Stress Due to Alkali-Silica Reaction in Mortars.
Stress Due to Alkali-Silica Reaction in Mortars.
(619 K)
Ferraris, C. F.; Garboczi, E. J.; Davis, F. L.; Clifton,
J. R.
Materials for the New Millennium. Proceedings.
Materials Engineering Conference, 4th. Volume 2.
American Society of Civil Engineers (ASCE). November
10-14, 1996, Washington, DC, American Society of Civil
Engineers, New York, NY, Chong, K. P., Editor(s),
1379-1387 pp, 1996.
Keywords:
building technology; alkali-silica reaction; hydration;
moduli; mortar; stress (mechanics); stress relaxation
Abstract:
Alkali-silica reaction (ASR) deterioration in mortars
and concretes is often attribute to the swelling of gel
formed by the reaction of alkali hydroxides with
reactive silica in aggregates, in the presence of water.
The swelling of the gel can generate sufficient tensile
stresses resulting in expansion and cracks. Most tests
designed for ASR rely on measurements of the length
change. A new test, designed to measure the stress
generated by the swelling of the gel, has a cylindrical
mortar specimen placed in a frame under a load cell.
The force required to prevent expansion is measured over
time while the specimen and frame are immersed in a
solution of 1-N NaOH at 50 deg C. The design of the
apparatus, together with some early results, are
presented. The ASR-induced stress and expansion caused
by different aggregates was investigated. Stress
measurements showed a strong influence of stress
relaxation and self-desiccation/water absorption on the
mechanical response of the material subjected to ASR. A
preliminary study of the effect of hydration on stress
relaxation and self desiccation/water absorption was
made, using non-reactive aggregate.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899