This standard applies to earthworks and foundation engineering. It specifies the test methods for diaphragm wall clays (preferably bentonite) and for supporting fluids made from diaphragm wall clays used for construction of diaphragm walls according to DIN EN 1538 or uncased drilled piles according to DIN EN 1536. The results from the test methods are required for the verification of stability, for example for diaphragm walls according to DIN EN 4126 and for the design of diaphragm walls according to DIN EN 1536. This standard has been prepared by Working Committee NA 005-05-13 AA "Schlitzwände" ("Diaphragm walls") at the Building and Civil Engineering Standards Committee (NABau) at DIN, the German institute for standardization. It replaces DIN 4127:1986-08.