Additive for ground mortar, preparation method thereof and ground mortar

The invention relates to an additive for ground mortar, a preparation method of the additive and the ground mortar. The additive is mainly prepared from the following components in parts by weight: 0.1-0.3 part of hydroxypropyl methyl cellulose ether and an air entraining aid, and the addition amount of the air entraining aid is 2-8% of the weight percentage of the hydroxypropyl methyl cellulose ether; the viscosity of the hydroxypropyl methyl cellulose ether is 80,000 to 120,000 mPa.s. The preparation method of the additive comprises the following steps: stirring and mixing the components. The additive is applied to the ground mortar. According to the invention, the air entraining auxiliary agent is added into the hydroxypropyl methyl cellulose ether, and the air entraining auxiliary agent can reduce the viscosity of the hydroxypropyl methyl cellulose ether, improve the water-retaining property of the ground mortar, and significantly improve the working performance of the ground mortar. In addition, the prep