Testing Self-Consolidating Concrete

The primary test used in the field for SCC is slump flow, although there are other fields tests currently in use. Here is a brief description of each—more information can be found in the appropriate ASTM test method.

VIDEO: SCC – SPREADING

Self-Consolidating Concrete flows easily when the slump cone is removed. Thanks to Euclid Chemical for this video segment. — Length: 00:39

  • Slump flow—Flowability is measured with the slump flow test, which has been standardized as ASTM C 1611, "Slump Flow of Self-Consolidating Concrete." This test starts like a standard slump test, although many testing technicians will turn the cone upside down to make it easier to fill. When the cone is lifted, the SCC spreads out like pancake batter. The slump flow is measured as the diameter of the pancake. Typical SCC mixes have slump flows ranging from 18 to 30 inches.
ASTM
The J-Ring test measures the passing
ability of the SCC through a rebar cage. ASTM		 ConcreteNetwork.com
A slump flow test is often performed
with the slum cone upside down. Bill Palmer
  • J-ring—The J-Ring is a measure of the concrete's passing ability—how easily it flows through obstructions and reinforcing. The J-Ring test is standardized as ASTM C 1621, "Passing Ability of Self-Consolidating Concrete by J-Ring." The J-Ring is a cage of rebar that is set up around the slump cone. The slump flow test is run both with and without the J-Ring in place and the passing ability is the difference in slump flow. A difference greater than 2 inches indicates poor passing ability.

Transportation Research Board
The T20 test measures viscosity by timing how many seconds
it takes for the concrete to spread to 20 inches in diameter.
Transportation Research Board

  • T20 (or T50) test—This is a measure of the concrete's viscosity and is measured as the amount of time it takes for concrete in the slump flow test to reach a diameter of 20 inches (or 50 centimeters). A T20 between 2 and 5 seconds is taken as a low viscosity concrete. Recently, pads with a printed 20-inch circle have been developed to make this test easier. The T20 is specified in ASTM C 1611.
  • Visual Stability Index (VSI)—This is a purely subjective test that is also described in ASTM C 1611. The technician observes the concrete as it spreads out in the slump flow test. A number from 0 to 3 is assigned—0 for no segregation to 3 for obvious segregation and paste separation (cement, water, and fines) from the concrete matrix. A VSI of 0 or 1 indicates a stable mix, while a 2 or 3 is unstable.
  • Segregation probe—Not yet standardized, this test measures segregation by placing a thin wire ring atop the SCC and measuring how far it sinks into the concrete in two minutes. This test promises to provide a quantitative value for segregation potential.

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