Curing effects on fracture of high-performance cement based composites with hybrid steel fibers

In this work, effects of fiber strength and curing conditions on the mechanical behaviour and fracture properties of high performance cement based composites with hybrid steel fibers were investigated. Depending on the high temperature curing conditions, concretes with hybrid steel fibers showed behaviour of enhanced toughness and ductility. Fracture energy of the matrix increased up to 96 times owing to normal strength steel fibers, while in concretes with high strength steel fibers the increase in fracture energy due to steel fibers was 168 times. Petrographic examinations indicated that a connected crack system occurred which was filled with calcium hydroxide at 200 degrees C curing condition and no indication of delayed ettringite formation was observed. Furthermore, the prefabricated elements successfully produced with these materials, such as gully tops and manhole covers used in the city infrastructure, are presented along with selected examples from several applications.