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Stress Due to Alkali-Silica Reaction in Mortars.


pdf icon 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.