Use of Waste Concrete in Cement Production

Abstract

Use of waste concrete in tempered cement production was examined in this study. Waste concretes were used in limestone-tempered cement production. In tempered cement production, 5, 10, 15, 20 and 28% milled waste concrete was added instead of the limestone. As waste concrete, pressure experiments were performed on those and 15 cm cube samples were used. Compressive strength of waste concretes was 65 MPa on average. At the end of the study, six (6) types of cement were produced, one being without waste concrete addition in total. Chemical, physical and mechanical properties of waste concrete tempered and waste concrete additive free concretes were examined. 2, 7 and 28 day pressure and Flexural strengths of the produced cements were tested. In compressive strength, it was seen that the waste concrete additive-free cement reached its compressive strength values. Waste concrete addition increased the Flexural strength of the cement. Waste concrete addition slightly decreased the water need of the cement. Not a large change was observed in the setting beginning and setting end values. 20 and 28% waste concrete additions instead of limestone decreased the volume expansion value of cement. It slightly decreased its specific weight value. No big changes were observed in its chemical properties. It was concluded that waste concrete can be used instead of limestone especially in mixed cement production. Thus, waste concrete can be put in use for cement production and ecological balance can be contributed, too. However, sortation should be made well in order to use waste concrete in cement production.