The addition of lime into the cement mortar can improve the workability and construction performance, improve the bonding strength, reduce cracking and compensate for micro-cracks. When the dosage of lime paste is small, it has little effect on the strength of mortar, but when the dosage of lime paste is great, it will significantly reduce the strength of mortar.
Although the addition of lime into the mortar can improve the workability and water retention of mortar, hardened mortar is poor in the water resistance, large in the shrinkage, decreased in the compressive strength, and easy to cause pollution to the environment in the process of production and use, so we do not advocate the use of lime to improve the workability and water retention of mortar. There have now been many kinds of water-retaining and thickening materials to improve the performance of mortar, such as the plasticizer of masonry mortar, thickening powder of mortar and cellulose ethers.