Water-to-cementitious-materials ratio, the single number that best predicts strength and durability: 280 lb of water with 560 lb of cementitious material gives 0.50. Lower ratios leave less pore space, so specs for freeze-thaw, deicer or chloride exposure often cap it at 0.45 or 0.40. When the binder is straight portland cement it is written w/c, and water added on site counts against it, which is why inspectors log every gallon.
Ticket allows 8 gallons on site and he put in 12, so that truck is over the 0.45 w/cm now.
Site rule of thumb: each extra gallon per yard adds about an inch of slump and takes a real bite out of strength.
Also heard as
- w/c
- water-cement ratio
- water-cementitious ratio
Related terms
Mix design
The recipe for a concrete mix: the weights of cement, SCMs, water, aggregates and admixtures per cubic yard.
Soup
Concrete so wet it runs like liquid, usually because too much water went into the truck.
Compressive strength
The crushing load concrete can carry per unit area, the main property specified and tested for concrete.
SCM
Supplementary cementitious material: fly ash, slag cement or silica fume used alongside portland cement in a mix.
Slump
How far a cone-shaped sample of fresh concrete sags, the standard field measure of consistency.