mortar technology is just the economical and rational application of various additives in dry-mixed mortar to meet the needs for the development of modern building technology. In the cost of dry mortar products, additives account for a very big proportion. And the most commonly used additives are redispersible polymer powders, with a high price, leading to a substantial increase in the cost of dry-mixed mortar. Therefore, how to choose and well select additives is the core of preparing dry-mixed mortar. The performance of dry-mixed mortar can be improved by blending additives, so as to meet the needs of projects.
When additives are applied in dry-mixed mortar, it should be noted that the effect of additives on the mortar performance should be considered as a whole. Don’t just consider the improvement of a certain property, while ignoring the adverse effects on other properties. For example, the addition of redispersible polymer powder can greatly improve the bonding performance between mortar and base coat, but the powder will reduce the water resistance of mortar. Water-repellent agents can improve the ability of mortar to resist micro-pressure water, but may reduce the adhesion of mortar. Therefore, in the preparation of dry-mixed mortar products, we should take into account all the effects of various components on various performance indicators of mortar, and determine the economically rational, technologically advanced mortar formula by tests.