Construction and demolition waste (CDW) accounts for roughly a third of all solid waste generated worldwide. While its mineral fraction is a suitable partial replacement of natural aggregate in concrete production, industry uptake remains limited. This can be explained partly by differences in how national and regional standards regulate recycled aggregate (RA) use in concrete, with permitted replacement ranging from 20% to full replacement. This article reviews and compares these replacement allowances across ten national and international standards and guidelines and examines the technical reasoning behind the differences observed.