Title: Bonding of Polyester Polymer Concrete (PPC) to Ultra-High-Performance Concrete (UHPC)

Author(s): Abass Okeola and Saber Larfi

Publication: Web Session

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Date: 3/28/2022

Abstract:
Ultra-high-performance concrete (UHPC) offers superior mechanical and durability properties allowing for structural members of reduced dimensions and accelerated bridge construction. Transportation agencies are using UHPC in link slabs, girder-to-girder connections, and entirely UHPC structural members. In Delaware, latex modified concrete (LMC), polyester polymer concrete (PPC), and modified concrete type D overlays are commonly applied over UHPC components as a riding surface. The bond performance of overlays adhered to UHPC is unknown and the current literature does not address this knowledge gap. Moreover, there is also a need to verify existing bond test methods (e.g., pull-off bond test) on overlays bonded to UHPC. In this work, we investigate the sensitivity of ASTM C1583 bond pull-off test parameters, such as coring depth and overlay age to establish the most appropriate test conditions. Moreover, we evaluate the effects of UHPC surface preparation methods (specifically, diamond grinding, sandblasting, hydrodemolition, and surface retarder) on the pull-off bond strength. Preliminary experimental results show that after 7 days of PPC application on grinded UHPC, the bond strength exceeded the minimum recommended bond strength of 250 psi (AASHTO T-34, ACI 548.5R-16). The dominant failure mode shifted from cohesive failure in the PPC overlay at 14 days to cohesive failure in UHPC at 28 days. The results from this study will serve as a guide towards optimizing overlay-UHPC bond strength, thus, improving the longevity of bridges with UHPC components.