ACI mix design for fck 30 MPa (numerical)

Method: ACI 211.1, with the w/c given as 0.48.

Assumed data: maximum size 20 mm (19 mm in the ACI tables); slump 75-100 mm; non-air-entrained, entrapped air 2%; $G_{FA} = 2.65$, $G_{CA} = 2.70$, cement 3.15; dry-rodded density of CA = 1600 kg/m$^3$; FM of sand = 2.8.

Step 1: Water (ACI Table 6.3.3, 75-100 mm, 19 mm) = 205 kg/m$^3$, air = 2%.

Step 2: w/c = 0.48 (given). From the ACI w/c table (0.47 at 35 MPa, 0.54 at 30 MPa), this corresponds to an average strength of about 34 MPa, a margin of about 4 MPa over $f_{ck}$ = 30 MPa.

Step 3: Cement = $205/0.48 = 427$ kg/m$^3$.

Step 4: Coarse aggregate = $0.62 \times 1600 = 992$ kg/m$^3$ (Table 6.3.6, 19 mm, FM 2.8).

Step 5: Fine aggregate by absolute volume

$V_{FA} = 1 - 0.7280 = 0.2720$ m$^3$, $FA = 0.2720 \times 2650 = 721$ kg/m$^3$.

Answer (per m$^3$): cement 427 kg, water 205 kg, FA 721 kg, CA 992 kg; ratio 1 : 1.69 : 2.32 with w/c = 0.48 (total about 2345 kg/m$^3$). Correct for the moisture and absorption of the aggregates at site, then confirm by trial batches.