Title: Substrate Influence on Ultra-High-Performance Concrete Bond Strength

Author(s): W. K. Toledo, A. Alvarez, G. J. Gonzales, C. M. Newtson, and B. D. Weldon

Publication: Materials Journal

Volume: 119

Issue: 6

Appears on pages(s): 189-196

Keywords: bond strength; bridge deck; direct tension; moisture condition; overlay; repair concrete; surface preparation; surface texture; ultra-high-performance concrete

DOI: 10.14359/51736004

Date: 11/1/2022

Abstract:
This work investigated the effects of substrate surface moisture condition and texture on ultra-high-performance concrete overlay bond strength. This investigation was performed in three parts that studied extreme substrate moisture conditions, partially dried substrate moisture conditions, and surface texture. These studies investigated the effects of substrate surface moisture conditions, from dry to a surface with a thin layer of free moisture, and surface textures that provided various aggregate exposure conditions on overlay bond strength. Direct tension pull-off tests were conducted to assess overlay bond strength. Results for specimens with exposed fine aggregate surface textures showed that visibly moist substrate surfaces facilitated development of excellent bond strengths, and adequate bond was achieved for conditions with a thin layer of free moisture. For specimens with saturated surface-dry conditions, acceptable bond was achieved with a slightly exposed fine aggregate texture and increasing bond strength was observed with increasing aggregate exposure.