3-2-1 Concrete Mix Five Gallon Bucket Conversion
Concrete mix “by mass” to “by volume
Mix 1-2-3 (Approximately) → Should obtain at least 3500 psi (comp) @ 28 degrees.
Tests were completed and showed strength of 4000 psi to
5000 psi (comp). DO NOT ADD EXTRA WATER FOR
THESE STRENGTHS UNLESS WATER SEEMS
VERY LOW!!!!*
Known
Water Density = 62.4 lb/ft3
Cement Specific Gravity ≈ 3.15
Sand Specific Gravity ≈ 2.65
Gravel Specific Gravity ≈ 2.72
Water Specific Gravity = 1.00
Cement Density ≈ 3.15×62.4 lbs/ft3 (water density) = 195.56 lb/ft3
Sand Density ≈ 2.65×62.4 lbs/ft3 (water density)
= 165.36 lb/ft3
3
Gravel Density ≈ 2.72×62.4 lbs/ft (water density) = 169.73 lb/ft3
Design by Mass for 1 cubic yard (assuming average water content of sand/gravel)
Water
334 lbs
Cement
667 lbs
Sand
1222 lbs
Gravel
1843 lbs
334 lbs
÷ 62.4 lbs/ft3water
= 5.35 ft3
× 7.48 gal./ft3
= 40.0 gal. water
∼96 lbs/bag
1222 lbs
÷ 165.36 lbs/ft3sand
= 7.39 ft3
× 7.48 gal./ft3
= 55.3 gal. sand
1843 lbs
÷ 169.73 lbs/ft3gravel
= 10.86 ft3
× 7.48 gal./ft3
= 81.2 gal. gravel
Eleven (11) 5 gal.
buckets
⇒
Seven (7) bags
⇒
⇒
⇒
Eight (8) 5 gal. buckets
∼ 7 bags cement
Sixteen point two five
(16.25) 5 gal. buckets
* The amount of water needed is dependent on how much water is in the sand & gravel.
If the sand or gravel was rained on, reduce the water. But if the sand & gravel is very
very dry (bone dry) it may need 2 to 5 more gallons per 1 cubic yard.