a, Cementitious materials

The cementing materials used to build mortar are cement and lime.

The choice of cement is the same as that of concrete. The cement number should be 4 to 5 times of the mortar strength grade, and the cement number is too high, which will lead to insufficient water retention and poor water retention. Lime cream and hydrated lime are not only used as cementitious materials, but more important is to make the mortar have good water retention.

b, Fine aggregate

The fine aggregate is mainly natural sand, and the prepared mortar is called ordinary mortar. The clay content in sand should not exceed 5%; when the strength grade is less than M2.5, the clay content should not exceed 10%. The maximum particle size of the sand should be less than 1/4 to 1/5 of the thickness of the mortar, typically not more than 2.5 mm. As a mortar for stinging and plastering, the maximum particle size does not exceed 1.25 mm, and the thickness of the sand has a great influence on the amount of cement, workability, strength and shrinkage.