The slump flow test is a measure of mixture filling ability, as shown in Fig. 2.9. This test is performed similar to the conventional slump test using the standard ASTM C143-2006  slump cone. Instead of measuring the slumping distance vertically, however, the mean spread of the resulting concrete patty is measured horizontally. This number is recorded as the slump flow. The VSI is determined through rating the apparent stability of the slump flow paddy .