The incorporation of fine recycled concrete aggregates as a main constituent of cement

Studies on recycling of deconstruction concrete into new concretes show that it is difficult to integrate fine recycled concrete aggregates in new concrete due to the high proportion of cement paste in the fine fraction which is porous and absorbs a lot of water. A way to upgrade this fraction is to use it in ground form as a main constituent of cement. Four types of fine recycled concrete aggregates were ground and added to an ordinary Portland cement type with a substitution rate of “25% wt%” in order to form Portland cement type CEM II/B. The mechanical strengths of the mortars with these composite cements were performed at 2, 7 and 28 days. The study shows that these ground fine aggregates do not act only as fillers but also have a binding property. This is due to their carbonate content which comes either from the natural aggregates used for the manufacture of concrete or from the carbonation of portlandite released during the cement hydration.