Title: The Assessment Of The Residual Expansion Strain Due To Alkali-Silica Reaction In Bridge Structures

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Publication: CIA

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Date: 2/13/2011

Abstract:
This paper examines the field expansion performance of four Main Road’s bridge structures and one off shore jetty structure in relation to their residual alkali-silica expansion strain at an age of approximately 8 years onwards. These structures reside in environments from benign to very aggressive marine conditions. From very low rainfall of 500 mm/year to high rainfall zones of 2000 mm/year. The expansive response of the concrete due to alkali- silica (ASR) is related to the design concept, the chosen materials and the coexisting environment. The residual strains in the structures were measured mechanically using the Huggenberger dial gauge with studs glued at 250 mm centres. In this manner the individual transverse strain response of beams and the total response of the full bridge width were recorded. It was found that residual strains of the order of 6000 microstrain were possible indicating a total strain of approximately 12000 microstrain due to ASR expansion of the affected concrete members instead of the normal +/ 500 microstrain due to the wetting and drying of concrete members.