Title:
Fracture Characterization of Interfaces between Ultra-High-Performance Concrete and High-Performance Concrete
Author(s):
Ali Cicek
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
10/17/2021
Abstract:
The adoption of ultra-high-performance concrete (UHPC) to connect precast (high-performance concrete or HPC) bridge deck panels has resulted in improvements in constructability and structural performance of such connections. However, recent field evidence suggests that UHPC connections are susceptible to UHPC/HPC interfacial cracking under service loads. While such cracks may not compromise the structural strength of these bridges in the short-term, concerns were raised about the impacts of interfacial cracks on the serviceability and long-term durability of the connections. This work presents the development of a fracture mechanics test method to accurately characterize the cracking propensity of interfaces between the UHPC and HPC. The test is conducted by loading a bimaterial beam (consisting of UHPC and HPC) notched at the UHPC/HPC interface in a three-point bending setup (Figure 1). Closed-loop feedback was implemented to ensure stable crack growth and control the crack-opening displacement (COD) during the test. HPC substrate hygric state (dry and saturated surface dry or SSD) and surface preparation (as cast and exposed aggregate finish) were varied to evaluate the effect of substrate condition on the fracture energy and tensile strength of the interface. Tension-softening curve parameters for UHPC-HPC interfaces were generated by implementing an inverse analysis approach. The data indicate that UHPC/HPC interfaces are characterized with up to 70% reduction in fracture energy compared to neat HPC. Moreover, there was no significant difference in fracture energy and tension-softening curve parameters between ‘saturated surface dry’ and ‘dry’ interfaces.