Title:
Practical Quality Control Test Program for High-Performance Concrete in Precast Concrete Tunnel Liners
Author(s):
S. J. DeSouza, R. D. Hooton, and J. A. Bickley
Publication:
Symposium Paper
Volume:
191
Issue:
Appears on pages(s):
99-115
Keywords:
chlorides; concretes; deicing; durability; exposure; salts; tests
DOI:
10.14359/5737
Date:
12/1/1999
Abstract:
The performance needs of the Toronto Transit Commission (TTC), for the reinforced concrete tunnel liner segments for the Toronto Sheppard Line Subway required a service life of at least 100 years. Under the contract specification for chloride diffusion, compliance with this requirement was determined by the water permeability and chloride diffusion coefficients of the concrete. The specified test procedures required up to six months for final test results, after a segment was cast. From a practical point of view, what is required is confirmation that the segments are acceptable shortly after they have been cast. An in-situ rate of absorption (sorptivity) test was modified and implemented. This paper summarizes the implementation of this simple test procedure into the QC programme to non-destructively evaluate the quality of the concrete shortly after fog curing is complete. The primary research goal of this project was to develop a service life model that utilized the initial sorptivity value as determined by the in-situ sorptivity test combined with a diffusion value established for the concrete mix. The use of service life modelling to predict performance of reinforced concrete structures exposed to chlorides is the next logical step to provide assurance of longevity for owners.