Long-term Bond Characteristics of the Interface Between Substrate and Shotcrete Overlay

Presentation

Long-term Bond Characteristics of the Interface Between Substrate and Shotcrete Overlay

Shotcrete is becoming popular for vertical and overhead applications where conventional formwork and repairs are difficult and costly. However, the substrate and the shotcrete overlay interface can be vulnerable, and the bond properties in this region are not well understood. Furthermore, the interface bond could be adversely affected by long-term freeze-thaw weathering in northern states leading to debonding from the existing substrate and corrosion of rebars. Hence, characterization of the shotcrete-substrate interface bonds is critical for the performance evaluation of shotcrete construction. To this goal, this study evaluated the shotcrete-concrete interface bond using four representative substrate surface preparation methods: chipped, pressure-washed, sandblasted, and as-cast, under three different loading conditions: tensile, shear, and Mode-II fracture. The study also investigated the long-term freeze-thaw durability of these bonds and introduced a probabilistic damage model to predict their service lives. The estimated surface texture depth and bond behavior are also correlated using laser texture scans of the substrate. Recommendations are made in terms of specifying the substrate preparation and interface bond.

Speaker

Haifang Wen, PhD, PE Associate Professor
Washington State University

Dr. Haifang Wen is currently an Associate Professor and Director of Washington Center for Asphalt Technology (AASHTO Accredited) at Department of Civil and Environmental Engineering of Washington State University and graduate coordinator of Geotechnical and Transportation Group. He teaches and researches on infrastructure materials and design. He has published more than 70 journal papers and numerous conference papers. He has made significant contribution to the utilization of sustainable infrastructure materials for construction, based on work on NCHRP, NSF, FHWA, DOTs, local governments and industry. His research on the recycled concrete was recognized as AASHTO High Value Research Projects. A few of his papers are selected as practice-ready papers “which made a contribution to current or future problems or issue for practitioners.” He is serving as an editorial board member of International Journal of Geotechnical Engineering and Geological Engineering. He is also currently serving as a member of NCHRP 01-62, ASCE Committee and FHWA’s STIC Committee. He has served on numerous TRB committees and NCHRP panels. He received Outstanding Faculty Researcher Award by the College of Engineering and Architecture of Washington State University and Outstanding Mentor Award. He is elected as a Fellow of ASCE in 2021.