Approximate proportion requirements for cement-lime mortar are shown in Table 2.2. 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.
ASTM C270 refers in turn to other ASTM specifications. Even if sand doesn’t meet grading limits, it can still pass “by use” if mortar made with it can pass the property specifications of ASTM C270.

ASTM C207: Hydrated Lime for Masonry Purposes
Type N: No oxide limits (Type NA is air-entrained)
Type S: Oxide limits (Type SA is air-entrained)
ASTM C144: Aggregate for Masonry Mortar (sand gradations)
Property requirements for cement-lime mortar from ASTM C270 are repeated in Table 2.3.