Viability of using recycled powder from CDW to produce ternary cement type LC3

Limestone calcined clay cement (LC3) is one kind of the low-carbon binder in the recent years, contributing significantly to sustainable construction practice. This paper investigated the possibility of using the recycled powder from waste concrete as a substitution for limestone in the LC3. The results show that the mixtures containing equal amount of recycled powder demonstrate comparable rheological and mechanical properties to those containing limestone. The drying shrinkage of mortar with 30 % recycled powder was higher than the reference cement mortar, but the value at 90 ages decreased 18.75 % with the combination of calcined clay. The increasing of the normalized heat evolution for LC3 mixes was resulted from the filler effects provided by finer recycled powder and its sequential hydration with calcined clay. Compared to hydrated LC3 with limestone, the hydrated ternary system with recycled powder exhibits decreased formation of hemi- and mono-carboaluminate. The findings of this paper suggest that recycled powder exhibits considerable promise as a substitute for limestone in the production of LC3 and promoting carbon capture, utilization and storage (CCUS) of cement industry.