Composition of a fluid mix applicable as dummy fluid in wear testing of pumps

A composition of a fluid mix comprises water, stone aggregates and one or more binders in the form of pozzolanic additives comprising silicic fly ash, with the provision that it does not contain substantially other binding materials or substances which produce calcium hydroxide, in particular in the absence of cement or lime, both in the form of oxide and in the form of air-hardening lime or hydrated lime. This fluid mix does not harden or set over time in ambient temperature and is thus applicable as dummy fluid for testing wear in concrete pumps.