New Jersey

Department of Transportation

Standard Specifications

for Road and Bridge Construction

2007

NJDOT C-4 – Slump Flow Test and Visual Stability Index Test

1. Scope. The slump flow is used to assess the horizontal free flow of self-consolidating concrete (SCC) in the absence of obstructions. The test method is based on the test method for determining the slump (AASHTO T 119). The diameter of the concrete circle is a measure for the flowability of the SCC. The visual stability index (VSI) is a visual evaluation of the segregation of the SCC during the slump flow test.
   
   
2. Apparatus. Use the following apparatus:
   
   
   1. Mold in the shape of a truncated cone with the internal dimensions 8-inch diameter at the base, 4-inch diameter at the top, and a height of 12 inches.
   2. Base plate of a stiff non-absorbing material, at least 30-inches square, marked with a circle marking the central location for the slump cone.
   3. Hand-held wood or metal float or trowel.
   4. Wheelbarrow or other container to hold at least 0.2 cubic feet of SCC.
   5. Ruler or tape measure at least 30 inches long.
   6. A scoop or suitable container for filling specimen molds with SCC. Experience has shown pails and plastic cylinder molds to be suitable containers.
   
   
3. Procedure. Perform the following steps:
   
   
   1. Sample the freshly mixed SCC according to AASHTO T 141.
   2. Observe the SCC in the wheelbarrow for segregation.
   3. Moisten the base plate and inside of slump cone.
   4. Place base plate on level stable ground. Place the inverted slump cone centrally on the base plate and hold down firmly.
   5. Fill the cone with the scoop or other suitable container in 1 lift. Do not tamp, rod, or vibrate. Strike off the SCC level with the cone with the trowel.
   6. Remove any surplus SCC from the base plate around the cone.
   7. Raise the cone vertically and allow the SCC to flow out freely.
   8. Measure the final diameter of the SCC in 2 perpendicular directions.
   9. Calculate the average of the 2 measured diameters (this is the slump flow in inches).
   10. Rate the stability of the mixture in 0.5 increments by visual examination as specified in Table C-4-1.
   
   

   Table C-4-1 – Visual Stability Index (VSI) Rating Criteria
   Rating	Criteria
   0	No evidence of segregation in slump flow patty or in the wheelbarrow.
   1	No mortar halo or aggregate pile in the slump flow patty but some slight bleed or air popping on the surface of the concrete in the wheelbarrow.
   2	A slight mortar halo (<3/8 inch) and/or aggregate pile in the slump flow patty and highly noticeable bleeding in the wheelbarrow.
   3	Clearly segregating by evidence of a large mortar halo (>3/8 inch) and/or large aggregate pile in the center of the concrete patty and a thick layer or paste on the surface of the resting concrete in the wheelbarrow.

   
   
4. Report. Report the following:
   
   
   1. Identification number.
   2. Location of concrete represented.
   3. Date and time of testing.
   4. Slump flow in inches.
   5. VSI rating.
   6. Results of any other tests on the fresh concrete.