Oiled drilling wastes were heated at 105 degrees C for 24 h to remove moisture and then at 800 degrees C for 2 h to remove org. compds. to decomp. CaCO3, resp. The material was then shredded to a grain size below 0.1 mm and added (25% by mass) to Portland cement to det. the phys. and chem. parameters of the cement mortars. The hardened cement mortar was studies by X-ray diffraction anal. and found comparable to ref. mortar.