Effect of Stress Relaxation, Self-Desiccation, and Water Absorption on the Alkali-Silica Reaction in Low Water/Cement Ratio Mortars.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899