Dimensional stability of deflection-hardening hybrid fiber reinforced concretes with coarse aggregate: Suppressing restrained shrinkage cracking

Abstract

High Performance Fiber Reinforced Concretes (HPFRCs) with deflection-hardening capability are relatively novel materials with high damage tolerance. However, mixture proportions of such materials are mostly designed with fine aggregates for easier/homogenous fiber distribution and low matrix fracture toughness which increases the amount of cementitious materials as the main binder and related risk for dimensional instability, high cost, and environmental unfriendliness. Here, with the idea of developing concrete that is free of shrinkage-related cracking at a more reasonable price, deflection-hardening HPFRC mixtures incorporating different amounts of coarse aggregates (with maximum size of 12mm) were developed with different mixture parameters (fiber types/dosages and fly ash contents) and tested for their dimensional stability by focusing mainly on the drying and restrained shrinkage measurements. Experimental results reveal that the combined effectiveness of utilizing hybrid fiber reinforcement and high amounts of coarse aggregates by properly adjusting the matrix properties without compromising high ductility (deflection-hardening behavior) can help the realization of possible producibility of HPFRC mixtures that are completely free of restrained shrinkage-related cracking. The findings of this study are believed to make a significant impact on the wide-spread usage of deflection-hardening HPFRC mixtures with similar ingredients to that of conventional concrete in actual field conditions.