Utilization of recycled concrete aggregates in structural concrete by applying a fraction partitioning model

The recycling of concrete waste into new structural concrete reduces the utilization of raw materials, decreases transport and production energy cost, and saves the use of limited landfill space. Currently, recycling involves the use of recycled concrete aggregates (RCA) as road base material or in non-structural concrete with low strength requirements. Hence, the application in structural concrete is limited. In order to improve the applicability of RCA in structural concrete, a fraction partitioning – other than the norm sand and gravel fractions (0/4mm and 4/32mm respectively) – is advised. In this initial study, the theory is tested on a mortar level, dividing norm sand into sieve fractions towards an optimal particle packing. Subsequently, the obtained fractions are used in a particle packing model to define the quantity of each size fraction to be used in mortar production. With this tool, an optimised mortar particle distribution was created and compared to a standard mortar in terms of mechanical properties.