Approximate proportion requirements for masonry-cement mortar are given in Table 2.4. The proportions given in this table are near the midpoints of the ranges of proportions required by ASTM C270. When specifying a mortar by the proportion specifications of ASTM C270, it is not necessary to specify the proportions, only the mortar type.
The most common types are single-bag mixes (the first four lines of the table). However, Types M and S masonry-cement mortar can also be made by adding Portland cement to Type N masonry cement.
Property requirements for masonry-cement mortar from ASTM C270 are repeated in Table 2.5.