How do calculate quantity in concrete if concrete mix ratios are provided in weights? -lceted LCETED INSTITUTE FOR CIVIL ENGINEERS

## Jul 29, 2022

CONCRETE MIX DESIGN

How do calculate cement, sand and coarse aggregate quantity in concrete if concrete mix ratios are provided in weights?

Concrete contains cement, sand, aggregates (gravel), and water. Fine aggregates are another name for sand.

Mix ratios: Concrete mix ratios are provided in weights.

Find the cement, sand, and aggregate ratio of six sacks of mixed cement for 1 cubic yd of concrete. The contractor mixed 1700 lbs of sand and 2200 lbs of aggregates. Assume one sack of cement is 94 lbs.

Solution

Weight of cement = 6 × 94 = 564lbs

Weight of sand = 1700lbs

Weight of aggregates (gravel) = 2200lbs

Total = 564 + 1700 + 2200 = 4464lbs

Cement ratio = 564/4464 = 0.126

Sand ratio = 1700/4464 = 0.381

Aggregate ratio = 2200/4464 = 0.493

Make the cement ratio 1.0.

This can be done by dividing the cement ratio by 0.126.

Cement ratio = 0.126/0.126 = 1.0

Divide the sand ratio and aggregate ratio by 0.126 also.

Sand ratio = 0.381/0.126 = 3.02

Aggregate ratio = 0.493 = 0.126 = 3.91

Cement: Sand: Aggregates (by weight)

1:0 : 3:02 : 3:91