Ball Harp

The ball harp is used to determine the effective yield point of supporting slurries according to DIN 4127.

10 glass or steel balls from different diameters are dipped simultaneously into the slurry. At given density of the slurry, each ball is assigned to another critical effective yield point, at which it would be in suspense in the slurry.

Balls, whose critical yield point is smaller than the yield point of the slurry, swim on the slurry, those whose which is higher, immerse.

The balls are marked with continuous numbers from 1 to 10 in the sequence of their growing critical effective yield point. Thus, the effective yield point of the slurry lies between the critical yield point of the ball with the largest number which is still swimming and the critical yield point of the ball with the smallest number which is immersing in the slurry.

The critical effective yield points of a standard set of balls are declared in a table for densities between 1.02 and 1.70 g/cm³.

• Product information Ball Harp
• DIN 4127:2014-02: Earthworks and foundation engineering - Test methods for supporting fluids used in the construction of diaphragm walls and their constituent products