Title: Moisture Effect on the Durability of the Bond between FRP and Concrete
Speaker: BAOLIN WAN, PH.D.（Associate Professor，Department of Civil & Environmental Engineering，Marquette University）
Time: 10:00-11:30 AM, 18th Dec., 2015.
Venue: Room 7201, Building No. 7
Abstract:
The performance of reinforced concrete flexural members strengthened with externally bonded fiber reinforced polymer (FRP) composite materials depends on the bond between FRP and concrete. Moisture, as one of the most common environmental factors, is very important for durability of the bond between FRP and concrete. In this seminar, an experimental, numerical and analytical study of moisture effects on FRP/concrete bond durability will be presented. A modified double cantilever beam (MDCB) test was used to measure the interfacial fracture energy for the CFRP plate debonding from concrete substrate under Mode I loading to evaluate the bond deterioration after specimens were immerged in water for different periods. A simple method was developed to directly measure the FRP/concrete interface region relative humidity (IRRH). Finite-element analysis was performed to study the moisture diffusion in the FRP-adhesive-concrete system. Based on the experimental results and a moisture diffusion model, a bond mechanism based deterioration model of bond interfacial fracture energy was proposed for FRP-concrete bond joints in moist environments. Using the IRRH as the bridge, the time-dependent load-displacement curves of the MDCB specimens were obtained numerically. Finally, a cohesive zone model (CZM) of debonding along the FRP–concrete interface under peel load was analytically established by using a linear elastic separation-stress law. Based on the proposed nonlinear deterioration model, the analytical solution of the CZM was used to determine critical load vs. crack length relations (P-a curves) of MDCB specimens at different moisture exposure durations.

About the Speaker:
Dr. Baolin Wan is an Associate Professor of Structural Engineering in the Department of Civil, Construction and Environmental Engineering at Marquette University in Milwaukee, USA. He obtained his Bachelor of Engineering in Civil Engineering from Tsinghua University in 1996, Master of Science in 1999 and Ph.D. in 2002 from University of South Carolina. Dr. Wan is a Council Member of the International Institute for FRP in Construction (IIFC), and an Associate Member of Committee 440 – FRP of American Concrete Institute (ACI). He received the best paper award in the Third International Conference on FRP Composites in Civil Engineering (CICE2006). His major research interests include numerical and experimental modeling of repaired and retrofitted structures, and use of FRP in structural members.