Title:
Bond Strength of Reinforcing Bars in Reinforced Shotcrete
Author(s):
Virgilio A. Ghio and Paulo J. M. Monteiro
Publication:
Materials Journal
Volume:
94
Issue:
2
Appears on pages(s):
111-118
Keywords:
bond (concrete to reinforcement); repairs; rheological properties;
shotcrete;
DOI:
10.14359/291
Date:
3/1/1997
Abstract:
There is not as of yet a consensus on the quality parameters for the steel-concrete bond for shotcrete reinforced elements or whether or not shotcrete is comparable in performance to regular cast-in-place concrete. This paper presents the results of a series of laboratory experiments on the bond strength of lap-spliced (15 ft x 18 in. x 12 in.) beams cast using the wet shotcrete process; the ACI bond strength equations were used to evaluate the performance of shotcrete beams. The shotcrete beams were compared to cast-in-place concrete beams of the same dimensions, steel configuration, and approximately the same concrete compressive strength. The bond strength of beams repaired using the wet shotcrete process was also examined. The study includes the analysis of the performance of a new type of shotcrete admixture that enhances the steel-concrete bond. The test results reveal that the bond strength is slightly lower for bottom cast shotcrete, but that the top bar bond strength is increased considerably for the shotcrete beams when compared to regular cast-in-place concrete due to the reduced segregation and bleeding generated during the shotcrete process. When water-soluble polymers (Pumping Aid and Sag Resistance Additives [PASRA]) are added to shotcrete, the performance of shotcrete as compared to control shotcrete is superior due to the improved rheological behavior of concretes containing PASRA.