PROPERTIES OF BUILDING MATERIALS GAINED FROM WET-PROCESSED CRUSHED CONCRETE FINES

摘要

Although a large proportion of building rubble is already being recycled, most recycling applications, e.g. in roadbed foundations, can be considered as downcycling. This study is aimed at improving the material properties of crushed concrete fines by wet treatment, using a jig for density separation. Trial runs in a pilot plant with a flow rate between 0.45 and 0.65 t/h were conducted with two different materials (A and B). The materials were separated into heavy fraction, light fraction and finest fraction. Laboratory tests and tests for building materials were carried out on the output fractions and on the input materials. Laboratory tests showed an improvement of material properties such as loss by washing and content of binder matrix as well as water absorption for both materials A and B. The tests for building materials on mortar specimens showed that strength properties of specimens containing crushed concrete fines (heavy fraction) of type A were improved by wet treatment, but not for test specimens of material type B. Strength tests on concrete showed that a replacement of natural aggregates with wet-treated concrete fines up to 50 % had little effect on compressive strength, while untreated material exhibited a clearly lower compressive strength.