Development of flexural composite properties and dry shrinkage behavior of high-performance fiber reinforced cementitious composites at early ages

The results of an experimental study on the early age development of composite properties under flexural loading condition and on the dry shrinkage behavior under free, or restrained boundary condition of High-performance fiber reinforced cementitious composites (HPFRCCs) are presented. Dry shrinkage of HPFRCCs with high cement content is found to strongly influence the early age composite properties - first cracking strength, first cracking strain, and elastic modulus. This phenomenon can be correlated with shrinkage cracking caused by a humidity gradient across the thickness of specimens. On the other hand, modulus of rupture and flexural toughness of HPFRCCs are not significantly affected by dry shrinkage. A much larger dry shrinkage of HPFRCCs, compared with ordinary concrete, was measured; nevertheless, a significant reduction of the maximum crack width is found from the restrained shrinkage test. Hence, water permeability of these HPFRCCs is expected to be sharply reduced compared with concrete, even though they have higher dry shrinkage.