Mechanical Method for Recycling Original State Aggregate from Demolished Concrete

Abstract

The demolished concretes have ever been considered as homogeneous materials and simply crushed to produce recycled aggregates which can only be used for low strength concretes. In mechanical processes of intergrinding in combination with pre-crushing, the sieve residue in each size fraction varies with grinding time and residue-grinding time curves of most fractions have their inflection points that can be considered as termination of separation. The original state aggregates (OSA) so recycled are up to standard of grade II original coarse aggregates specified in China’s standard Pebble and Crushed Stone for Building (GB/T 14685-2001) and can be applied in moderate strength concretes with a bit higher strength than that of original concretes from which the OSA derived. In this method, the OSA can be separated furthest from cement pastes and mortars while suffering minimum damage in separation processes and can retain higher strength.