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Effect of Stress Relaxation, Self-Desiccation, and Water Absorption on the Alkali-Silica Reaction in Low Water/Cement Ratio Mortars.


pdf icon Effect of Stress Relaxation, Self-Desiccation, and Water Absorption on the Alkali-Silica Reaction in Low Water/Cement Ratio Mortars. (539 K)
Ferraris, C. F.; Garboczi, E. J.; Davis, F. L.; Clifton, J. R.

Cement and Concrete Research, Vol. 27, No. 10, 1553-1560, 1997.

Keywords:

mortars; stress (mechanics); water; cements

Abstract:

A device has been designed and tested for measuring the stress caused by the alkali-silica reaction (ASR) in mortars. Specimens were placed in a frame equipped with a load cell, allowing us to approximately fix the strain at zero and measure the total stress generated over time. The specimens and the frame were immersed in a 1-N NaOH solution at 50 deg C. Even without ASR, the specimens expanded due to water absorption that relieves the shrinkage caused by self-desiccation. In addition, applied stresses, as well stresses that were set up in the sample by expansion caused by ASR and/or water absorption, were subject to stress relaxation. By using companion samples having nonreactive aggregates, we were able to distinguish the stress caused by ASR from that caused by water absorption-driven expansion. The effects of stress relaxation could not be removed without further experimentation and theoretical analysis.