Comparative study of mechanical properties and heat of hydration of fine recycled aggregates and limestone fillers cement mortars

Abstract

Huge quantities of crushed concrete and construction waste demolition are produced annually
around the world, and their potential use as substitution of natural aggregates in concrete formulations has been widely studied. However, most of existing studies have mainly been dedicated to the use of recycled gravel and sand. Due to the lack of further investigations concerning the possibility of using the fine fraction of recycled aggregates smaller than 80µm, the aim of this paper is to achieve a better understanding of the impact of a partial replacement of Portland cement by those fine recycled aggregates (FRA) in terms of hydration, microstructural and mechanical properties. A comparison of performances obtained by replacing cement with limestone filler (LF) is also proposed in the present study. 

 Substitution rates of cement of 0, 10 and 20% by weight were considered. Five mixes of paste cement and mortar were prepared with a fixed ratio of water to binder of 0.5 and a normalized sand to binder ratio of 3.

The hydration kinetics by isothermal calorimetry on cement paste, showed a decrease in the heat released by addition-based mixtures compared to ordinary cement paste. Compressive strength results obtained on mortars at 7, 28 and 90 days respectively were almost similar between mixtures based on FRA or LF.