[en] A brief description is presented of a portable radiometric instrument for measuring the density and moisture content of concrete, building elements, bulk building materials and earth. The measurement results are summarized. The instrument surface probes for density measurement consist of a ¹³⁷Cs radiation source of an activity of about 0.5 mC and of a scintillation detector separated by lead shielding screens. The surface probe for moisture measurement consists of an Am-Be neutron source having a neutron flux of the order of 10⁵ n.s^-1 and of a gel proportional neutron counter. The device is surrounded by an iron reflector. The densimeter probe with an immersion source consists of a case, a device for introducing the densimeter in the material or earth depth at a distance of 60 cm from the surface, and of a gamma scintillation detector. ²²⁶Ra or ⁶⁰Co of an activity of about 5 mC is the radiation source. (B.S.)