Suspended floor systems constructed from inverted precast concrete T-beams with precast concrete block infill elements are a relatively new and expanding market. Infill blocks make only a minor contribution to the high performance achieved with such floors, and thus offer a low-risk route for the introduction of recycled aggregates. This paper details the results of a project in which blocks containing recycled aggregate were produced using conventional industrial plant and successfully tested in full-scale floor tests. It should be of interest to materials specifiers and the concrete/aggregate industry - particularly the precast and block industries and recyclers of construction and demolition materials. 5 pages.