This study investigates the effect of high limestone filler (LF) content concrete on natural coarse aggregate liberation, with a focus on end-of-life recyclability. The central hypothesis is that LF modifies concrete fracture mechanisms by promoting diffuse microcracking and preferential crack propagation along the paste–aggregate interface, rather than through the aggregates themselves. Cement pastes, mortars, and concretes with and without LF, and varying porosity, were produced to assess the combined influence of filler addition, aggregate presence, and porosity on mechanical properties (compressive strength, elastic modulus, and fracture energy), and aggregate detachment. LF incorporation reduces compressive strength and peak load but significantly increases material toughness. Increasing porosity and LF insertion enhanced the natural aggregate detachment. LF concrete presented an extended fracture process zone that favors paste-aggregate separation. These findings demonstrate that, despite lower total fracture energy, LF concretes promote aggregate liberation by reducing energy dissipation through aggregate fracture. The study concludes that limestone filler not only contributes to reducing CO₂ emissions associated with cement production but also enhances concrete recyclability, supporting its use as a design strategy for circular construction. • Fracture energy (mesoscale) investigation for high-content limestone filler (LF) concretes • Porosity increase and limestone filler enhanced cementitious matrix detachment in concrete • LF concrete has an extended fracture process zone that favors paste-aggregate separation • Adapted l ch correlated with the concrete recyclability
Hentges et al. (Wed,) studied this question.