Mechanical and shrinkage properties of cementitious composites with synthetic–inorganic hybrid fibres

To improve the mechanical and shrinkage cracking resistance properties of cementitious composites, hybrid fibres were added to a cement-based matrix. Through four-point bending tests, shrinkage tests, early crack resistance tests and scanning electron microscopy, the bending toughness and shrinkage cracking resistance of cementitious composites containing basalt fibres (BF) and different types of synthetic fibres (polypropylene fibres (PPF), polyethylene fibres (PEF) and polyvinyl alcohol fibres) were assessed. The results showed that the bending toughness increased with an increase in synthetic fibre content. Overall, the optimum bending toughness was obtained when BF were mixed with high-modulus PEF. Notably, at a 5:5 mass ratio of BF:PPF, composites containing coarse PPF exhibited lower bending toughness than those containing fine PPF. However, the opposite was found when the BF:PPF ratio was adjusted to 3:7. The shrinkage reduction effect of BF mixed with fine PPF was better than that of other fibre combinations, exhibiting the best performance at a BF:PPF ratio of 7:3. However, the shrinkage reduction of specimens was not commensurate with the early cracking resistance, the early cracking resistance being improved when high-modulus fibres were blended.