Abstract
In the sustainable development context, the use of demolition waste increases in the building industry. Recycled aggregates from the demolition of concrete structures are then mixed in new concrete. Furthermore, the performance evaluation of a these recycled aggregate concrete (RAC) mix is not only limited to the determination of its conventional mechanical properties. The failure risk of concrete elements in structures made from RAC needs a comprehensive analysis. For that, a study on the fracture process of RAC has been performed and compared with that of normal concrete of the same structural class. Acoustic emission technique and digital correlation method have been used to follow the cracking process. Also, a new modelling approach for the fracture behaviour of RAC at the mesoscopic scale has been developed. It has taken into account the old attached mortar surrounding recycled aggregates. Results show that RAC has a more brittle behaviour than ordinary concrete and the numerical analysis shows that cracks growth through the recycled aggregates which have brittleness behaviour.
Highlights
With the growing waste disposal crisis and depletion of natural construction materials, the use of recycled aggregate concrete (RAC) has been advocated in the past three decades
According to Poon et al [13], the loose and porous hydrates are usually found in interfacial transition zones (ITZs) of RAC whereas for normal concrete dense hydrates are observed in ITZ
A mesoscopic model has been developed to take into account the old attached mortar surrounding recycled aggregates in order to distinguish the cracks into the matrix, ITZ and aggregates
Summary
With the growing waste disposal crisis and depletion of natural construction materials, the use of recycled aggregate concrete (RAC) has been advocated in the past three decades. RAC is composed of natural aggregate, recycled aggregate, old residual mortar, old and new interfacial transition zones (ITZs), and cement mortar [7 – 9]. Since the recycled aggregate is composed of "original aggregate" and old attached mortar, the latter one is usually porous and impairs the properties of recycled aggregate [9]. Https://doi.org/10.10 51/matecconf /2019281010 17 suggested that the old attached mortar forms the weakest zone in RAC. According to Poon et al [13], the loose and porous hydrates are usually found in ITZ of RAC whereas for normal concrete dense hydrates are observed in ITZ. A mesoscopic model has been developed to take into account the old attached mortar surrounding recycled aggregates in order to distinguish the cracks into the matrix, ITZ and aggregates
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