Suitable Restrained Shrinkage Test for Fibre Reinforced Concrete: a Critical Discussion

Concrete performance traditionally refers to compressive strength and workability. Recently, high performance concrete evidenced the possibility of enhancing other material properties. Among these, resistance to shrinkage cracking is gaining more attention among practitioners, due to its strict relation to durability requirements. Shrinkage cracks occur in restrained structures: for this reason, material characterisation should be made on the basis of a restrained shrinkage test. The ring test is an easy-to-use tool since one can measure the time-to-cracking of a concrete mix. Focus of this paper is to critically discuss the actual standard test procedure and then to propose enhancements of the test set-up with the aim of reducing the time-to-cracking and making the test duration more suitable for practical uses. Furthermore, the effect of fiber reinforcement on shrinkage cracking is presented.