 Recycled construction and demolition waste, RCDW, can be used as an alternative to natural aggregates in concrete production leading to environmental benefits such as reduced pressure on landfills and reduced consumption of natural resources. However, the quality of RCDW is often inferior to that of natural aggregates due to its higher water absorption rate. This paper investigated the effects of RCDW quality on the physical and mechanical properties of concrete. Concrete mixtures containing varying proportions of RCDW were produced and tested for compressive strength, flexural strength, and water absorption. Results showed that RCDW can be successfully used in concrete production, but only when the quality of the RCDW is adequate. This article was authored by Teresa Pavlu, Luke Bohm, and Petra Hagek.