Title:
Effects of Shrinkage and Temperature in Bonded Concrete Overlays
Author(s):
Hak-Chul Shin and David A. Lange
Publication:
Materials Journal
Volume:
101
Issue:
5
Appears on pages(s):
358-364
Keywords:
bond strength; concrete; debonding; drying shrinkage; early ages of concrete; fiber-reinforced concrete; heat of hydration; overlay
DOI:
10.14359/13421
Date:
9/1/2004
Abstract:
Bonded concrete overlays are sometimes distressed by early age surface cracking and/or debonding of the interface between old and new concrete. This early age failure is mainly due to volume changes of the overlay concrete by shrinkage, thermal changes, and thermal gradients. To understand the early age behavior of bonded concrete overlays, extensive experimental measurements and numerical analysis were carried out. Laboratory overlay specimens were fabricated to measure opening displacement and debonding profiles at the interface. A finite element model was developed to assess debonding behavior due to volume changes. From the experimental measurements and numerical analysis, it was found that bonded concrete overlays with high-performance concrete (HPC) mixtures have a strong tendency toward early-age debonding. The main reason for this tendency is due to a high shrinkage gradient in the HPC mixtures and low bond strength at the interface.