Determine the volume of coarse aggregate (in m³), volume of fine aggregate (in m³) and cement (in kg), respectively, for preparing 1 m³ of 1:2:4 (by volume) concrete. (Assume 1 m³ of freshly mixed concrete corresponds to 1.54 m³ dry volume; take 1 m³ of cement = 1500 kg.)
Try it first: pick an option, then read the explanation.
Correct answer: D. 0.88 m³; 0.44 m³; 330 kg
How to Solve a 1:2:4 Mix Proportion
This is a nominal-mix proportioning problem. You’re asked for the quantity of each ingredient in 1 m³ of 1:2:4 concrete. Here’s the clean way to work it out.
Why 1.54? Loose dry materials bulk down once they’re mixed with water and compacted, so the dry volume is always larger than the final wet volume. We multiply the wet volume by 1.54 to get the dry volume to batch.
Step 1 — Dry volume.Dry volume = 1.54 × 1 = 1.54 m³
Step 2 — Total parts. For 1:2:4, the parts add up to 1 + 2 + 4 = 7.
Step 3 — Volume of each ingredient.Coarse aggregate = (4/7) × 1.54 = 0.88 m³Fine aggregate = (2/7) × 1.54 = 0.44 m³Cement (volume) = (1/7) × 1.54 = 0.22 m³
Step 4 — Cement volume to weight. Using 1 m³ cement = 1500 kg:Cement = 0.22 × 1500 = 330 kg
The quantities are 0.88 m³ coarse aggregate, 0.44 m³ fine aggregate, and 330 kg cement — which is option D.
Key takeaway
Keep aggregates in volume and convert only the cement to weight at the end, using its bulk density (1500 kg/m³). The dry-volume factor 1.54 is the step most people forget.