The consistency of concrete is a measure of its workability, which may be defined by its slump characteristics. Herewith is the slump test procedure:
1) To obtain a representative sample, take samples from three or more regular intervals throughout the discharge of the mixer truck. DO NOT take samples at the beginning or the end of the discharge.
2) Dampen inside of the cone and place it on a smooth, moist, non absorbent, level surface large enough to accommodate both slumped concrete and the slump cone. Stand on foot pieces throughout the test procedure to hold the cone firmly in place.
3) Fill cone 1/3 full by volume and rod 25 times with 5/8 inch diameter by 24 inches long bullet pointed steel rod. Distribute rodding evenly over the entire cross section of the sample.
4) Fill cone 2/3 full by volume. Rod this layer 25 times with rod penetrating into but not through first layer. Distribute rodding evenly over the entire cross section of the layer.
5) Fill cone to overflowing. Rod this layer 25 times with rod penetrating into, but not through second layer. Distribute rodding evenly over the entire cross section of this layer.
6) Remove the excess concrete from the top of the cone using tamping rod as a screed. Clean overflow from base of cone.
7) Lift cone vertically with slow, even-motion. Do not jar the concrete or tilt the cone during this process. Invert the withdrawn cone, and place next to, but not touching the slump concrete.
8) Lay a straight edge across the top of the slump cone. Measure the amount of slump from the bottom of the straight edge to the top of the slumped concrete at a point over the original center of the base. The slump operation should be completed in a maximum elapsed time of 1-1/2 minutes. Discard concrete, DO NOT use in any other tests.
9) The height of slump (reading from your measurement)/ concrete settlement determines its consistency.
