A test to determine the plasticity of concrete. A sample of wet concrete is placed in a cone-shaped container 12" high. The cone is removed by slowly pulling it upward. If the concrete flattens out into a pile only 4" high, it is said to have an 8" slump. This test is done on the job site. If more water is added to the concrete mix, the strength of the concrete decreases and the slump increases.