In the construction work, lime is mainly used for masonry wall or plastering work. The lime paste is used as a water-retaining thickening material, with such advantages as good water retention and low price, effectively avoiding the poor adhesion between the mortar and the substrate or the block material resulting from the water absorption of masonry like brick, and is a traditional material. However, due to the poor water resistance of lime and instable quality of lime paste, the mortar prepared has low strength and poor adhesion, affecting the quality of masonry construction. And due to more dust in mixing lime powder, it will lead to poor working conditions at the construction site, serious environmental pollution, and is not conducive to the civilized construction.
Quick lime should slake into the lime paste or hydrated lime before use, and then according to its uses, or diluted with water into the lime milk for interior painting, or added with an appropriate amount of sand or cement and sand to prepare the lime mortar or cement-lime mixed mortar for masonry walls or finishes. But hydrated lime powder cannot be directly used for masonry mortar.
In the preparation of masonry mortar, when quick lime slakes into the lime paste, the mesh with a pore size not greater than 3mm X 3mm should be used for filtering; the curing time should not be less than 7D; the curing time of finely ground quicklime powder shall not be less than 2D. For the lime paste stored in the sedimentation tank, measures should be taken to prevent drying, freezing and pollution, etc. Do not use the dehydrated hardened lime paste. In the preparation test of mortar, the consistency of lime paste should be controlled to (120 ± 5) mm.