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.
Ferraris, C. F.; Garboczi, E. J.; Davis, F. L.; Clifton,
Cement and Concrete Research, Vol. 27, No. 10,
mortars; stress (mechanics); water; cements
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.