Recycled brick fines for new alkali activated binder

The construction industry today produces huge quantities of wastes, especially during the deconstruction and demolition of buildings. Ceramics and bricks represent a significant part of this inert waste in Belgium and Northern France. The recycling of bricks is already carried out in the form of aggregates used in road embankments. But this constitutes what is called a "downcycling" operation. The investigated way is here a valorization with higher added value in alkali-activated materials through substitution of blast furnace slag (GGBFS) by brick fines with a grain size D50 = 20 µm. It is shown that brick fines can be a precursor equivalent to GGBFS and thus lead to mechanical performances equivalent to control even up to 50% substitution rate in brick fines. Under certain conditions of alkali-activated solution concentration, the addition of 30% brick fines can greatly improve workability time. But this leads to a decrease in mechanical performances, which is still in accordance with specific construction needs.