Stress Due to Alkali-Silica Reaction in Mortars.
Stress Due to Alkali-Silica Reaction in Mortars.
(575 K)
Ferraris, C. F.; Clifton, J. R.; Garboczi, E. J.; Davis,
F. L.
Chapter 9;
Mechanisms of Chemical Degradation of Cement-Based
Systems. Proceedings of the Materials Research
Society's Symposium on Mechanisms of Chemical
Degradation of Cement-Based Systems. November 27-30,
1995, Boston, MA, E & FN Spon, London, England,
Scrivener, K. L.; Young, J. F., Editor(s)(s), 75-82 pp,
1997.
Keywords:
building technology; alkali-silica reaction; mortar;
stress measurements; young modulus
Abstract:
Alkali-silica reaction (ASR) causing deterioration of
mortars and concretes is due to the swelling of gel
formed by the reaction of alkali in cement-based
materials with reactive silica in aggregates, in the
presence of water. The swelling of the gel generates
tensile stresses in the specimen 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. Along with the design of the apparatus, some
preliminary results are presented. Measurements of
stresses showed a strong influence of creep on the
mechanical response of the material subjected to ASR.
The aggregate influence on the stress and expansion due
to the ASR was investigated.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899