Comparative study of nanomaterials activated recycled powders from demolition and decoration wastes as supplementary cementitious material

Abstract

Powdered particles can significantly affect the technical performance of recycled aggregates and recycled concrete. Therefore, there has been a considerable focus on the disposal and utilization of recycled powder (RP) with high value. This study applied nano-CaCO3 (NC), nano–graphene oxide (GO) and nano–SiO2 (NS) to activate RP from demolition and decoration waste (RP1 and RP2, respectively). The results indicated that the nanomaterials had an activation effect on RP, but the effect was more pronounced for RP2. In addition, NC had the best activation effect on the RP among the three nanomaterials. Comparing to cement pastes with 30% RP2, compressive strength of cement paste activated by NC, GO, and NS were increased by 43.4%, 33.3% and 23.7% at 28d, respectively. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Scanning electronic microscopy (SEM), and mercury intrusion porosity (MIP) were utilized to further explore the activation mechanism. Results presented that nanomaterial activated RP could promote hydration degree to produce more Ca(OH)2 (CH), meanwhile, the nanomaterials activated RP refine and modified the orientation index of CH. This paper implies a useful activation method for RP, which is expected to fully stimulate the potential of RP to form new kinds of supplementary cementitious material.