Numerical modelling of the dehydration of waste concrete fines

Abstract

The ever-increasing interest on sustainable raw materials has urged the quest for recycled materials that can be used as a partial or total replacement of fine fractions in the production of concrete. This paper demonstrates a modelling study of recycled concrete waste fines and the possibility of turning them into active constituents for the production of concrete. When construction demolition waste (CDW) fines with particle size 0 - 4mm are exposed to a hot environment, different reactions will occur, especially dehydration and phase changes. A one- dimensional (1D) transient model is developed to predict the conversion of the hydrated concrete fines into their dehydrated state, in which the key processes inside the particle and at the boundary layer outside the particle are properly addressed. The model predicts a final composition of the particle that resembles cement clinker, which means a high potential for reuse in manufacturing concrete. Finally, model results for the mass loss during conversion are experimentally validated using thermogravimetric study.