How to choose sand for construction mortar

The aggregates in the mortar are inert materials that do not participate in chemical reactions and play the role of skeleton or filler in the mortar. The density of the mortar can be adjusted through aggregates, and the shrinkage properties of the material can be controlled. The particle size of fine aggregate used in mortar is generally less than 5mm, so it must be screened, and the maximum particle size should pass the 5mm sieve hole. Since the finer the sand, the greater its total surface area, and the more slurry that coats its surface. When the consistency of the mortar mixture is the same, the mortar prepared with fine sand requires more slurry than the mortar prepared with medium-coarse sand. Due to more water consumption, the strength of the mortar will also decrease. Therefore, the medium-coarse sand is preferred. Coarse sand is used to prepare building mortar. But it also needs to be selected according to the purpose, use part, matrix, etc. of the mortar. For example, for masonry mortar, medium sand should be used for brick masonry; coarse sand should be used for rubble masonry because the surface of the rubble is angular and rough. For brick masonry, medium sand should be used; for rubble masonry, coarse sand should be used because the surface of the rubble is angular and rough. For plastering mortar, the fineness modulus of the sand should not be less than 2.4.</p