In the ASTM C143 test a 12 in tall metal cone is filled in three layers, each rodded 25 times, then lifted straight up, and the drop of the concrete is measured to the nearest 1/4 in. Slip-form paving mixes run 1.5 in or less, flatwork and walls about 4 to 5 in, and pumped or plasticized mixes higher. Slump flags load-to-load changes in water or admixture but says nothing direct about strength.
That's a six-inch slump on a four-inch spec, and the driver swears he didn't add water.
A high slump from HRWR and a high slump from added water look identical in the cone and break very differently in the lab.
Also heard as
- slump test
- cone
Do not mix it up with
- Soup: Soup is crew slang for a load with far too much slump, usually from added water.
Related terms
w/cm
Water-to-cementitious-materials ratio: the weight of mix water divided by the weight of cement plus SCMs.
Soup
Concrete so wet it runs like liquid, usually because too much water went into the truck.
HRWR
High-range water reducer, the superplasticizer that makes concrete flow without adding water.
SCC
Self-consolidating concrete, a highly fluid mix that fills forms and wraps rebar under its own weight.
Air meter
A sealed pressure vessel used at the truck to measure the air content of fresh concrete.