Increased added value reuse of construction waste in clay based building ceramics

This paper illustrates a new way to explore reuse alternatives for construction and demolition waste, seeking higher added value applications for the reclaimed waste. Additions (up to 50 wt-%) of a clean construction waste were made to a red clay brick mixture, and sintered samples (950–1150°C, 1 h) were characterised (X-ray diffraction and fluorescence, thermal analysis, firing shrinkage, water absorption and flexural strength). The results show that waste additions below ∼10 wt-% result in no significant change in bricks properties; waste additions above ∼20 wt-% and a slightly higher firing temperature enable the manufacture of higher grade building products (tiles). The waste changes roles from inert to fluxing at 10–20 wt-% owing to the change of compatibility triangles in the phase diagram. Such large usages of clean construction wastes in applications other than the usual low grade ones demonstrate the importance of selective waste collection programmes.